Method and apparatus for manufacturing lap desks

A lap desk includes a top member and a subplanar element having a port through which a granular material may pass and air passages formed along its perimeter. A flexible casing is attached to the subplanar element and the casing has a border covering the air passages. A flowable granular material is located within the flexible casing and the flexible casing is attached to the perimeter of the subplanar element and the top member is attached to the fabric border of the flexible casing and the subplanar element.

TECHNICAL FIELD 
The present invention relates to lap desks and more particularly to such 
desks designed to facilitate the manufacture thereof. 
BACKGROUND ART 
Portable lap desks having a pillow-like portion of flexible material filled 
with a dry flowable material secured to a hard planar writing surface are 
well known in the art. These portable lap desks provide a light weight 
portable desk surface, which may be used almost anywhere, on almost any 
surface, which desk is durable and relatively inexpensive to manufacture. 
Examples of these portable lap desks and methods for their manufacture are 
described in U.S. Pat. No. 4,052,944 entitled "Portable Shuffle Desk." 
It is well known in the art to manufacture portable lap desks by cementing 
a flexible pillow-like casing to the perimeter of a rigid sheet material 
known as the subplanar, which subplanar has a port through which a 
flowable granular material may be inserted into the flexible pillow-like 
casing. In particular, the method of the prior art provides that the 
flowable granular material is inserted into the flexible pillow-like 
casing by hand, which method is a time consuming and inefficient 
operation. 
Generally, the subplanar member has door-like portions or elements to close 
the port through which the granular material is inserted. The rigid planar 
writing surface is attached to the pillow-like structure by the hand 
application of cement to the subplanar element and to the overlapping 
edges of the pillow-like portion to assure that the pillow is attached to 
the rigid planar member about its entire perimeter. 
The method of the prior art suffers numerous disadvantages, such as the 
difficulties experienced in locating the subplanar member with respect to 
the flexible pillow casing to assure that the flowable granular material 
is easily inserted into the interior of the casing, while simultaneously 
assuring that a uniform and proper amount of excess fabric is available 
from the border of the pillow to permit the fabric to overlap the 
subplanar and be cemented to the exterior planar surface. 
Further, the method of the prior art suffers the disadvantage of requiring 
a workman to load the pillow-like casing with a flowable granular material 
by hand, which operation is time consuming and inefficient as well as 
wasteful of the granular material. In particular, when the granular 
material is expanded polystyrene beads, the workman experiences great 
difficulty in placing the material within the pillow-like structure 
without excessive spillage and other losses of the material. Generally, 
shops which employ this hand loading method are subject to the persistent 
problem of excess granular material being present on the shop floors, 
requiring the additional labor expense of removing the waste granular 
material from the shop. 
Further, the method of the prior art provides no means by which the 
peripheral pillow material may be easily retained on the surface of the 
subplanar elements while cement is applied to the fabric for attachment to 
the exterior planar surface. 
Consequently, a need exists in the art for a means for easily locating the 
subplanar element relative to the pillow-like casing to allow easy 
insertion of the flowable granular material into the pillow, and for a 
means of placing the flowable granular material within the pillow casing 
in a quick and efficient manner without the risk of spilling any of the 
material. Further, a need exists in the art for retaining the fabric 
perimeter of the pillow-like casing on the surface of the subplanar 
element so that the fabric may overlap the subplanar element and allow 
efficient application of cement to ensure that the fabric is adequately 
secured to the surface of the rigid planar writing surface. 
SUMMARY OF THE INVENTION 
The present invention contemplates an apparatus for manufacturing a lap 
desk comprising a vacuum mold having an air passage means in its interior 
surface and connected to a vacuum source, whereby air is drawn through the 
air passage means to said vacuum source. The vacuum mold is sized to 
receive a pillow-like casing, and retains the casing in a secure position 
while allowing air to pass through the casing to the vacuum source. A 
storage means retains a flowable material, and a delivery means transports 
the flowable material from the storage means to the interior of the 
pillow-like casing located in the vacuum mold. 
Further, the present invention provides a method of producing lap desks, 
comprising the steps of locating a pillow-like casing element in a vacuum 
mold having an upper edge and drawing the casing to the sides of the mold 
by the use of a vacuum; locating a subplanar element on the casing in the 
vacuum mold to form a volume between the casing element and subplanar 
element; filling the volume with a flowable granular material; folding the 
excess casing material fabric to overlap the perimeter of the subplanar 
element; applying glue to the overlapping fabric and subplanar element to 
allow a portion of the glue to pass through the overlapping fabric by the 
action of the vacuum while the remaining glue stays on the overlapping 
fabric; attaching a rigid planar element to the casing fabric by the glue 
means; and removing the lap desk construction from the vacuum mold. 
And yet further, the present invention provides a vacuum mold to receive 
the pillow-like casing elements, wherein the vacuum mold may be of 
rectangular configuration and have a plurality of air passage means, or 
holes located about its entire surface to assure that the pillow-like 
casing is drawn to contact the entire inner surface of the vacuum mold by 
the force of air passing through the air passage means. The present 
invention provides in an alternative embodiment, a vacuum mold made of a 
flexible web or netting to receive the pillow-like casing element, and 
allow the pillow-like casing element to expand to its maximum volume 
within the confines of the web so as to better receive and retain the 
flowable material. In another aspect, the flexible web vacuum mold 
contemplated by the present invention has an enlarged air passage means so 
as to more efficiently cause the pillow-like casing element to be drawn 
into the full volume of the web by air passing therethrough, and to more 
efficiently receive and retain the flowable material by the natural 
movement of air through the air passage means. Further, the present 
invention contemplates a flexible web vacuum mold wherein the webbing is 
of adjustable length to permit the volume of the flexible web to be either 
increased or decreased depending upon the degree to which the pillow-like 
casing element is desired to be filled with the flowable material. 
In accordance with a further aspect of the present invention, an improved 
lap desk, comprising a rigid planar member, a subplanar element having a 
port through which a granular material may pass and a plurality of holes 
located about its perimeter sized to allow the passage of air 
therethrough, and a pillow-like casing sized to engage the subplanar 
element is provided, where said casing has a fabric border of sufficient 
width to overlap and cover the air holes located about the perimeter of 
the subplanar element. A flowable granular material is located within said 
pillow-like casing so as to substantially fill the casing, and the 
pillow-like casing is attached to the perimeter of the subplanar element. 
A rigid planar writing surface is attached to both the fabric border of 
the pillow-like casing and the subplanar element.

DETAILED DESCRIPTION 
Referring to FIG. 9 , the apparatus of the present invention comprises a 
cabinet 20 which has dual vacuum molds 22 and 24 and a hopper 26 for 
retaining a flowable material 30. In particular, vacuum molds 22 and 24 
have interior surfaces that have holes 33 and 34, respectively, which 
holes allow the passage of air from the interior of the vacuum molds to 
vacuum manifolds, where vacuum mold 24 extends beneath surface 36 into 
vacuum manifold 40 which is connected to vacuum pump 42 by ducts 44 and 
46. Similarly, vacuum mold 22 extends into a vacuum manifold which is 
connected to vacuum pump 42 by ducts (not shown). Vacuum pump 42 is user 
controlled by an on/off switch (not shown). 
A flexible tube 50 is connected to the bottom of hopper 26 and is of 
sufficient diameter to allow the passage of flowable material 30 
therethrough by the force of gravity. At the end of tube 50 most distant 
from hopper 26 is valve structure 52, having gate 54 to control the flow 
of material 30 through tube 50. Gate 54 is slidably engaged with valve 
structure 52 to move as indicated by arrow 56, and serves to control the 
flow of material 30 from hopper 26. Valve structure 52 has handle 60 which 
is sized to be grasped by the human hand and allow the operator to lift 
valve structure 52 and the end of tube 50 from surface 36 to positions 
located over vacuum molds 22 or 24. As shown in FIG. 1, hopper 26 is 
located above cabinet 20 so that flowable material 30 may pass through 
tube 50 under the influence of gravity. It will be further understood that 
the present invention also contemplates hopper 26 located at the same 
level as is cabinet 20, where flow of material 30 may be fed into tube 50, 
or its equivalent, by means of a conveyor belt (not shown), by an air 
blower (not shown), or by any other suitable means. 
Also located on surface 36 is holder 62 adapted to receive electric glue 
gun 64 containing a heat setting glue, and powered by an electric cable 
66. Cable 66 is of sufficient length to allow glue gun 64 to reach the 
entire respective perimeters of vacuum molds 22 and 24. Electric cable 66 
is connected to an outside power source (not shown). 
Referring now to FIGS. 2 and 3, the lap desk produced by the method of the 
present invention is shown, being comprised of a rigid planar element 100, 
a flexible pillow-like casing 104, a subplanar element 102 and a 
longitudinal stop 106. In particular, subplanar element 102 has doors 110 
and 112 located proximate port 114, and a plurality of holes 116 located 
about its perimeter. It will be understood that the article produced by 
the method of the present invention also contains a sufficient amount of 
flowable material 30 to fill the volume of the pillow-like casing to the 
desired degree. 
Referring to FIG. 4a, according to the method of the present invention, 
casing 104 is placed in vacuum mold 24. It will be understood that vacuum 
mold 24 is of sufficient depth to receive casing 104 while simultaneously 
allowing the peripheral edge, or border, of the casing to extend from the 
mold. As shown, holes 34 allow air located within vacuum mold 24 to pass 
into vacuum manifold 40 to exit the manifold through duct 44. 
As shown in FIG. 4b, when vacuum pump 42 is operated, air is drawn through 
holes 34, as shown by arrows 96, drawing casing 104 to the interior 
surface of vacuum mold 24, and retaining casing 104 in this position while 
simultaneously allowing the border of the casing to extend from the vacuum 
mold. At this point, the border of the casing may be folded over the 
peripheral edge 140 of vacuum mold 24. Air drawn through holes 34 into 
vacuum manifold 40 exits the manifold through duct 44, as indicated by 
arrow 98. In alternative embodiments, vacuum molds 22 and 24 may have any 
suitable air passage means such as slits, slots, or meshes, for example, 
to allow casing 104 to be drawn and secured to the interior surfaces of 
the vacuum molds. 
While casing 104 is pressed against the interior surface of vacuum mold 24, 
and the border of the casing is extended over peripheral edge 140, 
subplanar element 102 is positioned over the vacuum mold so that its 
peripheral edge rests on peripheral edge 140 of vacuum mold 24, with the 
border of casing 104 located between peripheral edge 140 and the subplanar 
element. 
Referring now to FIG. 4c, with subplanar element 102 secured to peripheral 
edge 140 by vacuum pressure, doors 110 and 112 are opened so that valve 
structure 52 may be placed between the open doors and gate 54 is opened to 
allow flowable material 30 to pass through port 114 to fill the volume 
between casing 104 and subplanar element 102. In particular, flowable 
material 30 travels down tube 50 from hopper 26 under the force of gravity 
and tends to fill the volume between the casing and subplanar element by 
the force of the air moving through holes 34, as shown by arrows 96. When 
the volume between the casing and subplanar element is substantially 
filled with flowable material, gate 54 is closed and valve structure 52 is 
removed from the space between doors 110 and 112. Doors 110 and 112 are 
then closed. Generally, it will be understood that flowable material 30 is 
drawn into the volume between casing 104 and subplanar element 102 by the 
vacuum drawn through holes 34 in mold 24, for example, and is secured in 
casing 104 by air passing through the casing and into manifold 40, for 
example. Further, in alternative embodiments, port 114 need not have doors 
110 and 112, but may have a single door, or no door at all. It will be 
further understood that because of the natural flow of air through port 
114, any flowable material 30 which may be displaced from gate 50 onto the 
surface of subplanar element 102 is drawn back towards port 114 by the 
natural flow of air, thus avoiding any spillage or other losses of 
flowable material 30 during the filling operation. 
As shown in FIG. 4d, air is drawn through holes 116 as shown by arrow 150. 
When doors 110 and 112 are closed, the excess border of casing 104 is 
folded over onto the peripheral edge of subplanar element 102 and the 
force of air passing through holes 116 retains the border material of 
casing 104 in a position overlapping subplanar element 102. Glue 68 is 
applied to the exterior surface of casing 104, and directly to subplanar 
element 102. As shown in FIG. 4e, rigid planar element 100 is pressed 
against the glue-coated surface of subplanar element 102 and the 
glue-coated surface of the peripheral material of casing 104 to be secured 
thereto. 
Further, glue 68 is placed on the exterior surface of the peripheral 
material of casing 104, and in particular, glue 68 is placed over holes 
116, so that glue 68 is partially drawn through the fabric by vacuum 
action to contact the periphery of subplanar element 102, while the 
remainder of glue 68 remains on the outer surface of the peripheral 
material of casing 104 where originally applied. Thus, glue 68 serves to 
form an integral bond between rigid planar element 100, casing 104, and 
subplanar element 102. It is the use of a vacuum that "clamps" all of the 
elements together to allow glue 68 to be efficiently and properly applied 
thereto. When glue 68 is sufficiently set, the completed article is 
removed from vacuum mold 24. 
It will be understood that glue 68 preferably should be in a liquid or 
semiliquid state prior to solidification, so that it may be partially 
drawn through the fabric periphery of casing 104 to contact the periphery 
of subplanar element 102. As described, glue 68 is a heat setting glue, 
but in alternative embodiments glue 68 may be any water based glue, may be 
based upon any other solvent, may be a liquid or semiliquid epoxy 
formulation, or may be any other suitable glue. It will be further 
understood, however, that in alternative embodiments, attachment means 
other than glue may be employed to assemble the casing, subplanar and 
rigid planar elements, such as, for example, pressure or heat sensitive 
tape. 
The present invention also contemplates the alternative method of applying 
glue 68 t subplanar element 102, wherein glue 68 is directly applied to 
subplanar element 102 before the border material of casing 104 is folded 
over onto the peripheral edge of the subplanar elements, and subsequently, 
glue 68 is applied to the exterior surface of casing 104, and directly to 
the subplanar element. 
Referring to FIG. 5, vacuum mold 24 and surface 36 are removable from 
vacuum mold 40 and cabinet 20. As shown in FIG. 5, vacuum mold 24 and 
surface 36 are shown in an inverted position, where vacuum mold 24 
comprises sides 124, 126, 128, and 130, and bottom run 132. Holes 34 are 
seen in vacuum mold 24's sides and bottom, and holes 34 serve as an air 
passage means, allowing air to pass from the interior of vacuum mold 24 
(not shown) through the four sides and bottom, and into vacuum manifold 
40, as shwon in FIG. 1. Surface 36 contacts vacuum mold 24 at each of its 
four sides and has air seal 122 located about its periphery and sized so 
as to engage with cabinet 20 when vacuum mold and surface 36 are located 
in vacuum manifold 40, as shown in FIG. 1. Air seal 122 is made from 
rubber or any other suitable material to assure that air does not pass 
between cabinet 20 and surface 36, thus protecting the integrity of vacuum 
manifold 40, and assuring that the air within vacuum mold 24 passes into 
vacuum manifold 40 only through holes 34. 
Referring to FIG. 6, in an alternative embodiment, surface 36 has mounted 
on it a web, so that the web will project into vacuum manifold 40 when 
surface 36 is located on cabinet 20 as shown in FIG. 1. In particular, the 
web contemplated by the present invention comprises a plurality of 
flexible bands, where bands 134 cross bands 136 in a perpendicular 
fashion. As shown in FIG. 6, bands 134 and 136 pass through cleats 138 and 
are secured to cleats 138 by doubling over each respective end of bands 
134 and 130 to engage loop 142 and hook 144 material. Loop 142 and hook 
144 material is more commonly known by the tradename Velcro.RTM.. It will 
be understood that each of the bands will be attached at either end to 
cleats 138, and that by adjustment of the velcro.RTM. attachments at 
either end of each band the length between cleats 138 may be either 
increased or decreased. It will be understood that by either increasing or 
decreasing the respective lengths of bands 134 and bands 136 the amount by 
which this web protrudes into vacuum manifold 40 may be either increased 
or decreased, respectively. The web shown in FIG. 6 serves as a vacuum 
mold to receive and retain pillow-like casing 104 and its corresponding 
flowable material 30 during the above described assembly steps, and the 
web can be adjusted between assemblies to receive and retain pillow-like 
casings of either greater or smaller volume to produce lap desks having 
variable sized pillow-like portions. 
The method and apparatus of the present invention satisfy a need in the art 
for a means for easily locating a subplanar element relative to a 
pillow-like casing to allow easy insertion of a flowable granular material 
into the pillow, and the need for a means and method of placing the 
flowable granular material within the pillow casing in a quick and 
efficient manner without the risk of spilling any of the material. 
Further, the method and apparatus of the present invention satisfy the need 
in the art for retaining the fabric perimeter of a pillow-like casing on 
the surface of a subplanar element so that the fabric may overlap the 
subplanar element and allow efficient application of cement to assure that 
the fabric is adequately secured to the surface of the rigid planar 
writing surface, and to assure that the fabric and the rigid planar 
writing surface are adequately secured to the subplanar element. 
The method and apparatus of the present invention provide the novel concept 
of using a vacuum to facilitate the insertion of a flowable granular 
material into a pillow casing, and to "clamp" the perimeter of the 
pillow-like casing to a subplanar element to allow the proper application 
of a cement thereto, and the vacuum also causes the cement to partially 
migrate from the exterior surface of the fabric perimeter to contact the 
subplanar element, thus resulting in an integral attachment of the rigid 
planar element to the pillow-like casing's perimeter and to the subplanar 
element. The resulting lap desks produced by the method and apparatus of 
the present invention are of superior construction because of the integral 
attachment of the rigid planar elements, pillow-like casing, and subplanar 
elements. 
Although preferred embodiments of the invention have been described in the 
foregoing Detailed Description and illustrated in the accompanying 
Drawings, it will be understood that the invention is not limited to the 
embodiments disclosed, but is capable of numerous rearrangements, 
modifications, and substitution of parts and elements without departing 
from the spirit of the invention. The present invention is therefore 
intended to encompass such rearrangements, modifications, and substitution 
of parts and elements as fall within the scope of the invention.