Color coding filter for charge-coupled-device camera

Claim 2

A color coding filter for use with an imaging device for converting light into electrical signals using a multiple-field format, the imaging device having a sensing surface being divided into an array of rectilinear resolution cells distinctive for each field, the cells defining a grid-pattern in each field and the cell boundaries in successive fields being displaced in at least one dimension to form overlapping grid patterns in the successive fields, the filter comprising a plurality of rectilinear zones which are arranged in direct correspondence to the cell array of the sensing surface so that all light from a scene impinging on any cell of the sensing surface passes through a corresponding zone in the filter, a plurality of discrete color areas being contained within each filter zone and being arranged so that the zone boundaries may be redefined with the change of cell boundaries during successive fields, the transmissivity characteristic of each color filter area being selected to produce a desired color coding for each zone.

Claim 3

A filter as claimed in claim 1 wherein the color transmissivity characteristic of each zone is determined by the sum of the color transmissivities of the color filter areas within its boundaries, the areas being arranged to produce a repetitive pattern of zones having different effective color transmissivity characteristics.

Claim 4

A filter as claimed in claim 2 wherein the filter areas are arranged to produce during successive fields different repetitive patterns of zones having different effective color transmissivity characteristics.

Claim 5

A filter as claimed in claim 1 wherein the number of filter areas in each zone is equal to the number of fields and each area includes a combination of adjacently located subareas formed of materials of different transmissivities, the effective color transmissivity of an area being the sum of the color transmissivities of the individual materials weighted in accordance with the size of the subareas.

Claim 6

A filter as claimed in claim 1 wherein the interlace format includes two fields, and the zone boundaries in one field include a first set of parallel equally spaced lines in one direction and a second set of parallel equally spaced lines in an orthogonal direction, and the zone boundaries in the successive field include parallel equally spaced lines located midway between the parallel lines of the first set of lines in the first field.

Claim 7

A filter as claimed in claim 5 wherein the boundaries in the successive field include the same parallel equally spaced lines of the second set of lines in the first field.

Claim 8

A filter as claimed in claim 1 wherein the interlace format includes two fields and in the first field each zone has one of four effective color transmissivity characteristics, the characteristics alternating in pairs in two orthogonal directions.

Claim 9

A filter as claimed in claim 7 wherein the horizontally displaced cells in the imaging device constitute a scan line and the imaging device produces for each cell in each scan line an electrical indication of the color transmissivity characteristics of its corresponding zone, the sum of the indications from any two adjacent cells in a scan line producing a luminance signal and the difference between these indications from two adjacent cells in the scan line producing a color difference signal, the filter being arranged so that successive scan lines produce two different color difference signals on sequential lines and the same two line-sequential color difference signals are produced in both fields, the luminance signal being the same for all scan lines in both fields.

Claim 10

A filter as claimed in claim 1 wherein the filter areas each have any one of five effective color transmissivity characteristics, J, K, L, M, N, the characteristics being selected so that K + L = M + N and K + L + 2J yields a luminance signal.

Claim 11

A filter as claimed in claim 9, wherein ##EQU4## where G is total transmissivity of green light, B is total transmissivity of blue light, and R is total transmissivity of red light.

Claim 12

A color television camera system for producing signals representative of the color content of a scene comprising: an area-imaging charge-coupled-device having an array of electrodes arranged in a pattern of rectilinear resolution cells, the device producing a charge accumulation proportional to the light impinging upon each resolution cell, the device including means for converting the plurality of charge accumulations into video signals, the video signals being produced in two fields, the signal in the first field being representative of a first cell pattern and the signal in the second field being representative of a second cell pattern, the first and second cell patterns overlapping spatially, a color coding filter having color filter areas arranged in rectilinear zones, each zone formed from a combination of filter areas arranged so that a first-field zone corresponds to every cell in the first field, the filter areas being arranged so that different combinations of filter areas also form a second-field zone corresponding to every cell in the second field, the filter being positioned so that all light impinging upon every cell in the first and second fields passes exclusively through a corresponding first and second field zone, respectively.

Claim 13

A color television camera system for producing signals representative of the color content of a scene comprising: an area-imaging charge-coupled-device having an array of electrodes arranged in a pattern of rectilinear resolution cells, the device producing a charge accumulation proportional to the light impinging upon each resolution cell, the device including means for converting the plurality of charge accumulations into video signals, the video signals being produced in two fields, the signal in the first field being representative of a first cell pattern and the signal in the second field being representative of a second cell pattern, the first and second cell patterns overlapping spatially, a color coding filter having color filter areas arranged in rectilinear zones, each zone formed from a combination of filter areas arranged so that a first-field zone corresponds to every cell in the first field, the filter areas being arranged so that different combinations of filter areas also form a second-field zone corresponding to every cell in the second field, the filter being positioned so that all light impinging upon every cell in the first and second fields passes exclusively through a corresponding first and second field zone, respectively.

Claim 14

A color television camera system as claimed in claim 11 wherein the charge-coupled-device operates in a three-phase frame transfer mode to produce the video signals in the two fields in a 2:1 line interlace format.

Claim 15

A color television camera system as claimed in claim 11 wherein each rectilinear zone is formed from a combination of two filter areas and the two areas in a zone in one field are each combined with another area to form a different rectilinear zone in the second field.

Claim 16

A color television camera system as claimed in claim 11 wherein the video signals constitute scan lines consisting of sequences of discrete components representative of the charge accumulations associated with horizontally adjacent resolution cells, and wherein the filter is arranged so that successive scan lines produce two different color difference signals and the same two line-sequential color difference signals are produced in both fields, so that the same luminance signal is produced for all scan lines in both fields.

Claim 17

A color television camera system as claimed in claim 14 further comprises means for processing the video signals, said processing means including means for subtracting in each scan line the discrete components derived from each two horizontally adjacent resolution cells to form line-sequential color difference signals and means for adding in each scan line the discrete components derived from each two horizontally adjacent resolution cells to form a luminance signal.

Claim 18

A color television camera system as claimed in claim 11 wherein each filter area includes a combination of adjacently located subareas formed of materials of different transmissivities, the effective color transmissivity of the area being the sum of the color transmissivities of the individual materials weighted in accordance with the size of the subareas.

Claim 19

A color television camera system as claimed in claim 11 wherein the color coding filter is arranged so that the zone boundaries in one field include a first set of parallel equally spaced lines in one direction and a second set of parallel equally spaced lines in an orthogonal direction, and the zone boundaries in the successive field include parallel equally spaced lines located midway between the parallel lines of the first set of lines in the first field.

Claim 20

A color television camera system as claimed in claim 17 wherein the boundaries in the successive field include the same parallel equally spaced lines in the second set of lines in the first field.

Claim 21

A color television camera system as claimed in claim 11 wherein each zone in each field has one of four effective color transmissivity characteristics, the characteristics alternating in pairs in two orthogonal directions.

Claim 22

A color television camera system as claimed in claim 11 wherein the color filter areas each have any one of five effective color transmissivity characteristics, J, K, L, M, N, the characteristics being selected so that K + L = M + N and K + L + 2J yields a luminance signal.

Claim 23

A color television camera system as claimed in claim 20, wherein ##EQU5## where G is total transmissivity of green light, B is total transmissivity of blue light, and R is total transmissivity of red light.