Background of the Invention
[0001] This invention relates to boxes for shipping and storing sheets of photosensitive
material, and is more particularly concerned with boxes for shipping and storing photosensitive
lithographic plates. The invention is more specifically directed to light-tight containers
made of corrugated board, in which unexposed lithographic plates can be stored, and
from which the plates can be fed automatically to a lithographic plate setter in a
hands-off lithographic printing operation.
[0002] Lithographic plates of this type are employed in a computer-to-plate system, which
includes a computer-to-plate imagesetter. Equipment of this type comprises a filmless
system, preparing press-ready plates for the printing industry, and can print from
digital files directly to lithographic plates. The finished plates are completed on
the press floor, giving the press crew complete control of just-in-time preparation
of the plates to reduce make-ready time and for shorter run lengths. Systems of this
type are employed by publishers who rely on electronic processes to create their finished
product.
[0003] The lithographic plates themselves are flat plates of aluminum, typically about 24
inches by 35 inches, and packed 50 -- 100 to a box. A fully loaded box of plates weighs
about 35 -- 70 pounds (i.e., 16 - 32 Kg). The boxes are stored and shipped flat, but
the box is tilted in use for automated withdrawal of the plates for exposure in the
plate setter.
[0004] The boxes or containers are flat and rectangular. The plate setter machine automatically
opens the box and withdraws the sheets as needed, one at a time. When finished, the
machine automatically replaces the lid, and the partly filled box or container is
removed and stored. The box has to be light-tight, and the walls of the box have to
be strong enough to support the weight of the plates, e.g., about 35 -- 70 lbs. The
boxes are shipped and stored flat, i.e., horizontal, but in use the box is pitched
at about 70 degrees so the weight of the unused lithographic plates bears on one of
the side walls. The box or container has to be made light-tight, so that stray light
does not leak into the container and expose or fog the plates.
[0005] A number of corrugated containers and containers of other materials have been proposed
for storing and shipping photographic or other light-sensitive sheets.
[0006] Mikulin U.S. Pat. No. 4,984,688 describes a packaging system for photographic film
sheets. This system involves a container with inner tray elements. The inner tray
elements are made of plastic, while the container proper is formed of corrugated board.
[0007] Laido U.S. Pat. No. 4,802,619 describes a box and lid system for storing heavy, flat
items, and these can be photographic plates or X-ray film plates. The container has
side and end walls that are folded at score lines to create a hollow wall of rectangular
section. An end flap created in the side walls folds over and fits into the hollow
space of the end walls.
[0008] Rulon U.S. Pat. No. 2,354,706 shows another box for packaging sheets of photographic
film.
[0009] In each of these containers, the corrugated or fiber material is folded at score
lines to form the container walls. This means that the material itself has to be of
limited thickness. As a result, the boxes have a limited inherent strength, and cannot
support great amounts of weight. Also in these patents, little attention has been
paid to the problem of light leakage into the container at the corners where the side
walls join the end walls. As a result of this, the plates must be wrapped and sealed
in a light barrier material. However, the automatic plate setter cannot feed from
a sealed barrier box or container, and so a container has been needed that is suitable
for storage and handling of these lithographic sheets, and which could be used with
an automatic plate setter. None of the containers described in the above-mentioned
U.S. patents are suited to this application.
[0010] Further, lithographic plates are rather sensitive to moisture, and the container
for them should prohibit moisture in the storage area from entering the container
and contaminating the plates. However, none of the prior containers has addressed
this problem.
Objects and Summary of the Invention
[0011] Accordingly, it is an object of this invention to provide a strong, light-tight container
which avoids the drawbacks of the prior art, and which is both suitable for storing
photosensitive lithographic plates and suitable for use in an automatic feed plate
setter.
[0012] It is another object of the invention to provide a durable container of simple design
and which can support the full weight of lithographic plates during shipment and storage,
and which can be tilted on one side without crushing.
[0013] It is a further object to provide a container that can be made of a durable, high
strength corrugated sheet material, in which a V-grooving technique defines the side
and end walls.
[0014] It is yet another object to provide a container that will not allow moisture to enter
into contact with the lithographic sheets or plates.
[0015] According to an object of this invention, a shipping or storage container is constructed
for use with lithographic plates or similar photosensitive sheets. The container is
formed of a heavyduty corrugated board or other sheet material of a predetermined
thickness and in which a filler is sandwiched between an inner liner and an outer
liner. A generally rectangular base panel is defined on the sheet material to form
the floor or base of the container. A first end panel is formed unitary with the base
panel at one end edge of the base panel. Similarly, there are a second end panel formed
unitary with the base panel at an opposite end edge thereof, a first side panel unitary
with said base panel at one side edge of the base panel, and a second side panel unitary
with the base panel at an opposite side edge thereof. Four respective first V-grooves
are cut in the sheet material through the inner liner and filler at the end edges
and side edges of the base panel. Each of the end panels and each of the side panels
has a series of three parallel V-grooves, i.e., second, third, and fourth V-grooves,
cut through the inner liner and the filler and extending parallel to the associated
first V-grooves. The end panels and the side panels also each have a free edge parallel
to the V-grooves. Accordingly, the first and second V-grooves define between them
an outer wall panel, the second and third V-grooves define an upper wall panel, the
third and fourth V-grooves define an interior wall panel, and said fourth V-groove
and the associated free edge define a base wall panel. Each of the V-grooves forms
a ninety-degree bend such that the end panels and side panels form respective tubular
box walls. In these box walls, the associated base wall panel extends the said interior
wall panel to the outer wall panel parallel to the upper panel and lies adjacent the
base wall. The tubular box walls meet at stepped corners so that the adjoining side
and end walls define a zig-zag junction, and obstruct light leakage through the corners
of the container. The tubular walls define a rectangular space within them, and a
fill material, such as a corrugated honeycomb, is placed within each of the rectangular
spaces. Preferably, the fill material comprises a honeycomb material having flutes
oriented perpendicular to the plane of the base panel.
[0016] In a preferred mode, the outer wall panels of the first and second end panels have
ends aligned with the side edges of the base panel, and the associated upper, interior,
and base wall panels have square ends aligned with one another and offset a predetermined
amount from the ends of the respective outer wall panels. Favorably, the predetermined
amount of offset is substantially equal to the width of the upper wall panel of the
adjoining side panel. When the end and side panels are folded on the V-grooves to
form the tubular side and end walls, this construction forms the zig-zag or stepped
corner joint, and avoids any straight line path for light leakage, Thus, this construction
provides an advantage over a standard, mitered corner. The container will also comprise
opaque tape affixed over the corners.
[0017] The container is provided with a cover formed of an upper rectangular flat sheet
member dimensioned to reach to the outer wall panels of the box walls, and a lower
rectangular sheet member attached thereto and dimensioned to reach between the interior
wall panels of the box walls. This cover also avoids any straight line path for light
leakage when the cover is taped or clamped in place.
[0018] The V-grooved corrugated container of this invention is of simple, economical construction
and is sturdy and robust enough to stack horizontally for shipping, with sufficient
wall strength to support the lithographic plates while tilted on one side within the
plate setter. The light-tight container also maintains the lithographic plates free
from exposure to stray light, without need for special foils and liners that can reduce
the post-use recyclability of the container.
[0019] The above and many other objects, features and advantages of this invention will
become apparent from the ensuing description of a preferred embodiment, which should
be read in conjunction with the accompanying Drawing.
Brief Description of the Drawing
[0020]
- Fig. 1
- is an assembly view of a container, pad, and lid according to one embodiment of the
present invention.
- Fig. 2
- is a plan view of a corrugated blank from which the container of this embodiment is
constructed.
- Fig. 3
- is an enlargement of one side wall panel of the corrugated blank of this embodiment,
taken at 3-3 of Fig. 2,
- Fig. 4
- is a cross sectional view showing the box wall construction of this embodiment, taken
at 4-4 of Fig. 1.
- Fig. 5
- shows details of a corner of the container of this embodiment.
Detailed Description of a Preferred Embodiment
[0021] With reference to the Drawing, and initially to Fig. 1, a container 10 for storing
and shipping lithographic plates is constructed of a die-cut, V-grooved and folded
sheet or blank of a corrugated paper material, or of another suitable sheet material.
Here, the container 10 has a base or floor 12, with box-construction end walls 14
and box construction side walls 16. A rectangular pad 18 of corrugated material fits
into the rectangular opening defined between the end walls 14 and between the side
walls 16 and provides a cushion for the underside of the lithographic sheets or plates.
[0022] A lid 20 is made of two parts, i.e., an upper panel 22 and a lower panel 24 that
is centrally secured, by an adhesive, to the lower side of the panel 22. The upper
panel 22 has the same dimensions as the outer dimensions of the container 10, and
the lower panel 24 is dimensioned to span the opening defined by the end walls 14
and the side walls 16.
[0023] The end walls 14 and side walls 16 meet to form stepped corners 26, i.e., non-mitered
corners, that avoid any straight line path for stray light leakage through the corners
of the container. The corners 26 are formed with at least one step, and could have
several to create a zig-zag path for stray light.
[0024] Fig. 2 shows a die-cut blank 30 of corrugated material that is used to create the
container 10. The blank 30 is V-grooved as shown to create a rectangular base panel
32 that is defined between a pair of side V-grooves 34 and a pair of end V-grooves
36. The blank 30 has opposed end wall portions 38 unitarily formed with the base panel
32 at first and second ends of the base panel and separated from it by the respective
V-grooves 36. There are also opposed side wall portions 40 formed unitarily with the
base panel 32 at first and second lateral sides thereof, and separated from it by
the respective V-grooves 34. An enlargement of the blank 30, featuring one of the
side wall portions 40, is shown in cross-section in Fig. 3.
[0025] On each of the side wall portions of the blank there is a series of parallel V-grooves
42, 44, and 46 between the associated V-groove 34 and a free edge 48, and parallel
to them. The V-grooves 34 and 42 define between them an outer side wall panel 50,
the V-grooves 42 and 44 define between them a top wall panel 52, the V-grooves 44
and 46 define between them an interior wall panel 54, and the V-groove 46 and associated
free edge 48 define between them a base wall panel 56. As also shown in Fig. 3 a filler
body 58 of a honeycomb corrugated material, and of rectangular cross section, is employed
to fill the rectangular void defined by the four wall panels 50, 52, 54, and 56.
[0026] The blank itself is made of a corrugated sheet material 60, comprising an upper liner
62, a lower liner 64 and a corrugated filler 66. The V-grooves 34, 42, 44, and 46
are cut through the upper liner 62 and the filler 66 at a forty-five degree angle,
leaving the lower liner 64 intact. The side wall portion 40 is folded at ninety-degrees
at each of the V-grooves, forming a box wall around the honeycomb filler 58, as shown
in cross section in Fig. 4.
[0027] Returning to Fig. 2, the end wall portions 38 are also provided with parallel V-grooves
142, 144, and 146 between the V-groove 36 and the associated free edge 148, to define
an outer wall portion 150, a top wall portion 152, an interior wall portion 154, and
a base wall portion 156. Here, the elements that have been described in respect to
the side wall portions 40 are identified th similar reference numbers, but raised
by 100. There is a honeycomb filler body also enclosed within the end walls 14, similar
to that of the side walls 16.
[0028] As shown in Fig. 2, the outer wall portions 150 of the end wall portions 38 have
square ends 158 that are aligned with the V-grooves 34. The remaining wall panels
152, 154, and 156 have aligned square ends 159 that are offset inwards from the ends
158 a predetermined amount, i.e., by the width of the box wall. This construction
forms the stepped corner joint to be described shortly.
[0029] To form the box construction of the side walls 16, an adhesive is applied to the
V-grooves 34, 42, 44, and 46 and to the upper liner 62 on the wall portions 50, 52,
54, and 56. Adhesive is also applied to the margin of the base panel 32 where the
base wall panel 56 is to contact it. Then, the filler body 58 is placed on the wall
portion 50, the wall portion is bent at 90 degrees at each of the V-grooves, and the
wall panels are wrapped around the filler body 58. This results in the tubular box
wall construction shown in cross section in Fig. 4. The base panel portion lies horizontal
on the margin of the base panel 32, i.e., parallel to the upper wall panel 52, with
the interior wall panel facing the inside of the container, and the outer wall panel
facing outwards. Preferably, the filler body has its flutes oriented vertically, that
is, perpendicular to the plane of the base panel 32.
[0030] The end walls 14 are similarly formed, and so the description thereof can be omitted
here.
[0031] As mentioned above, the offsets in the end walls 14 results in a non-mitered, stepped
corner construction that helps block stray light from entering the container. The
ends of the side walls 16 meet the stepped-out or offset ends of the outer wall panels
150 of the end wall panels, and the ends of the end walls 14 abut the upper liner
on the outer wall panels 50 of the side walls 16. This creates a zig-zag path 66 with
sharp turns that any stray light would have to take to reach the interior of the container
through the corner 26. In addition, an opaque tape 68 is applied over the corners,
as shown in Fig. 5, and then additional opaque tape 70 is applied along the walls
14, 16 over the corners 26. In the latter positions, a short slit is cut at the corners,
and the tape 70 is folded under the container 10 at the dash line shown in Fig, 5.
[0032] The lid 20 also provides a stepped path for blocking any light leakage when the container
is closed.
[0033] The container 10 is intended to hold about fifty to one-hundred aluminum lithographic
plates. For shipment or storage, these are supported on the pad 18 that rests on the
base 12. A container fully loaded with one hundred plates typically weighs thirty-five
to seventy pounds. Within the plate setter, the container is tilted onto one side
edge, and so the side wall 16 has to be robust enough to support the thirty-five to
seventy pounds of lithographic plates.
[0034] The V-grooved, box-wall construction of this embodiment permits the container to
be constructed out of sheet material of one-quarter inch (¼") corrugated or of even
greater thickness. The sheet material can be single wall, double wall, or triple wall
material, if desired.
[0035] For shipping and storing, the containers can be bundled twenty-five deep on a pallet
or skid, and then banded or shrink-wrapped in place on the skid.
[0036] Because the light-tight, rugged container can be constructed without foils or other
nonrecyclable materials, post-use disposal does not present a problem for the user.
[0037] Most preferably, the container is constructed not to allow moisture into the area
of the container where the plates are stored. This can be accomplished by using a
specially coated corrugated board, a moisture barrier laminated to corrugated board,
or a plastic corrugated board. Also, the container can employ an interior pre-formed
plastic tray inside the corrugated lid, and a plastic tray liner below the lithographic
sheets.
[0038] While this invention has been described in detail with reference to a preferred embodiment,
it should be recognized that the invention is not limited to that embodiment. Rather,
many modifications and variations would present themselves to persons skilled in the
art without departure from the scope and spirit of the invention, as defined in the
appended claims.
1. A shipping or storage container for photosensitive sheets, the container being formed
of a sheet material of a predetermined thickness and in which a filler is sandwiched
between an inner liner and an outer liner; comprising a generally rectangular base
panel, a first end panel unitary with the base panel at one end edge of the base panel,
a second end panel unitary with the base panel at an opposite end edge thereof, a
first side panel unitary with said base panel at one side edge of the base panel,
and a second side panel unitary with the base panel at an opposite side edge thereof,
with respective first V-grooves cut in said sheet material through the inner liner
and filler at each of said end edges and said side edges of the base panel, and with
each of said end panels and said side panels having a respective plurality of parallel
V-grooves cut therein through said inner liner and said filler extending parallel
to the associated first V-grooves, and each having a free edge parallel to said V-grooves,
such that the V-grooves and said free edge define therebetween a plurality of parallel,
successive wall panels; each said V-groove forming a ninety-degree bend such that
said end panels and side panels form respective tubular box walls; and wherein said
tubular box walls meet at stepped corners such that the adjoining side and end walls
define a zig-zag junction to obstruct light leakage through the corners of the container.
2. The container of claim 1, wherein the wall panels of each of said tubular walls define
a rectangular space therewithin; and comprising a body of a fill material within each
of the rectangular spaces.
3. The container of claim 2, wherein the body comprises a honeycomb material having flutes
oriented perpendicular to the plane of the base panel.
4. The container of claim 1, wherein each said plurality of parallel V-grooves includes
a second, a third, and a fourth V-groove, such that the first and second V-grooves
define therebetween an outer wall panel, the second and third V-grooves define therebetween
an upper wall panel, the third and fourth V-grooves define therebetween an interior
wall panel, and the fourth V-groove and the associated free edge define therebetween
a base wall panel, in which the associated base wall panel extends from the interior
wall panel to said outer wall panel parallel to said upper wall panel and lies adjacent
said base panel.
5. The container of claim 4, wherein the outer wall panels of said first and second end
panels have ends aligned with the side edges of the base panel, and the associated
upper, interior, and base wall panels have square ends aligned with one another and
offset a predetermined amount from the ends of the respective outer wall panels.
6. The container of claim 5, wherein the predetermined amount of offset is substantially
equal to the width of the upper wall panel of the adjoining side panel.
7. The container of claim 4, further comprising a cover formed of an upper rectangular
flat sheet member dimensioned to reach to the outer wall panels of the box walls,
and a lower rectangular sheet member attached thereto and dimensioned to reach between
the interior wall panels of said box walls.
8. The container of claim 1, further comprising an opaque tape affixed over said corners.