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Patent Issued for Light Bar Structure and Display Device

July 23, 2014



By a News Reporter-Staff News Editor at Electronics Newsweekly -- From Alexandria, Virginia, VerticalNews journalists report that a patent by the inventors Chao, Sheng-Chieh (Taoyuan County, TW); Chiang, Cheng-Sheng (Taipei County, TW); Kuo, Po-Fu (Taipei, TW), filed on January 20, 2011, was published online on July 8, 2014.

The patent's assignee for patent number 8770791 is Chunghwa Picture Tubes, Ltd. (Bade, Taoyuan, TW).

News editors obtained the following quote from the background information supplied by the inventors: "The invention relates to a light bar structure and a display device and, more particularly, to a light bar structure and a display device capable of providing a uniform light field.

"Since liquid crystal display (LCD) device has advantages of light weight, thin thickness, low power consumption and no radiation, it has been popularly applied to laptop computer, personal computer, television and so on. However, because an LCD panel of the LCD device cannot emit light by itself, a backlight module is needed to provide sufficient illumination for the LCD panel, so as to enable the LCD panel to display images.

"Referring to FIG. 1, FIG. 1 is an exploded view illustrating an LCD device 1 of the prior art. As shown in FIG. 1, the LCD device 1 comprises an outer frame 10, a display panel 12, a backlight module 14 and a back cover 16. The display panel 12 is disposed on the backlight module 14. The display panel 12 has an active area 120. The backlight module 14 comprises a frame 20, an optical film assembly 22, a light guide plate 24, two light bar structures 26 and a reflective sheet 28. The optical film assembly 22 is disposed on the light guide plate 24. The reflective sheet 28 is disposed under the light guide plate 24. The two light bar structures 26 are disposed at opposite sides of the light guide plate 24 respectively. Each of the light bar structure 26 consists of a plurality of light emitting diodes 260 and a circuit board 262. Light emitted from the light emitting diodes 260 is projected out of the optical film assembly 22 via the light guide plate 24. The display panel 12 and the backlight module 14 are fixed within the outer frame 10 and the back cover 16, so as to assemble the LCD device 1.

"Referring to FIG. 2, FIG. 2 is an enlarged view illustrating a partial area B shown in FIG. 1. As shown in FIG. 2, the light bar structure 26 comprises a plurality of light emitting diodes 260 and a circuit board 262. The light emitting diodes 260 are disposed on the circuit board 262. Each of the light emitting diodes 260 comprises a main body 2600 and a pair of leads 2602. Furthermore, the main body 2600 has a light emitting surface 2604 and the light emitting diode 260 emits light from the light emitting surface 2604. In general, each of the light emitting diodes 260 is fixed on the circuit board 262 by surface mount technology (SMT). Since the light emitting diodes 260 are disposed on the circuit board 262, a total thickness of each light bar structure 26 is equal to the sum of a thickness of the circuit board 262 and a height of each light emitting diode 260.

"Referring to FIG. 3 along with FIG. 1, FIG. 3 is a partial top view illustrating the display device 12 and the light bar structure 26 shown in FIG. 1. As shown in FIG. 3, a distance A is between the light emitting surface 2604 of the light emitting diode 260 and an edge of the active area 120 of the display panel 12, and a span P is between two adjacent light emitting diodes 260. Light emitted from the light emitting surface 2604 of the light emitting diode 260 will form a fan-shaped light field. The larger the distance A is and the more uniform the fan-shaped light field spreads into the light guide plate 24. If the distance A between the light emitting diode 260 and the active area 120 is too small, a bright area will appear on the light emitting surface 2604 of the light emitting diode 260 and a dark area will appear between two adjacent light emitting diodes 260. Consequently, a hot spot phenomenon may occur at the edge of the active area 120. However, if the distance A increases due to the conventional light bar structure 26, the whole size of the backlight module 14 will increase correspondingly. On the other hand, another method for modifying the hot spot phenomenon is to increase the number of light emitting diodes 260 (i.e. to decrease the span P). However, if the number of light emitting diodes 260 increases, the production cost of the backlight module 14 will increase correspondingly."

As a supplement to the background information on this patent, VerticalNews correspondents also obtained the inventors' summary information for this patent: "Therefore, an objective of the invention is to provide alight bar structure and a display device capable of providing a uniform light field, so as to solve the aforesaid problem.

"According to one embodiment of the invention, a light bar structure comprises a circuit board and a plurality of light emitting units. A plurality of holes is formed on the circuit board. Each of the light emitting units comprises a main body and a plurality of leads. The main body is disposed in one of the holes. The main body has a light emitting surface and a non-light emitting surface opposite to the light emitting surface. Each of the leads has a first connecting portion, a second connecting portion and an extending portion. The first connecting portion is connected to the non-light emitting surface, the extending portion is extended from the first connecting portion toward the light emitting surface, and the second connecting portion is extended from the extending portion and connected to a surface of the circuit board.

"According to another embodiment of the invention, a display device comprises a display panel and a backlight module. The backlight module comprises a frame, a light guide plate and a light bar structure. The display panel is disposed on the frame. The light guide plate is disposed in the frame. The light bar structure is disposed in the frame and located at one side of the light guide plate. The structural design of the light bar structure is mentioned in the above.

"As mentioned in the above, the main body of the light emitting unit of the invention is sunk into the corresponding hole of the circuit board due to the structural design of the leads, such that the height of the light bar structure is reduced. Furthermore, since the main body of the light emitting unit is sunk into the corresponding hole of the circuit board, the distance between the light emitting surface of the main body and an active area of the display panel can be increased, so as to prevent the hot spot phenomenon from occurring at an edge of the active area.

"These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings."

For additional information on this patent, see: Chao, Sheng-Chieh; Chiang, Cheng-Sheng; Kuo, Po-Fu. Light Bar Structure and Display Device. U.S. Patent Number 8770791, filed January 20, 2011, and published online on July 8, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=8770791.PN.&OS=PN/8770791RS=PN/8770791

Keywords for this news article include: Electronics, Circuit Board, Light-emitting Diode, Chunghwa Picture Tubes Ltd..

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Source: Electronics Newsweekly


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