Integrated interface circuit between a television receiver and i

Details Integrated interface circuit between a television receiver and i Integrated interface circuit between a television receiver and i

1982-03-29

1984-06-26

Murray, Richard

Facsimile and static presentation processing

Facsimile

Specific signal processing circuitry

H04N 522

Patent

active

044569289

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

This invention concerns an integrated interface circuit between a television receiver and its peritelevision connector, to allow the connection of an external source such as a magnetoscope.
Such circuits, usually constructed from discrete components, are used for the selection of different audio and video tracks, either from a black-and-white or colour television receiver, or from an external source, such as a magnetoscope.
This invention proposes an integrated circuit comprising, in a single circuit, all the stages needed for an effective interface between the television receiver and its peritelevision connector. This considerably reduces the space required, compared with circuits known in the prior art, as well as providing a much better layout inside the receiver, since the peritelevision connector is attached and close to the switching unit. Such a circuit also has the advantage of being much cheaper to produce than existing circuits.
This new integrated interface circuit between a television receiver and its peritelevision connector, for the connection of an external source, such as a magnetoscope, comprises, within a single circuit, a video interface stage, an audio interface stage, and a switching stage, which uses logic signals at its inputs to switch or not switch, on the one hand a selector switch in the video stage, in order to select either the internal video signal from the television receiver, or the external video signal from the external source, and on the other hand selector switches in the audio stage, in order to select either the internal audio signal from the television receiver, or the external audio signal from the external source.
Other benefits and features of the invention will be made clear in the following description of one of many possible embodiments of the invention, illustrated by the accompanying FIGURE, showing the interface circuit in diagrammatical form.


DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

The integrated interface circuit comprises a video stage E.sub.V, an audio stage E.sub.A, and a switching stage E.sub.C.
The video stage E.sub.V comprises an input 1, which receives, through a linking capacitor C.sub.1, the internal video signal from the output of the video detector circuit of the television receiver.
This internal video signal is fed, on the one hand, into the input of a 1-gain integrated amplifier A.sub.3, the output of which is output 2 of the integrated interface circuit. This output 2 is a external low-impedance video output (75 ohms, 1 v), and a 75-ohm cable is used to feed the video signal from the television receiver into a magnetoscope input. The same internal video signal is fed into the input of a one half-gain integrated amplifier A.sub.2, the output of which is connected to the first contact point 30 of an electrically controllable switch I.sub.1, such as a balanced double differential switch. Operation of this switch is symbolized by the movement of a connecting bar between two contact points.
The second contact point 31 of this switch I.sub.1 is connected to the output of a 1-gain integrated amplifier A.sub.4, the input of which is the external video input 3 of the integrated interface circuit. This input 3 can receive, through a linking condenser C.sub.3, a video signal supplied by an external source, such as a magnetoscope or an "Antiope" decoder, and it accordingly constitutes the video part of the peritelevision connector.
Switch I.sub.1 strip is connected to the input of a 1-gain final amplifier A.sub.1, the output of which is output 18 of the integrated interface circuit, on which the video signal fed into the television receiver video circuits appears.
When switch I.sub.1 strip is positioned on contact point 30, the internal signal from input 1 is conveyed to output 18; when it is on contact point 31, it is the external video signal from input 3 that is conveyed to output 18.
Switch I.sub.1 can thus select either the internal video signal or the external video signal from the peritelevision conne

REFERENCES:
patent: 3795762 (1974-03-01), Willis

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