DC restore circuit in a video interface for medical imaging system
First Claim
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1. A DC restore interface apparatus for a medical imaging system comprising:
- input means for receiving an analog video signal from a medical imaging source, said analog video signal having an active video portion and a composite sync portion with a back porch interval;
a summing amplifier having first and second inputs;
means for coupling said analog video signal from said input means to said first input of said summing amplifer;
a difference amplifier having inverting and non-inverting inputs connected to said second input of said summing amplifier;
a track and hold amplifier, coupled to the inverting input of said difference amplifier, for sampling the signal level of said analog video signal during said back porch interval, said sampling being accomplished before said analog signal is input to said summing amplifier;
a one shot multivibrator connected to said track and hold amplifier for determining the timing and duration of said sampling by said track and hold amplifier;
a buffer amplifier connected to said noninverting input of said difference amplifier, and having inverting and non-inverting inputs, said non-inverting input being connected to ground;
a variable direct current (DC) source connected to the inverting input of said buffer amplifier; and
an analog-to-digital converter connected to the output of said summing amplifier;
wherein said output of said difference amplifier is a negative DC voltage which is summed with said analog video signal in said summing amplifier so that the output video signal from said summing amplifier is dynamically shifted to the reselected range of said analog-to-digital converter.
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Abstract
A medical imaging system includes a video interface having a DC restore circuit for dynamically shifting an analog video signal so that its peak to peak amplitude is equal to the preselected range of an analog-to-digital converter.
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Citations
2 Claims
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1. A DC restore interface apparatus for a medical imaging system comprising:
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input means for receiving an analog video signal from a medical imaging source, said analog video signal having an active video portion and a composite sync portion with a back porch interval; a summing amplifier having first and second inputs; means for coupling said analog video signal from said input means to said first input of said summing amplifer; a difference amplifier having inverting and non-inverting inputs connected to said second input of said summing amplifier; a track and hold amplifier, coupled to the inverting input of said difference amplifier, for sampling the signal level of said analog video signal during said back porch interval, said sampling being accomplished before said analog signal is input to said summing amplifier; a one shot multivibrator connected to said track and hold amplifier for determining the timing and duration of said sampling by said track and hold amplifier; a buffer amplifier connected to said noninverting input of said difference amplifier, and having inverting and non-inverting inputs, said non-inverting input being connected to ground; a variable direct current (DC) source connected to the inverting input of said buffer amplifier; and an analog-to-digital converter connected to the output of said summing amplifier;
wherein said output of said difference amplifier is a negative DC voltage which is summed with said analog video signal in said summing amplifier so that the output video signal from said summing amplifier is dynamically shifted to the reselected range of said analog-to-digital converter. - View Dependent Claims (2)
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Specification
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Current AssigneeCareStream Health Incorporated
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Original AssigneeEastman Kodak Company
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InventorsMcNeilly, Peter J.
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Primary Examiner(s)Groody, James J.
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Assistant Examiner(s)Harvey, David E.
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Application NumberUS07/797,840Time in Patent Office693 DaysField of Search358/171, 358/172, 358/168, 358/169, 358/166, 358/174US Class Current348/695CPC Class CodesH04N 5/16 Circuitry for reinsertion o...
