Stock material or miscellaneous articles – Structurally defined web or sheet – Including components having same physical characteristic in...
Reexamination Certificate
1998-07-08
2001-01-16
Speer, Timothy M. (Department: 1775)
Stock material or miscellaneous articles
Structurally defined web or sheet
Including components having same physical characteristic in...
C428S426000, C428S428000, C428S430000, C428S432000, C428S436000, C428S437000, C428S480000, C428S524000, C428S698000, C428S701000, C428S702000, C204S192100, C204S192110, C204S192260, C204S192140
Reexamination Certificate
active
06174592
ABSTRACT:
FIELD AND BACKGROUND OF THE INVENTION
The present invention is directed on a composite glass and to a method for producing a coated plastic foil, thereby preferably to be used for such composite glass.
At first, some entities shall be defined:
Visible light range:
Spectral range between 380 nm and 780 nm.
Sunlight:
Spectral range between 200 nm and 2500 nm.
Near infrared:
Spectral range between 780 nm and 1200 nm.
Reflection coefficient R
VIS
:
With the spectral sensitivity to luminosity of the human eye weighted ratio of reflected and impinging light:
R
vis
=
∫
380
nm
780
nm
R
(
λ
)
V
(
λ
)
S
(
λ
)
ⅆ
λ
∫
380
nm
780
nm
V
(
λ
)
S
(
λ
)
ⅆ
λ
wherein:
R(&lgr;) is the reflection value at a specific wavelength &lgr;
V(&lgr;) is the spectral sensitivity to luminosity of the human eye
S(&lgr;) is the spectral radiation distribution of standard light D65 (color temperature 6500K).
Transmission coefficient T
VIS
:
With the spectral sensitivity to luminosity of the human eye weighted ratio between transmitted and impinging light:
T
vis
=
∫
380
nm
780
nm
T
(
λ
)
V
(
λ
)
S
(
λ
)
ⅆ
λ
∫
380
nm
780
nm
V
(
λ
)
S
(
λ
)
ⅆ
λ
wherein there is further valid:
T(&lgr;) Transmission value at a specific wave length &lgr;,
Transmission coefficient T
SUN
:
With the spectral radiation distribution of the sun weighted ratio of transmitted light and impinging light:
T
SUN
=
∫
200
nm
2500
nm
T
(
λ
)
S
s
(
λ
)
ⅆ
λ
∫
200
nm
2500
nm
S
s
(
λ
)
ⅆ
λ
wherein there is valid:
S
S
(&lgr;) spectral distribution of the sun radiation.
Reflection coefficient R
SUN
:
With spectral radiation distribution of the sun weighted ratio of reflected light and impinging light:
R
SUN
=
∫
200
nm
2500
nm
R
(
λ
)
S
s
(
λ
)
ⅆ
λ
∫
200
nm
2500
nm
S
s
(
λ
)
ⅆ
λ
Absorption A
SUN
:
A
SUN
=
∫
200
nm
2500
nm
A
(
λ
)
S
s
(
λ
)
ⅆ
λ
∫
200
nm
2500
nm
S
s
(
λ
)
ⅆ
λ
wherein there is valid:
A(&lgr;) the absorption value at a specific wave length &lgr;.
Sun heat-up specification value.
E
SUN
=T
SUN
+A
SUN
/2
The smaller E
SUN
of a sun radiation protection system becomes the better is its protection ability.
The minimum value possible for E
SUN
for car windows is given by the fact that within the visible spectral range a minimum transmission is required, e.g. of 75% for front screens of cars according to ECE Standard No. 43. E
min, SUN
is defined by the so-called “ideal glass”. It has within the visible spectral range a constant required transmission of e.g. 75% according to a constant absorption of 25% and further features in the ultraviolet spectral range (&lgr;<380 nm) as well as in the infrared range (&lgr;>780 nm) a constant reflection of 100%. Thereby, a maximum sun protection ability would be reached and simultaneously the standard of 75% transmission in the visible spectral range would be fulfilled.
Protection from sun radiation is realized today substantially by two approaches:
Absorbing glass, e.g. “green glass”: Green glass is a colored, absorbing glass which appears in the visible spectral range and in transmission greenish. A typical transmission course for light impinging perpendicularly and considered along the entire sun light spectral range is shown in
FIG. 1
(solid line) altogether with the transmission course of the ideal glass (dashed line). In dependency of the concentration of coloring and of the thickness of the glass, the absorption may be increased or lowered, but the transmission varies in the visible spectral range too as the course remains qualitatively the same.
Absorbing glass is limited with respect to its sun protection effect because it only acts via absorption, which and according to E
SUN
leads as well to heating up a room which is situated opposite to impinging sun radiation, as e.g. and especially to heating up of the interior room of a vehicle which is provided with such a sun protection system. Besides of that, the slope of the absorption edge between visible spectral range and near infrared spectral range is limited; if within the visible spectral range there is requested a minimal transmission, then the transmission in the near infrared spectral range may not be realized infinitely low.
So-called D/M/D layer systems (dielectric layer/metal layer/dielectric layer) which are deposited either on glass substrates, as e.g. and especially on car window glass directly or on a foil, mostly on a polyester foil, which latter is subsequently embedded into a composite glass. Thereby, the plastic foil provided with the coating is typically assembled to a composite glass via a polyvinylbutyral-PVB-foil. As typical dielectric layer materials oxides of Zn, Ti, In etc. are used, as metal layer especially silver.
Thereby, it is known that silver is best suited to effectively separate light within the visible spectral range from light in the infrared spectral range. Due to its optical constants, namely refractive index n and extinction coefficient k, silver allows for a high transmission in the visible spectral range and for a high reflection in the near infrared spectral range. Attention is led thereabout on (1) H. A. Macleod, “Thin Film Optical Filter”, Second Edition, Adam Hilger Ltd.; pp 292.
Equally known is nevertheless that silver is most sensitive to influences from the surrounding, as to humidity, formation of silver sulphide etc., and this irrespective whether such layer system is deposited on glass or on a plastic foil. Thereabout, attention is drawn to the following literature:
U.S. Pat. No. 5,532,062: ZnO/Ag/ZnO; for improving resistance against surrounding Zn, ZnO respectively is doped (e.g. with Si, Ti, Cr, . . . )
U.S. Pat. No. 5,320,893: D/M/D; here a protection system is “sealed” by means of a specific glass compound technique and in thereby protected with respect to surrounding.
U.S. Pat. No. 5,510,173: D/M/D; to increase resistance of a protective system with respect to the surrounding the system is modified to a D/M/DD (typically indium oxide/Ag/indium oxide/indium tin oxide)
DE 30 27 356: D/M/D; to increase resistance with respect to the surrounding the dielectric layers of a protecting system are realized as metal oxide nitride compounds.
Characteristic for the behavior of a D/M/D system is that the requested transmission within the visible spectral range may only be reached by suppression of the reflection of the metallic layer. Thereabout, we again refer to (1). This is only possible for a narrow wave length range, and light which is transmitted through the D/M/D system is there significantly absorbed too. Thereby, especially the following two drawbacks result:
with increasing thickness of the metal layer the absorption in the visible reflection-suppressed spectral range as well as the reflection in the infrared range rise. This leads to the fact that the metal layer thickness is not freely selectable, but must be tailored so that the transmission in the visible spectral range still reaches the requested value of e.g. 75%. If a higher transmission is to be reached in the visible spectral range, this automatically leads to a lower infrared reflection and thus to a lower sun protection effect.
The suppression of reflection in the visible spectral range has a so-called “V characteristic”, which
Bluher Peter
Sperger Reinhard
Zarfl Hartmut
Balzers Hochvakuum AQ
Notaro & Michalos P.C.
Speer Timothy M.
Stein Stephen
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