Plural sequential operating mode automatic kinescope beam current limiter

Claim 2

In a system for processing an image representative video signal having a peak amplitude component determinative of image contrast and a D.C. component determinative of image brightness, said system including a video signal processing channel; and an image reproducing kinescope including an intensity control electrode for reproducing an image in response to video signals applied to said intensity control electrode from said channel; apparatus comprising: means for deriving a signal representative of the magnitude of peak and average beam currents conducted by said kinescope; first sensing means responsive to said derived signal for providing a first peak control signal representative of excessive peak beam currents above a peak threshold level within a first range of peak beam currents, and for providing a second peak control signal representative of excessive peak beam currents with a second range of relatively greater peak beam currents; second sensing means responsive to said derived signals for providing a first average control signal representative of excessive average beam currents above an average threshold level within a first range of average beam currents, and for providing a second average control signal representative of excessive average beam currents within a second range of relatively greater average beam currents; first control sequencing means for supplying said first peak control signal to said video channel to modify one of said peak amplitude and D.C. components of said video signal in a direction to limit beam currents conducted by said kinescope above said peak threshold level, in the presence of peak beam currents within said first range of peak currents; and for supplying said second peak control signal to said video channel to modify the other of said peak amplitude and D.C. components of said video signal in a direction to limit beam currents above said peak threshold level, in the presence of peak beam currents within said second range; and second control sequencing means for supplying said first average control signal to said video channel to modify said other of said peak amplitude and D.C. components of said video signal in a direction to limit beam currents above said average threshold level, in the presence of average beam currents within said first range of average currents; and for supplying said second average control signal to said video channel to modify said one of said peak amplitude and D.C. components of said video signal peak component in a direction to limit beam currents above said average threshold level, in the presence of average beam currents within said second range.

Claim 3

Apparatus according to claim 1, wherein: said first peak control signal is supplied to said video channel for modifying said peak video signal component in a direction to limit beam currents conducted by said kinescope above said peak threshold level, in the presence of peak beam currents within said first range of peak currents; and said second peak control signal is supplied to said video channel for modifying said D.C. component of said video signal in a direction to limit beam currents above said peak threshold level, in the presence of peak beam currents within said second range; and wherein said first average control signal is supplied to said video channel for modifying said D.C. component of said video signal in a direction to limit kinescope beam currents above said average threshold level in the presence of average beam currents within said first range of average currents; and said second average control signal is supplied to said video channel for modifying said peak video signal component in a direction to limit beam currents above said average threshold level, in the presence of average beam currents within said second range.

Claim 4

In a system for processing an image representative video signal having a peak amplitude component determinative of image contrast and a D.C. component determinative of image brightness, said system including a video signal processing channel; and an image reproducing kinescope including an intensity control electrode for reproducing an image in response to video signals applied to said intensity control electrode from said channel, currents conducted by said kinescope through said intensity control electrode being responsive to said peak amplitude and D.C. components of said video signal and corresponding to beam current conducted by said kinescope; apparatus comprising: means coupled to said intensity control electrode for deriving a signal representative of the magnitude of said kinescope beam current, directly from said currents conducted through said intensity control electrode; first sensing means responsive to said derived signal for providing a first peak control signal representative of excessive peak beam currents above a peak threshold level within a first range of peak beam currents, and for providing a second peak control signal representative of excessive peak beam currents within a second range of relatively greater peak beam currents; second sensing means responsive to said derived signals for providing a first average control signal representative of excessive average beam currents above an average threshold level within a first range of average beam currents, and for providing a second average control signal representative of excessive average beam currents within a second range of relatively greater average beam currents; first control sequencing means for supplying said first peak control signal to said video channel to modify one of said peak amplitude and D.C. components of said video signal in a direction to limit beam currents conducted by said kinescope above said peak threshold level; in the presence of peak beam currents within said first range of peak currents; and for supplying said second peak control signal to said video channel to modify the other of said peak amplitude and D.C. components of said video signal in a direction to limit beam currents above said peak threshold level, in the presence of peak beam currents within said second range; and second control sequencing means for supplying said first average control signal to said video channel to modify said other of said peak amplitude and D.C. components of said video signal in a direction to limit beam currents above said average threshold level, in the presence of average beam currents within said first range of average currents; and for supplying said second average control signal to said video channel to modify said one of said peak amplitude and D.C. components of said video signal peak component in a direction to limit beam currents above said average threshold level, in the presence of average beam currents within said second range.

Claim 5

In a system for processing an image representative video signal having a peak amplitude component determinative of image contrast and a D.C. component determinative of image brightness, said system including a video signal processing channel; and an image reproducing kinescope including an intensity control electrode for reproducing an image in response to video signals applied to said intensity control electrode from said channel, currents conducted by said kinescope through said intensity control electrode being responsive to said peak amplitude and D.C. components of said video signal and corresponding to beam current conducted by said kinescope; apparatus comprising: means coupled to said intensity control electrode for deriving a signal representative of the magnitude of said kinescope beam current, directly from said currents conducted through said intensity control electrode; first sensing means responsive to said derived signal for providing a first peak control signal representative of excessive peak beam currents above a peak threshold level within a first range of peak beam currents, and for providing a second peak control signal representative of excessive peak beam currents within a second range of relatively greater peak beam currents; second sensing means responsive to said derived signals for providing a first average control signal representative of excessive average beam currents above an average threshold level within a first range of average beam currents, and for providing a second average control signal representative of excessive average beam currents within a second range of relatively greater average beam currents; first control sequencing means for supplying said first peak control signal to said video channel to modify one of said peak amplitude and D.C. components of said video signal in a direction to limit beam currents conducted by said kinescope above said peak threshold level; in the presence of peak beam currents within said first range of peak currents; and for supplying said second peak control signal to said video channel to modify the other of said peak amplitude and D.C. components of said video signal in a direction to limit beam currents above said peak threshold level, in the presence of peak beam currents within said second range; and second control sequencing means for supplying said first average control signal to said video channel to modify said other of said peak amplitude and D.C. components of said video signal in a direction to limit beam currents above said average threshold level, in the presence of average beam currents within said first range of average currents; and for supplying said second average control signal to said video channel to modify said one of said peak amplitude and D.C. components of said video signal peak component in a direction to limit beam currents above said average threshold level, in the presence of average beam currents within said second range.

Claim 6

Apparatus according to claim 3, wherein: said first peak control signal is supplied to said video channel for mofidying said peak video signal component in a direction to limit beam currents conducted by said kinescope above said peak threshold level, in the presence of peak beam currents within said first range of peak currents; and said second peak control signal is supplied to said video channel for modifying said D.C. component of said video signal in a direction to limit beam currents above said peak threshold level, in the presence of peak beam currents within said second range; and wherein said first average control signal is supplied to said video channel for modifying said D.C. component of said video signal in a direction to limit kinescope beam currents above said average threshold level in the presence of average beam currents within said first range of average currents; and said second average control signal is supplied to said video channel for modifying said peak video signal component in a direction to limit beam currents above said average threshold level, in the presence of average beam currents within said second range.

Claim 7

Apparatus according to claims 3 or 4, wherein: said intensity control electrode corresponds to a cathode electrode of said kinescope.

Claim 8

Apparatus according to claim 5, wherein: said signal deriving means comprises an active current conduction device having a first electrode for receiving said video signals, a second electrode coupled to said kinescope cathode electrode, and a third electrode coupled to a point of reference potential and defining a main current conduction path of said active device for cathode current conduction between said second and third electrodes.

Claim 9

Apparatus according to claim 6, wherein: said active device comprises a PNP conductivity type transistor having a base electrode for receiving said video signals, an emitter electrode coupled to said kinescope cathode electrode, and a collector electrode coupled to said point of reference potential.

Claim 10

In a color television receiver for processing a color image representative video signal having a peak amplitude component determinative of image contrast and a D.C. component determinative of image brightness, said system including a video signal processing channel; and a color image reproducing kinescope including plural intensity control electrodes for reproducing a color image in response to video signals applied to said intensity control electrode from said channel, currents conducted by said kinescope through said intensity control electrodes being responsive to said peak amplitude and D.C. components of said video signal and corresponding to beam currents conducted by said kinescope; apparatus comprising: plural means respectively coupled to said intensity control electrodes for deriving signals representative of the magnitude of beam currents conducted by said kinescope, directly from said currents conducted through said intensity control electrodes; first sensing means responsive to said derived signals for providing a first peak control signal representative of excessive peak beam currents above a peak threshold level within a first range of peak beam currents, and for providing a second peak control signal representative of excessive peak beam currents within a second range of relatively greater peak beam currents; second sensing means responsive to said derived signals for providing a first average control signal representative of excessive average kinescope beam currents above an average threshold level within a first range of average beam currents, and for providing a second average control signal representative of excessive average beam currents within a second range of relatively greater average beam currents; first control sequencing means for supplying said first peak control signal to said video channel to modify said peak video signal component in a direction to limit beam currents conducted by said kinescope above said peak threshold level, in the presence of peak beam currents within said first range of peak currents; and for suplying said second peak control signal to said video channel to modify said video signal D.C. component in a direction to limit beam currents above said peak threshold level, in the presence of peak beam currents within said second range; and second control sequencing means for supplying said first average control signal to said video channel to modify said video signal D.C. component in a direction to limit beam currents above said average threshold level, in the presence of average beam currents within said first range of average currents; and for supplying said second average control signal to said video channel to modify said video signal peak component in a direction to limit beam currents above said average threshold level, in the presence of average beam currents within said second range.

Claim 11

In a color television receiver for processing a color image representative video signal having a peak amplitude component determinative of image contrast and a D.C. component determinative of image brightness, said system including a video signal processing channel; and a color image reproducing kinescope including plural intensity control electrodes for reproducing a color image in response to video signals applied to said intensity control electrode from said channel, currents conducted by said kinescope through said intensity control electrodes being responsive to said peak amplitude and D.C. components of said video signal and corresponding to beam currents conducted by said kinescope; apparatus comprising: plural means respectively coupled to said intensity control electrodes for deriving signals representative of the magnitude of beam currents conducted by said kinescope, directly from said currents conducted through said intensity control electrodes; first sensing means responsive to said derived signals for providing a first peak control signal representative of excessive peak beam currents above a peak threshold level within a first range of peak beam currents, and for providing a second peak control signal representative of excessive peak beam currents within a second range of relatively greater peak beam currents; second sensing means responsive to said derived signals for providing a first average control signal representative of excessive average kinescope beam currents above an average threshold level within a first range of average beam currents, and for providing a second average control signal representative of excessive average beam currents within a second range of relatively greater average beam currents; first control sequencing means for supplying said first peak control signal to said video channel to modify said peak video signal component in a direction to limit beam currents conducted by said kinescope above said peak threshold level, in the presence of peak beam currents within said first range of peak currents; and for suplying said second peak control signal to said video channel to modify said video signal D.C. component in a direction to limit beam currents above said peak threshold level, in the presence of peak beam currents within said second range; and second control sequencing means for supplying said first average control signal to said video channel to modify said video signal D.C. component in a direction to limit beam currents above said average threshold level, in the presence of average beam currents within said first range of average currents; and for supplying said second average control signal to said video channel to modify said video signal peak component in a direction to limit beam currents above said average threshold level, in the presence of average beam currents within said second range.