Direct type back light device and display apparatus having the same
A direct type backlight device includes a lower chassis, a reflective sheet disposed on a bottom portion of the lower chassis, and a plurality of light emitting diode (LED) bars disposed on an upper surface of the reflective sheet. Each of the plurality of LED bars includes a bar-shaped printed circuit board disposed on the upper surface of the reflective sheet, a plurality of LEDs disposed on an upper surface of the printed circuit board, and a reflective member provided on the upper surface of the printed circuit board. A reflectance of the reflective member is at least 90% of a reflectance of the reflective sheet.
1. A direct type backlight device comprising:
a lower chassis;
a reflective sheet disposed on a bottom portion of the lower chassis; and
a plurality of light emitting diode (LED) bars disposed on an upper surface of the reflective sheet,
wherein each LED bar of the plurality of LED bars comprises:
a bar-shaped printed circuit board disposed on the upper surface of the reflective sheet;
a plurality of LEDs disposed on an upper surface of the printed circuit board; and
a reflective member provided on the upper surface of the printed circuit board,
wherein the reflective member comprises a photo solder resist (PSR) layer having a high reflectance, the PSR layer being formed by applying a PSR ink to the printed circuit board,
wherein the plurality of LEDs are fixed to the printed circuit board, on which the PSR layer has been provided, via a reflow soldering process performed twice on the printed circuit board, including the PSR layer, and the plurality of LEDs, and
wherein a reflectance of the PSR layer reduces each time after the reflow soldering processing is performed on the PSR layer, and the PSR ink has a reflectance such that the reflectance of the PSR layer, on which the reflow soldering processing has been performed twice, is at least 90% of a reflectance of the reflective sheet, and is less than the reflectance of the reflective sheet.
2. The direct type backlight device as claimed in claim 1 , wherein the reflectance of the PSR layer is 87% or more.
3. A display apparatus comprising:
a liquid crystal panel;
a diffusion plate disposed under the liquid crystal panel;
a plurality of light emitting diode (LED) bars disposed under the diffusion plate;
a reflective sheet disposed under the plurality of LED bars; and
a lower chassis disposed under the reflective sheet and configured to support the reflective sheet,
wherein each LED bar of the plurality of LED bars comprises:
a bar-shaped printed circuit board disposed over the reflective sheet;
a plurality of LEDs disposed on an upper surface of the printed circuit board; and
a reflective member provided on the upper surface of the printed circuit board,
wherein the reflective member comprises a photo solder resist (PSR) layer having a high reflectance, the PSR layer being formed by applying a PSR ink to the printed circuit board,
wherein the plurality of LEDs are fixed to the printed circuit board, on which the PSR layer has been provided, via a reflow soldering process performed twice on the printed circuit board, including the PSR layer, and the plurality of LEDs, and
wherein a reflectance of the PSR layer reduces each time after the reflow soldering processing is performed on the PSR layer, and the PSR ink has a reflectance such that the ft reflectance of the PSR layer, on which the reflow soldering processing has been performed twice, is 90% or more of a reflectance of the reflective sheet, and is less than the reflectance of the reflective sheet.
4. The display apparatus as claimed in claim 3 , wherein the reflectance of the PSR layer is 87% or more.