Apparatus to display graphic messages transmitted by videotext systems
First Claim
Patent Images
1. An apparatus for displaying videotext information on a television receiver screen, said apparatus comprising:
- internal synchronization means,phase locking means coupled to be driven by received video signals from a television receiver,first switching means for selectively connecting the phase locking means to the internal synchronization means,means including a first and a second means for respectively controlling interlaced and non-interlaced scanning of displays by said television receiver screen,second switching means for selectively switching between the respective interlaced and non-interlaced scanning control means,data demodulator means including a means for giving a working status indication,central management control circuit means including a first byte type recognition circuit means for recognizing a type of synchronization in the bytes of a first row of each page of videotext information, andfirst logic means coupled between said first byte type recognition circuit means and said first and second switching means and being responsive to the working status indication of the data demodulator means for selectively operating the first and second switching means responsive to said first byte type recognition circuit means and to said demodulator means to select between external synchronization contained within said received video signals and said internal synchronization means.
1 Assignment
0 Petitions
Accused Products
Abstract
A TV receiver is adapted to display either the regularly broadcast video signals or videotext information. The video signals contain their own internal synchronization signals. The videotext information requires locally generated synchronization signals which may be used to replace the normal video internal synchronization signals. The invention provides means for switching between the normally broadcast and the internally generated synchronization signals.
33 Citations
3 Claims
-
1. An apparatus for displaying videotext information on a television receiver screen, said apparatus comprising:
-
internal synchronization means, phase locking means coupled to be driven by received video signals from a television receiver, first switching means for selectively connecting the phase locking means to the internal synchronization means, means including a first and a second means for respectively controlling interlaced and non-interlaced scanning of displays by said television receiver screen, second switching means for selectively switching between the respective interlaced and non-interlaced scanning control means, data demodulator means including a means for giving a working status indication, central management control circuit means including a first byte type recognition circuit means for recognizing a type of synchronization in the bytes of a first row of each page of videotext information, and first logic means coupled between said first byte type recognition circuit means and said first and second switching means and being responsive to the working status indication of the data demodulator means for selectively operating the first and second switching means responsive to said first byte type recognition circuit means and to said demodulator means to select between external synchronization contained within said received video signals and said internal synchronization means. - View Dependent Claims (2, 3)
-
Specification