Tuners – With shielding or housing means
Reexamination Certificate
2000-06-09
2002-06-11
Bettendorf, Justin P. (Department: 2817)
Tuners
With shielding or housing means
C361S816000, C361S818000
Reexamination Certificate
active
06404309
ABSTRACT:
BACKGROUND
In a television tuner or other high-frequency receiving equipment, a tuner often includes a printed circuit board on which circuit components have been mounted and which is housed in a shielding case. It is common for low level RF signals, such as signals received from an antenna, CATV device or DSB device to be coupled to the receiver through a connector which permits the receiver to be easily connected or disconnected to/from this RF source. Such RF signals are then processed by a tuner section within the receiver. From a signal point of view, it would be best to place the printed circuit board of the tuner located right at the RF connector within a shielded enclosure In a television tuner or other high-frequency equipment, a circuit board on which circuit components have been mounted is housed in a shielding case, such as shown in U.S. Pat. No. 5,053,910 of Goldstein, where the RF signal is directly connected through an electrically conductive pin from the RF connector to the printed circuit board mounted at the back of the connector. However, in the usual case, this is not practical and the tuner is located at a distance from the RF signal input connector.
Additionally, it is often necessary to use shock hazard precautions for the externally accessible RF connector because of “hot chassis” considerations since the chassis often is connected to one side of the AC line. Such situations are shown in U.S. Pat. No. 5,351,018 of Lehmann et al. and U.S. Pat. No. 4,816,612 of Yeom. Such “isolation barrier” precautions are provided between the connector and the tuner requiring the tuner to be located at a distance from the RF signal input connector.
In the situations discussed above, because of the low RF signal level, it is desirable to use a shielded coaxial interface cable with a connector at the distal end of the cable to carry the signal to the modular tuner, which has a complementary connector for receiving the RF signal. Such a situation is shown in '612 cited above. Horizontally mounted tuners with a connector for receiving such a shielded cable are shown in U.S. Pat. No. 6,001,700 of Matsuzaki, U.S. Pat. No. 4,920,455 of Maier et al. and U.S. Pat. No. 4,628,412 of Nigorikawa. This shielded cable and the pair of complementary connectors represent a significant cost and it is desirable to eliminate these parts costs along with the respective assembly steps, especially in consumer electronics products which have very competitive pricing.
Further, if a shielded cable is not used, then it is desirable for the connection to the tuner to be direct and short to eliminate picking up extraneous signals and to prevent radiation of RF signals e.g., if the receiver is used on a cable system which has a large signal level. This would be the case if the RF signal input to the tuner had to be led in a long conductive path on the tuner printed circuit board to make contact at an edge connection of the board. Additionally, a long unshielded lead can cause an impedance mismatch at the termination points.
SUMMARY OF THE INVENTION
A shielded modular tuner is horizontally mounted onto a chassis printed circuit board and is provided, through an aperture in the shield, with lead connections from the edge of the tuner printed circuit board to the chassis printed circuit board, for power supply, control signals, outputting a processed signal, etc. However, the RF signal is coupled to the tuner via a conductive pin extending from an RF signal conducting path on the chassis printed circuit board, passing through a second aperture in the shield, directly to the point on the tuner printed circuit board where the signal is to be inputted for tuner processing. In this way, the RF signal is injected directly into the tuner precisely where it is needed without being led along a longer path from the edge of the tuner printed circuit board, and without a shielded coaxial cable and accompanying connectors.
REFERENCES:
patent: 4841414 (1989-06-01), Hibino et al.
patent: 6011700 (2000-01-01), Matsuzaki
patent: 6118672 (2000-09-01), Yamauchi et al.
Fatt Tey Tiam
Hall Edward Allen
Suan Pang Kim
Bettendorf Justin P.
Cathey Damian
Shedd Robert D.
Thomson Licensing S.A.
Tripoli Joseph S.
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