Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B3/00—Ohmic-resistance heating
  • H05B3/84—Heating arrangements specially adapted for transparent or reflecting areas, e.g. for demisting or de-icing windows, mirrors or vehicle windshields
  • H05B3/845—Heating arrangements specially adapted for transparent or reflecting areas, e.g. for demisting or de-icing windows, mirrors or vehicle windshields specially adapted for reflecting surfaces, e.g. bathroom - or rearview mirrors
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B2214/00—Aspects relating to resistive heating, induction heating and heating using microwaves, covered by groups H05B3/00, H05B6/00
  • H05B2214/02—Heaters specially designed for de-icing or protection against icing

Definitions

• the present invention relates to a heated mirror. Its most widespread but not exclusive applications are in the automotive field and in the field of transportation in general as rear-view mirrors. Background Art
• Rear-view mirrors manufactured with conventional technologies in fact are affected, especially during the winter period, by the inconvenience of misting or, worse still, frosting and icing on their external surface.
• the resistive element substantially consists of a coil formed by an electric conductor which is applied to the rear of the reflective surface and has, at its ends, terminals for connection to an electric power source.
• the reflective surface does not have per se particular conductive characteristics and is unable to independently generate the heat required to demist the mirror; said heat must instead be supplied by the resistive element.
• the reflective layer regardless of its position (at the front or at the rear), can actually be a hindrance to the flow of heat: it is in fact an interface which has different physical characteristics with respect to glass, and it is necessary to take this additional layer into account as regards heat transmission.
• the heating time is therefore obviously longer with respect to a system which has no additional layers between the heating system and the surface to be heated.
• the heat generated by the resistive coil can, over time, degrade the characteristics of the adhesive of the film, no longer ensuring good thermal contact between the glass and the conductive film; accordingly, the efficiency of the entire heating system can be compromised and degraded over time. Disclosure of the Invention
• the aim of the present invention is to provide a mirror which allows to perform defrosting and/or demisting in a time which is not longer than achieved with conventional mirrors.
• an object of the present invention is to provide a heated mirror which is capable of ensuring excellent viewing of the reflected image and, in case of strong lighting, for example in the presence of headlights, better visibility than conventional mirrors.
• Another object of the present invention is to provide a heated mirror which ensures good heating uniformity on the entire surface thereof.
• a further object of the invention is to provide a heated mirror which can be manufactured in a shorter time than conventional models and by means of simpler and quicker assembly steps.
• a further object of the invention is to provide a heated mirror which can be manufactured at very low costs.
• a further object of the invention is to provide a heated mirror which allows to vary the coloring of the reflective surface thereof.
• a further object of the present invention is to provide a heated mirror which ensures a longer life time than conventional mirrors.
• a further object of the invention is to provide a heated mirror in which deterioration of the reflective surface caused by the action of weather is prevented.
• a further object of the present invention is to provide a heated mirror which ensures good electric and optical characteristics over time.
• a further object of the invention is to provide a heated mirror which can operate even with very low temperatures (down to -50°C).
• a still further object is to provide a heated mirror which has a lighter structure than conventional models and at the same time has a higher mechanical strength, thus reducing the risk of breakage due to impact.
• a heated mirror characterized in that it comprises a glass body on one face whereof a film of an electrically conductive metal is deposited so as to form an actual reflective surface, two conductive busbars being associated with said metal film and being suitable to allow the flow of an electric current in said film.
• Figure 1 is a sectional view of a first embodiment of the mirror according to the invention, with the heating coating applied on the glass body of the mirror, at the side whereon the rays of light are directly incident;
• Figure 2 is a sectional view of a second embodiment of the mirror according to the invention, with the heating coating applied on the glass body of the mirror, at a side which is opposite to the one whereon the rays of light are incident;
• Figure 3 is a cross-sectional view of the mirror according to the invention, with the conductive elements arranged according to a first embodiment
• Figure 4 is a cross-sectional view of the mirror according to the invention, with the conductive elements arranged according to a second embodiment. Ways of carrying out the invention
• a heated mirror according to the present invention comprises a glass body 1 which in this case has a planar structure and which, in this constructive solution, has a reduced thickness of approximately 1-2 mm.
• the planar glass body 1 can be conveniently curved with currently used methods in order to obtain a mirror which has a cylindrical, spherical or aspheric shape.
• two conductive busbars 3 are provided, of a per se known type, obtained by means of a per se known screen-printing process, using silver paste in this case.
• the screen-printed silver paste that constitutes the pair of busbars 3 is preferably dried by means of a thermal treatment in order to improve the adhesion thereof to the glass body 1.
• a coating surface 2 is delimited, by masking the complementary surface, according to per se known treatment methods, on the same rear face of the glass body 1 on which the conductive busbars 3 have been screen-printed. Thereafter, the glass body 1 is placed inside a deposition chamber, of a per se known type, in order to deposit onto the rear face thereof a thin titanium film 2 which thus constitutes the actual reflective surface of the mirror.
• the thin titanium film 2 is deposited according to a technique commonly known as Vacuum Arc Deposition.
• the thin titanium film is a single layer.
• the two conductive busbars are meant to constitute electrodes of the heated mirror; for this purpose, they are welded to conducting terminals (preferably made of copper or silver) in order to allow connection to an electric power source, which can be, very simply, the battery of a motor vehicle.
• the protective layer can be composed of multiple layers of different materials in other embodiments.
• the protective layer must also conveniently insulate the welding regions between the terminals and the conductive busbars in order to prevent the generation of electrical discharges if water is present.
• the glass body 1 is then placed in a controlled environment (i.e., in an environment wherein the relative humidity, the temperature and all the other environmental conditions are kept within preset limits) so that the protective layer of paint dries.
• the heated mirror thus obtained is characterized in that the pure titanium film constitutes the reflective surface and simultaneously acts as a resistive element, since after the appropriate connection of the two conductive busbars 3 to the electric power source it allows the direct flow of an electric current and accordingly generates heat by means of the Joule effect.
• the heat can then be transmitted directly toward the front face of the mirror, since there is no interposed material that slows its transmission.
• the heat is practically unaffected by any dispersion from the rear face of the mirror 2 toward the outside environment thanks to the presence of the layer of protective paint, which also acts as a heat insulator.
• the layer of protective paint which also acts as a heat insulator.
• a heated mirror is obtained whose reflective surface has a different color and/or a different surface resistivity.
• the reflective surface is provided on the front face of the mirror so that it has water-repellent properties.
• the two conductive busbars 3 can be provided, as an alternative to deposition on glass, directly on said film made of an electrically conductive metallic material, so as to simplify all the operations for assembly to the conductive terminals for connection to the electric power source (see Figure 4).
• the conductive busbars 3 can be constituted by thin metal strips (made for example of copper, aluminum, silver, et cetera) which are applied to the metal film 2. Contact can be provided by pressure or, in other cases, by fixing the conductive busbars to an adhesive film to be applied to the layer of electrically conductive metal.
• the adhesive film which must of course be able to withstand the operating temperatures reached during the heating step, also has a useful safety function, since in case of accidental breakage of the mirror it prevents fragments from detaching.
• the conductive busbars 3 thus provided can be welded or fixed to suitable connectors in order to provide connection to the electric power supply system. In practice it has been observed that the present invention effectively achieves all of the intended aim and objects.
• the above-described heated mirror according to the present invention allows, in an equal time, to defrost a much larger surface than conventional mirrors.
• an important advantage of the present invention is that a heated mirror has been provided which is capable of ensuring optimum viewing of the reflected image and better visibility with respect to conventional types in case of strong lighting, such as for example in the presence of headlights.
• a further important advantage of the present invention is that a heated mirror has been provided which ensures good heating uniformity on the entire surface, since the titanium film itself constitutes not only the actual reflective surface but also the resistive element that generates heat by means of the Joule effect.
• a further advantage is that a heated mirror has been provided which can be manufactured in a shorter time than conventional models.
• a further advantage is certainly that it is possible to produce a heated mirror in practice at very low costs.
• a further advantage of the present invention is that a heated mirror has ben provided whose coloring is determined by the physical characteristics of the reflective surface.
• the present invention also achieves the advantage of providing a heated mirror which ensures a longer life time than conventional mirrors.
• a further advantage is that a heated mirror has been provided which is protected against degradation of the reflective surface caused by the action of weather.
• a further advantage of the present invention is that a heated mirror has been provided which ensures good electric and optical characteristics over time.
• a further advantage is that the above-described heated mirror can operate even with very low temperatures (down to -50°C) simply by varying the physical characteristics of the titanium film and without having to insert other resistive elements.
• a further advantage is that a heated mirror has been provided which has a lighter structure than conventional models and at the same time has a greater mechanical strength, so as to reduce the risk of impact breakage.
• the weight reduction and increase in mechanical strength can be achieved by means of a chemical tempering process. It should also be observed that the above-described mirror can be subjected to additional treatments, such as marking or painting, all of which are per se known, so as to accordingly provide equivalent configurations.
• Another alternative is achieved by providing a mirror according to the invention in which the reflective layer on the front face is obtained by deposition of the film made of an electrically conductive metal.
• the conductive reflective layer can be coated with a coating of titanium oxide with water-repellent characteristics, so that as a whole said layer is a single element with reflective, heating, water-repellent and color characteristics at the same time.

Landscapes

• Optical Elements Other Than Lenses (AREA)
• Rear-View Mirror Devices That Are Mounted On The Exterior Of The Vehicle (AREA)
• Mirrors, Picture Frames, Photograph Stands, And Related Fastening Devices (AREA)
• Chemically Coating (AREA)
• Surface Treatment Of Glass (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=11392236

Family Applications (1)

Country Status (5)

Families Citing this family (11)

Family Cites Families (3)

• 1998
  • 1998-05-28 IT IT98PD000134A patent/ITPD980134A1/it unknown
• 1999
  • 1999-05-26 WO PCT/EP1999/003627 patent/WO1999062303A1/en not_active Ceased
  • 1999-05-26 BR BR9910767-8A patent/BR9910767A/pt not_active IP Right Cessation
  • 1999-05-26 AU AU43688/99A patent/AU4368899A/en not_active Abandoned
  • 1999-05-26 EP EP99926422A patent/EP1082880A1/de not_active Withdrawn

Non-Patent Citations (1)

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