Education and demonstration – Means for demonstrating apparatus – product – or surface... – Chalkboard or equivalent means having easily erasable surface
Reexamination Certificate
2000-03-30
2003-10-07
Banks, Derris H. (Department: 3712)
Education and demonstration
Means for demonstrating apparatus, product, or surface...
Chalkboard or equivalent means having easily erasable surface
Reexamination Certificate
active
06629847
ABSTRACT:
TECHNICAL FIELD
This invention relates to a magnetic display panel mainly applied to picture drawing b y infants and a method for manufacturing the same, and more particularly to a magnetic display panel improved in structure by integrally combining a core block and a member for sealing both sides of the core block with each other and a method for manufacturing the same.
BACKGROUND OF THE INVENTION
As a drawing board for infants, a magnetic drawing panel has been conventionally known in the art, which includes a transparent or semi-transparent drawing plate or a base plate, a plate-like face member arranged opposite to the base plate, and a honeycomb core including a number of hexagonal cells and sealedly arranged between the base plate and the plate-like face member wherein the cells each are sealedly charged therein with a plastic dispersion liquid containing magnetic particles.
In the conventional magnetic drawing panel thus constructed, a magnetic pen is contacted at a tip thereof with a drawing faceplate of the plate-like face member to act a magnetic field on the dispersion liquid, to thereby permit the magnetic particles kept sinking on a bottom of the cells to rise to the drawing faceplate of the plate-like face member, resulting in displaying a picture or a character on the drawing faceplate due to a difference in contrast between the dispersion medium and the magnetic particles. Also, movement of an erasing bar provided thereon with a magnet or the like under the base plate permits the rising magnetic particles to sink on the bottom of the cells, leading to erasure of the picture or character drawn.
Infants often take an unpredictable action. For example, they often strongly knock or hit the tip of the magnetic pen against the base plate of the magnetic drawing panel. This possibly causes the drawing faceplate to be broken or a wall of the honeycomb core to be deformed due to impact of the magnetic pen, resulting in joining between the drawing faceplate and the honeycomb core being broken.
Breakage of the drawing faceplate causes the plastic dispersion liquid encapsulated in the cells to leak out, so that infants possibly stain their clothing, drink the liquid by mistake or get it into their eyes. The plastic dispersion liquid adhering to clothing is hard to come off, to thereby render washing of the clothing highly troublesome or substantially impossible. More fearfully or troublesomely, drinking of the liquid by infants by mistake possibly causes the infants to damage their stomach and intestines, because the dispersion liquid contains magnetic particles made of metal. Likewise, getting of the liquid into infants' eyes possibly leads to damages to a surface of the eyes due to infants' unintentional rubbing of the eyes. Further, breakage of the drawing faceplate tends to cause a broken portion thereof to be acute, so that the broken portion of the drawing faceplate may possibly damage parts of the body such as the hands, arms or the like. In addition, the magnetic display panel is substantially applied to infants. Thus, the magnetic display panel is required to exhibit satisfactory safety to the internal organs and body of the infants.
Also, deformation of a part of the drawing faceplate due to the above-described impact of the magnetic pen often leads to breakage of a joint between the drawing faceplate made of a relatively rigid vinyl chloride material and the honeycomb core, resulting in the adjacent cells communicating with each other through the broken joint. This will be more detailedly described with reference to
FIGS. 12A and 12B
. When a drawing faceplate
22
is deformed, to thereby be formed with a deformation, cells
20
adjacent to each other are caused to communicate with each other through a joint therebetween positioned at the deformation, so that a plastic dispersion liquid
21
in the cells
20
flows between the cells through the joint. Meanwhile, charging of the plastic dispersion liquid
21
into a honeycomb core causes air to be introduced into the liquid
21
, resulting in the air forming bubbles in the liquid. Stirring of the plastic dispersion liquid
21
permits bubbles of a large size to burst, to thereby be discharged to an ambient atmosphere. However, microsized bubbles
25
are taken in the plastic dispersion liquid
21
in spite of the stirring, resulting in remaining in the liquid, because the plastic dispersion liquid
21
exhibits properties like an emulsion. When the magnetic display panel thus constructed is operated to slide a magnetic pen on the adjacent cells
20
while a partition
23
between both cells
20
is kept broken, a pressure in the cells
20
is varied when a pressure of the magnetic pen is applied to the cells. Also, forced movement of the magnetic drawing panel causes the plastic dispersion liquid in each of both cells
20
to flow therebetween. Thus, the micro-sized bubbles
25
present in the plastic dispersion liquid
21
of both cells
20
are caused to collide with each other during flowing of the liquid, to thereby be gradually increased in size. Such growth or increase in size of the bubbles causes the bubbles to rise in the plastic dispersion liquid
21
, resulting in the bubbles being adhered to a rear side of the drawing faceplate
22
. Such situation fails to permits the magnetic particles
23
to rise to the rear surface of the drawing faceplate
22
even when it is attempted to rub the drawing faceplate
23
with the magnetic pen to carry out rising of the magnetic particles, because the thus-growing bubbles
25
interfere with rising of the magnetic particles in the plastic dispersion liquid
21
. This renders external observation of the magnetic particles through the drawing face plate
22
impossible or highly difficult, resulting in lines drawn on the drawing faceplate
22
being highly indistinct.
Further, in the conventional magnetic drawing panel, the base plate, drawing faceplate and honeycomb core each are made of vinyl chloride. This causes the magnetic drawing panel to readily generate static electricity. In particular, in the winter in which air is dried, static electricity is readily charged on the magnetic drawing panel. Charging of static electricity on the magnetic drawing panel causes the magnetic particles to be attracted onto the base plate and drawing faceplate to a degree sufficient to interfere with smooth flowing of the magnetic particles by magnetic force of the magnetic pen, leading to a variation in brightness or contrast of a line drawn on the drawing faceplate or a failure in drawing of a line thereon. Thus, in the conventional magnetic drawing panel, it is required to move an erasing bar throughout the magnetic drawing panel to facilitate flowing of the magnetic particles prior to operation of the magnetic drawing panel. Unfortunately, this renders handling of the magnetic drawing panel troublesome.
In addition, formation of vinyl chloride into the honeycomb core causes an end surface of each of the cells to be relatively thick. Thus, when any external light is reflected by the end surfaces of the cells, a configuration of the honeycomb is caused to be projected on the drawing faceplate. This reduces an effective area of the drawing faceplate and often deteriorates free drawing.
Furthermore, the magnetic display panel made of vinyl chloride generates toxic dioxin when it is incinerated at a low temperature for disposal. Dioxin is considered to have any relationship to a so-called environmental hormone although it is not sure because of being under investigation. In particular, the magnetic display panel is applied to infants, therefore, it is required not only to be fully safe by itself but not to damage to the human body when it is subject to disposal. Thus, it is highly demanded to develop a means of safely disposing of the magnetic drawing panel.
In the conventional magnetic display panel, encapsulation of the plastic dispersion liquid containing the magnetic particles in the cells of the honeycomb core is carried out by adhering open end surfaces of the hon
Banks Derris H.
Fernstrom Kurt
Takara Co. Ltd.
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