SPECIFICATION

Field of the Invention

This invention relates generally to drawing and recording apparatus and particularly to such devices intended to be erasable and capable of repeated use.

Background of the Invention

One of the more entertaining amusement devices and educational apparatus available to persons practicing graphic arts and artistic activities is generally referred to as a recording or drawing device. Such devices have included many well known and well established devices such as chalkboards, erasable marker boards as well as various writing and drawing easels which support a plurality of paper sheets or the like.

U.S. Patent 4,139,965 issued to Curry, et al. sets forth a DEVICE USING COATED PAPER AND CHEMICAL REACTIVE MARKER which utilizes a paper impregnated with an indicator dye together with a chemically reactive marker. A box-like housing includes a translucent planar surface having light projected from within the box onto the rear side of the translucent surface. Means are provided for supporting the impregnated paper upon the surface. The marker pens having substances therein which are chemically reactive with the indicator dye produce visible marks upon the paper. The chemical reaction between the marker solution and the coating renders

portions of the paper translucent and thus tending to glow due to the light within the device.

U.S. Patent 4,212,393 issued to Lenkof sets forth MAGIC PICTURES in which pictures consist of printed papers having various figures outlined therein in a dark color such as black. The space within the outlines is printed with a uniform water soluble ink distribution including one or more latent water soluble coloring materials printed in a dot-like pattern. When the insoluble imprints of ink are contacted by a water bearing felt tip pen, the coloring material is released producing a colored area on the paper.

U.S. Patent 4,176,273 issued to Fujie, et al. sets forth a LIGHT AND HEAT WRITING PEN FOR PHOTOSENSITIVE MATERIAL utilized in developing photoconductive material. The pen includes an elongated cylindrical housing supporting a nib formed of a material of high thermal conductivity and pervious to light. The pen further includes a battery powered light source for illuminating the photosensitive material through the nib and a heater embedded within the nib coupled to the battery power source for elevating the nib temperature.

U.S. Patent 3,235,706 issued to Newmann, et al. sets forth a ELECTRICALLY HEATED DRAWING INSTRUMENT having an elongated generally cylindrical housing supporting an electric heating element together with a conventional lightbulb. The lightbulb and heating element are coupled to a source of conventional electric power. A flexibly mounted support member is adapted to receive a meltable marker such as a wax crayon in proximity to the heating element. The marker holder may be flexibly moved to a position in which the meltable marker or crayon is contacted by the heating element and caused to melt and flow for deposit upon a paper or other recording surface.

U.S. Patent 3,864,684 issued to Shimuzu sets forth a MULTICOLOR ELECTROTHERMIC RECORDING SHEET which comprises a support having a layer of metal compound formed thereon. The metal compound exhibits the property of being electrically reducible to a metal or lower valence metallic compound in a heat sensitive element layer. A heated stylus and power source are anticipated in the normal use of the recording sheet.

U.S. Patent 4,917,643 issued to Hippely, et al. sets forth a TOY VEHICLE WITH THERMOCHROMIC MATERIAL in which a toy vehicle is covered with a paint containing a thermochromic material. The thermochromic material within the paint produces a temperature sensitive color change property which permits the thermochromic material to alter color presented on selected portions of the toy vehicle in response to temperature variation.

While the foregoing described prior art devices are representative of various attempts to provide improved recording and drawing apparatus, there remains a continuing need in the art for evermore improved and entertaining drawings and recording devices. There remains a particularly unsatisfied need within the art for improved drawing devices which may amuse, educate and entertain children.

Summary of the Invention

Accordingly, it is a general object of the present invention to provide an improved recording or drawing device. It is a more particular object of the present invention to provide an improved recording or drawing device which readily and easily facilitates erasure and reuse. It is a still more particular object of the present invention to provide an improved recording or drawing device which adds interesting and amusing color

and other dramatic effects to the recording and drawing process.

In accordance with the present invention, there is provided a drawing device comprises: a heated pen having a pen nib; an eraser having means for cooling an erasing surface; a palette defining a drawing surface; a layer of decorative material formed on at least a portion of the drawing surface; and a layer of thermochromic material overlying at least a portion of the layer of decorative material, the thermochromic layer being generally opaque at lower temperatures and light transmissive at higher temperatures.

Brief Description of the Drawings

The features of the present invention, which are believed to be novel, are set forth with particularity in the appended claims. The invention, together with further objects and advantages thereof, may best be understood by reference to the following description taken in conjunction with the accompanying drawings, in the several figures of which like reference numerals identify like elements and in which:

Figure 1 sets forth a perspective view of a thermographic drawing device constructed in accordance with the present invention in a typical use;

Figure 2 sets forth a section view of the thermographic drawing device of Figure 1 taken along section lines 2-2 therein;

Figure 3 sets forth a section view of the recording pen portion of the present invention thermographic drawing device taken along section lines 3-3 in Figure 1; and

Figure 4 sets forth a section view of the eraser portion of the present invention thermographic drawing device taken along section lines 4-4 in Figure 1.

Description of the Preferred Embodiment

Figure 1 sets forth a perspective view of a thermographic drawing device constructed in accordance with the present invention and generally referenced by numeral 10. Drawing device 10 includes a generally planar housing 11 preferably formed of a molded plastic material or the like defining a generally rectangular palette recess 15 having a planar palette surface 20 extending thereacross. Housing 11 further defines a generally rectangular eraser recess 16 and an elongated pen recess 17. In its preferred form, housing 11 is fabricated of a single integrally molded high strength plastic material. Drawing device 10 further includes a layer of colored material 21 extending upon and generally covering palette surface 20. In accordance with an important aspect of the present invention, color layer 21 further includes a plurality of visually distinct colored areas such as colored portions 30 through 35. It will be apparent to those skilled in the art that while colored layer 21 is shown in the preferred embodiment of Figure 1 as a separate material layer covering surface 20, it may also be formed by other means such as imparting the desired color to the material from which housing 11 is _, formed. It will be equally apparent to those skilled in the art from the discussions which follow that the character and pattern of colored areas defined by color layer 21 may assume a variety of shapes and patterns and utilize a variety of colors without departing from the spirit and scope of the present invention. While the multiple colored areas utilized in color layer 21 in their preferred form comprise a variety of exciting colors and patterns, it will be equally apparent to those

skilled in the art that colored layer 21 may, under certain circumstances, be preferred to comprise a single color layer. In either event, the operative character of color layer 21 is the provision of a layer of material which is visually distinguishable from the color or other optical characteristic of thermographic layer 22. Thermographic layer 22 is supported upon color layer 21 and, in its preferred form, comprises a thermographic paint material having a light transmissive characteristic which changes in response to temperature changes. Thermographic paints of the character useful for thermographic layer 22 are well known in the art and may, for example, comprise the thermochromic paint sold by Matsui Shikiso Chemical Company, Ltd., Kyoto, Japan, under the trademark Chromic Epoxy Spray Paint. It will be apparent to those skilled in the art, however, that a variety of thermographic or thermochromic material may be utilized to form thermographic layer 22 with the essential feature being the presentation of a generally opaque characteristic or a more light transmissive characteristic depending upon the material temperature.

In either event, thermographic layer 22, in its preferred form, generally covers the entirety of color layer 21 and generally fills palette recess 15. Also, in its preferred form, thermographic layer 22 is configured to present a generally opaque characteristic at lower temperatures and a light transmissive characteristic at elevated temperatures.

A recording pen 50 includes a generally cylindrical housing 51 supporting a forwardly extending rounded nib 52 together with a generally dome-shaped end cap 53. A power switch 54 is slidably supported upon housing 51 and internal apparatus including a battery power supply (better seen in Figure 3) are supported within housing 51 and operatively coupled to nib 52 and switch 54. By

means set forth below in greater detail, the movement of switch 54 to its operative or "on" position produces a heating effect upon nib 52 and properly configures pen 50 for recording use. In accordance with the intended or anticipated play pattern of drawing device 10, a user's hand 60 holds pen 50 in a comfortable grip such that pen 50 may be moved to glide nib 52 across the surface of thermochromic layer 22 during the user's drawings or recording process.

In accordance with an important aspect of the present invention, the heating action provided by nib 52 upon the contacted area of thermographic layer 22 provides a localized heating thereof and thus causes thermographic layer 22 to assume the above-described light transmissive characteristic thereby exposing a portion of color layer 21 through the thermographic layer. In the example shown in Figure 1, nib 52 and pin 50 have been moved by user hand 60 across thermographic layer 22 to create a plurality of drawn objects 45, 46 and 47 which, for purposes of example, are configured to generally represent fanciful depictions of flowers or the like. The important characteristic of objects 45, 46 and 47 is their formation due to the localized heating of thermographic layer 22 to produce transparent or light transmissive image objects. In further accordance with the preferred embodiment of the present invention, the underlying colored elements of color layer 21 are therefore exposed and cause objects 45, 46 and 47 to assume a brightly colored appearance against the dark background of the remainder of thermographic layer 22. For example, image object 46 reveals a plurality of colored areas 36, 37 and 38 while image object 47 reveals a plurality of colored areas 39, 40 and 41 and thus appear in their preferred form as brightly colored objects.

The user is, of course, free to sketch virtually any pattern or image objects upon thermographic layer 22. At some point, it will be desirable to restore thermographic layer 22 to its previously dark background configuration over some or all of the area within recess 15. To produce this erasing action, an eraser generally referenced by numeral 70 is provided. Eraser 70 comprises a hollow housing 71 having an interior cavity 75 (better seen in Figure 4) and further defining a pad 72 and a cap 73. As is set forth and described below in greater detail in discussions accompanying Figure 4, eraser 70 is intended to receive a quantity of liquids such as water having a substantially cooler temperature than the thermographic transition temperature of thermographic layer 22. Thus, in accordance with the anticipated play pattern of the present invention, eraser 70 having a quantity of cooled liquid or the like received therein is placed in contact with the to-be- erased portion of thermographic layer 22 such that pad 72 communicates with layer 22. The cool temperature of pad 72 produced by the liquid within housing 71 absorbs heat from thermographic layer 22 causing it to cool and simultaneously causing the underlying portion of thermographic layer 22 to assume its opaque characteristic. Eraser 70 may be moved freely about the surface of thermographic layer 22 to produce the desired extent of erasure and thus restore drawing device 10 for continued use and reuse.

It will be apparent to those skilled in the art that while the preferred embodiment of the present invention thermographic drawing device utilizes a thermographic material which facilitates a clear characteristic in response to higher temperature and an opaque characteristic under lower temperature, the relationship could be reversed without departing from the spirit and scope of the present invention. In such case, pen 50 may

accommodate a cooling apparatus while eraser 70 accommodates a heating apparatus.

Figure 2 sets forth a section view of drawing device 10 taken along section lines 2-2 in Figure 1. Drawing device 10 includes a molded plastic housing 11 defining a palette recess 15 and a generally planar palette surface 20. Housing 11 further defines an elongated pen recess 17 for receiving a pen 50 shown in dashed-line representation. A plurality of elongated support ribs 27 extend beneath palette surface 20 and are integrally formed with housing 11. Support ribs 27 provide additional support for palette surface 20 to absorb the writing pressure and similar forces against palette surface 20 anticipated by a typical user. Housing 11 further defines a plurality of closed end bosses such as bosses 23 and 24 which, in their preferred form, are spaced about the periphery of palette recess 15. A palette frame 18 is configured to be received within palette recess 15 and includes a corresponding plurality of cylindrical posts such as posts 25 and 26. Posts 25 and 26 are received within bosses 23 and 24 respectively of housing 11 and cooperate therewith to secure palette frame 18 within recess 15. As mentioned above, in its preferred form, housing 11 defines a plurality of bosses such as bosses 23 and 24 spaced about the periphery of palette recess 15. Correspondingly, in its preferred form, palette frame 18 defines a corresponding plurality of cylindrical posts such as posts 25 and 26 to be received within such bosses and to cooperate therewith to secure and maintain palette frame 18 within palette recess 15.

In accordance with an important aspect of the present invention described above, a color layer 21 extends across and preferably covers palette surface 20. A thermographic material layer 22 is received upon and

supported by color layer 21 in the manner described above. In its preferred form, housing 11 including sidewall 14, palette surface 20 and support ribs 27 together with the above-mentioned bosses such as bosses 23 and 24 are formed of a single integral molded plastic unit.

Figure 3 sets forth a section view of pen 50 taken along section lines 3-3 in Figure 1. Pen 50 includes a generally cylindrical housing 51 forming a cylindrical interior battery cavity 55 extending therethrough. A domed-shaped end cap 53 is received upon and secured to housing 5 _. 1 by use of a conventional snap-fitting attachment. Housing 51 further defines an elongated slot 66 which receives a conventional switch button 54 which in turn is supported by a conventional slide switch 49 received within cavity 55. Thus, switch button 54 is slidably movable within slot 66 to operate conventional switch 49. A generally disk-shaped contact support 58 is received and supported within end cap 53. A coiled spring contact 59 is secured to and supported by contact support 58. Contact support 58 and spring contact 59 are removable from cylindrical housing 51 with the removal of end cap 53. A pair of conventional batteries 56 and 57 are received within battery cavity 55 and provide a source of electrical power for pen 50.

Housing 51 further supports a generally frusto- conical nib shroud 62 in a conventional attachment. Shroud 62 further defines an aperture 63 near the apex portion thereof. A nib 52 is received within shroud 62 and extends through aperture 63. A nib support 61 is received within shroud 62 and cavity 55 and defines a generally annular member which in turn receives and supports nib 52. An electrical contact 64 is received within nib support 61 and is maintained in electrical connection with the enclosed heating element within nib

52 (not shown) . Thus, it should be understood that nib 52 in accordance with conventional fabrication techniques supports an internal heating element which in response to the application of electrical power produces a heating action and elevates the temperature of nib 52. For example, nib 52 may support a conventional resistance heating element such as resistive wire together with appropriate insulation in accordance with conventional fabrication techniques. A retainer 65 is received within nib support 61 and properly positions contact 64 to provide electrical connection between nib 52 and battery 56. Batteries 56 and 57 are maintained in a conventional series configuration. While not shown in Figure 3, a conventional electrical connection is provided within battery cavity 55 between contacts 59 and 64 and switch 49 to complete the electrical circuit between batteries 56 and 57 and nib 52 such that switch 49 may be moved to the on position and cause nib 52 to be heated by the electrical energy within batteries 56 and 57.

In its preferred form, cylindrical housing 51, end cap 53, and nib shroud 62 are formed of molded plastic materials or the like in accordance with conventional plastic molding processes.

In operation, the user manipulates switch button 54 to close switch 49 and complete the above-mentioned conventional electrical circuit which causes the electrical energy within batteries 56 and 57 to heat nib 52 to a sufficient temperature to produce the above- described local heating of portions of thermographic layer 22 which the user touches in the drawing process shown in Figure 1. Thus, each time the user desires to undertake the drawing process shown in Figure 1, the user simply turns on switch 49 and after a brief heating interval, is able to "draw" upon drawing device 10 and produce colorful image objects in the manner described

above. Once the drawing process is terminated, switch 49 is returned to the off position interrupting the flow of electrical power to nib 52 and conserving the electrical energy within batteries 56 and 57. It will be apparent to those skilled in the art that while a heated pen such as pen 50 is shown as the preferred means for carrying forward the present invention, other heated elements may be utilized to provide the above-described drawing process upon drawing device 10 without departing from the spirit and scope of the present invention. For example, in some uses, it may be desirable to provide a heated stylus which derives its heat from a reservoir of heated water or other liquid within its interior and thereby avoids the need for batteries and so on. In addition, with the proper selection of the material for thermographic layer 22, drawing device 10 may be operated in response to the heat produced by the user's fingers or hand to provide a "finger painting" type activity.

Figure 4 sets forth a section view of eraser 70 taken along section lines 4-4 in Figure 1. As can be seen, eraser 70 includes a housing 71 defining an upwardly extending generally cylindrical neck 74 which in turn defines a cylindrical neck passage 79. Housing 71 further defines a peripheral lip 76 which in turn defines an internal groove 77 on the interior portion thereof. Eraser 70 further includes a thin walled pad member 72 which includes a generally planar lower surface 70 together with an outwardly extending lip 78. In accordance with the preferred fabrication of eraser 70, lip 78 is received within groove 77 to position surface 80 in a downwardly extending position and to complete an interior cavity 75 within the combination of housing 71 and pad 72. The attachment between lip 78 and housing 71 within groove 77 is, to a large extent, a matter of design choice and may, for example, utilize conventional sonic welding, adhesive attachment, or a precise snap-

fit. In any event, the essential quality of the assembly of pad 72 to housing 71 is the provision of a liquid- tight seal therebetween whereby cavity 75 forms a liquid- tight reservoir within eraser 70 which is completely sealed with the exception of neck passage 79. To complete the closure of eraser 70, a sealing cap 73 is received upon and securable to neck 74 by a conventional attachment such as snap-fitting or the like. In the embodiment shown in Figure 4, a conventional threaded attachment is shown between neck 74 and cap 73.

In accordance with the present invention, interior cavity 75 is partially filled with a quantity of water 81. A pair of ice cubes 82 and 83 are received within interior cavity 75 and are utilized to cool water 81. The cooling action of water 81 operates upon pad 72 to cool surface 80 to a sufficiently low temperature to reverse the heating process which the user applied to thermographic material layer 22 (seen in Figure 1) to form drawn objects 45 through 47 as described above.

Thus, eraser 70 is, in accordance with user choice, placed upon and held in contact with all or part of thermographic layer 22 to produce cooling thereof. The cooling action of eraser 70 upon the contacted areas of thermographic layer 22 reverses the thermochromic action of layer 22 and restores it to its darkened opaque characteristic producing the apparent "erasure" of image objects previously drawn upon drawing device 10.

Thus, the user is able to freely draw colorful image objects upon drawing device 10 using heated pen 50 and to erase some or all of the image objects drawn in accordance with user preference to repeatedly utilize and enjoy the present invention drawing device.

What has been shown is a novel thermographic drawing device which facilitates drawing colorful image objects upon an apparently opaque drawing surface without the use of messy markers, ink pens, or the like using a simple heated stylus and cooled eraser. The device shown is virtually free of the normal mess and other difficulties generally associated with conventional drawing apparatus. In addition, the absence of ink, markers or other chemical devices provides for a safe and easy to use drawing activity which may be readily undertaken by young children.

While particular embodiments of the invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects. Therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention.