EP0178044A2
Expired / Lapsed
EP
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Analogue-to-digital converting apparatus for video signals
Assignee: Victor Company of Japan Ltd
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Filing: 1985-07-29
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Granted: —
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Expires: 2005-07-29
Abstract
Abstract An analog-to-digital converting apparatus comprises a clamping circuit (32) for clamping a reference level of an input analog video signal supplied thereto, an amplifying circuit (33) for amplifying an output signal of the clamping circuit, an analog-to-digital converting circuit (34) for generating a digital video signal by subjecting an output signal of the amplifying circuit (33) to an analog-to-digital conversion, and a control signal generating circuit (35, 36) for generating at least for the duration of a horizontal synchronizing signal of the input analog video signal a control signal responsive to a difference between the value of the output digital video signal of the analog-to-digital converting circuit (34) and the value of a preset reference signal. The control signal is supplied to one or two out of the clamping circuit (32), the amplifying circuit (33), and the analog-to-digital converting circuit (34) to variably control one or two out of a clamping voltage of the clamping circuit (32), an offset voltage of the amplifying circuit (33), and a first reference voltage of the analog-to-digital converting circuit (34) so that the value of the difference becomes a minimum.
Inventors
- 👤 Tsuneo Furuki
- 👤 Fujio Suzuki
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-30 15:42
CPC Classifications
H; H03; H03M; H03M1/00; H03M1/10; H03M1/12; H03M1/124; H03M1/129; H03M1/1295; H04; H04N; H04N5/00; H04N5/14
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
187 words
An analog-to-digital converting apparatus comprising clamping means (32) for clamping a reference level of an input analog video signal supplied thereto, amplifying means (33) for amplifying an output signal of said clamping means, and analog-to-digital converting means (34) for generating a digital video signal by subjecting an output signal of said amplifying means to an analog-to-digital conversion, characterized in that there is provided control signal generating means (35, 36; 59) for generating at least for the duration of a horizontal synchronizing signal of said input analog video signal a control signal responsive to a difference between the value of the output digital video signal of said analog-to-digital converting means (34) and the value of a preset reference signal; and that said control signal is supplied to one or two out of said clamping means (32), said amplifying means (33), and said analog-to-digital converting means (34) to variably control one or two out of a clamping voltage of said clamping means, an offset voltage of said amplifying means, and a first reference voltage of said analog-to-digital converting means so that the value of said difference becomes a minimum.
Claim 2
Dependent Claim
187 words
An analog-to-digital converting apparatus comprising clamping means (32) for clamping a reference level of an input analog video signal supplied thereto, amplifying means (33) for amplifying an output signal of said clamping means, and analog-to-digital converting means (34) for generating a digital video signal by subjecting an output signal of said amplifying means to an analog-to-digital conversion, characterized in that there is provided control signal generating means (35, 36; 59) for generating at least for the duration of a horizontal synchronizing signal of said input analog video signal a control signal responsive to a difference between the value of the output digital video signal of said analog-to-digital converting means (34) and the value of a preset reference signal; and that said control signal is supplied to one or two out of said clamping means (32), said amplifying means (33), and said analog-to-digital converting means (34) to variably control one or two out of a clamping voltage of said clamping means, an offset voltage of said amplifying means, and a first reference voltage of said analog-to-digital converting means so that the value of said difference becomes a minimum.
Claim 3
Dependent Claim
98 words
An analog-to-digital converting apparatus as claimed in claim 1, characterized in that said control signal generating means (35, 36) comprises digital-to-analog converting means (35) for generating at least for the duration of the horizontal synchronizing signal an analog signal which is obtained by subjecting the output digital signal of said analog-to-digital converting means to a digital-to-analog conversion, and analog comparing means (36) for comparing the value of an output analog signal of said digital-to-analog converting means with the value of a preset reference signal and for generating a control signal responsive to a difference between the compared values.
Claim 4
Dependent Claim
78 words
An analog-to-digital converting apparatus as claimed in claim 2, characterized in that said digital-to-analog converting means (35) comprises a digital-to-analog converter (49) for subjecting the output digital signal of said analog-to-digital converting means to a digital-to-analog conversion, a switching circuit (50) for passing an output signal of said digital-to-analog converter for at least the duration of said horizontal synchronizing signal, and a capacitor (51) which is supplied with an output signal of said switching circuit and charged thereby.
Claim 5
Dependent Claim
118 words
An analog-to-digital converting apparatus as claimed in claim 2, characterized in that said digital-to-analog converting means (35) comprises a digital-to-analog converter (49) for subjecting the output digital signal of said analog-to-digital converting means to a digital-to-analog conversion, a switching circuit (50) for passing an output signal of said digital-to-analog converter for at least the duration of said horizontal synchronizing signal, and a capacitor (51) which is supplied with an output signal of said switching circuit and charged thereby, and said analog comparing means comprises an analog comparator (52) supplied with a terminal voltage of said capacitor and a second reference voltage for generating as said control signal a voltage responsive to a difference between the voltages supplied thereto.
Claim 6
Dependent Claim
61 words
An analog-to-digital converting apparatus as claimed in claim 1, characterized in that said control signal generating means (59) comprises digital comparing means (59) for generating at least for the duration of said horizontal synchronizing signal a control signal responsive to a difference between the value of the output digital signal of said analog-to-digital converting means and a preset digital reference value.
Claim 7
Dependent Claim
82 words
An analog-to-digital converting apparatus as claimed in claim 5, characterized in that said digital comparing means (59) comprises a digital comparator (60) for generating at least for the duration of said horizontal synchronizing signal an error signal responsive to a difference between the value of the output digital signal of said analog-to-digital converting means and said preset digital reference value, and a control signal generating circuit (62) for generating a control signal responsive to the output error signal of said digital comparator.
Claim 8
Dependent Claim
30 words
An analog-to-digital converting apparatus as claimed in claim 6, characterized in that said control signal generating circuit generates said control signal only for the duration of said horizontal synchronizing signal.
References Cited (Backward Citations)
No citation records indexed.
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