EP0313278A2
Expired / Lapsed
EP
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Defect compensation for solid state cameras
Assignee: Sony Corp
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Filing: 1988-10-14
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Granted: —
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Expires: 2008-10-14
Abstract
Abstract A solid state television camera for producing output signals corresponding to an object image includes a solid state image sensor (2). Data corresponding to the positions of defective picture elements attributable to crystal defects in a semiconductor material forming the solid state image sensor (2) and the levels of the defective components determined by the temperature sensing means (13) are previously stored as defective picture element data in a memory (10). Defect compensating signals corresponding to the actual image pickup operating states are formed by a compensating signal generator circuit (11) on the basis of the defect picture element data read out from the memory (10) to correct the output signals from the defective picture elements in such a manner that image pickup output signals having a superior picture quality are obtained.
Inventors
- 👤 Hiroyuki C/O Patents Division Itakura
- 👤 Takashi C/O Patents Division Asaida
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-06 08:46
CPC Classifications
H; H04; H04N; H04N23/00; H04N23/60; H04N23/667; H04N25/00; H04N25/60; H04N25/68; H04N25/69
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
260 words
A solid state television camera comprising: solid state image sensor means (2) of semiconductor material for providing an output signal corresponding to an image of an object, the image sensor means including picture elements (S) arranged in a raster having parallel scanning lines which are, in turn, arranged in order in a direction orthogonal to the direction of said scanning lines, said semiconductor material having crystal defects at locations of a plurality of said picture elements which will create noise at corresponding times in said output signal; memory means (10) for memorising position data corresponding to the positions of said crystal defects in the semiconductor material and defect level data corresponding to the level of a compensating signal for compensating the output signal associated with each of said defect locations, said defect level data being measured at a higher temperature than a normal operating temperature; readout means for reading out said position data and said defect level data from the memory means (10); temperature sensing means (13) for sensing the temperature around the solid state image sensor means (12); compensating signal generating means (11) connected to be supplied with said position data and defect level data and operative to generate the compensating signal at the timing at which said crystal defect is scanned and having a level which is determined by temperature compensated defect level data compensated by the output of the temperature sensing means (13); and control means (8, 9) respective to said compensating signal for cancelling said noise from said output signal of the image sensor means (2).
Claim 2
Dependent Claim
260 words
A solid state television camera comprising: solid state image sensor means (2) of semiconductor material for providing an output signal corresponding to an image of an object, the image sensor means including picture elements (S) arranged in a raster having parallel scanning lines which are, in turn, arranged in order in a direction orthogonal to the direction of said scanning lines, said semiconductor material having crystal defects at locations of a plurality of said picture elements which will create noise at corresponding times in said output signal; memory means (10) for memorising position data corresponding to the positions of said crystal defects in the semiconductor material and defect level data corresponding to the level of a compensating signal for compensating the output signal associated with each of said defect locations, said defect level data being measured at a higher temperature than a normal operating temperature; readout means for reading out said position data and said defect level data from the memory means (10); temperature sensing means (13) for sensing the temperature around the solid state image sensor means (12); compensating signal generating means (11) connected to be supplied with said position data and defect level data and operative to generate the compensating signal at the timing at which said crystal defect is scanned and having a level which is determined by temperature compensated defect level data compensated by the output of the temperature sensing means (13); and control means (8, 9) respective to said compensating signal for cancelling said noise from said output signal of the image sensor means (2).
Claim 3
Dependent Claim
73 words
A camera according to claim 1, wherein said compensating signal generating means (11) includes a two-series signal processing system operative to separately process timing information indicating the positions of defective picture elements in the semiconductor material forming the image sensor means (2) and amplitude information indicating the level of defective components included in the output signals, said amplitude information being sampled in analog form by said timing information for generating defect compensating signals.
Claim 4
Dependent Claim
148 words
A camera according to claim 1, comprising means for discerning, on the basis of data read out from the memory means (10), mode codes of defective picture elements corresponding to the defect compensating signals formed by the compensating signal generating means (11), the memory means (10) having previously stored therein mode codes indicating the locations of white and black flaw defect picture elements in the semiconductor material forming the image sensor means (2), the levels of the white and black flaw defect components contained in the output signals thereof, and the kinds of the defective picture elements, the compensating signal generating means (11) being operative to form defect compensating signals on the basis of said discerning means and as a function of the mode codes of the defective picture elements, and said defect compensating signal having been selectively temperature-compensated by the output of said temperature sensing means (13).
Claim 5
Dependent Claim
105 words
A camera according to claim 1, wherein: the charge accumulation time in each picture element of the image sensor means (2) can be variably set; and the compensating signal generating means (11) is operative to form signal level defect compensating signals in association with a preset charge accumulating time on the basis of data read out from the memory means (10) and to effect defect compensation of output signals from the solid state image sensor means (2) by defect compensating signals, the signal level of which is controlled in dependence upon the charge accumulation time in each picture element of the image sensor means (2).
Claim 6
Dependent Claim
128 words
A camera according to claim 1, wherein: a signal charge readout mode of the solid state image sensor means (2) can be switched between a first readout mode for reading out the signal charges of the totality of the picture elements in the course of approximately one field period and a second readout mode for reading out the signal charges of the totality of the picture elements in the course of approximately one frame period; defective picture element data in said first and second readout modes is previously stored in the memory means (10); and the readout means is operative selectively to read from the memory means (10) defective picture element data associated with the readout mode of signal charges from the solid state image sensor means (2).
Claim 7
Dependent Claim
113 words
A camera according to claim 1, wherein the distance between a defect position An (except a first defect position A0 counting as a reference point) where n stands for any arbitrary integer, and a defect position A(n-1) immediately preceding the defect position An is encoded and stored in the memory means (10) as the position data of defective picture elements in the semiconductor material forming the image sensor means (2), and wherein, in case of a large distance between said arbitrary defective picture element and the next adjacent defective picture element, a dummy defective picture element is set between said defective picture elements and corresponding data are stored in the memory means (10).
Claim 8
Dependent Claim
72 words
A camera according to claim 1, wherein said readout means causes the memory means (10) to operate only for a predetermined period including the time duration during which data necessary for forming defect compensating signals in the compensating signal generating means (11) are read out from the memory means (10), with some time allowance before and after said time duration, the memory means (10) being controlled to remain inoperative during other period.
Claim 9
Dependent Claim
69 words
A camera according to claim 1, comprising comparator means for comparing the signal level of the defect compensating signal generated by the compensating signal generating means (11) with a reference signal level which changes with the image pickup conditions, defect compensating signals of a signal level greater than the reference signal level being taken out on the basis of the output of said comparator means for performing defect compensation.
Claim 10
Dependent Claim
226 words
A camera according to claim 1, wherein: the image sensor means (2) of semiconductor material comprises first to third solid state image pickup elements (2R, 2G, 2B), the first solid state image pickup element (2R) being displaced by one half of a picture element pitch (P) in the horizontal direction with respect to the second and third solid state image pickup elements (2G, 2B); the memory means (10) stores data concerning the positions of the defective picture elements in the first to third solid state image pickup elements (2R, 2G, 2B) and the levels of the defective components included in the output signals; the compensating signal generating means (11) is operative to separately form defect compensating signals for the first to third solid state image pickup elements (2R, 2G, 2B) on the basis of data read out from the memory means (10), and to separately adjust the locations of generation of said defect compensating signals; and the compensating signal generating means (11) is operative to generate defect compensating signals for the solid state image pickup elements (2R, 2G, 2B) at the timing of output signals of said defective picture elements of the first to third solid state image pickup elements and to add the defect compensating signals to the output signals of the first to third solid state image pickup elements for compensating for the defects.
References Cited (Backward Citations)
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