Glass sheet having high transmission of infrared radiation
View Patent ↗The invention relates to a glass sheet having high transmission of infrared (IR) radiation. More specifically, the invention relates to a glass sheet having a composition which comprises, in a content expressed as percentages by total weight of glass: SiO 2 55-85%; Al 2 O 3 0-30%; B 2 O 3 0-20%; Na 2 O 0-25%; CaO 0-20%; MgO 0-15%; K 2 O 0-20%; BaO 0-20%; Total iron (expressed in the form of Fe 2 O 3 ) 0.002-0.06%, a chromium content (expressed in the form of Cr 2 O 3 ) ranging from 0.0015% to 1% and a cobalt content (expressed in the form of Co) ranging from 0.0001% to 1%. By virtue of its high transmission of IR radiation, the glass sheet according to the invention can advantageously be used in a device using a technology requiring very good transmission of IR radiation, whether through the main faces or starting from their sheared edge (for example, a screen or panel or pad, the glass sheet defining a touch surface). The invention thus also relates to the use of such a glass sheet in a device using infrared radiation propagating essentially inside said sheet.
1. A glass sheet having a composition which comprises, in a content expressed as percentages by total weight of glass:
SiO 2
55-85%
Al 2 O 3
0-30%
B 2 O 3
0-20%
Na 2 O
0-25%
CaO
0-20%
MgO
0-15%
K 2 O
0-20%
BaO
0-20%
Total iron (expressed in the form of Fe 2 O 3 )
0.002-0.02%;
wherein said composition comprises, by weight with respect to the total weight of the glass, a chromium content (expressed in the form of Cr 2 O 3 ) ranging from 0.0015% to 1% and a cobalt content (expressed in the form of Co) ranging from 0.0001% to 1% and
wherein said composition comprises a Fe2+(expressed in the form of FeO) content of less than 20 ppm.
2. The glass sheet as claimed in claim 1 , wherein the composition comprises a chromium content, expressed as percentage by weight with respect to the total weight of the glass, such that: Cr 2 O 3 ≤(−17*Co)+0.0535; Co being the cobalt content, expressed as percentage by weight with respect to the total weight of the glass.
3. The glass sheet as claimed in claim 2 , wherein the composition comprises a chromium content such that: Cr 2 O 3 ≤(−17*Co)+0.0290.
4. The glass sheet as claimed in claim 2 , wherein the composition comprises a cobalt content such that: (Cr 2 O 3 /25)≤Co≤(Cr 2 O 3 /5).
5. The glass sheet as claimed in claim 2 , wherein the composition comprises a cobalt content such that: (Cr 2 O 3 /20)≤Co≤(Cr 2 O 3 /10).
6. A device comprising a glass sheet as claimed in claim 2 , wherein the device uses infrared radiation propagating essentially inside said sheet.
7. The glass sheet as claimed in claim 1 , wherein the composition comprises a chromium content, expressed as percentage by weight with respect to the total weight of the glass, such that: Cr 2 O 3 >(−17*Co)+0.0535; Co being the cobalt content, expressed as percentage by weight with respect to the total weight of the glass.
8. The glass sheet as claimed in claim 7 , wherein the composition comprises a chromium content such that: Cr 2 O 3 ≤1.5−Co.
9. The glass sheet as claimed in claim 8 , wherein the composition comprises a chromium content such that: Cr 2 O 3 ≤1−Co.
10. The glass sheet as claimed in claim 7 , wherein the glass sheet has a light transmission LTD4 of less than 50%.
11. The glass sheet as claimed in claim 1 , wherein the composition comprises a Fe2+(expressed in the form of FeO) content of less than 10 ppm.
12. The glass sheet as claimed in claim 1 , wherein the glass sheet has a coefficient of absorption at the wavelength of 1050 nm of less than 5 m −1 .
13. A touchscreen or touch panel or touchpad comprising at least one glass sheet as claimed in claim 1 defining a touch surface.
14. The screen or panel or pad as claimed in claim 13 , using the FTIR or PSD optical technology.
15. A device comprising a glass sheet as claimed in claim 1 , in a device using infrared radiation propagating essentially inside said sheet.
16. The use as claimed in claim 15 , wherein the propagation of the infrared radiation takes place by total internal reflection.