RF shielded LCD assembly and PCB assembly including the same

Details RF shielded LCD assembly and PCB assembly including the same RF shielded LCD assembly and PCB assembly including the same

1999-09-22

2001-10-16

Gaffin, Jeffrey (Department: 2841)

Electricity: electrical systems and devices

Housing or mounting assemblies with diverse electrical...

For electronic systems and devices

C361S800000, C361S816000, C361S818000, C174S034000, C379S433020, C455S347000, C455S344000, C455S300000, C455S301000, C455S296000

Reexamination Certificate

active

06304458

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to shielding and, more particularly, to devices for shielding electronic components and/or circuitry within electronic devices.
BACKGROUND OF THE INVENTION
With the advent of smaller and smaller cellular telephones, it has become increasingly necessary to provide means for shielding the user and various electrical components of the telephone from radio-frequency (RF) emissions from other components of the telephone and/or from the environment. Electrically conductive shield cans may be mounted on a printed circuit board (PCB) and shaped to surround the components which are to be protected from RF noise or, more commonly, to suppress RF noise from the components contained in the shield cans. Shield cans according to the prior art may suffer from a number of drawbacks. The shield cans may be costly to install. Typically, shield cans are manually soldered, a labor intensive process, or mounted on a PCB during the surface mount assembly (SMA) process.
A liquid crystal display (LCD) assembly may be mechanically fastened to the inside of a front cover of a telephone or attached to one or more edges of a PCB. A light guide and associated fastening means often require a large amount of space on the PCB. The assembly process for mounting the light guide and the LCD on the PCB may be costly and labor intensive as well.
The LCD electrical connections to the PCB may be made using elastomer or spring connectors. This arrangement may be unreliable. Elastomer connectors may be improperly installed, resulting in failed electrical connections or shorting of adjacent pads on the PCB. The elastomer connectors may leave the LCD pads on the PCB vulnerable to contamination, particularly when the LCD-elastomer interface is subjected to temperature and humidity stresses over time.
If repairs of the PCB are required, the entire shield can often must be removed. This often requires expensive shield can removal equipment, fixtures and trained technicians. Typically, the PCB and surrounding components are placed under additional heat stress during both the removal and replacement of the shield can. There is also risk of flux and solder contamination of critical areas on the PCB such as LCD, SIM, or battery pads. If the board is not successfully repaired or if components reflow and shift during the re-application of the shield can, the process typically must be repeated. Snap-on shield cans are known, but are typically expensive and add additional labor to the assembly process.
SUMMARY OF THE INVENTION
The present invention is directed to a light guide/shield assembly for use with a PCB. The light guide/shield assembly includes an upstanding, electrically conductive shield wall adapted to be mounted on and electrically grounded to the circuit board. The shield wall defines an opening. A light guide member including a light transmissive guide body and an electrically conductive shield layer is mounted on the shield wall such that the shield layer overlies the opening. The light guide/shield assembly thereby defines an RF shielded chamber.
The light guide/shield assembly may include an LCD panel mounted on the light guide member. The LCD panel may be removably secured to the light guide member.
Preferably, the shield wall comprises a substantially continuous ring and the shield layer covers the substantial entirety of the opening. The light guide member may be removably mounted on the shield wall.
The light guide/shield assembly may include an integral connector assembly. Preferably, the connector assembly includes a first electrical connector secured to the shield wall and a second electrical connector secured to the light guide member, the second connector adapted to engage the first connector. Further, the first connector may be adapted to engage a connector pad of the circuit board and the second connector may be adapted to engage a connector pad of an LCD panel.
According to a further aspect of the present invention, an RF shielded PCB assembly includes a circuit board including an electrical ground and a light guide/shield assembly as described above mounted thereon. An LCD panel may be mounted on the light guide member of the light guide/shield assembly. An RF emissive component and/or an RF sensitive component may be disposed in the RF shielded chamber. The RF shielded PCB assembly may include a light source, the light source and the light guide member being relatively arranged such that light from the light source is transmitted by the light guide member to the LCD.
According to a further aspect of the present invention, a wireless communications device includes an RF shielded PCB assembly as described above.
Objects of the present invention will be appreciated by those of ordinary skill in the art from a reading of the Figures and the detailed description of the preferred embodiments which follow, such description being merely illustrative of the present invention.


REFERENCES:
patent: 5815224 (1998-09-01), Hasegawa et al.
patent: 5844166 (1998-12-01), Halttunen et al.
patent: 5986726 (1999-11-01), Murai
patent: 6149062 (2000-11-01), Danielson et al.
patent: 2 297 868 A (1996-08-01), None
patent: 06 347786 A (1994-12-01), None
patent: 10 153766 A (1998-06-01), None

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