Backlight unit with one dimensional dimming
A backlight unit suitable for use as an illuminator for liquid crystal display devices. The backlight unit comprises a glass light guide plate with a glass sheet including a first glass surface comprising a plurality of channels separated by peaks and arranged periodically therein, and a plurality of light emitting diodes arranged in an array along at least one edge surface of the glass sheet.
1. A glass article for one dimensional dimming, the glass article comprising a glass sheet comprising a light guide plate and including a first glass surface, a second glass surface and a maximum thickness T defined therebetween, the first glass surface and the second glass surface comprising a plurality of channels formed therein, the plurality of channels separated by and alternating with peaks, each channel of the plurality of channels comprising a depth H in a range from about 5 pm to about 300 pm, a width S defined at a location across each channel at H/2, and wherein a ratio S/H is in a range from about 1 to about 15, wherein the glass article further comprises a backlight unit, wherein the backlight unit comprises a local dimming index LDI defined as:
LDI
=
⌈
1
-
(
L
n
+
1
+
L
n
-
1
)
/
2
L
*
⌉
×
100
where L n is a luminance of an nth area of a zone of the backlight unit and the LDI of the backlight unit is equal to or greater than about 0.70.
2. The glass article according to claim 1 , wherein T is in a range from about 0.1 mm to about 2.1 mm.
3. The glass article according to claim 2 , wherein T is in a range from about 1.1 mm to about 2.1 mm.
4. The glass article according to claim 1 , wherein the at least one channel comprises a rectangular, arcuate, or trapezoidal cross sectional shape.
5. The glass article according to claim 4 , wherein the at least one channel comprises a trapezoidal cross sectional shape including a sidewall with a wall angle Θ relative to a floor of the at least one channel in a range from greater than about 90° to less than about 160°.
6. The glass article according to claim 1 , wherein the at least one channel comprises a cross sectional shape including a circular arc with a radius R in a range from about 0.5 μm to about 1 cm.
7. The glass article according to claim 6 , wherein the radius R is in a range from about 0.5 μm to about 100 μm.
8. The glass article according to claim 1 , wherein S/H is in a range from about 2 to about 10.
9. The glass article according to claim 1 , wherein S/H is in a range from about 5 to about 10.
10. The glass article according to claim 1 , wherein H is in a range from about 0.1 T to about 0.9 T.
11. The glass article according to claim 1 , wherein H is in a range from about 0.5 T to about 0.45 T.
12. The glass article according to claim 1 , wherein the at least one channel is at least partially filled with a material comprising an index of refraction at least about 10% lower than an index of refraction of the glass sheet.
13. The glass article according to claim 1 , wherein S is in a range from about 10 μm to about 600 μm.
14. The glass article according to claim 1 , wherein the at least one channel comprises a sidewall with an RMS roughness equal to or less than about 5 μm when measured by white light interferometry.
15. The glass article according to claim 1 , wherein the glass article further comprises a reflector plate positioned adjacent to the second glass surface.
16. The glass article according to claim 1 , wherein the glass article comprises a display device.
17. The glass article according to claim 1 , wherein the plurality of channels and the peaks are periodic.