US 5,847,773 AGranted

Video system including apparatus for deactivating an automatic control arrangement

AssigneeThomson Consumer Electronics, Inc.

InventorsWilliam Adamson Lagoni, Robert Lawrence O'Brien

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Abstract

A projection television system includes an automatic contrast control section for controlling the amplitude of the luminance signal in response to the peak value of a luminance-representative image component signal in order to prevent white-spot blooming. Circuitry is provided for deactivating the automatic contrast control section when a user sets the contrast control level above a given threshold level, e.g., corresponding to the maximum contrast control level. As a result white-spot blooming is inhibited in order to ensure sharp images for a contrast control range below the given threshold level while allowing maximum white image components to be produced (at the expense of white spot blooming) when the contrast control level is set above the threshold level, depending on the preference of the user.

Claims19

Dependent claims

Apparatus comprising:

a channel for processing an information bearing signal including means for continuously controlling a characteristic of said information bearing signal in response to a control signal;
means subject to a user's manual adjustment and responsive to said information bearing signal for generating a combined control signal representing both a manual control level and an automatic control level in combined form;
said means for coupling said combined control signal to said controlling means;
and
means subject to the user's manual adjustment for generating an auxiliary control signal representative of said manual control level independent of said automatic control level;
wherein:
said means for generating said combined control signal includes means for generating a pulse signal encoded to represent said manual control level;
means for generating an automatic control signal in response to said information bearing signal;
and a common filter element for filtering both of said pulse signal and said automatic control signal to produce said combined control signal;
and
said auxiliary control signal generating means includes another filter element for filtering said pulse signal to produce said auxiliary control signal.

8 more elements

Apparatus, comprising:

a channel for processing an information bearing signal including means for controlling a characteristic of said information bearing signal in response to a control signal;
means responsive to a user's manual adjustment for generating a manual control signal;
means for comparing said manual control signal to a reference level corresponding to a particular manual adjustment level and for generating a switching control signal when said manual control signal exhibits a predetermined relationship to said reference level;
means responsive to said information bearing signal for generating an automatic control signal in a first mode of operation;
means responsive to said switching control signal for switching said automatic control signal generating means from said first mode of operation to a second mode of operation;
means for coupling said manual control signal independent of said comparing means to said controlling means so that said controlling means controls said characteristic of said information bearing signal in response to said manual control signal;
and
means for coupling said automatic control signal to said controlling means so that said controlling means controls said characteristic of said information bearing signal in response to said automatic control signal.

5 more elements

In a television system, apparatus comprising:

a video channel for processing a video signal including means for controlling an amplitude characteristic of said video signal in response to a control signal;
a display arrangement including at least one picture tube for reproducing an image in response to said video processed by said video channel, said display arrangement drawing a beam current in response to said video signal;
means responsive to a user's manual adjustment for generating a manual control signal;
means for comparing said manual control signal to a reference level corresponding to a particular manual adjustment level and for generating a switching control signal when said manual control signal exhibits a predetermined relationship to said reference level;
means responsive to said video signal for generating an automatic control signal, in a first mode of operation, for limiting said beam current drawn by said display arrangement;
means responsive to said switching control signal for switching said automatic control signal generating means from said first mode of operation to a second mode of operation;
means for coupling said manual control signal independent of said comparing means to said controlling means so that said controlling means controls said amplitude characteristic of said video signal in response to said manual control signal;
and
means for coupling said automatic control signal to said controlling means so that said controlling means controls said amplitude characteristic of said video signal in response to said automatic control signal.

6 more elements

In a television system, apparatus comprising:

a video channel for processing a video signal including means for controlling a peak amplitude of said video signal in response to a control signal;
a display arrangement including at least one picture tube for reproducing an image in response to said video signal processed by said video channel, said display arrangement drawing a beam current in response to said video signal;
means responsive to a user's manual adjustment for generating a manual control signal representative of a desired level of image contrast;
means for comparing said manual control signal to a reference level corresponding to a particular image contrast level and for generating a second control signal when said manual control signal exhibits a predetermined relationship to said reference level;
means responsive to said video signal for generating an automatic control signal, in a first mode of operation, for limiting said beam current drawn by said display arrangement;
means responsive to said second control signal for switching said automatic control signal generating means from said first mode of operation to a second mode of operation;
means for coupling said manual control signal independent of said comparing means to said controlling means so that said controlling means controls said peak amplitude characteristic of said video signal in response to said manual control signal;
and
means for coupling said automatic control signal to said controlling means so that said controlling means controls said peak amplitude characteristic of said video signal in response to said automatic control signal.

6 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/582,404Filed 3 Jan 1996 · continuation
Priority: 30 Aug 1991
Granted: 8 Dec 1998
Term ends: Not estimatedThe source records don’t support an estimate.

Classification4 codes

H04N 5/57
Receiver circuitry for the reception of television signals according to analogue transmission standards: control of contrast or brightness
H04N 5/59
Control of contrast or brightness: in dependence upon beam current of cathode ray tube
H04N 21/4854
End-user interface for client configuration: for modifying image parameters, e.g. image brightness, contrast
H04N
Pictorial communication