Stock material or miscellaneous articles – Light transmissive sheets – with gas space therebetween and...
Reexamination Certificate
2000-02-25
2002-11-12
Loney, Donald J. (Department: 1772)
Stock material or miscellaneous articles
Light transmissive sheets, with gas space therebetween and...
C156S109000, C052S786130
Reexamination Certificate
active
06479112
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a glass panel, and more particularly to a glass panel including a plurality of glass sheets, a plurality of spacers interposed between opposed faces of the glass sheets for forming a space therebetween, and a sealing material disposed along the peripheries of the opposed faces for maintaining the space under a gas-tight condition and binding the glass sheets together. The invention relates also to a method of manufacturing such glass panel as well as the spacer to be used therein for maintaining the opposed faces at a predetermined distance therebetween.
BACKGROUND ART
With the conventional glass panel of the above-noted type, for the purpose of improvement of heat insulating performance, it is extremely advantageous that the space be evacuated for restricting the heat transfer rate. However, as the inside of the space is evacuated, it becomes necessary for the two glass sheets to be able to endure the external pressure applied thereto.
Incidentally, if the inside of the space is evacuated to about 0.1 atm., the external pressure applied to the outer faces of the glass sheets due to the atmospheric pressure can reach as high as 10 tons/m
2
approximately. In order to endure such external pressure, spacers need to be disposed along the opposing faces of the glass sheets.
Conventionally, the above-described glass panel, as shown in FIG.
60
and
FIG. 61
, employs flat-plate like or column-like spacers
3
, which are simply bound between the opposing face
2
of the first glass sheet
1
A and the opposing face of the second glass sheet
1
B. And, in the manufacture of this glass panel P, the respective spacers
3
are disposed with a predetermined distance therebetween on the opposing face
2
of the first glass sheet
1
A and the opposing face
2
of the other second glass sheet
1
B is disposed in contact with the spacer
3
, and then a sealing material
6
made of low melting glass is sealed by melting on a peripheral edge
1
a.
However, with the conventional glass panel described above, since the entire end faces of the spacer
3
are placed in contact with the opposing faces
2
of the glass sheets
1
, heat conduction can occur through the spacer
3
in spite of the evacuation of the inside of the space C, leading to deterioration of heat insulating performance of the glass panel P. In order to reduce such heat conduction through the spacer
3
, its heat conducting cross sectional area may be reduced. Yet, if the contact face of the spacer
3
for contacting the glass sheet
1
is minimized in order to reduce its heat conducting cross sectional area, such contact face may result in stress concentration to the glass sheet
1
, so that hertzian crack due to external pressure is apt to occur.
Further, if the spacer
3
is formed thin in order to reduce its heat conducting cross sectional area, the spacer
3
may be broken by an external bending force when the glass panel P is warped due to a difference in the heat expansion rates of the two glass sheets
1
because of the temperature difference between the outside and the inside of the glass panel P.
Then, an object of the present invention is to provide a glass panel which can restrict heat conduction via the spacer
3
while effectively protecting the glass sheets
1
against development of crack in the glass sheets such as the hertzian crack and which can also prevent damage of the spacer
3
and also to provide a spacer for use in such glass panel.
DISCLOSURE OF THE INVENTION
According to a glass panel relating to claim
1
, as shown in
FIG. 1
, a plurality of spacers
3
are disposed in a space C formed between and along e.g. a first opposing face
2
A of a first glass sheet
1
A and a second opposing face
2
B of a second glass sheet
1
B. The spacer
3
includes, in one side
3
a
thereof, a plurality of projections and recesses. The projections
4
of these projections and recesses are formed to have a predetermined height from the other side
3
b
, so that these form a contact portion
5
capable of coming into contact with the first opposing face
2
A. And, this contact portion
5
is movable relative to the first opposing face
2
A.
In this construction, the plurality of projections
4
are formed on the one side
3
a
of the spacer
3
so as to form the contact portion
5
for coming into contact with the glass sheet
1
. Thus, the spacer
3
may come into contact with a greater area of the glass sheet
1
. Hence, it becomes possible to prevent stress concentration at the portion of the glass sheet
1
contacting the contact portion
5
, thus preventing development of crack such as the hertzian crack in the glass sheet
1
.
Further, as the heights of the projections
4
for contacting the glass sheet
1
are set at a predetermined constant height from the other side
3
b
, all of the projections
4
come into contact with the glass sheet
1
, thus assuring a large contact area to the glass sheet
1
. On the other hand, as it is possible to prevent the entire surface of the one side
3
a
of the spacer from coming into contact with the glass sheet
1
, the heat resistance may be increased.
Also, since the contact portion
5
of the spacer
3
is movable relative to the opposing face
2
, even if there is developed a warp in the glass panel P, the resultant displacement between the spacer
3
and the glass sheet
1
along the direction of its surface may be offset by such relative movement, thereby to prevent development of associated shearing force within the glass sheet
1
or the spacer
3
, so that damage of the glass sheet and the spacer
3
may be avoided.
A glass panel relating to claim
2
is characterized in that the projections are formed by means of cutting.
With this construction, in addition to the effect achieved by the glass panel of claim
1
described above, there is obtained a further effect of facilitation of the manufacture of the spacer
3
.
That is to say, if the projections forming the contact portion
5
are formed by means of cutting, the cutting operation per se is simple and easy and the adjustment of the height of the projections from the other side too is easy. For instance, the side face to be cut will be formed in advance as a flat face adjusted to the predetermined height from the other side and then grooves will be formed by cutting, whereby the projections and recesses are formed. Accordingly, the projections may be formed to the predetermined height.
A glass panel relating to claim
3
, as shown in
FIG. 1
, is characterized in that the other side
3
b
of the spacer
3
is fixedly formed on the second opposing face
2
B.
With this construction, in addition to the effect achieved by the glass panel of claim
1
or
2
, there are obtained further advantages that the assembly of the glass panel may be facilitated and that the spacer
3
will hardly be displaced inside the space C during use.
That is to say, with this construction, by fixedly forming the other side
3
b
of the spacer
3
on the second opposing face
2
B, it is possible to effectively prevent tumbling or rolling of the spacer
3
. Moreover, as the spacer
3
need not be maintained in position especially, as shown in
FIG. 9
for instance, the second glass sheet
1
B may be superposed with a desired posture over the first glass sheet
1
A. Further, when the glass sheets
1
are flexed due to e.g. wind pressure so as to relax the distance between the two glass sheets
1
A,
1
B, there will occur no dislocation of the spacer
3
inside the space C.
A glass panel relating to claim
4
, as shown in
FIG. 1
, is characterized in that the other side
3
b
of the spacer
3
is bonded to the second opposing face
2
B.
With this construction, the effect of the construction of claim
3
described above may be obtained more reliably. That is to say, by bonding the other side
3
b
of the spacer
3
to the second glass sheet
1
B, the fixation of the spacer
3
may be surer. For instance, as shown in FIG.
9
and
FIG. 10
, after the spacer
3
is fixed, the second glass sheet
1
Asano Osamu
Horiguchi Naoto
Miura Tomonori
Okajima Keiichiro
Shukuri Kyoichi
Fulbright & Jaworski L.L.P.
Loney Donald J.
Nippon Sheet Glass Co. Ltd.
LandOfFree
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