US3872246A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for elimination of interference from video signals
Assignee: Siemens AG
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Filing: 1973-12-20
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Granted: 1975-03-18
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Expires: 1993-12-20
Abstract
Abstract Apparatus is described for eliminating interferences in the video signals in video telephony or in other applications where the image receiving tube at the transmitter has a short storage time. A filter circuit is described for accomplishing the elimination of such interference, and this filter circuit is preferably placed at the transmission end of the video telephone circuit. The filter basically comprises a series arrangement of a logarithmic amplifier, a band elimination filter tuned to double the power frequency, a limiter and a exponential amplifier. The video signal is clamped to the black level prior to being coupled to the aforementioned filter arrangement. After the signal has been so filtered, the necessary picture gating, line gating and synchronizing signals may be added, as necessary. Other arrangements are described in which the interference frequency is branched off from the main circuit to be mixed with the disturbed video signal. This branching may be accomplished either electrically or optically.
Inventors
- 👤 Adolf Schneider
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 15:32
CPC Classifications
H; H04; H04N; H04N7/00; H04N7/14; H04N7/141; H04N23/00; H04N23/80; H04N23/81
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
172 words
An apparatus for eliminating an interference frequency, resulting from the frequency of the light illuminating the subject being photographed, from video signal transmission means having an image conversion means for receiving light from the subject and producing an electrical signal corresponding thereto, comprising: optical means for diverting a portion of said light from the subject prior to the reception of same by said image conversion means, said light being modulated by said interference frequency, means for converting said diverted light to electrical signals, logarithmic amplifier means connected to receive the output of said converting means, band-pass filter means connected to receive the output of said logarithmic amplifier and tuned to pass only said interference frequency and, electro-optical modulator means having an optical input for receiving said light from the subject and an electrical input for receiving the output of said band-pass filter, the output from said band-pass filter modulating said light for removing said interference frequency therefrom, the optical output of said modulator means being optically coupled to said image conversion means.
Claim 2
Independent Claim
172 words
An apparatus for eliminating an interference frequency, resulting from the frequency of the light illuminating the subject being photographed, from video signal transmission means having an image conversion means for receiving light from the subject and producing an electrical signal corresponding thereto, comprising: optical means for diverting a portion of said light from the subject prior to the reception of same by said image conversion means, said light being modulated by said interference frequency, means for converting said diverted light to electrical signals, logarithmic amplifier means connected to receive the output of said converting means, band-pass filter means connected to receive the output of said logarithmic amplifier and tuned to pass only said interference frequency and, electro-optical modulator means having an optical input for receiving said light from the subject and an electrical input for receiving the output of said band-pass filter, the output from said band-pass filter modulating said light for removing said interference frequency therefrom, the optical output of said modulator means being optically coupled to said image conversion means.
Claim 3
Dependent Claim
139 words
Apparatus for eliminating an interference frequency, resulting from the frequency of the light illuminating the subject being photographed, from video signal transmission means havving an image conversion means for receiving light from the subject and producing an electrical signal corresponding thereto, comprising: optical means for diverting a portion of said light emanating from the subject prior to the reception of same by said image conversion means, said light being modulated by said interference frequency, means for converting said diverted Light to electrical signals, logarithmic amplifier means connected to receive the output of said converting means, band-pass filter means connected to receive the output of said logarithmic amplifier and tuned to pass only said interference frequency, and means for modulating the electrical output of said image conversion means with the output of said band-pass filter for removing the interference frequency.
Claim 4
Dependent Claim
139 words
Apparatus for eliminating an interference frequency, resulting from the frequency of the light illuminating the subject being photographed, from video signal transmission means havving an image conversion means for receiving light from the subject and producing an electrical signal corresponding thereto, comprising: optical means for diverting a portion of said light emanating from the subject prior to the reception of same by said image conversion means, said light being modulated by said interference frequency, means for converting said diverted Light to electrical signals, logarithmic amplifier means connected to receive the output of said converting means, band-pass filter means connected to receive the output of said logarithmic amplifier and tuned to pass only said interference frequency, and means for modulating the electrical output of said image conversion means with the output of said band-pass filter for removing the interference frequency.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-03-17 | 1978-09-16 | 1979-03-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-17 | 1982-09-16 | 1983-03-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-17 | 1986-09-16 | 1987-03-18 | $7700.00 | Window Closed / Lapsed |