U.S. Philips Corporation

Herman J Schmitz

Wilhelmus F Fekkes

Marcellinus J Annegarn

Wilhelmus J Christis

Daniele Santilli

Petrus J Van Den Hombergh

Lauens Doornheim

Melchert H Froling

Michael P Geerings

In interactive teletext, an individual user establishes a connection (6) with a central computer (14). Requested information is applied to a television transmitter (12) via a teltext inserter (11) and transmitted to the user as personal teletext pages for display on the user's receiver (3). However, other users (4) may be 'co-viewers'. In accordance with the invention, each personal page is transmitted with a teletext page number P and a sub-code S. Subsequently, a pseudo-page having the same page number P but a different sub-code S' is transmitted. Consequently, the personal page appears on the display screen of the co-viewer's receiver (4) only for a short time.

Method and device for securely transmitting teletext pages to specific

In a television receiver which comprises a video memory for noise reduction, large-area flicker reduction, still pictures and the like, an additional picture is generated by also storing its pixels in the video memory. The pixels of the additional picture are generated once by a pixel generator protected from being overwritten by the video signal applied at a field frequency of 50 hz by also storing a blanking bit for each pixel, preventing the pixel from being overwritten by the video signal. The additional picture may be, for example, a teletext page or an operating menu.

Television receiver for selectively blocking video signal samples via

A television receiver which is suitable for displaying teletext pages comprises a control system including a microcomputer. The microcomputer is coupled to a volatile memory which comprises a plurality of page number registers. A page number can be temporarily stored in each of these registers. With the aid of a keyboard the user makes known which page numbers he wants to have stored in the different registers and the stored page numbers represent a first series of pages. One single read key (RCL) is provided for the display of such a page. Each time this key is depressed once, a different page belonging to the first series appears on the picture screen. The sequence in which the pages appear is the same as the sequence in which the user has keyed-in the relevant page numbers. This sequence can be interrupted by the occurrence of a preselected operating instruction in response to which a number of teletext pages not associated with said first series can be displayed on the picture screen. Thereafter, the display of the teletext pages of the first series can be continued.

Television receiver comprising a teletext decoding circuit and a page

In order to obtain fast and simple processing of a recieved page address (65, 67, 69) into a write command (95) for a multi-page memory (99) of a teletext processing circuit, a page-number memory (81) is used which can be addressed by the received page address and in which a write command for the multi-page memory is stored for the desired pages.

Teletext signal processing circuit for a teletext receiver

Arrangement for receiving and processing digital signals in teletext or associated systems, comprising a picture store and a background store, the background store being arranged immediately after the source for the digital input signals such that output signals of the background store can be applied to the customary input circuit for further processing, while the picture store is arranged after this input circuit. The background store can store at least two but preferably a larger number of pages. Because of this implementation the waiting times occurring when new pages are requested are reduced to zero or substantially zero after the first request, while no additional control actions by the user are required.

Teletext device with reduced page-access time

Digital information is usually displayed as a set of pixels which are arranged according to a line pattern within a two-dimensional area. For the storage of the information to be displayed, use is normally made of a picture memory. The content of an information pixel is stored in the memory as m bits (m&gt;1). When use is made of a color map memory, the information can be displayed in different colors to be selected by a user. Selective display of the information is also possible, which means that only a selected number of the m bits are displayed. The invention provides a device for the display of digital information which enables selective display. In order to realize selective display, a device in accordance with the invention comprises a gate circuit with a control input on at least one connection between the display memory and the color map memory. Selective display in the form of picture pages and resolution enhancement is made possible by selected control signals on said control input.

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Eindhoven, Netherlands

Herman J Schmitz