Direct type back light device and display apparatus having the same

Patent metadata

Field	Value
Publication number	US-11366355-B2
Application number	US-202016926131-A
Country	US
Kind code	B2
Filing date	Jul 10, 2020
Priority date	Oct 21, 2019
Publication date	Jun 21, 2022
Grant date	Jun 21, 2022

Abstract

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.

First claim

What is claimed is:

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.

Assignees

• Samsung Electronics Co Ltd

Inventors

• Kim Jongbin
• Kim Hyungsuk
• Lee Youngmin
• Jeon Dukjin
• Cho Byoungjin
• Choi Sukju

Classifications

• H05K1/0274

  Optical details, e.g. printed circuits comprising integral optical means (H05K1/0269 takes precedence; coupling light guides with opto-electronic components G02B6/42) · CPC title

• G02F1/133603 Primary

  with LEDs · CPC title

• G02B6/0055 Primary

  Reflecting element, sheet or layer · CPC title

• H05K3/282

  for inhibiting the corrosion of the circuit, e.g. for preserving the solderability · CPC title

• G02F1/133608

  including particular frames or supporting means · CPC title