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Patent EP0004798A2 successfully refreshed from Google Patents.
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EP0004798A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

Video display control apparatus

Assignee: DATA RECALL Ltd
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Filing: 1979-04-12
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Granted: —
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Expires: 1999-04-12
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Abstract

Abstract Video display control apparatus tor a cathode ray display tube has an input terminal 11 for a composite video signal conveying raster synchronising information and video information. Line and frame deflection coils 12 and 13 supplied by line and frame output circuits 17 and 18 are supplied with scanning raster currents produced in response to the composite video signal. To adapt the raster to two different display formats a phase locked loop tone generator 37 receives the composite video signal and indicates by producing a binary output signal whether or not the composite video signal includes a line frequency line within the acquisition bandwidth of the generator 37, this frequency being the line frequency for one of the two display formats and another frequency which is outside the acquisition bandwidth of the generator 37 being the line frequency for the other display format. This binary signal is supplied to switches 21, 24, 28, 32 and 36 which are respectively set either open or closed in dependence on the value of the binary output signal and thus adapt the scanning raster circuitry to the component values required for one or the other format.

Inventors

  • 👤 Mark-Eric Jones

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-10-31 20:59
CPC Classifications
H; H04; H04N; H04N3/00; H04N3/10; H04N3/16; H04N3/27; G; G09; G09G; G09G1/00; G09G1/04; G09G5/00; G09G5/34; G09G5/343; H04N3/22; H04N3/223

Claims Analysis

Total Claims: 4
Claim 1
Independent Claim 130 words
Video display control apparatus for use with a visual display device employing a television-type raster, the control apparatus including an input terminal for a composite vide^ signal conveying raster synchronising information and video information, and means for producing scanning raster signals from composite video signals supplied to the said input terminals, characterised in that a frequency detecting circuit (37) is arranged to receive at least line synchronising information included in the raster synchronising information of a composite video signal when supplied to the said input terminal (11), and is so coupled to the said means (12,13, 17,18,19) for producing scanning raster signals as to determine the shape and/or size of the resultant raster in dependence upon the response of the frequency detecting circuit (37) to the synchronising information received thereby.
Claim 2
Dependent Claim 130 words
Video display control apparatus for use with a visual display device employing a television-type raster, the control apparatus including an input terminal for a composite vide^ signal conveying raster synchronising information and video information, and means for producing scanning raster signals from composite video signals supplied to the said input terminals, characterised in that a frequency detecting circuit (37) is arranged to receive at least line synchronising information included in the raster synchronising information of a composite video signal when supplied to the said input terminal (11), and is so coupled to the said means (12,13, 17,18,19) for producing scanning raster signals as to determine the shape and/or size of the resultant raster in dependence upon the response of the frequency detecting circuit (37) to the synchronising information received thereby.
Claim 3
Dependent Claim 75 words
Apparatus according to claim 1, wherein the frequency detecting circuit is a phase locked loop tone generator (37) connected to receive the composite video signal and such as to produce a binary output signal having one of its binary values whenever the composite video signal contains a frequency within the acquisition bandwidth of the tone generator (37) and having the other of its values whenever the composite video signal does not contain such a frequency.
Claim 4
Dependent Claim 54 words
Apparatus according to claim 2, wherein the tone generator (37) is arranged to supply its output signal to a plurality of switches (21,24,28, 32,36) to determine the respective states of these switches which are arranged to determine the values of respective electrical characteristics of elements (20,22-23,26-27,30-31,33-34) of the circuitry of the said means .(12,13,17,18,19).

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