U.S. patent application number 10/405667 was filed with the patent office on 2004-10-07 for packing of thin glass sheets.
Invention is credited to Hayashi, Takayoshi, Okamoto, Fumio.
Application Number | 20040195142 10/405667 |
Document ID | / |
Family ID | 33097147 |
Filed Date | 2004-10-07 |
United States Patent
Application |
20040195142 |
Kind Code |
A1 |
Hayashi, Takayoshi ; et
al. |
October 7, 2004 |
Packing of thin glass sheets
Abstract
Articles and methods for packing thin glass sheets are
disclosed. The articles and methods include placing the glass
sheets in a container at an angle with respect to the container
wall. Spacers contact the glass sheets on the periphery of the
sheets.
Inventors: |
Hayashi, Takayoshi; (Tokyo,
JP) ; Okamoto, Fumio; (Kamakura, JP) |
Correspondence
Address: |
CORNING INCORPORATED
SP-TI-3-1
CORNING
NY
14831
|
Family ID: |
33097147 |
Appl. No.: |
10/405667 |
Filed: |
April 1, 2003 |
Current U.S.
Class: |
206/545 |
Current CPC
Class: |
B65D 85/48 20130101;
B65D 57/006 20200501 |
Class at
Publication: |
206/545 |
International
Class: |
A45C 011/20 |
Claims
What is claimed is:
1. A package for thin glass sheets comprising: at least one
substantially vertical wall and a substantially horizontal floor; a
main support member tilted at an angle with respect to the wall;
and a plurality of spacers adapted to separate the glass sheets by
contacting the sheets on the peripheral edges of the sheets, each
spacer supporting at least one glass sheet at four corners of the
sheet.
2. The package of claim 1, wherein the glass sheets are liquid
crystal display substrates.
3. The package of claim 2, wherein the glass sheets have a
thickness less than about 0.8 mm.
4. The package of claim 3, wherein the glass sheets have a
thickness less than equal to about 0.5 mm.
5. The package of claim 1, wherein the angle between the wall and a
portion of the main support member is greater than about 5
degrees.
6. The package of claim 1, wherein the angle between the wall and a
portion of the main support member is greater than or equal to
about 20 degrees.
7. The package of claim 1, wherein the angle between the wall and a
portion of the main support member is between about 15 degrees and
30 degrees.
8. The package of claim 1, wherein spacer has a thickness less than
about 5 mm.
9. The package of claim 8, wherein the spacer is in the shape of a
flexible frame that contacts the glass sheets only on the
peripheral edges of the sheets.
10. The package of claim 9, wherein the spacer includes a main
frame made from acrylic material and an auxiliary cushion material
associated with the main frame.
11. The package of claim 1, wherein the main support member is
L-shaped including an upper portion for supporting a major surface
of the glass sheets and a lower portion for supporting the edges of
the glass sheets.
12. The package of claim 12, wherein the upper portion of the main
support member is curved.
13. A method of packaging thin glass sheets comprising: providing a
container having a substantially vertical wall and a substantially
horizontal floor; disposing a portion of the main support member in
the container at an angle with respect to the wall; separating the
glass sheets with a frame-shaped spacer; and placing the glass
sheets in the container so that the glass sheets rest on the main
support member in a spaced apart relation and each spacer supports
at least one glass sheet at four corners of the sheet.
14. The method of claim 13, further comprising placing spacers
between the glass sheets, wherein the spacers contact only the
periphery of the glass sheets.
15. The method of claim 13, wherein the glass sheets have a
thickness of less than about 0.8 mm.
16. The method of claim 15, wherein the angle between a portion of
the main support member and the wall is less than about 30 degrees
and greater than about 5 degrees.
17. The method of claim 15, wherein the angle between a portion of
the main support member and the wall is less than about 20 degrees
and greater than about 5 degrees.
18. The method of claim 15, wherein the angle between a portion of
the main support member and the wall is between about 15 degrees
and 30 degrees.
19. The method of claim 14, wherein the spacer includes a flexible
acrylic frame and a cushioning element associated with the
frame.
20. The method of claim 19, wherein the frame has a width of
between about 10 mm and 20 mm.
21. The method of claim 14, wherein the main support member is
L-shaped having an upper portion for supporting the major surface
of the sheets and a lower portion for supporting the edges of the
sheets.
22. The method of claim 13, wherein during the step of placing the
sheets in the container the container is placed on a horizontal
surface and the container is tilted such that the angle of the
sheets with respect to the horizontal surface is decreased.
23. The method of claim 22, further including securing the glass
sheets between a secondary support member and the main support
member so that the glass sheets are sandwiched between both support
members and securing a lid on the container.
Description
FIELD OF THE INVENTION
[0001] This invention relates to packing of thin glass sheets, and
in particular, liquid crystal display glass substrates.
BACKGROUND OF THE INVENTION
[0002] Large, thin glass sheets, such as liquid crystal display
(LCD) substrates are flexible. LCD substrates typically are one
square meter in area and have a thickness of less than 0.8 mm. The
drive towards larger and lighter LCD substrates has resulted in LCD
substrates that exceed one square meter in area and have a
thickness less than 0.7 mm, and in some cases, less than or equal
to 0.5 mm. At present, LCD substrates are typically packed
vertically in a box made from foamed plastic. The peripheral edges
of each substrate are held in the vertical grooves on the sidewall
of the box. As the length and width of thin glass sheets such as
LCD sheets increase and the thickness decreases, the substrate
becomes more flexible, and the glass spacing in the box must be
increased to avoid glass damage and breakage by mutual contact due
to excess vibration during transportation. In view of these
limitations, improved methods and articles for packing thin glass
sheets for storage and shipping that provide sufficient packing
density and prevent breakage are needed.
SUMMARY
[0003] Certain embodiments of the invention relate to methods and
articles for packing thin glass sheets in a container having at
least one wall. The glass sheets are placed in the container at an
angle with respect to the wall of the container. The sheets rest
against a main support member, and spacers keep the sheets in a
spaced apart relationship. In certain embodiments, each spacer
supports four corners of the glass sheets, and in one particular
embodiment, the spacer is frame-shaped. In certain embodiments, the
container is tilted during loading and unloading of the container
so that the tilt angle of the glass sheets during loading and
unloading is reduced. It is to be understood that both the
foregoing general description and the following detailed
description are exemplary and are intended to provide further
explanation of the invention as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] FIG. 1 is a perspective view of a spacer used according to
some embodiments of the invention;
[0005] FIG. 2 is a side view of a stack of glass sheets spaced
apart by the spacers shown in FIG. 1;
[0006] FIG. 3 is a side view of glass sheets packed in a container
according to one embodiment; and
[0007] FIGS. 4a and 4b are side views of glass sheets packed in
containers according to alternative embodiments.
DETAILED DESCRIPTION
[0008] Before describing several exemplary embodiments of the
invention, it is to be understood that the invention is not limited
to the details of construction or process steps set forth in the
following description. The invention is capable of other
embodiments and of being practiced or carried out in various
ways.
[0009] One embodiment of the invention relates to a spacer for thin
glass sheets, and in particular LCD glass sheets. Referring to
FIGS. 1 and 2, a spacer 10 is shown that includes a main
frame-shaped member 12 and a cushion 14 on the surfaces of the
member in contact with the glass. The spacer 14 according to the
present invention supports the glass sheets at four corners.
Supporting the glass sheets at four corners while tilting the glass
sheets induces sufficient stiffness in the glass sheets to prevent
the sheets from sagging or breaking during transportation of the
package. In the embodiment shown in FIG. 1, the cushion 14 is a
continuous piece that extends around the entire periphery of the
main frame-shaped 12 member. However, according to certain
embodiments, the cushion can be placed in discrete and separate
sections on the periphery of the frame-shaped member. One example
of a suitable frame for a sheet of glass having dimensions of 985
mm.times.1300 mm.times.0.7 mm is a frame-shaped member made from an
acrylic material. The frame shaped member has a thickness "t" of
about 4 mm and a frame width "w" of between about 10 mm and 50 mm,
and more preferably between about 10 mm and 20 mm. The overall
width and length dimensions of the frame-shaped member are selected
to be approximately the same as the dimensions of the glass sheet.
The frame width "w" is selected so that the cushion 14 contacts
only a peripheral portion of the glass sheet that is intended to be
discarded. In one particularly preferred embodiment, the frame
shaped member 12 has at least one end 15 in which the frame has a
width "w" that is less than the width of the other three ends of
the frame-shaped member. For example, in one embodiment, the end 15
of frame shaped member may have a width "w" that is approximately
the same as the width of the cushion material. In preferred
embodiments, end 15 of the frame-shaped member 12 supports the
glass sheets at the bottom of the container as shown in FIG. 2. The
cushion material, according to one embodiment, includes a rubber
tape having a thickness of between about 0.2 mm and 2 mm, and
preferably about 0.5 mm or less. Any soft material can be used for
the cushion material, including, but not limited to rubber tape,
plastic tape, and foamed plastic tape such as foamed polyethylene
tape. In certain embodiments, a sufficiently rigid material that
also provides cushioning for the glass sheets so that the
frame-shaped member provides both support and cushioning for the
sheets. In other words, a single frame shaped member having
cushioning properties and sufficient rigidity to support the glass
sheets in the container at an angle can be used without a separate
cushioning material placed on the frame-shaped member. Utilizing a
frame and cushion of these dimensions, the spacing between each
glass sheet is between about 2 mm and 10 mm, and preferably between
about 3 mm and 4 mm. The spacer 10 should be made from a material
that has sufficient stiffness and strength to support a stack of
glass sheets. Suitable materials, include, but are not limited to,
acrylic resin, polyvinyl chloride resin and foamed plastics. FIG. 2
shows a plurality of glass sheets 16 stacked using a plurality of
spacers shown in FIG. 1.
[0010] A thinner spacer element is desirable to achieve a higher
packing density of glass sheets, but the spacer should be thick
enough so that adjacent glass sheets do not contact each other
during transportation of the shipping container holding the glass
sheets. Accordingly, spacer thickness will depend on the size and
thickness of the glass sheet and stacking parameters discussed in
more detail below. The spacer should have sufficient rigidity to
maintain the shape of the spacer when the spacer is stacked
vertically in a container.
[0011] Referring now to FIG. 3, a container 20 for shipping thin
glass sheets 21 is shown. The container 20 includes at least one
substantially vertical wall 22, a floor 24 and a cover 26. The
container 20 should be made from a material having enough
mechanical strength to hold the packaged glass sheets. As used
herein, substantially vertically means the wall 22 is generally
perpendicular to the floor 24 of the container 20. A main support
member 28 tilted at an angle "a" with respect one of the walls 22
is placed in the container. The main support member 28 preferably
is L-shaped and includes an upper portion 29 and a lower portion
30. The upper portion 29 rests against the wall 22 of the container
20. The main support member 28 should provide sufficient mechanical
strength to hold the glass sheets and spacers in place, and meet
cleanliness requirements of packaged LCD glass sheets. According to
one embodiment, the main support member 28 is made from acrylic
plates reinforced with a steel frame. In preferred embodiments, the
container 20 holds between about 20 and 100 glass sheets and the
required number of spacers. An optional backing board (not shown)
may be placed between the upper portion and the first sheet of
glass that leans against the main support member 28.
[0012] Although the upper portion 29 of the main support member 28
is shown as straight, the upper portion may be curved, as shown in
FIGS. 4a-4b. In FIG. 4a, similar components are designated with
reference numerals and a followed by ', and in FIG. 4b, similar
components are designated with reference numerals followed by ". As
shown in FIG. 4a, a main support member 28' includes a curved upper
portion 29' that allows a higher packing density of sheets to be
packed in the container 20'. In an alternative embodiment shown in
FIG. 4b, the main support member 28" may be straight and a curved
backing board 31 may be used to allow a higher packing density of
sheets in the container 20".
[0013] Referring again to FIG. 3, the major surfaces of the glass
sheets 21 rest upon the upper portion of the main support member
28, and the edges of the glass sheets 21 are supported by the lower
portion 30 of the main support member 28. Spacers 10 maintain the
glass sheets 21 in a spaced apart relation and contact the glass
sheets only on the outer periphery of the sheets. The stack of
glass sheets 21 may be secured by a secondary support member 32
which encloses the stack of sheets in the container 20. The main
support member 28 and the secondary support member 32 when secured
together form an inner package that is placed in the container
20.
[0014] According to certain embodiments of the present invention, a
method is provided in which glass sheets and frame-shaped spacers
are stacked alternately and leaned against a support member
disposed at an angle "a" to a substantially vertical wall of the
container. By packing the glass sheets in this manner, each glass
sheet is supported along four edges, and the unsupported central
area of the sheet sags by gravity. The amount of sag is controlled
by adjusting the tilt angle. An optimal level of sag can be
imparted to the glass sheets so that the sheets are strained by
elastic deformation and thus stiffened. When an optimal tilt angle
is selected, the glass sheets become stable against external forces
such as vibration and shaking during transportation. The glass
sheets are arranged in the container such that adjacent sheets are
not in contact. Referring again to FIG. 3, according to one
preferred embodiment, during loading and unloading of the glass
sheets, the container 20 is tilted at an angle "b" with respect to
the surface upon which the container rests, so that the tilt angle
of the glass sheets is decreased with respect to the surface upon
which the container rests during the loading and unloading steps.
Typically, the surface upon which the container rests is a
horizontal surface, and tilting of the box in this manner
facilitates loading and unloading of the sheets because the sheets
can be loaded in the container in a substantially vertical
orientation with respect to the lower portion of the main support
member. In preferred embodiments, during transportation and storage
of the container, the angle "b" of the container with respect to
the surface upon which the container rests is reduced so that the
bottom surface of the box lies flat on the supporting surface.
[0015] A test was conducted to determine the optimum tilt angle and
spacing of glass sheets in a container. Glass sheets having a
thickness of about 0.7 mm and dimensions of about 985 mm.times.1300
mm were loaded in a support member of the type shown in FIG. 3 with
acrylic frame shaped spacers 3 mm thick in contact with the
periphery of the sheet. The spacer also included 0.5 mm of cushion
(rubber tape) around the frame-shaped spacer, providing a total
thickness of about 4 mm. Five glass sheets and six spacers were
placed in a container, and no secondary support member was placed
in the container. The amount of sag was measured at the center of
the glass sheet using either calipers or a laser distance meter.
The sag values at various angles are reported in Table I.
[0016] A secondary support was placed in the container as shown in
FIG. 3, and the secondary support member and support member were
tied together firmly. The stack of glass sheets tied between the
support members was shaken back and forth in the direction shown by
arrow 40 in FIG. 3. Glass stiffness was observed at different tilt
angles, and the observations are reported in Table I. As indicated
in Table I, the glass sheets become sufficiently stiff when the
angle "a" between the upper portion of the main support member and
the wall is about 20 degrees.
1 TABLE I Angle "a" Sag (mm) Stiffness Observation Upon Shaking 0 0
Flexible, rattled easily. 5 2.0 Flexible, rattled easily. 10 2.5
Increase in stiffness and decrease in rattle. 15 3.0 Increase in
stiffness and decrease in rattle. 20 3.5 Nearly stiff; no rattle 25
4.0 Sufficiently stiff; no rattle. 30 4.5 Sufficiently stiff; no
rattle.
[0017] The packaging method described above has also been
successfully applied to LCD substrates having dimensions of about
1500 mm.times.1800 mm.times.0.7 mm. Twenty glass sheets and
twenty-one spacers were alternately placed in a boxed tilted 5
degrees. The box was made of acrylic plates reinforced with a steel
frame. The spacers were made from an acrylic material having a
thickness of about 3 mm and a cushion made from foamed polyethylene
tape having a thickness of about 0.5 mm or less. The stacked glass
sheets and spacers were tied together firmly, and then lifted at an
angle of between about 5 degrees and 30 degrees. As the tilt angle
increased, the glass deformed more by gravity sag, and was more
stabilized against mechanical vibration. The optimum tilt angle
will be determined by further experiments measuring the expected
external vibration during package transportation.
[0018] The various embodiments of the invention are particularly
useful for storing and shipping LCD glass substrates having an area
greater than one square meter. As discussed above, these glass
sheets typically have a thickness less than about 0.8 mm, and some
sheets have a thickness less than or equal to about 0.5 mm. The
present invention has been successfully demonstrated on LCD
substrates having dimensions of about 1500 mm.times.1800
mm.times.0.7 mm. The front and back major surfaces of the glass
sheet are not contacted by the spacers, except for a peripheral
portion of the sheet which typically discarded by the end user. No
films or surface coatings are required on the glass sheets to
prevent scratching, reducing the cost of processing of the glass
sheets. Handling of the glass sheets is simplified and loading and
unloading of the shipping container is simple and requires no
special equipment. According to certain embodiments of the present
invention the glass sheets packed in containers are stiffened by
the gravitational force induced when the sheets are packed at an
angle in a package. The stiffening reduces the glass flexibility
and reduces the chance of glass breakage due to external vibration
during transportation.
[0019] It will be apparent to those skilled in the art that various
modifications and variations can be made to the present invention
without departing from the spirit or scope of the invention. Thus,
it is intended that the present invention cover modifications and
variations of this invention provided they come within the scope of
the appended claims and their equivalents.
* * * * *