Heat insulating glass with multilayer coating

A gray-colored heat insulating glass plate has a transparent glass plate and a multilayer coating formed on one side of the glass plate. The multilayer coating includes first, second and third layers. The first layer is formed on a surface of the glass plate, is a film of a tantalum oxide, and has a thickness ranging from 5 to 20 nm. The second layer is formed on the first layer, is a film of an oxynitride of a metal selected from Cr, Ni--Cr alloy and stainless steel, and has a thickness ranging from 5 to 25 nm. The third layer is formed on the second layer, is a film of a tantalum oxide, and has a thickness ranging from 5 to 20 nm. The heat insulating glass plate is sufficiently low in transmittance for solar radiation, sufficiently high in transmittance for radio waves, relatively low in transmittance for the visible light and good in durability.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a heat insulating glass plate for use in 
buildings or vehicles, and more particularly to a glass plate with a heat 
insulating multilayer coating, which has a gray color and is fairly low in 
transmittance for solar radiation and fairly high in transmittance for 
radio waves. 
2. Description of the Prior Art 
Hitherto, various heat insulating multilayer coatings have been proposed to 
be formed on a transparent glass plate. For example, JP-A-60-36355 
discloses a heat reflecting three-layer coating consisting of a first 
layer of an oxide of a metal selected from Sn, Ti and Al, a second layer 
of chromium nitride, and a third layer of a dielectric material. The first 
layer has an optical thickness ranging from 20 to 280 nm. The second layer 
has a geometrical thickness ranging from 10 to 40 nm. The coated glass 
plate has a transmittance ranging from 5 to 40% for the visible light. 
Color of light reflected from the uncoated side of the glass plate is 
adjusted by the optical thickness of the first layer. 
JP-A-3-208837 discloses a heat insulating four-layer coating consisting of 
a first layer of SiOx or Al.SiOx, a second layer of TiNx, a third layer of 
TiOx, and a fourth layer of SiOx or Al.SiOx. The four-layer coating is 
formed on a transparent glass plate by the sputtering method. The first to 
fourth layers have thicknesses of 10-30 nm, 10-40 nm, 0-20 nm and 30-50 
nm, respectively. Light reflected from the uncoated side of the glass 
plate has a bluish color. 
JP-A-3-252332 discloses a heat reflecting three-layer coating with low 
reflectance for radio waves, which is formed on a transparent glass plate. 
The three-layer coating consists of first and third layers of colored 
dielectric films having a surface resistivity not lower than 10.sup.4 
M.OMEGA./.quadrature. and a second layer interposed between the first and 
third layers. The second layer is a metal film or a metal nitride film, 
and has a surface resistivity not lower than 200 .OMEGA./.quadrature.. 
Light reflected from the uncoated side of the glass plate has a blue color 
or a golden color. However, in view of recent strict demand for low 
reflectance for radio waves, reflectance of the three-layer coating for 
radio waves is still unsatisfactory. 
Recently, a so-called shade band has been proposed to be formed on an upper 
end portion of a front windshield of an automobile for the purpose of 
lowering glare of the sunshine. The shade band of the front windshield is 
usually prepared by incorporating a colorant into an interlayer (polyvinyl 
butyral film) of a laminated glass plate. For example, it is desired to 
have a shade band having a gray color which is in harmony with the color 
of automobile interior and the color of automobile windshields. However, 
the above-mentioned three publications disclose multilayer coatings which 
provide the glass plates with colors other than gray color. 
SUMMARY OF THE INVENTION 
It is therefore an object of the present invention to provide a 
gray-colored heat insulating glass plate with a multilayer coating, which 
is sufficiently low in transmittance for solar radiation, sufficiently 
high in transmittance for radio waves, relatively low in transmittance for 
the visible light and good in durability. 
It is another object of the present invention to provide an improved method 
for forming a thin film band having a gradated portion on each of a 
plurality of transparent glass plates by means of jigs. 
According to a first aspect of the present invention, there is provided a 
gray-colored heat insulating glass plate having a transparent glass plate 
and a multilayer coating formed on one side of the glass plate, the 
multilayer coating comprising: 
a first layer formed on a surface of the glass plate, said first layer 
being a film of a tantalum oxide and having a thickness ranging from 5 to 
20 nm; 
a second layer formed on said first layer, said second layer being a film 
of an oxynitride of a metal selected from Cr, Ni--Cr alloy and stainless 
steel and having a thickness ranging from 5 to 25 nm; and 
a third layer formed on said second layer, said third layer being a film of 
a tantalum oxide and having a thickness ranging from 5 to 20 nm. 
According to a second aspect of the present invention, there is provided a 
method for forming thin film bands on first and second transparent glass 
plates by means of first and second jigs, each of the first and second 
jigs being formed with a projection portion, the method comprising the 
steps of: 
(a) placing the first glass plate on a base member such that a first major 
surface of the first glass plate is exposed, the first major surface 
having a first end portion and a first adjacent portion which bounds on 
the first end portion; 
(b) placing the first jig on the first glass plate so as to precisely 
position the first jig relative to the first glass plate such that a major 
portion of the first major surface is masked by the first jig, such that 
the first end portion of the first glass plate remains exposed and such 
that the projection portion of the first jig is positioned above the first 
adjacent portion; 
(c) placing the second glass on the first jig so as to precisely position 
the second glass plate relative to the first jig such that a second major 
surface of the second glass plate is exposed, the second major surface 
having a second end portion and a second adjacent portion which bounds on 
the second end portion, and such that the first end portion of the first 
glass plate still remains exposed; 
(d) placing the second jig on the second glass plate so as to precisely 
position the second jig relative to the second glass plate and to form a 
structure having the first and second glass plates and the first and 
second jigs such that a major portion of the second major surface is 
masked by the second jig, such that the first and second end portions 
remain exposed and such that the projection portion of the second jig is 
positioned above the second adjacent portion; 
(e) placing the structure in a physical vapor deposition device such that 
the first and second end portions are exposed to a target of the device; 
and 
(f) actuating the device such that a first thin film portion deposits on 
each of the first and second end portions and a second thin film portion 
deposits on each of the first and second adjacent portions, the first and 
second thin film portions being merged with each other so as to form the 
thin film band, the first thin film portion being uniform in thickness and 
color, the second thin film portion being wedge like in shape and thus 
gradated in color. 
According to a third aspect of the present invention, there is provided a 
jig for positioning and masking a glass plate, the glass plate having a 
major surface having an end portion and an adjacent portion bounding on 
the end portion, said jig being sized so as to mask a major part of the 
major surface when said jig is placed on the glass plate, said jig 
comprising: 
a projection portion which is to be positioned above the adjacent portion 
when the jig is placed on the glass plate; 
means for adjusting a projected length of the projection portion; and 
means for adjusting a height of the projection portion, the height being 
defined as a distance between the projection portion and the glass plate 
when the jig is placed on the glass plate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
A heat insulating multilayer coating according to the present invention 
will be described in the following. 
The multilayer coating is made up of a first layer formed directly on one 
surface of a transparent glass plate, a second layer which is laid on the 
first layer, and a third layer which is laid on the second layer. The 
first layer is a film of a tantalum oxide (TaOx) and has a thickness 
ranging from 5 to 20 nm. The second layer is a film of an oxynitride of 
stainless steel (SUSNOx) and has a thickness ranging from 5 to 25 nm. The 
third layer is a film of TaOx and has a thickness ranging from 5 to 20 nm. 
The multilayer coating is formed on the glass plate by the sputtering 
method. 
Due to the use of the TaOx film having a thickness ranging from 5 to 20 nm 
as the first layer, adhesion of the SUSNOx film to the glass plate is 
substantially improved. The thickness of the first layer is preferably 
from about 5 to about 15 nm, and more preferably from about 5 to about 10 
nm. If the first layer is too thick in thickness, interference color is 
produced by the optical interference of the multilayer coating. With this, 
the color tone changes according to the angle of view. 
Due to the use of the SUSNOx film having a thickness ranging from 5 to 25 
nm as the second layer, the multilayer coating has a gray color and 
becomes superior in durability. Therefore, the glass plate with the 
gray-colored multilayer coating matches with, for example, the automobile 
interior, suppresses glare of the sunshine, and improves the habitability. 
The multilayer coating is particularly suitable to be used as a shade band 
of an automobile. Furthermore, due to the use of the SUSNOx film as the 
second layer, the multilayer coating has a surface resistivity not lower 
than 1 k.OMEGA./.quadrature.. That is, the multilayer coating is high in 
electrical resistance, and hence it transmits radio waves without great 
attenuation. The radio wave transmittance of the heat insulating glass 
plate is almost comparable to that of the uncoated glass plate. Therefore, 
the heat insulating glass plate is suitable to be used in high-rise 
buildings. With this, ghost phenomenon of TV sets of the nearby houses can 
be minimized. Still furthermore, due to the use of the SUSNOx film as the 
second layer, the multilayer coating becomes superior in wear resistance, 
durability, chemical resistance, and the like. The thickness of the second 
layer is preferably from about 6 to about 23 nm, and more preferably from 
about 8 to about 20 nm. With this, visible light transmittance is suitably 
lowered, thereby lowering glare of the sunshine. If a film of stainless 
steel is used as the second layer instead of the SUSNOx film, the second 
layer will usually provide a silver or golden color due to a high 
reflectance, for example, not lower than about 20%. Only in the case that 
the stainless steel film has a thickness not more than about 10 nm, it 
will provide a gray color. Furthermore, the stainless steel film has a 
surface resistivity not higher than 1 k.OMEGA./.quadrature. even if the 
visible light transmittance is adjusted to about 60%. This value of 
surface resistivity is insufficient in terms of radio wave transmittance. 
If a film of a nitride of stainless steel is used as the second layer 
instead of the SUSNOx film, the second layer will provide a gray color. 
The stainless steel nitride film will have a surface resistivity which is 
higher than that of the stainless steel film but is still not higher than 
1 k.OMEGA./.quadrature. . If a film of CrN, SiC or the like is used as the 
second layer, the second layer becomes satisfactory in visible light 
transmittance, surface resistivity, durability and the like. However, the 
second layer will not provide a gray color, but a bronze or golden color. 
Instead of the SUSNOx film, it is optional to use a film of an oxynitride 
of either Cr or Ni--Cr alloy (nichrome) as the second layer. The surface 
resistivity of the second layer increases by increasing the oxygen content 
of the oxynitride. With this, the color tone of the second layer turns 
gradually from a gray color to a bronze color, and the mechanical strength 
of the second layer tends to increase. According to the present invention, 
the oxygen content of the oxynitride is preferably not higher than 30%. 
Due to the use of the TaOx film having a thickness ranging from 5 to 20 nm 
as the third layer (the outermost layer), durability of the multilayer 
coating is improved. Stains such as fingerprints can be easily removed 
from the multilayer coating because the TaOx film as the third layer has a 
very smooth surface. The thickness of the TaOx film is preferably from 
about 5 to about 15 nm, and more preferably from about 5 to about 10 nm. 
The multilayer coating is formed such that the heat insulating glass plate 
has a transmittance ranging from 10% to 60% for the visible light. The 
transmittance for the visible light can be arbitrarily adjusted within 
this range. If it is lower than 10%, visible light reflectance of the 
uncoated side of the glass plate becomes higher than about 25%. Therefore, 
the color tone of the glass plate turns into a silver or golden color. The 
visible light reflectance of the uncoated side of the glass plate is 
preferably not higher than 18%, and more preferably not higher than 15%. 
If the transmittance for the visible light is more than 60%, glare of the 
sunshine can not be sufficiently suppressed and the heat insulating 
capability of the glass plate becomes unsatisfactory. The transmittance 
for the visible light is preferably from about 20 to about 55%, and more 
preferably from about 30 to about 50%. 
In the present invention, the transparent glass plate is either a colorless 
glass plate or a colored glass plate as long as the coated glass plate has 
a gray color tone. The glass is not necessarily an inorganic glass and may 
be a so-called organic or plastic glass. The glass plate is not 
necessarily used as a single plate, and may be used as a component of a 
laminated glass or an insulated glass. 
The following nonlimitative examples are illustrative of the present 
invention. 
EXAMPLE 1 
A three-layer coating according to the present invention was formed on an 
about 300 mm square and about 3.1 mm thick plate of a gray glass (NG 3.1). 
The glass plate was washed with a neutral detergent, rinsed with water and 
further with isopropyl alcohol and dried. Then, the glass plate was set 
horizontally on a carrier which was horizontally movably installed in a 
vacuum chamber of a DC magnetron reactive sputtering apparatus. The 
carrier reciprocatively movable so as to be positioned alternately above a 
stainless steel target and a Ta target. Initially the chamber was 
depressurized to the extent of about 5.times.10.sup.-6 Torr. Then, a mixed 
gas of O.sub.2 and Ar was introduced into the vacuum chamber to maintain 
the degree of vacuum at about 2.times.10.sup.-3 Torr. Flow rate ratio of 
O.sub.2 to Ar was adjusted to 100:0 to 50:50. Under such condition, the Ta 
target was sputtered at a power of about 2.0 kW while the glass plate was 
horizontally transferred in a region above the Ta target at a constant 
speed of about 250 mm/min. As the result, a TaOx film having a thickness 
of about 10 nm deposited on the glass plate as the first layer. 
Then, the feed of the gas and the power supply to the Ta target were 
stopped, and about 68 cc of N.sub.2 gas and about 2 cc of O.sub.2 gas were 
introduced into the vacuum chamber to maintain the degree of vacuum at 
about 2.times.10.sup.-3 Torr. The flow rate ratio of N.sub.2 to O.sub.2 
was adjusted to 99:1 to 90:10. Under such condition, the glass plate was 
transferred to a region above the stainless steel target, and the 
stainless steel target was sputtered at a power of about 0.5 kW while the 
glass plate was horizontally transferred at a constant speed of about 900 
mm/min. As the result, a SUSNOx film having a thickness of about 5 nm 
deposited, as the second layer, on the first layer. 
Then, the feed of gas and the power supply to the stainless steel target 
were stopped, and O.sub.2 gas and Ar gas were introduced into the vacuum 
chamber to have a flow rate ratio of O.sub.2 gas to Ar gas in a range from 
100:0 to 50:50 and to maintain the degree of vacuum at about 
2.times.10.sup.-3 Torr. Under such condition, the glass plate was carried 
back to the region above the Ta target, and the Ta target was sputtered at 
a power of about 2.0 kW while the glass plate was horizontally transferred 
at a constant speed of about 250 mm/min. As the result, a TaOx film having 
a thickness of about 10 nm deposited, as the third layer, on the second 
layer. Then, the feed of the gas and the power supply to the Ta target 
were stopped. 
By the above process a three-layer coating was formed on one side of the 
glass plate. The coated glass plate had a gray color. Several samples were 
produced by the same process and under the same conditions. 
On the samples of the coated glass plate the transmittance and reflectance 
for the visible light (380-780 nm) and transmittance for solar radiation 
(340-1800 nm) were measured with an automatic recording spectrophotometer 
(Type 340 of Hitachi Ltd.) by the methods according to JIS Z 8722 and JIS 
R 3106. The results are shown in Table 2. 
Besides, wear resistance of the multilayer coating was examined by the 
Taber test. The test was made on 10 cm square specimens of the coated 
glass plate with a Taber's abrasion tester (MODEL 503 of TYBER Co.) using 
two abrading wheels of CS-10F type. A load of 500 g was applied to each 
abrading wheel, and the test was continued until 1000 turns of the 
abrading wheels on the surface of the multilayer coating. Before and after 
the Taber test the haze value of each specimen was measured with a haze 
meter (NDH-20D of Nippon Denshoku Kogyo Co.) to find a difference between 
the two measurements, .DELTA.H. The result is shown in Table 2. 
Further, acid and alkali resistances of the multilayer coating were 
examined by immersing some specimens of the coated glass plate in 1N HCl 
solution at room temperature for about 6 hr and separate specimens in 1N 
NaOH solution at room temperature for about 6 hr. In both cases the degree 
of deterioration of the coating was examined by visual observation. On 
every specimen, deterioration of the coating was hardly perceptible 
according to JIS R 3221. 
The surface resistivity of the coating was measured with a tester of the 
four-probe type (RT-8 of NAPSON Co.) for a specimen having a surface 
resistivity not higher than 10.sup.5 .OMEGA./.quadrature. or with a high 
surface resistivity tester (HIRESTA HT-210 of Mitsubishi Yuka Co.) for a 
specimen having a surface resistivity from 10.sup.5 .OMEGA./.quadrature. 
to 10.sup.5 M .OMEGA./.quadrature.. The result is shown in Table 2. 
EXAMPLES 2-5 
As shown in Table 1, in these examples, the multilayer coating of Example 1 
was modified in respect of the thickness of each layer. For this purpose, 
the sputtering method of Example 1 was modified only in respect of the 
transfer speed of the glass plate during the sputtering. That is, for 
obtaining each of the first and third layers, the transfer speeds were 
respectively about 500 mm/min (Example 2), about 177 mm/min (Example 3), 
about 250 mm/min (Example 4) and about 125 mm/min (Example 5). For 
obtaining the second layer, the transfer speeds were respectively about 
180 mm/min (Example 2), about 563 mm/min (Example 3), about 375 mm/min 
(Example 4), and about 300 mm/min (Example 5). 
The optical characteristics (the transmittance and reflectance for the 
visible light, transmittance for solar radiation, and the color of the 
coated glass plate) of the heat insulating glass plates of Examples 2-5 
are shown in Table 2. The surface resistivity of the multilayer coatings 
of Examples 2-5 and the result of the Taber test on the same are also 
shown in Table 2. The multilayer coatings of Examples 2-5 were subjected 
to the acid and alkali tests described hereinbefore. By these tests, the 
coating of every example exhibited little deterioration. 
COMATIVE EXAMPLE 1 
In Comparative Example 1, a stainless steel (SUS) film was formed as the 
second layer instead of the SUSNOx films of Examples 1-5. 
Similar to Example 1, a TaOx film having a thickness of 5 nm was formed on 
a glass plate by the sputtering method with a transfer speed of about 500 
mm/min. Then, a SUS target was sputtered at a power of about 0.2 kW under 
an Ar gas pressure of about 2.times.10.sup.-3 Torr while the glass plate 
was horizontally transferred at a constant speed of about 1150 mm/min. As 
the result, the SUS film having a thickness of about 10 nm deposited on 
the first layer. Then, similar to Example 1, a TaOx film having a 
thickness of 5 nm was formed on the second layer by the sputtering method 
with a transfer speed of about 500 mm/min. 
COMATIVE EXAMPLES 2-4 
In Comparative Examples 2-4, a stainless steel nitride (SUSNx) film was 
formed as the second layer instead of the SUSNOx films of Examples 1-5. 
Similar to Example 1, for forming the first and third layers, TaOx films 
having thicknesses of about 5 nm (Comparative Example 3) and about 10 nm 
(Comparative Examples 2 and 4) were formed on glass plates by the 
sputtering method with transfer speeds of about 500 mm/min (Comparative 
Example 3) and about 250 mm/min (Comparative Examples 2 and 4), 
respectively. For forming the second layers, a SUS target was sputtered at 
a power of about 0.5 kW under a N.sub.2 gas pressure of about 
2.times.10.sup.-3 Torr while the glass plates were horizontally 
transferred at constant speeds of about 345 mm/min (Comparative Example 
2), about 415 mm/min (Comparative Example 3), and about 138 mm/min 
(Comparative Example 4), respectively. As the result, the SUSNx films 
having thicknesses of about 12 nm (Comparative Example 2), about 10 nm 
(Comparative Example 3) and about 30 nm (Comparative Example 4 ) deposited 
on the first layers, respectively. 
COMATIVE EXAMPLE 5 
In Comparative Example 5, a chromium nitride (CrNx) film was formed as the 
second layer instead of the SUSNOx films of Examples 1-5. 
Similar to Example 1, for forming the first and third layers, TaOx films 
having a thickness of about 10 nm were formed on a glass plate by the 
sputtering method with a transfer speed of about 250 mm/min, respectively. 
For forming the second layer, a Cr target was sputtered at a power of 
about 0.4 kW under a N.sub.2 gas pressure of about 2.times.10.sup.-3 Torr 
while the glass plate was horizontally transferred at a constant speed of 
about 200 mm/min. As the result, the CrNx film having a thickness of 
about 15 nm deposited on the first layer. 
COMATIVE EXAMPLE 6 
In Comparative Example 6, a SiC film was formed as the second layer instead 
of the SUSNOx films of Examples 1-5. 
Similar to Example 1, for forming the first and third layers, TaOx films 
having a thickness of about 10 nm were formed on a glass plate by the 
sputtering method with a transfer speed of about 250 mm/min, respectively. 
For forming the second layer, a SiC target was sputtered at a power of 
about 1.0 kW under an Ar gas pressure of about 2.times.10.sup.-3 Torr 
while the glass plate was horizontally transferred at a constant speed of 
about 480 mm/min. As the result, the SiC film having a thickness of about 
20 nm deposited on the first layer. 
The optical characteristics of the heat insulating glass plates of 
Comparative Examples 1-6 are shown in Table 2. The surface resistivity of 
the multilayer coatings of Comparative Examples 1-6 and the result of the 
Taber test on the same are also shown in Table 2. The multilayer coatings 
of Comparative Examples 1-6 were subjected to the acid and alkali tests 
described hereinbefore. By these tests, each coating exhibited little 
deterioration. 
With reference to FIGS. 1-5, a method for forming a thin film band on each 
of a plurality of transparent glass plates by means of jigs in accordance 
with a first embodiment of the present invention will be described in the 
following. 
The thin film band 10 is of a functional film for various purposes, such as 
a film which is substantially high or low in transmittance for radio 
waves, a heat insulating film, and the like. The thin film band 10 may 
have various colors. However, it is preferable that the thin film band 10 
has a gray color. The gray-colored thin film band 10 is particularly 
suitable for a shade band of an automobile. The thin film band 10 has a 
certain optical characteristics, and is superior in wear resistance, 
chemical resistance, and the like. 
The first, second, third and fourth jigs 12, 14, 16 and 18 are specially 
designed for forming the thin film band 10 on each of the first, second 
and third transparent glass plates 20, 22 and 24. Each jig 12, 14, 16 or 
18 is made of fluororubber, fluororesin, a metal such as stainless steel 
or aluminum, or the like. It is necessary that each jig is heat resistant 
and corrosion resistant. As is seen from FIG. 1, each jig is formed at its 
left end portion with a projection portion 12a, 14a, 16a or 18a. As is 
seen from FIG. 2, the projection portion (for example, 14a) has a length 
"m", and a height "h". As is seen from FIG. 3, the first jig 12 has at its 
upper surface a heat resistant cushioning member 12b on which the first 
glass plate 20 is to be placed and positioned relative to the first jig 
12, a masking member 12c for masking a major part of the first glass plate 
20 during the sputtering process, and leg portions 12d having adjusting 
portions 12e for adjusting the height "h" of the projection portion 12a 
and fixing portions 12f having elongate holes 12g for adjusting the length 
"m" of the projection portion 12a. The second, third and fourth jigs 14, 
16 and 18 are similar to the first jig 12 in construction. 
Each glass plate is not necessarily an inorganic glass plate and may be a 
so-called organic or plastic glass plate. The glass plate with the thin 
film band 10 can be used as a front, rear, side or door windshield of an 
automobile. 
As is seen from FIG. 1, the glass plates 20, 22 and 24 are positioned 
relative to each other by the jigs 12, 14, 16 and 18 such that a left end 
upper surface of each glass plate is exposed. The thus positioned glass 
plates together with the jigs are disposed in a vacuum chamber of a 
sputtering device such that major surfaces of the glass plates are opposed 
to a target of the sputtering device. Then, the target is sputtered. As 
the result, as is seen from FIG. 2, a thin film band 10 deposits on the 
left end upper surface of the glass plate (for example, 20). The thin film 
band 10 consists of first and second portions 10a and 10b, and has a 
length "L". The first portion 10a has a flat upper surface, a uniform 
thickness, and a length "L1". The thus shaped first portion 10a is formed 
because the target material deposits perpendicularly uniformly on the 
glass plate 20. The second portion 10b is wedgelike in shape, and has a 
length "L2". The thus shaped second portion 10b is formed because the 
target material deposits obliquely on the glass plate due to the provision 
of the projection potion 14a of the jig 14. The first portion 10a has, for 
example, a uniform gray color, and the second portion 10b is gradated in 
color due to its wedgelike shape. Therefore, it becomes difficult to 
recognize a boundary between the uncoated portion of the glass plate and 
the coated portion of the same by the naked eye. It is the main feature of 
the present invention that a thin film band having a gradated portion is 
formed on each of a plurality of glass plates at the same time by the 
sputtering method by means of a specifically designed jigs. Therefore, the 
productivity is substantially improved as compared with a conventional 
technique. 
To use a coated glass plate according to the present invention for an 
automobile windshield, the length "L" of the thin film band 10 is 
preferably from about 100 to about 150 mm, the length "L2" of the second 
portion 10b is preferably from about 10 to about 75 mm, more preferably 
from about 15 to about 60 mm, still more preferably from about 20 to about 
50 mm and the most preferably from about 30 to about 40 mm, and the height 
"h" of the projection portion of the jig is preferably from about 7 to 
about 50 mm, more preferably from about 15 to about 45 mm, still more 
preferably from about 20 to about 40 mm and the most preferably from about 
25 to about 35 mm. When the length "L2" of the second portion 10b is less 
than about 5 mm, a linear boundary between the coated portion and the 
uncoated portion will appear. When the vertical distance between the 
uppermost and the lowermost glass plates 24 and 20 becomes too much, the 
glass plates will have the gradated (second) portions 10b which are 
different in color tone. 
According to a second embodiment of the present invention, as is seen from 
FIG. 6, it is optional to obliquely dispose the glass plates 20, 22 and 24 
for forming thin film bands thereon. In this case, the vertical distances 
between the sputtering target and the coating portions of the glass plates 
are substantially the same. Therefore, the gradated portions 10b will be 
substantially the same in color tone. The angle of the glass plates 
relative to a carrier 26 is preferably not greater than 45.degree., more 
preferably from about 5.degree. to 40.degree., and still more preferably 
from about 10.degree. to 30.degree.. 
In the present invention, it is optional to use other physical vapor 
deposition methods such as vacuum vapor deposition method. 
The following nonlimitative examples are illustrative of the present 
invention. 
EXAMPLE 6 
First, second and third transparent glass plates 20, 22 and 24 each of 
which has a length of about 150 cm, a width of about 80 cm and a thickness 
of about 3.5 mm were prepared. Then, the length "m" and the height "h" of 
the projection portion 12a, 14a, 16a or 18a of each of the first, second, 
third and fourth jigs 12, 14, 16 and 18 were respectively adjusted to 
about 25 mm and about 12 mm. Then, the first jig 12 was placed on a 
carrier 26, and then the first glass plate 20 was placed and positioned 
relative to the first jig 12. Similarly, the second jig 14 was placed on 
the first glass plate 20, and then the second glass plate 22 was placed on 
the second jig 14. Further, the third jig 16 was placed on the second 
glass plate 22, and then the third glass plate 24 was placed on the third 
jig 16. Finally, the fourth jig 18 was placed on the third glass plate 24. 
The carrier 26 on which the glass plates and the jigs had been thus placed 
was installed in a vacuum chamber of an inline sputtering device such that 
the glass plates were below and opposed to a stainless steel (SUS 316) 
target. Then, the chamber was depressurized to the extent of about 
5.times.10.sup.-6 Torr. Then, a mixed gas of N.sub.2 and O.sub.2 in the 
flow rate ratio of 92:8 was introduced into the vacuum chamber to maintain 
the degree of vacuum at about 2.times.10.sup.-3 Torr. Under such 
condition, the S US target was sputtered at a power of about 50 kW. As the 
result, a SUSNxOy film having a thickness of about 24 nm deposited on each 
glass plate as the first layer. 
Then, the feed of the gas and the power supply to the SUS target were 
stopped, and a mixed gas of O.sub.2 and Ar in the flow rate ratio of 95:5 
was introduced into the vacuum chamber to maintain the degree of vacuum at 
about 2.times.10.sup.-3 Torr. Under such condition, the carrier 26 was 
transferred to a region below a Ta target so as to oppose the glass plates 
to the Ta target, and the Ta target was sputtered at a power of about 50 
kW. As the result, a Ta film having a thickness of about 5 nm deposited, 
as the second layer, on the first layer of each glass plate. Then, the 
feed of the gas and the power supply to the Ta target were stopped. 
By the above process a two-layer thin film band 10a having a gradated 
portion 10b was formed on one side of each glass plate. The thin film band 
10 was grayish in color. The length "L2" of the gradated portion 10b was 
about 16 mm. 
EXAMPLES 7 and 8 
As is seen from Table 3, Example 6 was modified in respect to the types of 
the glass plates, and the height "h" and the length "m" of the projection 
portion of each jig. 
COMATIVE EXAMPLE 7 
The processes of Example 6 were repeated except that the height "h" and the 
length "m" of the projection portion were respectively adjusted to 0 mm. 
The length "L2" of the gradated portion 10b was only 1 mm, and thus a 
linear boundary between the coated portion and the uncoated portion was 
clearly recognized by the naked eye. 
COMATIVE EXAMPLE 8 
Only one layer of TiNxOy was formed on each glass plate by the sputtering 
method. The height "h" and the length "m" of the projection portion were 
respectively adjusted to 2 mm and 5 mm. The length "L2" of the gradated 
portion 10b was only 2 mm, and thus a linear boundary between the coated 
portion and the uncoated portion was clearly recognized by the naked eye. 
On the samples of the coated glass plates according to Examples 6-8 and 
Comparative Examples 7 and 8, the transmittance and reflectance for the 
visible light and transmittance and reflectance for solar radiation were 
measured. The results are shown in Table 4. Besides, wear resistance of 
the thin film band 10 was examined by a traverse test with 500 turns. By 
this test, all the samples of the thin film band 10 according to Examples 
6-8 and Comparative Examples 7 and 8 showed satisfactory wear resistances. 
Further, acid and alkali resistances of the thin film band 10 were 
examined by immersing some specimens of the coated glass plate in 1N HCl 
solution at room temperature for about 6 hr and separate specimens in 1N 
NaOH solution at room temperature for about 6 hr. In both cases the degree 
of deterioration of the thin film band was examined by visual observation. 
On every specimen according to Examples 6-8 and Comparative Examples 7 and 
8, deterioration of the thin film band 10 was hardly perceptible. 
FIG. 5 shows a relationship between the length "L2" of the gradated portion 
10b and the height "h" of the projection portion. This relationship was 
obtained by real data. It is understood that the length "L2" is increased 
by increasing the height "h". 
TABLE 1 
______________________________________ 
Glass Plate 
(thickness, Structure of Coating (thickness, nm) 
mm) 1st layer 2nd layer 3rd layer 
______________________________________ 
Example 
NG (3.1) TaOx (10) SUSNOx (5) 
TaOx (10) 
Example 
FL (3.5) TaOx (5) SUSNOx (25) 
TaOx (5) 
2 
Example 
NG (3.1) TaOx (15) SUSNOx (8) 
TaOx (15) 
3 
Example 
NG (3.5) TaOx (10) SUSNOx (12) 
TaOx (10) 
4 
Example 
FL (3) TaOx (20) SUSNOx (15) 
TaOx (20) 
5 
Comp. FL (3.5) TaOx (5) SUS (10) TaOx (5) 
Ex. 1 
Comp. NG (3.5) TaOx (10) SUSNx (12) 
TaOx (10) 
Ex. 2 
Comp. NG (3.1) TaOx (5) SUSNx (10) 
TaOx (5) 
Ex. 3 
Comp. NG (3.1) TaOx (10) SUSNx (30) 
TaOx (10) 
Ex. 4 
Comp. FL (3) TaOx (10) CrNx (15) 
TaOx (10) 
Ex. 5 
Comp. NG (3.5) TaOx (10) SiC (20) TaOx (10) 
Ex. 6 
______________________________________ 
TABLE 2 
__________________________________________________________________________ 
Visible Light 
Visible Light 
Solar Radiation 
Surface 
Transmittance 
Reflectance (%) 
Transmittance 
Color of 
Resistivity 
Taber Test 
(%) uncoated side 
coated side 
(%) Coated Glass 
(.OMEGA./.quadrature.) 
.DELTA.H 
__________________________________________________________________________ 
(%) 
Example 1 
58.1 12.3 18.0 61.9 gray 2.5 .times. 10.sup.5 
2.4 
Example 2 
26.7 17.7 28.4 28.9 gray 1.5 .times. 10.sup.3 
4.0 
Example 3 
46.6 13.2 21.5 50.0 gray 5.5 .times. 10.sup.4 
2.1 
Example 4 
37.8 12.1 21.8 42.3 gray 3.3 .times. 10.sup.4 
2.7 
Example 5 
40.8 10.1 20.6 38.1 gray 8.5 .times. 10.sup.3 
3.1 
Comp. Ex. 1 
28.3 21.0 29.2 27.3 silver gray 
160 4.1 
Comp. Ex. 2 
33.7 12.4 24.1 31.1 gray 250 2.6 
Comp. Ex. 3 
40.5 8.5 21.1 38.0 gray 300 3.5 
Comp. Ex. 4 
7.0 27.9 40.0 6.8 silver gray 
70 5.0 
Comp. Ex. 5 
32.1 16.8 30.4 25.7 bronze gray 
7.0 .times. 10.sup.3 
5.3 
Comp. Ex. 6 
36.1 29.7 42.7 48.2 bronze 1.0 .times. 10.sup.8 
1.6 
__________________________________________________________________________ 
TABLE 3 
__________________________________________________________________________ 
Glass Plate 
Structure of film (thickness, nm) 
Height "h" 
Length "m" 
Length "L2" 
(thickness, mm) 
1st layer 
2nd layer 
(mm) (mm) (mm) 
__________________________________________________________________________ 
Example 6 
FL (3.5) 
SUSNxOy (24) 
TaOx (5) 
12 25 16 
Example 7 
NFL (3.5) 
SUSNxOy (24) 
TaOx (5) 
24 40 28 
Example 8 
NFL (3.5) 
SUSNxOy (10) 
TaOx (5) 
38 70 42 
Comp. Ex. 7 
FL (3.5) 
SUSNxOy (24) 
TaOx (5) 
0 0 1 
Comp. Ex. 8 
FL (3.5) 
TiNxOy (50) 
-- 2 5 2 
__________________________________________________________________________ 
TABLE 4 
__________________________________________________________________________ 
Visible Light 
Visible Light 
Solar Radiation 
Solar Radiation 
Transmittance 
Reflection (%) 
Transmittance 
Reflectance (%) 
Color of 
(%) uncoated side 
coated side 
(%) uncoated side 
coated side 
Coated 
__________________________________________________________________________ 
Glass 
Example 6 
33.2 28.5 20.4 36.6 26.3 16.4 gray 
Example 7 
29.5 34.3 16.5 31.4 30.4 13.5 gray 
Example 8 
44.6 19.9 9.2 45.2 19.9 9.2 gray 
Comp. Ex. 7 
33.2 28.5 20.4 36.6 26.3 16.4 gray 
Comp. Ex. 8 
39.3 31.0 27.8 31.6 31.0 22.0 bronze 
__________________________________________________________________________