Double-glazing unit

Details Double-glazing unit Double-glazing unit

1999-05-04

2001-04-03

Loney, Donald J. (Department: 1772)

Stock material or miscellaneous articles

Light transmissive sheets, with gas space therebetween and...

C052S786130

Reexamination Certificate

active

06210763

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a double glazing including a pair of glass sheets, a plurality of spacers disposed between opposed sheet faces of the glass sheets by a predetermined pitch, and a sealing member interposed between the glass sheets along the entire peripheries thereof, with a space between the glass sheets being sealed in a vacuum condition.
BACKGROUND ART
As a glass sheet structure providing a higher heat-insulating performance than a single glass sheet, there is known a double glazing comprising a pair of glass sheets assembled together with an air layer interposed therebetween as a heat-insulating layer. This type of double glazing, however, has the problem that the significant thickness of the glazing tends to impair the aesthetic appearance including that of the sash. Then, as a double glazing having smaller thickness yet providing superior heat-insulating performance, there has been proposed a double glazing in which a plurality of spacers (cylindrical spacers formed small so as not to impair the aesthetic appearance) are distributed between the pair of glass sheets and a sealing member made of e.g. low melting-point glass is provided between and along the entire peripheral edges of the glass sheets so as to keep the space under an evacuated condition.
By providing the respective spacers and the sealing member, a predetermined distance between the two glass sheets may be maintained although the space is evacuated. With this type of conventional double glazing, however, the spacer is formed of material (e.g. stainless steel, nickel, molybdenum, tungsten, tantalum, titanium, ceramics) having a high strength and low tendency of plastic deformation so as to be able to maintain the predetermined distance between the glass sheets against not only a normal static external pressure normally applied in the direction of sheet thickness but also against an impact dynamically applied in the sheet thickness direction.
With the conventional double glazing described above, it is possible indeed to constantly maintain the distance between the glass sheets at a predetermined value due to the high strength and low elastic deformability of the spacer per se. However, since the spacer per se has a high strength and low tendency of plastic deformation, when the double glazing is subjected to an impact, it is difficult to relieve the impact applied in a concentrated manner at the point of contact between the spacer and the glass sheet, so that the glass sheet tends to be broken.
Accordingly, the object of the present invention is to provide a double glazing which can overcome the above-described problem and which cannot be readily broken by a dynamically applied external force.
DISCLOSURE OF THE INVENTION
According to the characterizing features of the present invention relating to claim
1
, as illustrated in
FIGS. 1
,
2
, in a double glazing including a pair of glass sheets, a plurality of spacers disposed between opposed sheet faces of the glass sheets by a predetermined pitch, and a sealing member interposed between the glass sheets along the entire peripheries thereof, with a space between the glass sheets being sealed in a vacuum condition, each spacer is formed so as to maintain a predetermined distance between the glass sheets when subjected to a static normal external pressure normally applied thereto in the direction of sheet thickness and also to relieve stress through plastic deformation when subjected to an impact dynamically applied in the sheet thickness direction.
With the characterizing features of the present invention relating to claim
1
, the spacer is capable of maintaining the predetermined distance between the glass sheets when subjected to a static normal external pressure normally applied thereto in the sheet thickness direction and the spacer is also capable of relieving stress through plastic deformation thereof when subjected to an impact dynamically applied in the sheet thickness direction. Accordingly, it becomes possible to maintain the predetermined distance between the glass sheets against the effect of normal external pressure. And, at the same time, when the impact applies, there occurs plastic deformation in the spacers due to the effect of the external force, so that it is possible to receive the impact in a relieved state. As the result, it becomes possible to relieve a strong impact which would be applied in a concentrated manner at the point of contact between the glass sheets and the spacers in the case of the conventional art. Hence, with this double glazing, its glass sheets can hardly be broken.
Further, such effect as above may be achieved not only when the sealing member has plastic deformation capability like that of the spacer, but also when the member is formed of such material as low melting point glass that can hardly be plastically deformed.
That is to say, when the sealing member is formed of material having low tendency of plastic deformation, the amount of deformation in the direction of compression occurring due to the effect of the impact will be greater in each spacer than in the sealing member. And, in association with the difference between the deformation amounts, a tensile stress tends to be applied especially to the outer edge (in the vicinity of its portion bonded with the sealing member) of the glass sheet. However, as long as this tensile stress is within the tensile-stress strength of the glass sheets, the spacers may provide their relieving effect on the impact.
Further, according to the characterizing feature of the present invention relating to claim
2
, the spacers have a diameter ranging between 0.30 and 1.00 mm, a disposing pitch of 10 to 25 mm and a normal-temperature strength of 4.5 to 9.5 kg/mm
2
in the above-described numerical ranges. With these features, the spacers may be less conspicuous. Hence, the function/effect of the invention relating to claim
1
may be achieved without significantly impairing the aesthetic appearance.
Here, the pressure applied to the spacer may be given by the following expression (1), provided the spacer has a diameter Do and a disposing pitch of L.
P=L
2
×Po/&pgr;(Do/2)
2
  (1)
where Po is a pressure applied from the outside of the double glazing.
Namely, regarding the spacer diameter, if its value is too small, the supporting force by the spacer will tend to act as a concentrated load on a limited portion of the glass sheet, whereby the possibility of local breakage of the glass sheets will increase. On the other hand, if its value is too large, the spacer will become conspicuous thereby to impair the aesthetic appearance. Especially, when transparent glass sheets are employed, the transparency will tend to be reduced. In addition, when the value is large, the thermal transmittance will increase, thereby to invite another problem of reduction in the heat insulating effect. Therefore, within the range capable of achieving the function/effect of the invention of claim
1
, the diameter range of the spacer is set as 0.30 to 1.00 mm as a range in which the above-described respective problems are less likely to occur.
Further, regarding the disposing pitch of the spacers, this is closely related to the diameter size and the normal-temperature strength of the spacer, within the range capable of achieving the function/effect of the invention of claim
1
, this disposing pitch of the spacers is set at 10 to 25 mm as a range in which the spacers may be formed less conspicuous thus avoiding deterioration of the aesthetic appearance and in which the predetermined space between the opposed glass sheets may be maintained even if distortion may be developed in the glass sheets due to the effect of external force. If this spacer disposing pitch exceeds 25 mm, the load due to the normal external force applied to each spacer will increase, whereby the spacer will be deformed by an amount that cannot be neglected substantially, so that it will lose its function as a spacer. In addition, this will result in increase in the tensile stress devel

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