Stock material or miscellaneous articles – Composite – Of quartz or glass
Reexamination Certificate
2000-08-02
2004-06-08
Morris, Terrel (Department: 1771)
Stock material or miscellaneous articles
Composite
Of quartz or glass
C428S423100, C428S425500, C428S425600, C428S426000, C428S428000, C428S446000, C428S448000, C428S697000, C428S699000, C428S701000, C428S702000, C269S238000, C269S240000, C269S245000, C269S265000, C269S267000, C269S273000
Reexamination Certificate
active
06746775
ABSTRACT:
The present invention relates to glazing having electrically controllable optical and/or energy properties.
Thus, it relates to glazing some of whose characteristics can be modified by a suitable electrical supply, most particularly the transmission, absorption and reflection within certain wavelengths of electromagnetic radiation, especially in the visible and/or in the infrared, or else the light scattering.
There is in fact an increasing demand for so-called “smart” glazing whose properties may be varied.
Thus, from the thermal standpoint, glazing whose transmission/absorption may be varied within at least part of the solar spectrum allows the solar heat influx into rooms or passenger areas/compartments to be controlled when linen it is fitted as the external glazing in buildings or as windows in transportation means of the type comprising cars, trains, aeroplanes, etc., and thus it allows excessive heating of the latter to be prevented should there be strong sunlight.
From the optical standpoint, the glazing allows the degree of vision to be controlled, thereby making it possible to prevent glare should there be strong sunlight, when it is mounted as exterior glazing. It may also have a particularly advantageous shutter effect, both as exterior glazing and if it is used as interior glazing, for example for equipping internal partitions between rooms (offices in a building), or for isolating compartments in trains or aeroplanes, for example.
There are many other applications: for example, glazing having variable light transmission/reflect on may be used for making rear-view mirrors, which can darken as required in order to prevent the driver of the car becoming dazzled. They may also be used for indicating panels on roadways, or any display panel, for example so as to reveal the drawing/message only intermittently in order to attract greater attention.
One particularly advantageous application of the systems having variable light absorption relates to display screens, especially all those with which televisions and computing hardware are equipped. This is because this type of glazing makes it possible to improve the contrast of the image, especially taking the ambient brightness into account.
The advantage that such glazing may provide justifies the fact that many systems have already been studied.
Thus, known systems allowing the light transmission or absorption of glazing to be varied are especially so-called viologen-based systems, such as those described in U.S. Pat. No. 5,239,406 or in Patent EP-A-0,612,826. These make it possible to obtain variable absorption, essentially in the visible region.
To the same end, there are also so-called electrochromic systems, the operating principle of which will be briefly recalled: these comprise, in a known manner, a layer of an electrochromic material capable of reversibly and simultaneously inserting ions and electrons, the oxidation states of which electrochromic material corresponding to the inserted and extracted states have a distinct colour, one of the states having a higher light transmission than the other. The insertion or extraction reaction is controlled by a suitable electrical supply using a current generator or a voltage generator. The electrochromic material, usually based on tungsten oxide, must thus be brought into contact with a source of electrons, such as a transparent electrically conductive layer, and with a source of ions (cations) such as an ionically conductive electrolyte.
Moreover, it is known that, in order to guarantee at least the order of a hundred switching operations, the layer of electrochromic material must be connected to a counterelectrode which is itself capable of reversibly inserting cations, symmetrically with respect to the layer of electrochromic material, so that, macroscopically, the electrolyte appears as a single ion medium.
The counterelectrode must consist of a layer which is either neutral in terms of colour or is at least transparent or barely coloured when the electrochromic layer is in the bleached state. Since tungsten oxide is a cathodic electrochromic material, that is to say its coloured state corresponds to the most reduced state, an anodic electrochromic material based on nickel oxide or iridium oxide is generally used for the counterelectrode. It has also been proposed to use an optically neutral material in the oxidation states in question, such as, for example, cerium oxide or organic materials such as electronically conductive polymers (polyaniline, etc.) or Prussian blue.
A description of such systems will be found, for example, in European Patents EP-0,338,876, EP-0,408,427, EP-0,575,207 and EP-0,628,849.
At the present time, these systems may be put into two categories, depending on the type of electrolyte that they use:
either the electrolyte is in the form of a polymer or a gel, for example a polymer which conducts via protons, such as those described in European Patents EP-0,253,713 and EP-0,670,346, or a polymer which conducts via lithium ions, such as those described in Patents EP-0,382,623, EP-0,518,754 or EP-0,532,408;
or the electrolyte is an inorganic layer which is ionically conductive but electronically insulating—these are then referred to as “all-solid” electrochromic systems. For the description of an “all-solid” electrochromic system, reference may be made to European Patent Applications EP-97/400702.3 (filed on March 27, 1997) and EP-0,831,360.
Other systems use electrochromic-type reversible ion-insertion materials slightly differently. These are, for example, so-called gasochromic systems, in which the electrochromic material is provided with a thin catalytic layer capable of decomposing hydrogen and mounted in a double-glazing unit on the internal gas-cavity side: by sending hydrogen into the internal space of the double-glazing unit, tungsten oxide becomes coloured. It returns to the bleached state by injecting oxygen, instead of hydrogen, into the internal space.
These systems having one or more reversible-insertion materials are particularly advantageous in the sense that they allow the absorption to be varied over a broader wavelength range than viologen-based systems: they allow variable absorption not only in the visible but also, in particular, in the infrared, which may confer on them an effective optical and/or thermal role.
Viologen-based or electrochromic systems, deposited on or associated with transparent substrates, firm glazing whose light absorption and transmission as well as energy transmission) may vary within given ranges, especially ranges determined by the choice of electrochromic materials used and/or by the choice of their thicknesses.
Another type of “smart” glazing is formed by what is termed an “optical valve”: this is a film comprising a generally crosslinked polymer matrix in which microdroplets are dispersed, these microdroplets containing particles which have the property of being aligned in a preferred direction due to the action of an electric or magnetic field. The film has variable optical properties depending in particular on the potential applied to he terminals of the conductive layers placed on either side of the film and on the concentration and nature of the orientable particles. Thus, Patent WO-93/09460 discloses an optical valve based on a film comprising a crosslinkable poly-organosilane matrix and inorganic or organic orientable particles, more particularly light-absorbing particles such as particles of polyiodides. When a voltage is applied to the film, the particles intercept the light much less than when no voltage is applied.
Glazing with variable light scattering, the operating principle of which is similar, is also known by the expression “liquid-crystal glazing”. This is based on the use of a film placed between two conductive layers based on a polymeric material in which droplets of liquid crystals are dispersed, especially nematic liquid crystals of positive dielectric anisotropy. When a voltage is applied to the film, the liquid crystals orient in a preferred direction, thereby allowing visio
Boire Philippe
Fix Renaud
Giron Jean-Christophe
Morris Terrel
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Piziali Andrew T
Saint-Gobain Vitrage
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