JPH11243513A - Teletext receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a teletext recriver in which a signai for displaying a caption display area is not requred and no hard-to-read capation occurs, even when the caption is overlapped on a telop of a video signal. SOLUTION: This teletext receiver is provided with a tuner 1 that receives a teletext broadcast, a graphic processing circuit 6 that demodulates a received caption signal and that surrounds display area of the signal with a primary color signal of a prescribed level, a switching signal generating circuit 8 that slices the primary color signal to generate a switching signal, and a switch 9 that selects either the video signal received, while being controlled with the switching signal or the caption signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a text multiplex broadcast receiving apparatus for displaying a text multiplex broadcast subtitle broadcast on a display device.

[0002]

2. Description of the Related Art In a conventional teletext receiver, when a video signal such as a broadcast wave and a subtitle signal of a teletext are combined and displayed, the subtitle signal is displayed on the screen as an all-white signal on the back side. I have. For this reason, if the video signal is an all-white signal, it is difficult to read the subtitle. Therefore, the level of the luminance signal in the area where the subtitle signal of the video signal is multiplexed is reduced to about half so that the subtitle is easy to read.

[0003]

However, in order to lower the level of a luminance signal of a video signal such as a broadcast wave as described above, a dedicated circuit is required, and further, a display area of a subtitle signal is defined. A circuit for generating another signal different from the caption signal is required, and a circuit to be added to the circuit is required, which results in a complicated circuit configuration and high cost.

Further, since the telop in a video signal such as a broadcast wave is an all-white signal, even if the luminance signal level is reduced to about half, it becomes difficult to read when a subtitle signal of a text multiplex broadcast overlaps. There was also.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has a circuit for lowering the level of a luminance signal and another signal different from the subtitle signal for defining a display area of the subtitle signal. It is a first object of the present invention to obtain a text multiplex broadcast receiving device provided with a caption display means that does not require a subtitle.

It is a second object of the present invention to provide a text multiplex broadcast receiving apparatus which does not make subtitles difficult to read even when a telop in a video signal such as a broadcast wave and a caption signal of a text multiplex broadcast overlap. I do.

[0007]

In a teletext broadcast receiving apparatus according to the present invention, a tuner for receiving teletext broadcast, a received caption signal is demodulated, and a display area of the signal is converted to one primary color of a certain level. A graphic processing circuit enclosing the signal, a switching signal generating circuit for slicing the one primary color signal to generate a switching signal, and a switch for switching between a received video signal controlled by the switching signal and the subtitle signal. It is a thing.

Also, a tuner for receiving teletext, a graphic processing circuit for demodulating the received subtitle signal and surrounding a display area of the signal with one primary color signal of a fixed level, and slicing the one primary color signal. A switching signal generating circuit for generating a switching signal, a switch for switching between the received video signal and the above subtitle signal controlled by the switching signal, and adjusting the phase to the horizontal and vertical synchronizing signals of one of the reference video signals And a video controller for outputting the other video signal.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be specifically described with reference to the drawings showing the embodiments. Embodiment 1 FIG. Hereafter, NT, a broadcasting system in Japan,
The SC method will be described as an example. FIG. 1 is a block diagram showing a teletext broadcast receiving apparatus according to Embodiment 1 of the present invention. In the figure, 1 is a tuner that receives and demodulates a broadcast wave, 2 is a character multiplexed signal demodulation circuit that demodulates a character multiplexed signal superimposed on a vertical flyback period among video signals received by the tuner 1, and 3 is A color demodulation / synchronization separation circuit 4 that color-demodulates the video signal received by the tuner 1 and separates a synchronization signal is a primary color signal processing circuit that adjusts the level of the primary color signal and outputs it to the display device 5.

Reference numeral 6 denotes a graphic processing circuit for synchronizing the character multiplexed signal demodulated by the character multiplexed signal demodulation circuit 2 with the horizontal synchronizing signal HD and the vertical synchronizing signal VD separated by the color demodulation / synchronization separation circuit 3 to produce an image. Convert to a signal. Reference numeral 7 denotes a memory for developing a video signal of the graphic processing circuit 6, and reference numeral 8 denotes a switching signal generation circuit, which is a slice for slicing one primary color signal, for example, a blue signal, of a caption signal output from the graphic processing circuit 6 at a certain threshold value. It is composed of a circuit.
Reference numeral 9 denotes a switching signal output from the switching signal generating circuit 8, which switches between the video signal output from the color demodulation / synchronization separation circuit 3 and the subtitle signal output from the graphic processing circuit 6 and outputs the same to the primary color signal processing circuit 4. Switch.

FIG. 2 shows the principle of switching the subtitle display area of the video signal according to the first embodiment to a subtitle signal. Reference numeral 11 denotes a video signal of a video signal such as a broadcast wave displayed on the display device 5; 12 is a subtitle displayed on the display device 5 in synchronization with the video signal, 13 is a horizontal synchronization signal HD generated from the video signal, 14 is a vertical synchronization signal VD generated from the video signal, and 15 is a video signal and a subtitle signal. Is a display image obtained by synthesizing and displaying the video 11 and the subtitle 12.

Next, the operation of the first embodiment will be described with reference to the timing charts of FIGS. The broadcast wave received by the tuner 1 is demodulated into an NTSC video signal,
The video signal is output to a character multiplexed signal demodulation circuit 2 and a color demodulation / synchronization separation circuit 3. The character multiplexed signal demodulation circuit 2
When the user selects subtitle reception for teletext broadcasting, the text demodulator superimposed during the vertical flyback period is demodulated to demodulate the subtitle signal and output it to the graphic circuit 6.

The graphic circuit 6 synchronizes the input subtitle signal with the horizontal synchronizing signal HD and the vertical synchronizing signal VD separated from the video signal by the color demodulation / synchronization separation circuit 3 in FIG.
The subtitle signal shown in (a) is developed in the memory 7, and the primary color signals of blue (hereinafter, referred to as "B"), red (hereinafter, referred to as "R"), and green (hereinafter, referred to as "G") of the subtitle signal One of the colors, for example, a B signal obtained by converting a B signal to a constant level irrespective of the content of a caption signal as shown in FIG.
"Frame signal") and R, shown in FIGS. 3 (c) and 3 (d).
The G signal is output to the switch 9. The frame signal fills the subtitle display area with one color and displays white subtitles with the R and G signals. In addition, FIG.
This is a luminance (hereinafter, referred to as “Y”) signal generated from (c) and (d).

The frame signal output from the graphic processing circuit 6 is input to a switching signal generation circuit 8. The switching signal generating circuit 8 is constituted by, for example, the slice circuit shown in FIG. 4, and slices at a certain threshold value Vc1 to generate a switching signal. The switch 9 is controlled by this switching signal to perform color demodulation and
The R, G, and B signals of the video signal input from the sync separation circuit 3 and the R, G, and B signals of the caption signal input from the graphic processing circuit 6 are switched and output to the primary color signal processing circuit 4. The primary color signal processing circuit 4 adjusts the contrast and the hue, and then outputs the adjusted signal to the display device 5, and outputs the signal to the display device 5.
The display image 16 shown in (b) is displayed. Note that the graphic processing circuit 6 controls the timing at which the subtitle signal is output so as to be completely synchronized with a synchronization signal extracted from a video signal such as a broadcast wave.

As described above, in the text multiplex broadcast receiving apparatus according to the first embodiment, when a text multiplex broadcast is received, the caption signal superimposed on the broadcast wave video signal is demodulated, and the In the graphic processing circuit, a frame signal that fills the area in which the subtitle is displayed with one of R, G, and B primary color signals is created, and the subtitle signal is converted into a color signal other than the filled color. Since the caption is generated, the displayed caption is displayed in white characters with the color of the frame signal as a background. For example, as described above, when the frame signal is a B signal, the caption signal input to the switch 9 is composed of R and G signals, and white characters are displayed on a screen on a blue background.

In synchronization with a video signal such as a broadcast wave,
Since the subtitle display area is replaced with a frame signal of one color, there is no need to create a signal indicating a subtitle area completely different from the subtitle signal. Furthermore, since the subtitle display area is replaced with a frame signal, the telop is not displayed even if there is a telop signal in the video signal. .

In the graphic processing circuit 6,
If the subtitle signal is not completely synchronized with a synchronization signal extracted from a video signal such as a broadcast wave, or if the horizontal and vertical frequencies of the display on the display device 5 are different, synchronization may be achieved even by using a memory controller. it can.

In the first embodiment, the horizontal and vertical synchronization signals are extracted by the color demodulation / synchronization separation circuit 3. However, horizontal and vertical deflection signals for driving the display device 5 may be used.

Embodiment 2 In the first embodiment, the processing is performed by the graphic processing circuit 6 in order to synchronize with a video signal such as a broadcast wave. However, in the second embodiment,
A subtitle signal synchronized with a video signal is generated using multi-screen processing.

FIG. 5 is a block diagram showing a configuration of a second embodiment of the present invention using a multi-screen display processing circuit.
In the figure, the same reference numerals as those in FIG. 1 denote the same or corresponding parts, respectively.
When the luminance signal Y and the chroma signal C of the TSC system are input, the R, G, and B signals, the horizontal synchronization signal HD, and the vertical synchronization signal VD are output. Reference numeral 21 denotes a primary color → color difference signal conversion circuit which converts the primary color signal of the input subtitle signal into color difference signals RY and BY.
And a Y signal, and further converted into a digital signal by an A / D converter and output. A multi-screen processing circuit 22 converts the input color difference signal and Y signal into a horizontal synchronization signal HD,
The data is written to and read from the field memory 23 in synchronization with the vertical synchronization signal VD. Reference numeral 24 denotes a color difference → primary color signal conversion circuit which converts an input color difference signal into a primary color signal, and further converts it into an analog signal by a D / A converter.

Next, the operation will be described. The luminance signal Y and the chroma signal C of the video signal input to the color demodulation / synchronization separation circuit 3
Are converted to R, G, B signals and output to the switch 9 without being digitally processed. The horizontal and vertical synchronizing signals HD and VD are separated from the luminance signal Y and output to the multi-screen processing circuit 22.

The subtitle signal of the teletext broadcasting is shown in FIGS.
A signal as shown in (d) (however, it is not synchronized at all at this point with a video signal such as a broadcast wave)
The signal is input to the primary color → color difference signal conversion circuit 21 and is converted into a digital signal by an A / D converter in the primary color → color difference signal conversion circuit 21. Here, the reason why the primary color signal is purposely converted into the color difference signal is that the frequency band of the color difference signal can be narrowed as compared with the primary color signal, that is, the data amount can be reduced. The multi-screen processing circuit 22 includes horizontal and vertical synchronization signals HD and V input from the color demodulation / synchronization separation circuit 3.
To synchronize with D, the primary color → color difference signal conversion circuit 21
Is stored in the temporary field memory 23, and the data input from the color demodulation / synchronization separation circuit 3
The data in the field memory 23 is read at the timing of the vertical synchronization signals HD and VD. At this point, the video signal and the subtitle signal are synchronized.

The data read from the field memory 23 is converted from a digital signal into an analog signal by a D / A converter in the multi-screen processing circuit 22, and is subjected to color difference →
The signal is output to the primary color signal conversion circuit 24, and is returned to the R, G, B primary color signals by the color difference → primary color signal conversion circuit 24, and the switch 9
Is output to The switching signal generation circuit 8 creates a switching signal from the B signal in the same manner as in the first embodiment, and outputs it to the switch 9. The display image 16 shown in FIG. 2B is realized by switching between the video signal and the subtitle signal which are input by the switching signal of the switch 9.

In the second embodiment, an example in which a video signal is not converted to a digital signal has been described. However, the video signal may be converted to a digital signal to digitally switch between the video signal and the subtitle signal.

[0025]

As described above, according to the present invention, a frame signal for filling an area in which a subtitle is displayed with one of R, G, and B primary color signals is created and the area signal is filled. Generate subtitle signals with color signals other than colors,
Since the video signal is replaced with the frame signal, the displayed caption is displayed in white characters with the color of the frame signal as the background. For this reason, a signal indicating a subtitle area completely different from the subtitle signal is not required, and further, since it is not necessary to change the level (gain) of a video signal such as a broadcast wave, these circuits are not required. Further, even if the caption display area overlaps with a primary color signal of a certain level and a video signal telop for replacing the caption signal with a video signal, the telop is not displayed, so that the subtitle does not become difficult to read.

[Brief description of the drawings]

FIG. 1 is a block diagram of a teletext receiver according to a first embodiment of the present invention.

FIG. 2 is a conceptual diagram showing a mode in which a subtitle signal is replaced with a video signal according to the first embodiment.

FIG. 3 is a waveform diagram of a caption signal according to the first embodiment.

FIG. 4 is a diagram illustrating a switching signal generation circuit according to the first embodiment;

FIG. 5 is a block diagram of a teletext receiver according to a second embodiment of the present invention.

[Explanation of symbols]

1 tuner, 2 character multiplexed signal demodulation circuit, 3 color demodulation / synchronous separation circuit, 4 primary color processing circuit, 5 display device, 6 graphic processing circuit, 7 memory, 8 switching signal generation circuit, 9 switch, 21 conversion from primary color to color difference signal Circuit, 22 multi-screen processing circuit, 23 field memory, 24 color difference → primary color signal conversion circuit.

Claims (2)

[Claims] 1. A tuner for receiving a text multiplex broadcast, a graphic processing circuit for demodulating a received caption signal and surrounding a display area of the signal with one primary color signal of a fixed level, and slicing the one primary color signal. A multiplexed broadcast receiving apparatus comprising: a switching signal generating circuit for generating a switching signal; and a switch for switching between a received video signal and the subtitle signal controlled by the switching signal. 2. A tuner for receiving a text multiplex broadcast, a graphic processing circuit for demodulating a received caption signal and surrounding a display area of the signal with one primary color signal of a fixed level, and slicing the one primary color signal. A switching signal generating circuit for generating a switching signal, a switch for switching between a received video signal controlled by the switching signal and the above-mentioned subtitle signal, and adjusting a phase to a horizontal and vertical synchronizing signal of one of the reference video signals And a video controller for outputting the other video signal.