Video imaging apparatus having a pliant clock
First Claim
1. An improved multisensor video imaging apparatus of the type using plural linear arrays of elemental electrical transducers nominally fixed with respect to one another with each array'"'"'s longitudinal axis functionally oriented in a "cross track" direction substantially perpendicular to a "track axis" along which the arrays are simultaneously moved relative to a scanned area so as to successively scan, in nominal synchronism, corresponding common incremental portions of that area, said improvement comprising:
- first and second linear arrays of elemental electrical transducers, each elemental transducer being capable of generating an electrical signal representative of its incident illumination and each array being capable of sampling and reading out a series of respectively corresponding electrical signals in response to applied clock signals;
master clock means for providing master clock signals and first arrayed driver means connected thereto and to said first array to control the sampling and reading of electrical signals output from said first array of electrical transducers; and
a controlled oscillator circuit means for providing pliant clock signals and second array driver means connected thereto and to said second array to control the sampling and reading of electrical signals output from said second array of electrical transducers;
said controlled oscillator circuit means being connected to said master clock means for nominal control by said master clock signal but also having at least one supplemental control signal input for controllably varying the timing of said pliant clock signals with respect to said master clock signals so as to controllably maintain desired synchronism with respect to said cross-track axis between the sampling and reading of electrical signals output from said first and second arrays of electrical transducers.
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Accused Products
Abstract
A video imaging apparatus for scanning an area during relative motion in a direction defining a track axis has at least two linear sensors each comprised of at least one array of charge coupled devices. The sensors are oriented substantially perpendicular to the track axis thereby defining a cross-track axis. The arrays are further fixed relative to each other and oriented for simultaneously scanning the same area. A master clock signal is used to readout the data produced by the first sensor. A phase-locked loop produces a slaved, pliant, clock signal for reading the data out of the second sensor. By varying the phase of the slaved clock signal relative to the master clock signal, mechanical offset between the two sensors is compensated. By varying the average frequency of the slaved clock signal relative to the master clock signal, scale differences between the two sensors are compensated. By cyclically varying the instantaneous clock frequency along the cross-track axis of the salved clock signal relative to the master clock signal, lens distortion is compensated. Thus, by utilizing the phase-locked loop to control plural characteristics of the slaved clock signal, the retreival of data from the sensors may be more accurately coordinated and the necessity of costly, complex, off-line post-processing avoided.
33 Citations
22 Claims
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1. An improved multisensor video imaging apparatus of the type using plural linear arrays of elemental electrical transducers nominally fixed with respect to one another with each array'"'"'s longitudinal axis functionally oriented in a "cross track" direction substantially perpendicular to a "track axis" along which the arrays are simultaneously moved relative to a scanned area so as to successively scan, in nominal synchronism, corresponding common incremental portions of that area, said improvement comprising:
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first and second linear arrays of elemental electrical transducers, each elemental transducer being capable of generating an electrical signal representative of its incident illumination and each array being capable of sampling and reading out a series of respectively corresponding electrical signals in response to applied clock signals; master clock means for providing master clock signals and first arrayed driver means connected thereto and to said first array to control the sampling and reading of electrical signals output from said first array of electrical transducers; and a controlled oscillator circuit means for providing pliant clock signals and second array driver means connected thereto and to said second array to control the sampling and reading of electrical signals output from said second array of electrical transducers; said controlled oscillator circuit means being connected to said master clock means for nominal control by said master clock signal but also having at least one supplemental control signal input for controllably varying the timing of said pliant clock signals with respect to said master clock signals so as to controllably maintain desired synchronism with respect to said cross-track axis between the sampling and reading of electrical signals output from said first and second arrays of electrical transducers. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An apparatus for scanning an area during relative motion in a direction defining a track axis, comprising:
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at least two linear sensor arrays each oriented substantially perpendicular to said track axis thereby defining a cross-track axis, said arrays being substantially fixed relative to each other and oriented for simultaneously scanning the same said area and each temporarily storing plural electrical data signals representative of a corresponding array of incremental portions of said area; clock means for producing a master clock signal; means for retrieving a series of electrical data signals from one of said sensor arrays in response to said master clock signal; a voltage controlled oscillator for producing a slave clock signal; means for retrieving a series of electrical data signals from the other said sensor array in response to said slave clock signal; means for variably delaying said slave clock signal; and phase detection means for comparing said slave clock signal and said master clock signal, said phase detection means controlling said voltage controlled oscillator in response to said comparison so as to coordinate said retrieval of electrical data signals from said sensor arrays. - View Dependent Claims (13, 14, 15, 16)
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17. An apparatus for scanning an area by moving thereover in a direction defining a track axis, comprising:
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at least two linear sensor arrays each being substantially fixed with respect to one another and oriented perpendicular to said track axis thereby defining a cross-track axis, said arrays being oriented for substantially simultaneously scanning the same area and arranged to provide plural electrical data signals representative of a corresponding array of incremental portions of said area; a clock for producing a master clock signal; means for retrieving a series of electrical data signals from one of said sensor arrays in response to said master clock signal; a voltage controlled oscillator for producing a slave clock signal; means for retrieving a series of electrical data signals from the other said sensor array in response to said slave clock signal; circuit means connected to said voltage controlled oscillator for varying both the phase and the frequency of said slave clock signal relative to said master clock signal; a programmable attenuator responsive to said master clock signals for producing variable supplemental inputs to said voltage controlled oscillator, wherein said voltage controlled oscillator is controlled by both said circuit means and said programmable attenuator so as to compensate for cross-track misalignment, distortion and scaling errors. - View Dependent Claims (18)
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19. An improved multisensor video imaging apparatus of the type using plural linear arrays of elemental electrical transducers nominally fixed with respect to one another with each array'"'"'s longitudinal axis functionally oriented in a "cross track" direction substantially perpendicular to a "track axis" along which the arrays are simultaneously moved relative to a scanned area so as to successively scan, in nominal synchronism, corresponding common incremental portions of that area, said improvement comprising:
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first and second linear arrays of elemental electrical transducers, each elemental transducer being capable of generating an electrical signal representative of its incident illumination and each array being capable of sampling and reading out a series of sets of respectively corresponding electrical signals in response to applied clock signals; means for generating signals for sampling and reading of the electrical signals output from said arrays; memory means for storing plural sets of said electrical signals output from at least one of said arrays; and means for producing a cyclical weighted output signal responsive to certain of said stored electrical signals thereby interpolating between said electrical signals with respect to the track axis and producing rotational compensation at an angle with respect to the track axis. - View Dependent Claims (20, 21, 22)
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Specification