FR2690591A1 - Receiver for letterbox television signals. - Google Patents

Abstract

A standard format television receiver for letterbox television signals, i.e. extended definition television signals, in which a wide aspect ratio and at least one horizontal (black) bar together form a standard format television picture. The horizontal bars can carry augmentation signals intended to improve the performance of an extended receiver. The receiver includes a disturbance reduction assembly (5, 7, 11) for reducing the visibility of the horizontal bars and a decoder (9) for an additional control signal encoded with the extended television signals to provide a signal of disturbance reduction control to the disturbance reduction assembly (5, 7, 11). According to the invention, the disturbance reduction assembly comprises a zoom processor (11) for substantially eliminating the horizontal bars from a visible part of a standard aspect display device (3), a circuit ( 5, 7) to replace the horizontal bars with another signal, so that a user control signal selects between the zoom processor (11) and the replacement circuit (5, 7).

Description

The present invention relates to a receiver for television signals.

  mailbox, i.e. extended definition television signals, in which a wide format picture and at least one horizontal bar jointly form a standard format television picture These compatible standard format pictures can be received by standard television receivers. These letter box television signals are known from the communication of William F Schreiber '6 M Hz single channel HDTV systems "presented at the HDTV Symposium in Ottawa in October 1987 The horizontal bars are used to transmit improvement signals to improve wide format image quality Although these enhancement signals are processed to reduce their visibility, standard receivers display moving noise bars, enhancement signals in these areas The level of annoyance could be reduced to some extent by proper signal design The usual overscan setting on most receivers would make the bars narrower If desired, an inexpensive adapter could remove the noise bars New NTSC receivers could be fitted as standard of this suppressor for negligible cost Schreiber does not specify how th t when this

  suppression device must be implemented.

  As explained in international application WO-A-91/11882, in addition to the additional scrambled information present in the lines of the noise bars, a recognition signal could be transmitted in the blanking interval or in the lines of the noise bars, this recognition signal having to allow an intermediate generation of 4: 3 receivers to recognize the lines belonging to the

  noise bars and adjust these lines to the black level.

  The object of the invention is to provide a simple and adaptive method to the preference of the user for reducing the visibility of said at least one horizontal bar. For this purpose, according to one aspect of the invention, a receiver is provided in accordance with the main claim Advantageous aspects of the invention are

  indicated in the subclaims.

  The invention therefore relates to a standard format television receiver which also displays the horizontal bars; an extended definition receiver would display a wide format picture without the horizontal bars The standard format television receiver is equipped with an additional control signal decoder for the additional control signal which is transmitted together with the definition television signal extended to control the various decoding operations of an extended definition television receiver This control signal decoder can control the suppressor for

  eliminate noise from bars when a letterbox television signal is received.

  According to the invention, the television receiver also includes a zoom processor controlled by the control signal decoder to eliminate said at least one horizontal bar affected by noise, from the visible part of the standard format display device Even when the horizontal bars do not send improvement signals it is advantageous to use an automatic zoom processor which shows the full height of the wide format image on the standard format screen A user command signal ensures the selection between the zoom processor and the blanking device so that, if the user wants to look at the full width rather than the entire height of the wide screen image, it is

even do it.

  In an advantageous embodiment, the user can also indicate the option (zoom or delete) which would be automatically selected on reception of a letterbox television signal; the user control signal

  can then be used to select the other of the two options.

  When the additional control signal indicates the format of the wide format image, for example if this format is 14: 9 or 16: 9, the disturbance reduction control signal advantageously depends on this format of the image wide format so the delete or zoom operation is

  adapted to the format of the wide format image.

  It should be noted that in the article "Marktubersicht, Fernsehspa 43 mit 16: 9" which appeared in the German periodical Funkschau 1/1992, pages 34 to 36, are described television receivers which comprise a screen of format 16: 9 To compensate for the current absence of 16: 9 programs, these new television receivers offer a possibility of zooming. Thus, the television image appears to be seen from a shorter distance. is however

  cut at its upper and lower sides.

  The aspects mentioned above and still other aspects of the invention will emerge clearly from the embodiments described below. In the accompanying drawing: Fig 1 is a block diagram of a known embodiment of a receiver, and Fig 2 is a block diagram of an embodiment of a

receiver according to the invention.

  In Fig 1, input television signals are applied to a video decoder 1 to perform all operations normally performed on television signals. The video decoder 1 supplies its output signals to a display device 3 A switch 5 is connected between the video decoder 1 and the standard format display device 3, this switch being able to apply the output signal of a montage 7 rather than that of the video decoder 1 to the display device 3 The montage 7 provides a signal of black level The switch 5 is controlled by an additional control signal decoder 9 which is provided for detecting whether the received television signal comprises a recognition signal indicating the horizontal bars of a letterbox television signal If such letterbox television signal is received, the decoder 9 actuates the switch 5 so that it connects the output of assembly 7 to the device display 3 during the horizontal bars. Fig 2 illustrates an embodiment of a receiver according to the invention The elements which correspond to those shown in Fig 1 bear the same reference numbers However, according to one aspect of the invention, the arrangement 7 can provide a colored signal like a blue background, or an attractive pattern, instead of a simple black level signal The main thing is that the original horizontal bars, which can carry increase signals which

  look like noise, are replaced by something that is more pleasing to the eye.

  The additional control signal decoder 9 is advantageously provided for detecting whether the received television signal comprises an additional control signal intended to control the decoding operations of an extended definition television decoder. If this additional control signal is received, the decoder 9 determines whether the received signal is a letterbox signal having a wide picture format and at least one horizontal bar. As in the PA Lplus television system, wide pictures in 14: 9 or 16: 9 format can be transmitted in a letterbox format between black bars, the output signal from the decoder 9 is advantageously adapted to the image format of the wide screen image

  actually transmitted so as to affect only the black bars.

  In a preferred embodiment of the invention, the additional control signal decoder 9 is formed by a teletext decoder which is also capable of decoding the additional control signal of a definition mailbox TV signal. scope Further details about the additional control signal and how to decode it can be found in the unpublished European patent application NO 92 200 407 2 filed on 13 02 92

  (RHN 13 988) cited here for reference.

  The standard picture format receiver can use the deleted bars to display additional status information, such as time information (graphics or alphanumeric), program information or information

  other audio-video equipment such as the VCR or satellite tuner.

  In the embodiment of the receiver according to the invention illustrated in FIG. 2, the output signal from the video decoder 1 is now applied to a zoom processor Il which is controlled by the additional control signal decoder 9 so to eliminate in substance the horizontal bar or bars from the visible part of the standard format display device 3 However, it is obvious that this zooming operation will cause the loss of certain lateral information of the screen located on the left side and on the side image right According to the invention, the user can therefore apply a UCS user control signal to the zoom processor 11 to invalidate the zooming operation and to switch 5 to validate the deleting operation, so as to obtain a display of the entire image width with horizontal bars removed, precisely as in the form of

  embodiment illustrated in Fig 1.

  In an advantageous embodiment, the user can also indicate the option (zoom or delete) which must be automatically selected when receiving a television signal from mailboxes; the control signal

  User can then be used to select the other of the two options.

  Since the introduction of PA Lplus can be carried out little by little and program by program, mailbox images can be transmitted without the black bars containing signals improving the vertical resolution. As a variant of the PA Lplus television system, it is proposed include in the black bars a digital data signal carrying either a sound service or a data service such as teletext when no signal for increase in vertical resolution is transmitted The digital data signal is concealed as much as possible in the vicinity of the black level and is free of continuous components An error correction is added to make the signal robust with regard to channel alterations (terrestrial) An augmented decoder includes a detector coupled to the IF stage and synchronized by a synchronization separation circuit The detector is followed by an error correction decoder whose output e st applied to a sound decoder or to a data service decoder It is obvious that the adaptive zoom / delete arrangement according to the invention is also capable of reducing the visibility of this digital data signal, in the same way that the visibility of

  image display increase signals is reduced.

  It will be clear that a person skilled in the art is able to conceive

  many variants which fall within the scope of the following claims.

Claims (3)

  1 television receiver for receiving extended television signals to be displayed on a standard picture format display device, the extended television signals carrying a wide picture format picture and at least one horizontal bar of so as to form a standard format image, the receiver comprising: means for decoding an additional control signal encoded with the extended television signals, so as to provide a disturbance reduction control signal, and disturbance reduction means coupled to receive the disturbance reduction control signal for reducing the visibility of said at least one horizontal bar, wherein the disturbance reduction means comprises: zoom processor means for substantially eliminating said at least one horizontal bar a visible part of the standard image format display device; means for replacing said at least one horizontal bar by another signal; and means for making a selection between the zoom processor means and   the replacement means in response to a user control signal.   2 television receiver according to claim 1, further comprising means for adjusting the preference to indicate whether the zoom processor means or replacement means should be automatically enabled according to the disturbance reduction control signal, the signal user command invalidating the means validated automatically and validating the other means among the   processor zoom means or replacement means.   The television receiver according to claim 1, wherein the additional control signal indicates a wide format picture image format, and the disturbance reduction control signal depends on the picture format of large format.