Electric lamp and discharge devices: systems – Cathode ray tube circuits – Cathode-ray deflections circuits
Reexamination Certificate
1999-11-05
2001-12-11
Wong, Don (Department: 2878)
Electric lamp and discharge devices: systems
Cathode ray tube circuits
Cathode-ray deflections circuits
C348S626000
Reexamination Certificate
active
06329770
ABSTRACT:
This invention relates generally to the field of video displays, and more particularly to an arrangement employed therein to detect and control generation of unwanted emissions.
BACKGROUND OF THE INVENTION
It is well known that electronic circuitry comprising image display apparatus can exhibit electronic characteristics which generate unwanted signal components that can degrade the displayed image or acoustic output signal. Many methods are known for linearizing circuit operation or reducing harmonic generation to prevent impairment of the audio or visual performance of the device. However, these efforts are directed to the prevention of degraded display performance with little or no regard to unwanted or unintentional emissions emanating from the display device.
A recently introduced Federal Communications Commission rule, 47 CFR § 15 subpart B, Unintentional Radiators, mandates levels of radiation for various electronic products including, for example, TV broadcast receivers, TV interface devices, cable system terminal devices, other receivers, personal computers and peripheral equipment. Specifically, all TV broadcast receivers offered for sale in the United States must comply with section rule 47 CFR § 15.117.
Although engineering efforts have been directed to the improvement of display image quality by the elimination of spurious image degrading artifacts, the desire to achieve the enhanced performance provided by the ATSC standards requires, among other things, wider circuit bandwidth and with attendant high frequency signal currents and voltages. Such wider bandwidth signals, while necessary to provide the desired level of enhanced performance, can unfortunately and inherently result in unintentional emissions with levels greater than those mandated by the FCC.
SUMMARY OF THE INVENTION
Unintentional emissions are controlled responsive to the spectral content of the display signal. A video display apparatus comprises a cathode ray tube for video image display. A processor controls a magnitude of a video image display signal coupled to the cathode ray tube for display in response to an emission control signal. A generating means is coupled to the processor for generating the emission control signal responsive to a component of the video image display signal.
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Allender Jeffrey Owen
Cromarty Brian Jonathan
Griepentrog Dal Frank
Clinger James
Davenport Francis A.
Fried Harvey D.
Thomson Licensing S.A.
Tripoli Joseph S.
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