FR2666475A1 - HEATED MIRROR. - Google Patents

Abstract

The invention relates to a laminated heated mirror comprising a first sheet of glass laminated by its face bearing the specular coating to a second sheet of glass by means of an adhesive polymer. The second sheet is laminated to the first by a face carrying an electrically conductive layer provided with current collectors (8, 9). An electrically conductive element (12) passes from its region of contact with its respective collector (8), inside the polymer, to a single connection region (13) located at the periphery of the mirror, and the edge of the mirror is surrounded by electrically insulating material (20). The heated mirror according to the invention is particularly useful as an auxiliary heater for a bathroom.

Description

1.

Heating mirror.

  The present invention relates to a laminated heating mirror comprising a specular coating deposited on a first sheet of glass which is laminated by its face bearing the coating to a second sheet of glass

  by means of an interposing polymeric adhesive material.

  s The known heating mirrors include a heating network, which

  extends over most of the surface of the mirror, in which a circula-

  The heat is distributed over the entire surface of the mirror so that each point of the surface accessible to the touch is at a temperature not too high to avoid any

  danger of burning Heated mirrors perform two different functions.

  In addition to their primary function of reflecting light rays like any mirror, they also emit heat A classic example is that of heated bathroom mirrors in which a slight heating is provided for

  remove the fog that forms on the front of the mirror.

  When these heating mirrors are powered by a source of

  electric current at very low voltage, for example 24 V, they do not

  no danger to people and in particular no danger of electro-

  However, the power supply at very low voltage, in homes, requires a transformation of the mains voltage, which leads to the presence of additional equipment expensive and cumbersome Moreover, if the necessary heating power is relatively the very low voltage supply requires the circulation of a high intensity electric current, which

  problems of electrical connection and sufficient size of collectors.

  Powering heating mirrors under mains voltage

  typical, for example 220 V, reduces the intensity of the electric current of

  tation, but requires electrical safety control for users.

  This can create difficulties when the heating mirror has to release enough

  heat to give a comfortable temperature to a room and function

  in a humid environment, such as a bathroom.

  The known heating mirrors do not meet the stringent safety standards that currently govern the field of electricity use.

humid environment.

  The object of the present invention is a heating mirror which has 2.

  high protection against electric shock.

  The invention relates to a laminated heating mirror comprising a specular coating deposited on a first sheet of glass which is laminated by its side bearing the coating to a second sheet of glass by means of an interposing polymeric adhesive material, characterized in that the second sheet of glass is laminated to the first sheet by a face which carries at least one electrically conductive layer provided with connected current collectors

  each to a conductive element of electricity to constitute a heating circuit

  fant adapted to be connected to a power source, in that at least one of said conductive elements (hereinafter referred to as "first conductive element") passes from its contact region to its respective collector to the immediate vicinity the end of the other conductive element in a single connection area located at the periphery of the mirror, along a path that is inside the polymeric material and in that the polymeric material and the

  heating circuit are surrounded by electrically insulating material.

  The heating mirror according to the invention facilitates the electrical connection

  to the power supply in good safety conditions by the fact that the two power supply son can be connected in the same area since the connecting end of the two conductive elements are in the immediate vicinity of one another , which facilitates connection by means of a single power cord with double electrical insulation The entire electrical circuit is isolated inside the laminated panel In addition, the presence of electrically insulating material which covers the edge of the polymeric material and which extends along the periphery of the laminate contributes to the realization of additional insulation It is thus possible to form an electric heating circuit having a heating surface as large as possible relative to the surface of the laminate and having a double electrical insulation On the other hand, by the fact

  conductive layer and the entire electrical circuit, except for the

  mites connecting the two conductive elements, are sandwiched inside the laminated assembly formed by the two sheets secured by the polymer material, electrical safety can be retained even in case of breakage

  leaves as the pieces will be held in place by the polymeric material.

  The term "double insulation" is used in this description.

  meaning of the presence of additional independent insulation, in addition to functional or main insulation, in order to

  protection against electric shock in case of failure of the functional isolation

  Functional or main insulation is the insulation necessary to ensure the proper functioning of the apparatus and the fundamental protection

  people against electric shocks.

  it is surprising to be able to manufacture a laminated assembly according to the

  usual technique while the heating circuit and the electric circuit of

  s are sealed inside the laminate, while providing a laminated mirror

  high quality optical and mechanical.

  it is also surprising to obtain a laminated assembly which does not delaminate during the operating and accelerated aging tests, whereas it comprises elements consisting of materials with coefficient of expansion

  different thermal and heating area as large as possible.

  The path arrangement of the conductive element within the surrounding polymeric material facilitates electrical isolation, particularly

  reflective coating of the mirror, which is also electrically conductive

  In all cases, this arrangement of the path of the conductive element favors

  the leafing of the leaves to form the mirror.

  The connection zone intended for the electrical connection may be, for example, in the center of one of the sides of the mirror, if it is of polygonal shape. The mirror may also be in the shape of a circle and the zone

  connection will therefore be located at a location in the circumference.

  However, the mirror is rectangular, the collectors extend along two opposite sides of the rectangle, and the said connection area is located in a corner of the mirror With the aid of a simple electrical circuit, only the first conductive element must pass through the polymer material and follow a relatively long path inside the laminate to transfer the electric current between the corresponding collector and the connection area, since one end of the other collector

  can directly end up near the corner, so that its element

  Corresponding driver can be very short.

  In this embodiment, at the location of the said zone of

  cord, the corner of one of the glass sheets is preferably cut to

  putting the passage of the supply son, and the connection thereof to said conductive elements is embedded in an insulating material The connection

  electrical system is thus facilitated and double electrical isolation of

  nexion can be more easily established with an acceptable aesthetic appearance can for example glue a piece of glass that covers the insulating material,

  to complete the double electrical insulation.

  Preferably, at least said conductive element comprises a flat metal strip, which is advantageously a Cu strip, which allows 4.

  the passage of a high intensity of electrical current without extra thickness

  The collectors can be formed using a conductive lacquer, for example a silver lacquer, deposited by screen printing, and the conductive element formed by the Cu strip is brought into electrical contact with this conductive lacquer A notch is made in the film of polymeric material to pass the copper strip forward.

the lamination operation.

  The conductive layer may be uniformly deposited over the entire surface of a glass sheet and, to facilitate the electrical isolation of the slices of the laminate, a groove may be formed in the conductive layer all along the periphery, for example mm from the edge, so as to electrically isolate the marginal portion from the remainder of the layer It is preferred, however, that the surface of the sheet carrying said conductive layer has a marginal zone greater than 5 min, devoid of any conductive material, which extends The high electrical insulation of the slice of the laminate is thus more easily obtained and preserved over time, especially in a humid environment. It is advantageous to leave a marginal zone up to, for example, 2 cm devoid of any electrically conductive material all around the periphery of the sheet For this, we can deposit uniformly the layer con duct on the entire surface of the sheet, then remove the marginal part, for example using an abrasive wheel can also have a cache on the

  marginal part of the sheet before depositing the layer, for example by spraying

  This cover prevents the formation of the layer on the glass at the place where it is placed. It is for example formed of an adhesive strip or a paint which

  crumbles under the action of heat.

  Preferably, the conductive layer extends to a zone 2 cm from the edge of the mirror substantially along its entire periphery. This is particularly the case with heating mirrors of relatively high heat output, because this arrangement contributes to preventing the edges of the mirror are the seat of

  thermal shocks due to high temperature gradients.

  The conductive layer may for example consist of a doped tin oxide layer. The doped tin oxide may form, on a glass sheet, a very hard heating layer that can be easily obtained in a known manner. The pyrolysis layer is highly resistant to handling and, therefore, to lamination operations. However, pyrolysis coating techniques may in certain circumstances have a detrimental effect on the flatness of the coated sheet, and this in turn may adversely affect 5. Such a conductive layer may alternatively be formed of metal deposited by chemical or electrochemical methods.

  that the conductive layer is formed by cathodic sputtering of metal.

  Such a layer may, for example, be made of gold, silver or copper.

  Such a technique makes it possible to maintain the flatness of the sheet after the deposit.

  Such a technique also makes it possible to form strongly adherent layers, and such layers can easily be adjusted in thickness, so as to easily control the resistivity of the layer. To obtain the best resistance to corrosion, it is particularly preferred to use a coating of However, a thickness of nm is very effective. Such a gold coating can be associated with one or more other layer (s) to confer special properties. optical or other, if desired; such a coating of gold can for example be taken in

  sandwich between two layers of bismuth oxide.

  If such a coating is deposited on a chemically toughened glass sheet, as is preferred, the sheet may then be thinner while maintaining a given strength, and this is advantageous for

obtaining a light mirror.

  Preferably, the reflective coating is deposited on a first

  first sheet of glass and is formed of a silver-based layer and / or copper which is electrically insulated from the conductive layer carried by another sheet by means of a heat-resistant protective paint and said material

  Polymer Heat Resistant Paint Improves Resistance to Aging

  The mirror assembly provides protection for the reflective coating despite the increased temperature of the laminated assembly. The paint and polymer material assembly also provides adequate insulation of the electrical heating circuit. Advantageously, the two glass sheets have undergone a strengthening treatment of their mechanical strength It may be for example a curing heat treatment These sheets thus more easily resist the thermal shock created by a projection of drops of cold water on their surface when the latter is hot, which further improves the electrical safety by preserving the integrity of the laminate Preferably, the glass sheet bearing the reflective coating is a glass sheet having undergone chemical quenching treatment. of glass carrying the reflective coating is a front sheet of the installed mirror since the primary function of a mirror is the specular reflection of the light so as to generate a reflection of that of a face 6. for example Chemical quenching gives the sheet of glass a very high impact resistance allowing it to withstand mechanical and thermal shock might apply Furthermore, the chemical tempering can be performed on a thin sheet, which favors the formation of a lighter mirror, and can much less likely s have a detrimental effect on the flatness of the glass sheet

  a quenching or thermal curing treatment.

  Preferably, the glass sheet carrying the reflecting coating has a thickness of less than 3 mm, for example 2 mm. This small thickness

  limits the thermal insulation formed by the front glass sheet.

  Preferably, the glass sheet carrying the conductive layer is a chemically quenched glass sheet. This quenching treatment has no negative effect on the flatness of the glass sheet, and therefore on the flatness of the laminate. Preferably, the mirror according to the invention comprises, on its external face, on the side not reflecting the light specularly, a low emissivity layer. The dorsal surface of the mirror being weakly emissive, it is thus possible to reduce thermal losses, by radiation to the wall on which the mirror is fixed Alternatively or in addition, the back of the mirror may be covered with a layer of thermal insulation If a foam is used, it will preferably be a closed-cell foam, to resist the moisture penetration Extruded polyethylene foam approximately 1 cm thick is suitable

  The edge of the mirror is preferably covered at least partially with

  Electrically insulating and watertight material to prevent the entry of moisture between the sheets. This seal improves the resistance over time, under wet conditions of use, of the electrical insulation between the conductive layer and the membrane. slice of the laminate can advantageously use a seal to

silicone base.

  In a first embodiment, the mirror according to the invention is surrounded by a metal frame, for example aluminum, or plastic, for example PVC The presence of electrically insulating material

  along the periphery of the laminate provides double insulation allowing the use

  However, special attention will be paid to maintaining a double electrical insulation of the connection area with respect to the frame. The space between the frame and the edge of the laminate can be used to improve the resistance. to the penetration of moisture, as explained

  above, by placing a seal.

  In a second embodiment, the sheet bearing the coating

  7. Reflective ment is larger than another sheet that is secured to it by leaving a margin all along the periphery of the mirror In this embodiment, the mirror has no frame and can therefore be made of a

  more economical way The margin can be lined with a self-rigid foam

  sticky material made of plastic, for example a polyurethane foam, and the

  between this edge and the edge of the laminate will be filled with the seal of electrically insulating material, preferably a watertight material, such as

silicone for example.

  Preferably, the heating power of the mirror according to the invention is greater than 500 W / m 2, and advantageously greater than 700 W / m J Such a heating power makes it possible to use the mirror according to the invention to ensure the

  heating, or auxiliary heating, a small room such as a bathroom.

  A power of 800 W / m 2 advantageously ensures this heating without risk of

  cause a dangerously high surface temperature of the frontier face

  The adaptation of the resistivity of the conductive layer to obtain the desired specific power can be easily achieved, depending on the dimensions of the mirror, by adjusting the thickness of this layer, for a given composition layer. also easily modify the specific conductivity by modifying the doping if the layer is formed by a semiconductor such as

  tin oxide A third possibility is to configure the conductive layer

  trice in the form of a network to limit the width and increase the length of the path of the heating current By combining these three adjustment possibilities,

  it is possible to vary the total resistance of the heating element.

  The collectors can be formed by spraying Cu with flame, either directly on the glass before depositing the layer, or after deposition of the layer. Advantageously, at least one of the collectors is formed by two bands of electrically conductive lacquer superimposed between which one edge

  of the conductive layer is sandwiched This arrangement makes it possible to obtain

  high electrical conduction which is conserved over time despite the circulation of a relatively intense current In addition, the conductive lacquer

  can easily be applied according to the current technique of screen printing.

  The present invention will now be described, by way of example only, with reference to the accompanying figures in which: Figure 1 is a partial plan view of the back face of an embodiment of the heating mirror according to the invention; Figures 2 and 3 are partial sections of the heating mirror according to Figure 1 viewed from the positions indicated by lines A-A 'and B-B' in 8. Figure 1; Figure 4 is a perspective view of a corner of the mirror of Figure 1 before its frame and before depositing the insulating material on the edge of the intermediate polymer material; and FIG. 5 is a partial sectional view of another embodiment

  of the heating mirror according to the invention.

  The heating mirror shown in FIGS. 1 to 4 comprises a set

  laminated film 1 consisting of a glass sheet 2, bearing an opaque metal coating 3 specularly reflecting light, laminated to a glass sheet 4 by means of an intermediate polymer material formed of two films 5 and it should be noted that the drawings are not to scale. It should also be noted that the two films 5 and 6 of intercalary polymeric material are drawn apart for ease of understanding, whereas in the finished laminate these films are substantially The glass sheet 4 carries a conductive layer 7 extending between two collectors 8 and 9. The collector 8 is formed by a strip of conductive lacquer 10 deposited on the edge of the conductive layer 7. the embodiment shown, the first conductive element of electricity

  is formed by a strip of Cu, one end of which extends over the entire length of

  8 and is held in electrical contact to increase the electrical conductivity of the collector, and which extends, in the form of the strip 12, to a connection zone 13. In this embodiment, the connection zone 13 is located in a corner of the mirror The strip 12 of the first conductive element passes through the sheet 6 of polymeric material at the location indicated by the reference 14 in Figure 1 and follows a path between the films 5 and 6 of polymeric material as shown in FIG. 3, thus located inside the laminate, up to the single connection zone 13. The electrical connection of the collector 8 is thus effected, via the strip 12 of the first conductive element, in the same connection zone 13 as the electrical connection of the collector 9 The collector 9 is also formed of a strip of lacquer on which an electric strip of Cu has been placed in electrical contact, which extends over the entire

  length of the collector, to increase the electrical conductivity of the collector.

  This Cu strip extends in the form of the conductive element 30 to the connection zone 13. The double insulated power supply cord 15, comprising two conducting wires, is connected to the strip 12 of the first conductive element and to the second conductive element 30, to this zone of

connection 13.

9.

  In FIG. 4, it can be seen that, at the location of the connection zone,

  13, the glass sheet 4 has a cut-off corner to allow the connection

  The Cu strip contacted with the collector 9 extends beyond the collector 9 beyond the cut in the corner of the sheet 4, in the form of the conductive element 30, to allow the electrical connection. in the connection zone 13 After connection, the recess is then filled with an insulating material 16 such as ARALDITE (brand

  commercial), which also keeps the end of Cu straps fixed.

  To achieve double electrical insulation, a small sheet of

  glass 17 4 mm thick can be glued above this area 13.

  In the embodiment of Figures 1 to 3, the laminate 1 is surrounded by a frame 18, for example aluminum or PVC, and the space between the slice 19 of the laminate 1 and the frame 18 is filled with an electrically insulating and watertight adhesive material 20, such as, for example, silicone. For the understanding of the drawing, this insulating material 20 has not been shown in FIG. 4. In FIG. broken lines,

  fasteners 21 for fixing the mirror on a wall.

  By way of specific example, the sheet 2 is a 2 mm thick glass sheet which has undergone a chemical quenching treatment. The reflective coating 3 is formed by silvering in a manner known per se and comprises a

  layer of silver, a layer of copper and a layer of protective paint.

  In this specific example according to the invention, the protective paint is a thermosetting heat-resistant paint sold under the trademark

  TRIGANUIE "and marketed by the company" Pearl Paint "The poly-

  The mother is formed of two films 5 and 6 0.38 mm thick PVB The sheet 4 is a 4 mm thick glass sheet The conductive layer 7 is a doped Sn O 2 layer with a thickness of about 70 nm obtained by pyrolysis

  Conductive lacquer 10 is a cold-hardening silver lacquer.

  To improve the electrical conductivity of the collectors, it is possible to deposit a strip 31 of lacquer with baked silver (shown in broken lines in FIG. 2) before depositing the layer Sn O 2 A at the collectors, the layer Sn O 2 is thus sandwiched between two strips 10 and 31 of conductive lacquer. In this case, for example, two strips of conductive lacquer are deposited by serigraphy on the glass sheet 4 at the location of the collectors and this sheet of film is heated. glass in an oven This conductive lacquer is fired At the exit of the oven, the Sn O 2 layer is deposited and the glass sheet is rapidly cooled, by blowing

  of cold air, so as to obtain thermally hardened glass.

  10. The strips of cold-hardening conductive lacquer are then deposited.

  and applying the Cu strip before proceeding with the lamination operation.

  In this specific example, the laminate 1 is a rectangle of 1183 mm by 683 min, the resistance per square of the heating layer is 143 ohm s and its total resistance is 82 ohm The specific heating power of the layer is 800 W / m 2 and the power dissipated by the laminated layer 1 is 600 W The temperature of the end face does not exceed 60 ° C. In order to prevent this temperature from being exceeded accidentally, it is possible to place a temperature limiter (not shown on the FIGS. figures) It is a small plastic case of 50 x 50 x 15 mm, double electrical insulation, containing a bimetallic strip which cuts the power supply circuit for example to 60 WC and restores it for example to 400 C This box is stuck on the outer face of the glass sheet 4, close to the connection zone 13 The power cord 15 is connected to this housing and this housing is connected to the power supply sector.

current.

  The glazing according to this embodiment has successfully passed the safety tests for an electric heating system operating in a humid atmosphere and in particular the insulation resistance and dielectric strength test at a voltage of 3,750 V. As a variant of this The glass sheet 4 is a 2 mm thick chemically tempered glass sheet. The conductive layer comprises three layers: a 6 nm thick bismuth oxide underlayer, a gold layer and a layer of The thickness of the gold layer is such that it provides a resistivity of about 12 ohms per square, or about 16 nm. A tellechain of gold is deposited on a sheet measuring 1183 mm × 683 mm in two spaced parallel strips, each having an effective surface between collectors of about 1150 mm × 330 mm. The strips are connected to a side edge of the panel by means of a collector. mun, and they are supplied with heating current by two separate collectors each running along about half

  the opposite side edge of the panel The resulting heating panel has a resistance

  The collectors 8, 9 are in this case made of copper strips which are glued to the conductive layers by means of a conductive adhesive, and extend through the polymeric material to a zone.

common connection.

  In another variant of the specific example described above, the collectors 8 and 9 were formed by Cu strips obtained by sputtering Cu of flame. In this example, the silver-based conductive lacquer has been omitted, as well as the end 11 of the first conductive element The latter is therefore formed by the strip 12 which is a Cu strip welded to the end of the

collector 8.

  In the embodiment of FIG. 5, the heating mirror has no frame. The reflective coating 21 is deposited on a sheet of glass 22 which has been chemically toughened. The conductive layer 23 is carried by the sheet 24 of heat-hardened glass. 22 and 24 are joined together by laminating with a polymeric material in the form of two films 25 and 26. The glass sheet 24 is smaller than the sheet 22 so as to leave a margin

  27 This margin 27 is lined with a strip of self-adhesive foam 28

  urethane and the space between the strip 28 and the edge of the sheet 24 is filled with an electrically insulating and waterproof adhesive material 29, for example

silicone.

  This embodiment has also successfully passed electrical insulation tests for humid environment Its structure is lighter and it meets a certain demand, aesthetically, for unframed mirrors. The exemplary embodiments shown in FIGS. 1 and 5 show a preferred solution in which the conducting layer 7, 23 has a surface area

  less than that of sheet 4, 24 which carries it. The edge of the conductive layer

  trice is thus isolated both by the intermediate polymer material and the material

sealing seal 20, 29.

12.

Claims (12)

claims   A laminated heating mirror comprising a specular coating deposited on a first sheet of glass which is laminated by its side bearing the coating to a second sheet of glass by means of an interposing polymeric adhesive material, characterized in that the second sheet of glass ( 4, 24) is laminated to the first sheet (2, 22) by a face which bears at least one layer   conductor (7, 23) provided with current collectors (8, 9) connected   each to an electrically conductive element (11-12, 30) for constituting a heating circuit for connection to a power supply, in that at least one of said conductive elements (11-12) (hereinafter referred to as "first conductive element") passes from its contact region with its respective collector (8) to the immediate vicinity of the end of the other conductive element (30) in a single connection zone (13). ) located at the periphery of the mirror, along a path that is inside the polymeric material (5, 6, 25, 26) and   the polymer material and the heating circuit are surrounded by electrically insulation (20, 29).   Heating mirror according to Claim 1, characterized in that the mirror is rectangular and the collectors (8, 9) extend along two opposite sides of the rectangle and in that the said connection zone (13) is situated in a corner of the mirror.   3 heated mirror according to claim 2, characterized in that at the location of said connection area, the corner of one of the glass sheets (4) is cut to allow the passage of the supply son (15) , and the connection thereof to said conductive elements (12, 30) is embedded in a material insulation (16).   Heating mirror according to one of Claims 1 to 3, characterized   in that at least said first conductive element (11-12) comprises a ribbon   flat metal, preferably a flat copper ribbon.   Heating mirror according to one of Claims 1 to 4, characterized   in that the surface of the sheet (4, 24) bearing said conductive layer (7, 23) has a marginal area greater than 5 mm devoid of any material   conductive, which extends substantially along its entire periphery.   Heating mirror according to one of Claims 1 to 5, characterized   in that the conductive layer (7, 23) extends to an area of 2 cm from the edge   of the mirror substantially over its entire periphery.   Heating mirror according to one of claims 1 to 6, characterized 13.   in that the conductive layer (7, 23) is a layer of gold.   Heating mirror according to one of Claims 1 to 7, characterized   in that the reflective coating (3, 21) is deposited on a first glass sheet (2, 22) and is formed of a silver-based and / or copper-based layer which is electrically insulated from the conductive layer (7, 23) carried by another sheet of glass (4, 24) by means of a heat-resistant protective paint and the   said polymeric material (5, 6, 25, 26).   Heating mirror according to one of Claims 1 to 8, characterized   in that the two glass sheets (2, 4, 22, 24) have undergone a reinforcing treatment   their mechanical strength, preferably a chemical quenching treatment. Heating mirror according to Claim 9, characterized in that the glass sheet (2, 22) carrying the reflecting coating (3, 21) has a thickness less than 3 mm.   Heating mirror according to one of Claims 1 to 10, characterized   in that it comprises, on its external face situated on the side that does not reflect the   specularly light, a low-emissivity layer.   Heating mirror according to one of Claims 1 to 11, characterized   in that its wafer is at least partially covered with electrical material   insulating and waterproof (20, 29).   Heating mirror according to one of Claims 1 to 12, characterized   in that the sheet (22) carrying the reflective coating (21) is larger than another sheet (24) which is secured thereto leaving a margin all along from the periphery of the mirror.   Heating mirror according to one of Claims 1 to 13, characterized   in that its heating power is greater than 500 W / m 2, and preferably greater than 700 W / m   Heating mirror according to one of Claims 1 to 14, characterized   in that at least one of the collectors (8) is formed by two strips of electrically conductive lacquer (10, 31) superimposed between which an edge of the   conductive layer (7) is sandwiched.