GB2324824A

GB2324824A - Patterned and partially reflecting insulating glazing unit

Info

Publication number: GB2324824A
Application number: GB9708878A
Authority: GB
Inventors: Mervyn John Davies
Original assignee: Pilkington United Kingdom Ltd; Pilkington PLC
Current assignee: Pilkington Group Ltd; Pilkington United Kingdom Ltd
Priority date: 1997-05-02
Filing date: 1997-05-02
Publication date: 1998-11-04
Also published as: GB9708878D0

Abstract

A multiple glazed unit 1 has an outer pane 2 and an inner pane 4, held apart by a spacer bar 6 to form an insulating air gap 8. The outer pane 2 is a patterned glass, which may be formed as translucent shapes acid etched into its exposed surface. The inner pane 4 is a mirror glass, which may be laminated from a low emissivity glass 16 and an exposed mirror glass 18. The low emissivity glass 16 has an infrared reflecting coating 22 and the mirror glass 18 has a partially reflecting coating 24.

Description

INSULATING GLAZING UNITS The invention relates to insulating glazing units and particularly to units which comprise two or more panes of glass held spaced apart to form one or more insulating air gaps. Such glazing is commonly known as multiple glazing.

Many UK homes are fitted with multiple glazing. Also, many UK homeowners are now choosing to add conservatories or predominantly glazed extensions to their homes.

Conservatories are often fabricated from multiple glazed units. Each unit generally comprises two panes of glass held spaced apart by a metal or plastic spacer frame. One or two sealants are applied around the frame to hold the panes together and to hermetically seal the air gap. The insulating ability of the unit may be improved by replacing the air in the gap with a noble gas, such as argon, which makes a better thermal insulator. It is also known to use a low emissivity, infra red reflecting glass, rather than a clear annealed glass, as one of the panes of the unit (usually the inner), also to improve its insulating ability. The infra red reflecting coating reflects infra red radiation that would otherwise escape to atmosphere by reflecting it back into the conservatory.

The invention provides a multiple glazing unit having an outer pane, an inner pane and a spacer frame arrangement holding the two panes spaced apart, characterised in that the outer pane is patterned glass and the inner pane comprises a mirror glass.

The term patterned glass is used in the field of building glass to mean any glass which has a pattern applied to one or both major surfaces for example by rolling it with a patterned roller during the glass production process, by etching the surface with acid or alkaline or by screen printing it with ink. The patterning affects light transmission, and visibility through the glass varies according to the particular pattern applied. Thus, patterned glasses are installed in situations where limited visibility of varying degrees is required, say, for reasons of privacy.

The applicants offer a range of patterned glasses in the UK under the trade mark PILKINGTON TEXTURE GLASS.

The term mirror glass is used herein to mean any glass which has been treated so as to render it partially reflecting, that is to say, having visible light reflectance greater than that of clear annealed glass but without any form of opaque, for example, sprayed or painted backing layer, so as to retain the ability to transmit visible light. The treating may involve applying a visible light reflecting coating. The applicants offer such a mirror glass in the UK under the trade mark PILKINGTON MIRAGE GLASS which is a so-called front surface mirror glass (the reflective coating is applied to the surface which in use is the front) with a visible light reflectance of at least 70%. Unbacked rear surface mirrors are also suitable.

Preferably, the inner pane is a laminated glass comprising two or more sheets which are bonded together and the mirror glass is one of the sheets, usually the room-side sheet. The sheets are generally bonded together with a polymeric material, such as polyvinylbutyral (PVB).

Further preferably, a second of the sheets in the laminated glass is a sheet of low emissivity glass. The term low emissivity glass is used herein to mean any glass whose infra red reflecting capability is sufficiently greater than that of clear annealed glass and would therefore improve the insulating ability of a multiple glazed unit in which it was used. The infra red reflecting capability may be produced by coating the glass with an infra red reflecting coating. The applicants offer a low emissivity coated glass in the UK under the trade mark PILKINGTON K GLASS.

The invention is particularly intended for use in conservatories where in certain circumstances there is a demand for the following combination of features: The patterned glass offers limited visibility so as to restrict the view into the conservatory of inquisitive passers-by and/or to restrict the conservatory occupants view of unsightly objects outside; the mirror glass enhances the obscuration offered by the patterned glass from outside by reflecting the pattern (especially with an etched pattern), offers an illusion of increased space by making the interior of the conservatory appear to the occupants to be larger than it actually is and offers an attractive visual effect by providing the occupants with partial visibility of the patterned glass.

The inclusion of a low emissivity glass in a laminated inner pane increases the insulating power of the unit. In addition, units according to the invention can serve as heated glazing by having a coated low emissivity glass and using the coating as a resistive heating element. A voltage can be applied across the coating through bus bars at opposite edges.

The invention will now be described by way of example with reference to the sole drawing, figure 1, which is a cross-sectional view of a multiple glazing unit according to the invention.

A multiple glazing unit for a conservatory indicated generally at 1 has an outer pane 2 and an inner pane 4. The two panes 2, 4 are held spaced apart by an aluminium spacer bar 6 so as to form an insulating air gap 8. The spacer bar 6 is bent to form a rectangle Df corresponding shape, albeit slightly smaller than, the panes 2, 4. Beads of butyl sealant 10, 12 between the spacer bar 6 and the panes 2,4 respectively seal the air gap 8 against moisture ingress. A secondary sealant 14 bonds the two panes 2,4 together at their margins.

The outer pane 2 is a patterned glass having translucent leaf-like shapes (not shown) acid etched into its exposed surface. The translucent shapes limit the visibility through the pane 2.

The inner pane 4 is a laminated glass comprising a sheet of infra red reflecting low emissivity glass 16 and a sheet of mirror glass 18 bonded together with a sheet of PVB 20.

The sheets 16, 18 are laminated together using conventional techniques.

The low emissivity glass 16 is adjacent the air gap 12. The illustrated embodiment has a coated low emissivity glass 16 with an infra red reflecting coating 22 (thickness exaggerated in the figure for ease of understanding) of fluorine doped tin oxide. As is conventional, the coating 22 faces the air gap 8.

The mirror glass 18 is the exposed one of the two sheets 16, 18. The illustrated embodiment has a front surface mirror glass 18 of the type described in EP 0583871: The mirror glass 18 is coated on its front, exposed surface with a partially reflecting coating 24 (thickness exaggerated in the figure for ease of understanding) made up of alternate layers of silicon.

Claims

1. A multiple glazing unit having an outer pane, an inner pane and a spacer frame arrangement holding the two panes spaced apart, characterised in that the outer pane is patterned glass and the inner pane comprises a mirror glass.

2. A multiple glazing unit according to claim 1 wherein the inner pane is a laminated glass comprising two or more sheets which are bonded together and the mirror glass is one of the sheets.

3. A multiple glazing unit according to claim 1 or claim 2 wherein a second of the sheets is a low emissivity glass.

4. A multiple glazing unit according to any of claims 1 to 3 wherein the patterned glass is an etched glass.

5. A multiple glazing unit according to any of claims 1 to 4 wherein the mirror glass is a front surface mirror glass or an unbacked rear surface mirror glass.

6. A multiple glazing unit substantially as herein described with reference to the sole drawing figure 1.