GB2042761A - Optical reflectors - Google Patents

Optical reflectors Download PDF

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Publication number
GB2042761A
GB2042761A GB8003733A GB8003733A GB2042761A GB 2042761 A GB2042761 A GB 2042761A GB 8003733 A GB8003733 A GB 8003733A GB 8003733 A GB8003733 A GB 8003733A GB 2042761 A GB2042761 A GB 2042761A
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United Kingdom
Prior art keywords
ply
glass
laminate
metal
reflector according
Prior art date
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Granted
Application number
GB8003733A
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GB2042761B (en
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BFG Glassgroup GIE
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BFG Glassgroup GIE
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Publication date
Application filed by BFG Glassgroup GIE filed Critical BFG Glassgroup GIE
Priority to GB8003733A priority Critical patent/GB2042761B/en
Publication of GB2042761A publication Critical patent/GB2042761A/en
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Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B32LAYERED PRODUCTS
    • B32BLAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B17/00Layered products essentially comprising sheet glass, or glass, slag, or like fibres
    • B32B17/06Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material
    • B32B17/10Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin
    • B32B17/10005Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing
    • B32B17/10009Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing characterized by the number, the constitution or treatment of glass sheets
    • B32B17/10018Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing characterized by the number, the constitution or treatment of glass sheets comprising only one glass sheet
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B32LAYERED PRODUCTS
    • B32BLAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B1/00Layered products having a non-planar shape
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B32LAYERED PRODUCTS
    • B32BLAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B15/00Layered products comprising a layer of metal
    • B32B15/04Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B32LAYERED PRODUCTS
    • B32BLAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B17/00Layered products essentially comprising sheet glass, or glass, slag, or like fibres
    • B32B17/06Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material
    • B32B17/10Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin
    • B32B17/10005Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing
    • B32B17/10165Functional features of the laminated safety glass or glazing
    • B32B17/10174Coatings of a metallic or dielectric material on a constituent layer of glass or polymer
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B32LAYERED PRODUCTS
    • B32BLAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B17/00Layered products essentially comprising sheet glass, or glass, slag, or like fibres
    • B32B17/06Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material
    • B32B17/10Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin
    • B32B17/10005Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing
    • B32B17/10165Functional features of the laminated safety glass or glazing
    • B32B17/10293Edge features, e.g. inserts or holes
    • B32B17/10302Edge sealing
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B32LAYERED PRODUCTS
    • B32BLAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B17/00Layered products essentially comprising sheet glass, or glass, slag, or like fibres
    • B32B17/06Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material
    • B32B17/10Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin
    • B32B17/10005Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing
    • B32B17/1055Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing characterized by the resin layer, i.e. interlayer
    • B32B17/10788Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing characterized by the resin layer, i.e. interlayer containing ethylene vinylacetate
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B32LAYERED PRODUCTS
    • B32BLAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/04Interconnection of layers
    • B32B7/12Interconnection of layers using interposed adhesives or interposed materials with bonding properties
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24SSOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S23/00Arrangements for concentrating solar-rays for solar heat collectors
    • F24S23/70Arrangements for concentrating solar-rays for solar heat collectors with reflectors
    • F24S23/81Arrangements for concentrating solar-rays for solar heat collectors with reflectors flexible
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00Optical elements other than lenses
    • G02B5/08Mirrors
    • G02B5/10Mirrors with curved faces
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00Energy generation through renewable energy sources
    • Y02E10/40Solar thermal energy, e.g. solar towers

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Sustainable Energy (AREA)
  • Thermal Sciences (AREA)
  • Sustainable Development (AREA)
  • Combustion & Propulsion (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Laminated Bodies (AREA)
  • Optical Elements Other Than Lenses (AREA)

Abstract

A flexible radiant energy reflector, useful e.g. in a solar energy concentrator, has the form of a laminate comprising a glass ply 13 bonded by means of a bonding layer to a metal ply 15; the thicknesses of the glass and metal plies and their elasticity moduli and the nature of the bond between those plies being such that the laminate can be flexed to impart a concave curvature to the exposed front face of the glass ply without subjecting the rear face of such ply to tensile stresses. The glass 13 may be silvered on its unexposed surface. The reflector may be mounted so that its curvature is fixed. Alternatively the curvature may be adjusted by, as shown, a bolt 17. <IMAGE>

Description

SPECIFICATION Mirror production This invention relates to flexible radiant energy reflectors and to methods of manufacturing them.
Flexible radiant energy reflectors are useful for various purposes. They can be used for example in the production of curved mirrors for decorative purposes or for achieving special visual effects. A very important field of use is the production of curved concave reflectors for reflecting visual light beams from artificial light sources or for reflecting solar radition, e.g. in solar heating installations.
It is known to use polished sheet metal as a flexible mirror. The use of a polished metal sheet is not satisfactory for some circumstances of use.
One reason is the vulnerability of the reflective surface to mechanical damage. Another is the liability of the sheet to distortion consequent upon small changes in temperature.
For meeting high optical specifications it would be better to employ coated glass, the coating comprising a radiant energy reflecting layer which is exposed to radiant energy through the glass.
However conventional glass mirrors are substantially non-flexible and in the known art of manufacturing curved glass reflectors the practice is to cast molten glass into a mould of the desired curved form, or to subject the flat glass to bending forces while it is heated over an extended period of time and/or while the glass is at such elevated temperature that it assumes a desired permanent curvature. The curvature may e.g. be determined by a suitably shaped former. The light-reflecting coating is applied the curved glass after it has been bent, otherwise the optical coating is liable to be spoiled.
These known methods of making curved glass reflectors are very expensive to perform under mass production conditions and to satisfy high product standards.
There is a need for a flexible reflector which incorporates a sheet of glass, and which benefits from the advantages that that material can confer, and which is nevertheless sufficiently flexible to permit it to be easily converted by a flexing operation, without need for the glass to be heated to a high temperature or even at all, into a reflector having a required curvature.
According to the present invention there is provided a flexible radiant energy reflector characterised in that the reflector is in the form of a laminate comprising a glass ply bonded over its whole area to a metal ply, said metal ply or a ply coating providing a radiant energy-reflecting surface, and in that the relative thicknesses of the glass and metal plies, their moduli of elasticity and the efficiency of the interply bond are such that that face (hereinafter called "rear face") of the glass ply which is nearer the metal ply is not subjected to tensile forces when the laminate is flexed within the elastic limit of the metal in such manner and to such a degree as to give the front face of the glass ply a concave curvature with a radius of 10 m.
When a reflector according to the invention is subjected to flexing forces causing its flexure in the sense above specified, the rear face of the glass ply becomes convexly curved but due to the presence of such metal ply and the bond between the two plies, tensile loading of that face is avoided or reduced. (Tensile loading of that face is avoided at least if the radius of curvature does not become lower than 10 m). This is important because the imposition of tensile surface stresses in a glass sheet can lead to breakage, particularly if there are surface flaws in the glass which may act as stress raisers.
Reflectors according to the invention can be conveniently made by mass production methods and reflectors so made can be converted to curved or more curved reflectors each conforming with a high degree of accuracy to a predetermined curvature. One or more reflectors according to the invention can be held in a predetermined curved qondition by a holding device made for that purpose.
Reflectors according to the invention are particularly suitable for use in making solar energy concentrators comprising an assembly of individual curved reflectors.
A degree of curvature corresponding with a radius of 10 m is adequate for various purposes, for example for a reflector to be used as or as part of a large solar energy concentrator. It is however ati important potential advantage of the invention that reflectors which can be flexed to considerably smaller radii can be produced by appropriate choice of the relationship between the products of the thicknesses and elasticity moduli of the glass and metal plies and the efficiency of the inter-ply bond.
Withe relative thickness of the glass and metal plies must be suitable having regard to the elasticity moduli of the glass and metal, the efficiency of the inter-ply bond and the radius or radii or curvature to which the laminate is to be flexed. Other things being equal, the higher the elasticity modulus of the metal is in relation to that of the glass, the lower can be thickness ratio tm/t9 wherein tm is the thickness of the metal ply and tg the thickness of the glass ply. By the efficiency of the inter-ply bond is meant the efficiency with which it can transmit stresses from the metal to the glass when the laminate is flexed. An ideal bond of 100% efficiency would be one which resulted in the laminate behaving as a monolithic structure in regard to the stress distribution profile through its thickness.In practice, for ensuring that the rear face of the glass is subjected only to compressive stresses the laminate should satisfy the condition tm. Em > tg. Eg where tm and tg are the thicknesses of the metal and glass plies, as above stated, and Em and Eg are their elasticity moduli, the difference in magnitude between the two values tm Em and tg.Eg being sufficient, having regard to the extent to which the laminate is flexed, to allow for the imperfect efficiency of the bond.
In preferred embodiments of the invention the relative thicknesses of the glass and metal plies, their moduli of elasticity and the efficiency of the inter-ply bond are such that the reflector can be flexed sufficiently to reduce the radius of concave curvature of the front face of the glass ply to 1 m, and most preferably to 30 cm or less, without the rear face of the glass ply becoming subjected to tensile forces. Reflectors having curvatures of radii between 1 m and 10 m are also useful in the manufacture of solar energy concentrators.
Reflectors having a concave curvature with a radius of 30 cm or even smaller, e.g. 1 5 cm, or even below 10 cm, are required for various purposes, for example as photodiode focussing reflectors.
Preferably the relative thicknesses of the glass and metal plies, their elasticity moduli and the efficiency of the inter-ply bond are such that not only the front face but also the rear face of the glass ply is subjected to compressive stresses when the laminate is flexed to an extent sufficient to reduce the radius of concave curvature of the front face of the glass ply to 10 m. If the rear face of the glass ply can be kept under compressive stress, that provides an important safety factor guarding against breakage of the glass.
Preferably t,. E, 1.1 Xtg Eg. When observing this condition it is easy by using various commercially available bonding media to achieve an inter-ply bond of adequate efficiency to maintain compressive stresses on the rear face of the glass during flexure of the laminate to quite small radii of curvature.
Preferably the laminate is between 1.0 and 4.0 mm in thickness. Such laminates have a favourably low weight and afford relatively low resistance to flexure.
The glass ply can be untempered or tempered e.g. chemically tempered.
Preferably the glass ply has a thickness between 0.6 and 1.0 mm. Such plies can be very easily flexed. Glass below about 0.6 mm in thickness tends to be too liabie to breakage before or during bonding to the metal ply. Glass plies in the said thickness range are very suitable in solar energy reflectors wherein a radiant energy reflecting coating is on the rear face of the glass ply because the glass absorbs very little solar energy.
Preferably the metal ply has a thickness less than 3.0 mm and most preferably from 0.3 to 2.5 mm. Such metal plies are preferred because of the ease with which they can be flexed.
Advantageously the metal ply is of steel. A steel ply has a high elasticity modulus, which enables a thinner ply to be used for achieving given flexural characteristics of the laminate than would otherwise be required. Preferably the steel ply is galvanised. Galvanised steel, particularly if it has been bonderised, is a very suitable material on account of its cost effectiveness, its capacity to be easily and efficiently bonded to the glass, and its resistance to corrosion.
Other metals which can be used for the metal ply include aluminium, stainless steel and brass.
Referring now the bonding layer(s): use can be made for example of one or more film-forming polymers which may be applied in sheet, e.g. thin foil, form and caused to adhere to the laminate plies by subjecting the assembly to heat and pressure.
A particularly preferred bonding medium is polyvinylbutyral. This material is convenient to use and enables very strong metal/glass bonds to be achieved which are durable under a useful range of temperature and other fluctuating environmental conditions.
Other bonding media which have been found to give very good results are in the class of epoxy resins, e.g. the adhesive marketed under the Trade Mark "Araldite". When employing epoxy resins it is beneficial to employ a mixture of epoxy resins of different molecular weights to achieve a favourable combination of high bond strength with sufficient elasticity of the bonding layer to allow for slight relative parallel displacement of the bonded faces of the metal and glass plies, for example in consequence of flexure of the laminate or differential thermal expansion of such plies.
Other suitable categories of bonding media comprise silicone-based adhesives, polyurethane adhesives and hot-melt adhsives.
The employment of hot-melt type adhesives affords a number of advantages. Among these are the facility with which they can be handled and applied to form bonding layers of predetermined thickness and uniformity. Reproducible results can be achieved under rapid assembly conditions. It is an easy matter to select a hot-melt adhesive formulation which will have a required combination of properties. The hot-melt adhesive composition can be selected to combine a very adequate bond strength with a high degree of impermeability by moisture. The use of a hot-melt type adhesive also contributes to lowering of production costs. This is due to the relatively low cost of the adhesive itself and the ease with which bonding can be achieved with very modest equipment and in a small working area.
The hot-melt adhesive is preferably one which is molten at a temperature of 1 500C or lower, preferably between 600 and 120"C.
Hot-melt adhesive formulations include an elastomeric or thermoplastic material which melts easily to a low viscosity fluid. In order to achieve solidified bonding layers of adequate strength and cohesiveness such easily meltable ingredient is blended with a higher molecular weight polymeric material. A very favourable balance of properties can be achieved by formulating the hot-melt adhesive to incorporate a combination of resins of different melt indices.
Examples of relatively easily meltable substances which can be used in hot melt adhesive formulations are various natural and synthetic resins and waxes, e.g. terpene resins, hydrocarbon resins, polyterpenes, phenolformaldehyde resins, alkyds, coumarone-indene resins, rosin and rosin derivatives and mineral, vegetable and petroleum waxes.
In preferred embodiments of the present invention a hot-meit adhesive composition is used which includes one or more tackifiers selected from terpene and phenolic resins and microcrystalline waxes. Very good results are also attainable with styrenes and low-molecular homolugues.
Examples of higher molecular weight synthetic polymeric materials suitable as reinforcing or toughening ingredient of the hot-melt adhesive composition, forming what is sometimes referred to as the adhesive backbone, are polyvinyl acetate, polyethylene, polyisobutylene (butyl rubber), polystyrene and styrene copolymers, ethyl cellulose, polyamides derived from dimerized fatty acids and diamines, and butyl methacrylates.
In preferred embodiments of the present invention a hot-melt adhesive is used which includes one or more elastomeric or thermoplastics selected from butyl rubber and ethylene/vinyl acetate copolymers.
The hot-melt adhesive may incorporate various other types of ingredients for confering required properties, for example as specified in our DE Patent Number 2,713,351. Examples of categories in which such supplementary ingredients fall are plasticisers, thermal stabilizers and fillers. Plasticisers are useful for improving adhesive wetting of the surfaces. Stabilisers are used for improving thermal stability. Fillers are susbstantially chemically inert and are useful for modifying the physical properties of the adhesive.
Preferably the thickness of the or each layer of hot-melt adhesive (when used) is less than 1 50 microns. This condition is recommended because it exploits an important property of hot-melt adhesives, namely their ability to give very effective bonds even as very thin layers, and because such thin layers leave a very small surface area of adhesive exposed to the environmental atmosphere.
In preferred embodiments, a hot-meit adhesive is used the water resistance of which is less than 0.5 and most preferably less than 0.1 g H20 per m2 of surface per 24 hrs per mm thickness per cm Hg of pressure.
The invention also includes reflectors as hereinbefore defined wherein the glass and metal plies are bonded by means of an acrylic resin based adhesive.
The invention further includes reflectors as hereinbefore defined wherein the glass and metal plies are bonded by means of a polyvinylchloride bonding layer.
In some embodiments of the invention, the metal and glass plies are bonded together by means of two or more different bonding media.
For example the invention includes reflectors in which said plies are bonded together by means of two or more bonding layers of different compositions. In certain products in this category the said plies are bonded together by means of an adhesively coated thermoplastics foil applied as such between the glass and metal plies prior to application of laminating conditions, normally heat and pressure. A specific example giving very good results employs for the bonding function a foil of a polyester bearing a coating of an acrylic resin based adhesive on each side thereof. Such double-coated foils are commercially available.
Suitable such foils are for example those marketed under the Trade Marks MACBOND 2800 and MACBOND 2132.
The bonding layer(s) of a reflector according to the invention can incorporate reinforcement, e.g. a fibrous or filamental reinforcement composed of glass or polyamide fibres of filaments. The reinforcement can be resin-impregnated.
The actual bonding step in the manufacture of the reflector may be achieved by means of calender rolls or by means of a press. In order to avoid occlusions or air or other gases between the plies, bonding under heat and pressure can be achieved within a chamber in which the assembly of plies and bonding medium or bonding media is subjected to a predetermined schedule of heat and pressure variations. The margins of the assembly may be placed in communication with a suction device by which suction forces are propagated to the inter-ply zone(s) to promote evacuation of gases therefrom. The exertion of such suction force can be controiled in timed relation to the incidence of predetermined ambient heat and/or pressure conditions in the course of a heating and pressing cycle within a said chamber.Such bonding techniques are known per se in relation to the manufacture of other kinds of laminates, in particular glass/glass laminates (see e.g. United Kingdom Patent No. 1,368,785).
Preferably the radiation-reflecting surface is provided by a coating on the glass ply. In the most preferred embodiments said coating is on the rear face of the glass ply. The metal ply then fulfils a protective role in respect of the coating. The reflector preferably incorporates between the reflecting coating and the metal ply, one or more protective layers for the optical coating, for example a layer of protective paint and a varnish layer such as are employed in the production of conventional glass mirrors.
The invention includes reflectors wherein the glass ply bears a light-reflecting coating on its front face. Such a front face coating can be applied e.g. after bonding the glass to the metal ply. In such a reflector the metal ply does not protect the reflecting coating but serves merely as a support for the glass ply.
The reflecting coating is preferably a coating of silver, the advantage being a very high lightreflectivity. This high reflectivity is very important for solar energy reflectors.
As an alternative to silver, other metals can be used for the reflective coating, for example metals with better resistance to the chemical action of agents in the atmosphere.
As an alternative to the use of a reflecting coating on the glass, a reflector according to the invention can comprise a metal ply which provides a radiant energy-reflecting inner face, this face being covered by the glass ply.
Preferably the metal ply is of such dimensions and is so positioned relative to the glass ply that at least two opposed margins of such metal ply project from the corresponding opposed edges of the glass ply. The projecting metal ply margins afford protection to the corresponding edges of the glass against mechanical damage, for example such as might be caused by impact against another object. Forces for imparting curvature or additional curvature to the laminate can then be exerted on the projecting margins of the metal ply.
Advantageously, there are projecting metal ply margins as above referred to and those margins assist in supporting protective deposits of material, for example of glue, against the corresponding edge faces of the glass ply.
Preferably opposed edges of the giass ply are buttressed to relieve the bonding medium of shear stresses tending to cause delamination when the laminate is flexed. In certain embodiments such edges are buttressed by abutments, e.g.
abutments of metal or elastically deformable material, which are secured against those edges of the glass ply. For example such abutments may be secured to a face of the metal ply at projecting margins thereof or the abutments may be interposed between the said glass ply edges and edge strips secured to opposed edges of the laminate.
A laminate according to the invention can be naturally flat or it can have a slight natural curvature such for example as may sometimes occur when producing the laminate from flat metal and glass plies which are very thin.
The invention includes a curved reflector which comprises a laminate according to the invention as above defined, the laminate being held in flexed condition against elastic recovery forces in the laminate by a holding device, the front face of the glass ply being concave.
Preferably the holding device maintains the laminate in flexed condition by forces transmitted wholly or in part through opposed edge faces of the glass ply. This form of co-operation between the laminate and the holding device is very advantageous for avoiding any tendency for the elastic recovery forces to encourage delamination.
In certain constructions giving good results, the holding device extends across the opposed edges of the laminate which are parallel with (an) axis or axes of curvature of the laminate and the device opposes elastic recovery forces in the laminate by bearing directly or through interposed bearing elements against the corresponding edges of the glass ply or against both those edges and the corresponding edges of the metal ply.
Advantageously, the margins of the metal ply which include those edges thereof project beyond the corresponding edges of the glass ply.
In certain very advantageous embodiments of the invention the holding device and the laminate have co-operating abutments via which the elastic recovery forces in the laminate are transmitted to the holding device to hold the laminate in curved condition and the abutments on the laminate and/or the holding device are screw-adjustable for adjusting the curvature of the laminate.
In particularly important embodiments of the invention the holding device has a plurality of holding locations at each of which a said laminate is installed and held in curved condition so that the individual laminates form constituent parts of a larger curved reflector.
Preferably the holding device for the laminate is made of metal but any other material or materials can be used provided the device has the necessary strength and rigidity.
The forces for elastically flexing the laminate can be exerted against opposed sides of the laminate, in directions general!y normal to its plane, for example in the case of a rectangular laminate by exerting such forces against one pair of opposed margins at one side of the laminate and against the other pair of opposed margins at the opposite side of the laminate. Flexing forces exerted in that way tend to oppose separation of the glass and metal plies. However, as an alternative the laminate can be elastically flexed by exerting forces acting towards each other on two opposed edges or margins of the laminate or of the glass ply. In the case of a circular laminate a spherical curvature can be imparted to it by exerting radially inward forces on the peripheral zone or by exerting opposite forces at the peripheral zone of the laminate and at its centre.
The invention includes a method of making a curved radiant energy reflector, characterised in that a glass ply is bonded to a metal ply to form a laminate having a radiant energy reflecting surface which is formed by said metal ply or by a ply coating, forces are applied to impart to the laminate a curvature such that the front face of the glass (i.e. its face which is remote from the metal ply) is concave, and the cured laminate is installed in a holding device which holds the laminate in curved condition, against elastic recovery forces in the laminate.
In carrying out this method, the face of the glass ply (hereafter called "rear face") which is bonded to the metal ply becomes convexity curved due to the presence of such metal ply and the bond between the two plies, tensile loading of that face is avoided or reduced. This is important because the imposition tensile surface stresses in the glass can lead to breakage, particularly if there are surface flaws in the glass which may act as stress raisers. If the metal ply is appropriately chosen and efficiently bonded to the glass, as herein described, the laminate can be flexed to an appreciable degree without breaking the glass, even when using a piece of untempered glass and one which has not been specially surface-treated to remove surface flaws.
The method according to the invention lends itself to mass production manufacture and is suitable for producing a multiplicity of mirrors each conforming with a high degree of accuracy to a predetermined curvature.
Preferably the laminate is held to a radius of curvature of 10 metres or less, and most preferably less than 1 metre.
Preferably the glass ply used in carrying out a said method according to the invention bears a radiant energy-reflecting coating of silver or other material on that face thereof which becomes covered by the metal ply.
In carrying out the said method it is preferred for the relative thicknesses of the glass and metal plies, their elasticity moduli and the efficiency of the inter-ply bond to be such that the rear face of the glass ply is not subjected to tensile stresses by the flexing of the laminate and most preferably said parameters are such that both the front face and the rear face of the glass ply are subjected to compressive stresses by such flexing step.
The laminate used in a method according to the invention can have any of the various optional features pertaining to a laminate in accordance with the invention as hereinbefore described.
Certain embodiments of the invention, selected by way of example, will now be described with reference to the accompanying diagrammatic drawings, in which: Figure 1 is a cross-section of a flat reflector; Figure 2 is a detail of a modification of the reflector shown in Figure 1; Figure 3 is a cross-sectional view of a curved reflector; Figures 4 and 5 are cross-sections of part of two further curved reflectors; Figure 6 is a side eievation of part of a further curved reflector, and Figure 7 is a cross-sectional elevation of part of a flat reflector.
In these figures the thicknesses of laminate plies and coatings have been exaggerated.
The reflector shown in Figure 1 comprises a glass ply 1 bearing on its rear face a silver coating 2 which specularly reflects a high proportion of the light which is incident on the coating via the glass ply. A protective coating 3 (which may be a single or plural-layer coating) is applied over the silver coating 2. The coated glass ply is bonded to a metal ply 4 by means of a layer of bonding medium 5.
In certain embodiments the metal ply is thinner than the glass ply (e.g. the metal ply may have a thickness a little in excess of one third of the thickness of the glass ply). Nevertheless the laminate can be flexed to impart to the front face 6 of the glass ply a concave curvature having a radius of 10 m without the rear face of the glass ply becoming subjected to tensile stresses.
Preferably the thicknesses and moduli of the plies and the efficiency of the bond between them are such that the neutral bending planes, that is the planes within the thickness of the laminate in which tensile and compressive stresses become balanced during the bending of the laminate, remain located within the thickness of the metal ply.
As shown in Figure 2 such a reflector can be formed using a metal ply 7 which is larger than the glass ply 8 so that margins of the metal ply project from the edges of the glass and can support a bead 9 of excess bonding medium against the edges of the glass ply to give better resistance to ingress of moisture between the plies.
In order to manufacture a curved reflector according to the invention, after making a flat or substantially flat laminate, for example as represented in Figure 1 or 2, it is flexed to impart a required radius of required radii or concave curvature to the front face of the glass ply. The laminate while in such flexed condition is mounted in a holding device which holds the laminate in flexed condition against the elastic recovery forces in the laminate.
In a laminate according to Figure 1 or 2, the metal ply reduces or avoids tensile stressing of the rear face of the glass ply during the flexing operation, depending on the degree of flexure.
A suitable and very simple form of holding device comprises a frame 10 (Figure 3) with a rebate groove 11 which receives opposed edges of the curved laminate 1 2. The elastic recovery forces urge the opposed edges of the laminate against opposed sides of the frame and the latter is of the correct size for ensuring that in that condition the laminate has the required predetermined cylindrical curvature.
Figure 4 shows a reflector according to the invention having screw adjustment facility whereby the reflector curvature can be adjusted.
The reflector comprises a laminate 13, constructed as described with reference to Figure 2, and a holding device 14 formed by a metal frame. Near each of two opposed edges of the laminate an abutment member is soldered or welded to the metal ply 1 5. The figure shows one of these abutment members 1 6. Each of such abutment members has a tapped hole for receiving a threaded adjustment bolt, such as 1 7. The framework has flanges such as 1 8 against which the extremities of the bolts 1 7 abut and which thereby hold the laminate in curved condition. Its curvature can be adjusted by turning the bolts and these are locked in adjusted position by nuts 1 9.
The composition of the laminate is such that it can be curved to a radius substantially less than 10 metres without the rear face of the glass ply becoming subjected to tensile stresses.
The reflector shown in Figure 4 can be part of a radiant energy concentrator composed of a multiplicity of such reflectors held in appropriately curved condition. For example the frame 1 4 may form part of a larger framework 20 part of which is indicated in broken lines, which has a multiplicity of similar holding locations so that a multiplicity of such laminates can be held in curved condition by the framework.
Referring now to Figure 5, the curved reflector comprises a laminate incorporating a metal ply ,21, a bonding layer 22 and a mirror which comprises glass ply 23 bearing on its rear face a light-reflecting coating and one or more protective coatings located between such light-reflecting coating and the bonding layer 22, such lightreflecting and protective coatings being together designated 24.
The laminate is of elongate rectangular form.
The glass and metal plies have the same width but the metal ply is longer than the glass ply and those plies are bonded together in relative positions such that marginal portions of the metal ply at the opposed ends of the laminate project proud of the corresponding end edge faces of the glass ply.
A very satisfactory laminate composition is one wherein the metal ply is a galvanised steel ply and is bonded to the coated glass ply means of a bonding layer 22 composed of polyvinylbutyral.
The laminate is held in this condition by a holder comprising a back wall 25 and end components such as 26 having flanges 27 which extend over the projecting marginal portions of the steel ply 21 and abut against the corresponding end edge faces of the glass ply 23 so as to prevent the laminate from flattening under the elastic recover forces stored therein as a result of its flexure. The face of the back wall 25 next to the laminate has a curvature corresponding with that imparted to the laminate so that the steel ply is in contact with such wall over its entire length. The end components 26 have a coating 28 of plastics or synthetic rubber in order to prevent damage to the glass ply. There is a clearance between the edges of the metal ply and the holder end components 26 to allow for thermal expansion of such ply.This illustrated construction is very suitable for a solar energy concentrator comprising a multiplicity of individual curved reflectors each composed and held in curved condition as shown in the figure.
In the curved reflector shown in Fig. 6 a laminate according to the invention and comprising a glass ply 29 bearing on one side a light-reflecting coating (not shown) is bonded at that side to a metal ply 30 by means of a bonding layer 31. At opposed ends of the laminate margins of the metal ply project beyond the corresponding edges of the glass ply. Before flexure of the laminate an abutment element such as 32 is secured to each of such margins so as to form buttresses against the opposed edges of the glass ply. For example such abutment elements may be metal elements which are soldered or welded or secured by adhesive to the metal ply. When the laminate is flexed these abutment elements wholly or partially relieve the bonding layer of shear stresses resulting from elastic recovery forces in the glass ply.The laminate is held in curved condition by a holding device similar to that shown in Figure 5 and comprising a backing 33 with end clamps such as 34 which extend over the projecting marginal portions of the metal ply.
Figure 7 shows a laminate according to the invention wherein a glass ply 35 bearing a lightreflecting coating (not shown) on its inner face is bonded by means of a bonding layer 36 to a metal ply 37 which projects beyond the edges of the glass ply at opposed margins of the laminate. On each such projecting margin of the metal ply there is located an abutment element such as 38 in the form of a strip of elastomeric material and those margins of the laminate are enveloped by metal end strips such as 39 of channel form. These channels can be secured in place by clamping forces or by adhesive or in some other manner.
When the laminate is flexed in a direction which imparts a concave curvature to the exposed face of the glass ply about an axis or axes of curvature parallel with the opposed end strips 39, the abutment elements 38, being held firmly against the adjacent edges of the glass ply, releive the bonding layer of shear stresses to a greater or lesser extent.
In a modification of the laminate shown in Figure 7 the metal ply has a polished inner face providing the light-reflecting surface of the laminate and there is no light-reflecting coating on the glass ply.
Various constructions alternative to those shown can be employed. For example there may be a reflector support which has a curved profile or form corresponding with that imparted to the reflector, and to which the reflector is secured by adhesive.
The foliowing are specific examples of laminates according to the invention.
EXAMPLE 1 A laminate as shown in Figure 1 was made by bonding a ply 1 of ordinary untempered glass, 0.75 mm in thickness, to a metal ply 4 formed of galvanised steel and having a thickness of 0.67 mm. Prior to such bonding the glass ply was provided with a light-reflecting coating 2 of silver and a protective coating 3 composed of a layer of copper and a layer of protective paint as used in conventional mirror production.
The coated glass and the metal ply were bonded together by a layer of an epoxy-based adhesive marketed under the Trade Mark "Araldite" by Ciba. It was found that the laminate could be flexed within the elastic limit of the metal to impart to the front face of the glass ply a concave curvature as small as 1 8.5 cm without breakage of the glass. Continued flexing beyond the elastic limit led to breakage of the glass when :the radius of curvature reached 12.5 cm.
Laminates manufactured in that way were used for forming curved mirrors by installing them in flexed condition in holding devices which held the laminates in flexed condition against their elastic recovery forces.
EXAMPLE 2 Laminates were produced as represented in Figure 1 using a glass ply 0.8 mm in thickness, galvanised steel for the metal ply and a hot-melt adhesive for bonding the metal ply to the coated glass. The adhesive layer was 40 microns in thickness and was formed by a hot-melt adhesive comprising ethylene/vinyl acetate. For one laminate the steel ply had a thickness of 1 mm. It was found that the laminate could be flexed down to a radius of curvature of 18 cm. As an alternative to said bonding medium a hot-melt adhesive comprising butyl rubber and wax can be used.
A very satisfactory laminate capable of being flexed without breakage of the glass ply was made, using glass and galvanised steel plies as above specified and a hot-melt adhesive of the following composition: Parts in Weight EVA 607 (ethylene/vinyl acetate copolymer marketed by Union Carbide Corporation) 40 Dylt (polyethylene marketed by Union Carbide Corporation) 5 CKM 2400 (phenolic resin tackifier marketed by Union Carbide Corporation 1 5 Klyrvel 90 (hydrocarbon-based plasticiser and tackifier marketed by Velsicol Chemical Corporation) 7.5 Piccolyte Al 1 5 (polyterpenc-based adhesive marketed by Pennsylvania Ind.
Chem. Corporation) 12.5 Be.Square 130-195 (microstyalline wax marketed by Bareco Division of Petrolite Corporation) 20 Antioxidant 330 marketed by Ethyl Corporation 0.1 EXAMPLE 3 Two laminates A and B were made each comprising a glass ply bonded to a galvanised steel ply. Laminate A comprised a glass ply 0.8 mm bonded by means of a hot-melt adhesive based on copoly (ethylene/vinyl acetate) to 3 steel ply also 0.8 mm in thickness. Laminate B comprised a glass ply 0.75 mm in thickness bonded by means of the epoxy-based adhesive marketed under the Trade Mark "araldite" to a galvanised steel ply 0.75 mm in thickness.
The two laminates were flexed to test their resistance to breakage. It was found that laminate A failed by rupture of the adhesive bond at a curvature of 21 cm. By contrast laminate B rernained unimpaired during flexure until the radius of curvature was reduced to 11.7 cm.
EXAMPLE 4 A curved reflector as represented in Figure 5 comprised a laminate incorporating a galvanised steel ply 21. This steel ply was bonded to a mirror produced by chemically tempering a sheet of glass 0.8 mm in thickness and then applying to such tempered glass a coating of silver and a protective over-coating in accordance with known practice in mirror production. The galvanised steel ply 0.8 in thickness and the mirror were assembled with an intervening polyvinylbutyral foil 0.76 mm in thickness and subjected to heat and pressure to cause the mirror to become firmly bonded over its entire area to the steel ply.The product t,. Em of the resulting laminate was greater than 1.1 x tg . Eg. The laminate was then flexed to make a solar energy concentrator. It was flexed to impart to the front face of the glass ply a radius of curvature of 1.8 metres and was held in this condition by a holding device as shown in the figure. In the flexed condition of the laminate the glass ply was free from tensile stresses. if required it is also possible in the same way to make curved solar energy concentrators having e.g. radii of curvature between 50 cm and 3 metres using similar laminates having a glass ply between 0.6 and 1.2 mm in thickness.

Claims (33)

1. A flexible radiant energy reflector characterised in that the reflector is in the form of a laminate comprising a glass ply bonded over its whole area to a metal ply, said metal ply or a ply coating providing a radiant energy-reflecting surface, and in that the relative thicknesses of the glass and metal plies, their moduli of elasticity and the efficiency of the inter-ply bond are such that that face (hereinafter called "rear face") of the glass ply which is nearer the metal ply is not subjected to tensile forces when the laminate is flexed within the elastic limit of the metal in such manner and to such a degree as to give the front face of the glass ply a concave curvature with a radius of 10 m.
2. A reflector according to claim 1, charscterised in that the relative thicknesses of the glass and metal plies, their moduli cf elasticity and the efficiency of the inter-ply bond are such that the reflector can be flexed sufficiently to reduce the radius of concave curvature of the front face of the glass ply to 1 m without the rear face of the glass ply becoming subjected to tensile forces.
3. A reflector according to claim 2, characterised in that the degree of said flexure can be such as to reduce said radius of curvature to 30 cm without said rear face becoming subjected to tensile forces.
4. A reflector according to any preceding claim, characterised in that the relative thicknesses of the glass and metal plies, their elasticity moduli and the efficiency of the inter-ply bond are such that not only the front face but also the rear face of the glass ply is subjected to compressive stresses when the laminate is flexed to an extent sufficient to reduce the radius of concave curvature of the front face of the glass ply to 10 m.
5. A reflector according to any preceding claim, characterised in that tm. Em > 1.1 x tg. Eg where tm and tg are the thicknesses of the metal ply and the glass ply respectively and E, and Eg are the elasticity moduli of the metal ply and the glass ply respectively.
6. A reflector according to any preceding claim, characterised in that it is between 1.0 and 4.0 mm in thickness.
7. A reflector according to any preceding claim, characterised in that the glass ply has a thickness between 0.6 and 1.0 mm.
8. A reflector according to any preceding claim, characterised in that the metal ply has a thickness less than 3.0 mm.
9. A reflector according to claim 9, characterised in that the metal ply has a thickness of from 0.3 to 2.5 mm.
10. A reflector according to any preceding claim, characterised in that the metal ply is of steel.
11. A reflector according to claim 10, characterised in that the metal ply is a galvanised steel ply.
12. A reflector according to any preceding claim, characterised in that the metal and glass plies are bonded together by means of an adhesive selected from the group: hot-melt, epoxy resin, polyvinylbutyral, polyurethane, acrylic resin and polyvinylchloride adhesives.
13. A reflector according to any preceding claim, characterised in that the glass and metal plies are bonded together by means of a thermoplastics foil, e.g. a polyester foil, bearing a coating of an adhesive, e.g. an acrylic resin adhesive, on each side thereof.
14. A reflector according to any preceding claim, characterised in that it incorporates a radition-reflecting coating which is borne by the glass ply.
1 5. A reflector according to claim 14, characterised in that said coating is on the rear face of the glass ply.
16. A reflector according to any preceding claim, characterised in that the glass ply bears a radiation-reflection coating of silver.
1 7. A reflector according to any preceding claim, characterised in that the metal ply is of such dimensions and is so positioned relative to the glass ply that at least two opposed margins of such metal ply project from the corresponding opposed edges of the glass ply.
18. A reflector according to claim 17, characterised in that said projecting margins support protective deposits of material against corresponding edge faces of the glass ply.
1 9. A reflector according to any preceding claim, characterised in that opposed edges of the glass ply are buttressed to relieve the bonding medium of shear stresses tending to cause delamination when the laminate is flexed.
20. A reflector according to claim 19, characterised in that said opposed edges of the glass ply are buttressed by abutments which are secured to a face of the metal ply at projecting margins thereof.
21. A reflector according to claim 18, characterised in that said opposed edges of the glass ply are buttressed by abutments interposed between such edges and edge strips which are secured to opposed edges of the laminate.
22. A curved reflector characterised in that it comprises a laminate according to any preceding claim, the laminate being held in flexed condition against elastic recovery forces in the laminate by a holding device, the front face of the glass ply being concave.
23. A curved reflector according to claim 22, characterised in that the holding device maintains the laminate in flexed condition by forces transmitted whoily or in part through opposed edge faces of the glass ply.
24. A curved reflector according to claim 22 or 23, characterised in that the holding device extends across the opposed edges of the laminate which are parallel with (an) axis or axes of curvature of the laminate and the device opposes elastic recovery forces in the laminate by bearing directly or through interposed bearing elements against the corresponding edges of the glass ply or against those edges and against the corresponding edges of the metal ply.
25. A curved reflector according to claim 24, characterised in that the margins of the metal ply which include said edges thereof project beyond the corresponding edges of the glass ply.
26. A curved reflector according to any of claims 22 to 25, characterised in that the holding device and the laminate have co-operating abutments via which the elastic recovery forces in the laminate are transmitted to the holding device to hold the laminate in curved condition and the abutments on the laminate and/or the holding device are screw-adjustable for adjusting the curvature of the laminate.
27. A curved reflector according to any of claims 22 to 26, characterised in that said laminate is one of a plurality of laminates which are installed and held in curved condition so that the inaividual laminates form constituent parts of a larger curved reflector.
28. A method of making a curved radiant energy reflector characterised in that a glass ply is bonded to a metal ply to form a laminate having a radiant energy reflecting surface which is formed by said metal ply or by a ply coating, forces are applied to impart to the laminate a curvature such that the front face of the glass (i.e. its face which is remote from the metal ply) is concave, and the curved laminate is installed in a holding device which holds the laminate in curved condition, against elastic recovery forces in the laminate.
29. A method according to claim 28, wherein said glass ply bears a radiant energy-reflecting coating on its face which becomes covered by the metal ply.
30. A method according to claim 28 or 29, characterised in that the relative thicknesses of the glass and metal plies, their elasticity moduli and the efficiency of the inter-ply bond are such that the rear face of the glass ply is not subjected to tensile stresses by the flexing of the laminate.
31. A method according to claim 30, characterised in that the relative thicknesses of the glass and metal plies, their elasticity moduli and the efficiency of the inter-ply bond are such that both the front face and the rear face of the glass ply are subjected to compressive stresses by the flexing of the laminate.
32. A method according to any of claims 28 to 31, characterised in that the laminate is held to a radius of curvature of 10 metres or less.
33. A method according to any of claims 28 to 32, characterised in that the laminate is a reflector according to any of claims 1 to 21.
GB8003733A 1979-02-09 1980-02-05 Optical reflectors Expired GB2042761B (en)

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Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5835360A (en) * 1981-08-21 1983-03-02 グラヴルベル Composite mirror panel
DE3216845A1 (en) * 1981-08-21 1983-03-03 Glaverbel, 1170 Bruxelles COMPOSITE MIRROR ARRANGEMENT
JPS5953304U (en) * 1982-09-29 1984-04-07 日本板硝子株式会社 Reflector
WO1995008785A1 (en) * 1993-09-22 1995-03-30 Hellmuth Costard Concave mirror
WO1996027771A1 (en) * 1995-01-26 1996-09-12 Myles John F Iii An improved solar energy concentrating system having replaceable reflectors
WO2007108837A1 (en) * 2006-03-23 2007-09-27 Centre Luxembourgeois De Recherches Pour Le Verre Et La Ceramique S.A. (C.R.V.C.) Method of making reflector for solar collector or the like and corresponding product
WO2009080741A2 (en) * 2007-12-21 2009-07-02 Agc Flat Glass Europe Sa Solar energy reflector
WO2010074748A1 (en) * 2008-12-23 2010-07-01 Eastman Kodak Company Multilayer devices on flexible supports
US7871664B2 (en) 2006-03-23 2011-01-18 Guardian Industries Corp. Parabolic trough or dish reflector for use in concentrating solar power apparatus and method of making same
US8454177B2 (en) 2011-02-16 2013-06-04 Toyota Motor Engineering & Manufacturing North America, Inc. Low cost parabolic solar concentrator and method to develop the same
WO2013135757A1 (en) * 2012-03-13 2013-09-19 Termopower, S.L Heliostat facet and procedure for making the same
WO2013171423A1 (en) * 2012-05-14 2013-11-21 Helioclim Method for shaping a film of a material that has low resistance to traction, and mirror comprising such a film
US8596802B2 (en) 2011-05-11 2013-12-03 Toyota Motor Engineering & Manufacturing North America, Inc. Adjustable reflector for directing energy to a receiver
WO2013013661A3 (en) * 2011-07-28 2014-04-03 Grenzebach Maschinenbau Gmbh Method and device for producing mirror units for heliostats
US9188714B2 (en) 2011-02-16 2015-11-17 Toyota Motor Engineering & Manufacturing North America, Inc. Method and apparatus to control a focal length of a curved reflector in real time
US9568653B2 (en) 2012-05-03 2017-02-14 3M Innovative Properties Company Durable solar mirror films
US9804305B2 (en) 2012-01-31 2017-10-31 3M Innovative Properties Company Methods for sealing the edges of multi-layer articles

Cited By (29)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5835360A (en) * 1981-08-21 1983-03-02 グラヴルベル Composite mirror panel
DE3216844A1 (en) * 1981-08-21 1983-03-03 Glaverbel, 1170 Bruxelles COMPOSITE MIRROR ARRANGEMENT AND METHOD FOR THE PRODUCTION THEREOF
DE3216845A1 (en) * 1981-08-21 1983-03-03 Glaverbel, 1170 Bruxelles COMPOSITE MIRROR ARRANGEMENT
FR2526552A1 (en) * 1981-08-21 1983-11-10 Glaverbel
JPH0548443B2 (en) * 1981-08-21 1993-07-21 Glaverbel
JPS5953304U (en) * 1982-09-29 1984-04-07 日本板硝子株式会社 Reflector
WO1995008785A1 (en) * 1993-09-22 1995-03-30 Hellmuth Costard Concave mirror
WO1996027771A1 (en) * 1995-01-26 1996-09-12 Myles John F Iii An improved solar energy concentrating system having replaceable reflectors
EP0805940A1 (en) * 1995-01-26 1997-11-12 Myles, John F. III An improved solar energy concentrating system having replaceable reflectors
EP0805940A4 (en) * 1995-01-26 1999-04-21 John F Myles Iii An improved solar energy concentrating system having replaceable reflectors
WO2007108837A1 (en) * 2006-03-23 2007-09-27 Centre Luxembourgeois De Recherches Pour Le Verre Et La Ceramique S.A. (C.R.V.C.) Method of making reflector for solar collector or the like and corresponding product
US8585225B2 (en) 2006-03-23 2013-11-19 Guardian Industries Corp. Parabolic trough or dish reflector for use in concentrating solar power apparatus and method of making same
US8303124B2 (en) 2006-03-23 2012-11-06 Guardian Industries Corp. Parabolic trough or dish reflector for use in concentrating solar power apparatus and method of making same
US7871664B2 (en) 2006-03-23 2011-01-18 Guardian Industries Corp. Parabolic trough or dish reflector for use in concentrating solar power apparatus and method of making same
WO2009080741A3 (en) * 2007-12-21 2011-02-24 Agc Glass Europe Solar energy reflector
US9322575B2 (en) 2007-12-21 2016-04-26 Agc Glass Europe Solar energy reflector
US9752799B2 (en) 2007-12-21 2017-09-05 Agc Glass Europe Solar energy reflector
WO2009080741A2 (en) * 2007-12-21 2009-07-02 Agc Flat Glass Europe Sa Solar energy reflector
WO2010074748A1 (en) * 2008-12-23 2010-07-01 Eastman Kodak Company Multilayer devices on flexible supports
US9188714B2 (en) 2011-02-16 2015-11-17 Toyota Motor Engineering & Manufacturing North America, Inc. Method and apparatus to control a focal length of a curved reflector in real time
US8454177B2 (en) 2011-02-16 2013-06-04 Toyota Motor Engineering & Manufacturing North America, Inc. Low cost parabolic solar concentrator and method to develop the same
US8596802B2 (en) 2011-05-11 2013-12-03 Toyota Motor Engineering & Manufacturing North America, Inc. Adjustable reflector for directing energy to a receiver
WO2013013661A3 (en) * 2011-07-28 2014-04-03 Grenzebach Maschinenbau Gmbh Method and device for producing mirror units for heliostats
US9315005B2 (en) 2011-07-28 2016-04-19 Grenzebach Maschinenbau Gmbh Method and device for producing mirror units for heliostats
US9804305B2 (en) 2012-01-31 2017-10-31 3M Innovative Properties Company Methods for sealing the edges of multi-layer articles
WO2013135757A1 (en) * 2012-03-13 2013-09-19 Termopower, S.L Heliostat facet and procedure for making the same
US9568653B2 (en) 2012-05-03 2017-02-14 3M Innovative Properties Company Durable solar mirror films
US9998070B2 (en) 2012-05-03 2018-06-12 3M Innovative Properties Company Durable solar mirror films
WO2013171423A1 (en) * 2012-05-14 2013-11-21 Helioclim Method for shaping a film of a material that has low resistance to traction, and mirror comprising such a film

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Effective date: 19950205