JPH10136401A - Digital broadcasting receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce cross color or an on-screen display screen. SOLUTION: An on-screen display rate deciding means 2010 adaptively changes a frequency characteristic of a luminance signal filtering means which is inputted by a luminance signal of an analog signal in which on-screen information is encoded from a multiplexed digital video signal in accordance with the ratio of separation characteristic information of a color signal on a monitor to an on-screen information area on the monitor screen. A 1st luminance signal Y filter 1010 and a 2nd luminance signal Y filter 1020 are automatically switched by the means 2010.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital broadcast receiver.

[0002]

2. Description of the Related Art Digital broadcasting and DSM (Digit) have been developed using digital compression coding technology of images developed in recent years.
al Storage Media), various devices using a digitally compressed image restoration apparatus have begun to be put into practical use. For example, in digital broadcasting, following the start of digital satellite broadcasting in the United States, in Europe and Asia including Japan,
Digital satellite broadcasting plans are in progress, and digital broadcast receivers related to the present invention are, for example, those used in digital satellite broadcast receivers.

Conventionally, a digital broadcast receiver is generally configured as shown in FIG. FIG. 4 is a block diagram showing a configuration of a standard digital satellite broadcast receiver which is an example of a digital broadcast receiver.

In FIG. 4, reference numeral 100 denotes a tuner unit.
A desired physical channel is selected from intermediate frequencies from the LNB such as BS and CS.

[0005] 110 is a demodulation device, 120 is an error correction device, and reproduces a digital signal from a selected physical channel. A program extraction / separation device 130 extracts desired programs and program information from a plurality of multiplexed programs. 14
Reference numeral 0 denotes a compressed image decompression device (hereinafter, referred to as a V decoder), which decompresses an encoded and compressed video signal. Reference numeral 170 denotes a compressed audio signal decompression device (hereinafter, referred to as an A decoder) which decompresses the encoded and compressed audio signal. Reference numeral 150 denotes an on-screen synthesizing device, which performs on-screen synthesizing of a restored program with a program table or the like. Reference numeral 160 denotes a digital video encoding device that converts a video signal into a desired signal format NTSC / NTSC.
Encode to a baseband signal in PAL or other format.

[0006] A microcomputer 180 performs initial setting and operation control of element devices in the receiver. Reference numeral 190 denotes an on-screen information generating device which generates on-screen information to be displayed based on program accompanying information from the program extracting / separating device 130 and the like. Reference numeral 200 denotes an IC card for decrypting an encryption key for descrambling a program, managing a viewing fee, and the like. With the above configuration, the received broadcast program is
The data is output to the television monitor 210, the VTR 215, and the like.

Next, the operation of the conventional digital broadcast receiver after the on-screen synthesis processing will be described with reference to FIG. FIG. 5 is a block diagram showing a detailed operation of the conventional digital broadcast receiver after on-screen synthesis.

The same components as those in FIG. 4 are denoted by the same reference numerals, and description thereof is omitted here. In FIG. 5, a luminance signal Y and a chroma signal C are output from a digital video encoding device 160 as shown in the figure, respectively, as a Y filter 1010, a Y filter 1020, and a C filter 103.
Output to 0.

This Y filter 1010, Y filter 10
FIG. 6 shows an example of characteristics in the 20 NTSC signal systems. FIG. 6 is a frequency characteristic diagram showing the frequency characteristics of the filter. As shown in FIG. 6, the Y filter 1010 has a substantially constant amplitude characteristic in the frequency band of the video signal, whereas the Y filter 1020 has a characteristic of 3.58 MHz.
That is, it has a trap characteristic at the color subcarrier frequency in the NTSC system. This is because the filter characteristics can be changed by a method of separating the luminance signal Y and the chroma signal C from the composite video signal in the TV monitor at the subsequent stage. For example, the Y / C signal separation method in the monitor is a trap filter method. In some cases, the characteristics of the Y filter 1020 are selected in order to reduce the display of the color subcarrier frequency of the luminance signal Y, that is, a frequency component near 3.58 MHz as cross color interference. On the other hand, when the Y / C signal separation system in the subsequent television monitor uses a comb filter system or the like, the components of the luminance signal Y in the vicinity of the color subcarrier frequency do not cause cross-color interference, so that the Y filter 1010 By selectively outputting the side, a composite signal having excellent frequency characteristics of the luminance signal Y can be output.

Next, description will be made again with reference to FIG. 1060
Is a resistor, 1070 is a switch as monitor characteristic information input means, 1050 is a changeover switch as filter characteristic control means, and switches the output of the Y filter 1010 and the Y filter 1020. In 1040, an addition device synthesizes a composite signal by adding the luminance signal Y and the chroma signal C. Here, the Y filter 1010 output is always selected for the Y signal at the time of separating and outputting the Y / C signal, whereas for the composite signal output, the changeover switch 1050 controls the Y filter 1010, selection can be made from the output of the Y filter.

This is because, as described above, manual selection of the Y filter is performed in accordance with the method of separating the Y signal and the chroma signal from the composite signal on the television monitor connected at the subsequent stage, thereby preventing cross color interference and the like. This is for reduction. For example, the user operates the switch 1070 while watching the display screen on the television monitor at the subsequent stage, thereby selecting the optimum filter characteristics.

[0012]

However, according to the above configuration, in the Y / C signal separation system or the like in the subsequent television monitor, the filter characteristics of the Y signal are manually set to a fixed value. When displaying a cross-color obstruction screen with many wide-range components of the Y signal consisting of a large number of characters and lines, such as a program guide display on the screen, and a screen with conspicuous cross-color interference such as a natural image In both cases, since the filter characteristics are the same, the fixed value of the Y filter selected to reduce the cross interference on the on-screen screen may cause the frequency characteristics of the luminance signal Y to deteriorate when displaying a natural image. Had problems.

[0013]

In order to solve such a problem, the present invention provides a luminance signal filtering means for inputting a luminance signal of an analog video signal encoded from a digital video signal on which on-screen information is multiplexed. The present invention provides a digital broadcast receiver characterized in that the frequency characteristics of the digital broadcast receiver are adaptively changed according to the color signal separation characteristic information of the monitor and the ratio of the on-screen information area on the monitor screen. .

According to the present invention, since the filter characteristics of the luminance signal Y are selected in a manner that is more suitable for the screen to be displayed, a high-quality image display that makes the most of the characteristics of the connected TV monitor is possible. Becomes

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The first invention of the present invention relates to a method of monitoring the frequency characteristics of a luminance signal filter means for inputting a luminance signal of an analog video signal encoded from a digital video signal on which on-screen information is multiplexed. A digital broadcast receiver characterized in that it is adaptively changed according to color signal separation characteristic information and a ratio of an on-screen information area on a monitor screen.

According to a second aspect of the present invention, there is provided a video decoder for reproducing a program video from compressed code data, digital on-screen synthesizing means for multiplexing on-screen information with the program video output from the video decoder, and a digital video signal. Digital video encoding means for encoding and outputting the composite video signal format or analog video signal format of luminance signal and chrominance signal separation format, and on-screen screen display ratio detection for detecting the ratio of the on-screen area of the video signal to the normal program screen area Means, monitor characteristic information input means for inputting separation characteristic information of a color signal from an analog video signal on a connected monitor, luminance signal filter means capable of changing frequency characteristics, and controlling the change of the luminance signal filter characteristics Filter characteristic control means .

Then, by first manually selecting the Y / C signal separation system of the monitor to be connected, and detecting the display ratio between the normal program screen and the on-screen screen,
This has the effect of automatically switching the frequency characteristics of the luminance signal to be output adaptively.

(Embodiment 1) An example of the first embodiment of the present invention will be described below with reference to FIG.

FIG. 1 is a block diagram showing a configuration of a main part of a digital broadcast receiver according to the present embodiment. FIG.
Components common to the configuration of the conventional device shown in FIG. 5 are denoted by the same reference numerals, and description thereof is omitted here.

In FIG. 1, reference numeral 2010 denotes an on-screen display ratio judging means which calculates an area ratio of an on-screen display screen displayed on a program screen and outputs a signal when the area ratio exceeds a certain area. Here, a specific configuration example of the on-screen display ratio determination means 2010 will be described with reference to FIG. FIG. 2 is a block diagram illustrating a specific configuration example of the on-screen display ratio determination unit 2010 of FIG. In FIG. 2, Ys is an on-screen display selection signal that becomes High (hereinafter simply referred to as H) at the dot timing for performing on-screen display, and is output from the on-screen information generating device 190 in FIG. 7 and 8 when the area ratio of the on-screen screen is small, and FIGS. 9 and 10 when the area ratio is large.
This will be described with reference to FIG.

FIG. 7 shows an example in which only the channel number is displayed on a part of the monitor screen by on-screen as an example when the on-screen display area is small. At this time, assuming that the horizontal effective screen period is 720 dots and the vertical effective screen period is 240 lines in the vertical synchronization period as shown in FIG. 7, the display of “CH400” in FIG. 5
This is performed with a size of 0 dots × 50 lines. FIG. 8 shows the Ys signal in this display example. FIG. 8 is a signal waveform diagram showing the timing of the Ys signal in the on-screen display example of FIG. As shown in FIG. 8, in this case, it can be seen that the Ys signal is valid only during the period from the dot 630 to the dot 50 in the lines 11 to 60.

Next, FIG. 9 shows an example when a program table is displayed on a large part of a monitor screen by on-screen as an example when the on-screen display area is large. At this time, the display of the program guide of FIG. 9 by the on-screen display is performed in a size of, for example, 640 dots × 220 lines as shown in the figure. FIG. 10 shows the Ys signal in this display example. FIG. 10 is a signal waveform diagram showing the Ys signal timing in the example of the on-screen display of FIG. At this time, as shown in FIG.
It can be seen that the dot is effective for the period from the dot 40 to the 640 dot in 30 periods.

Next, returning to FIG. 2, a specific configuration example of the on-screen display ratio determining means 2010 will be described.

Reference numeral 20101 denotes an AND device that converts a dot clock of a continuous signal into a burst clock in which the Ys signal is valid only. 20102 is a counter which is reset by the vertical synchronization signal and counts the burst clock. Reference numeral 20103 denotes a data flip-flop which outputs the counter value of the counter 20102 at the timing of the vertical synchronization signal. Reference numeral 20105 denotes a constant generator which outputs a set constant value. 20104 is a comparison device,
A comparison is made between the output value of the data flip-flop 20103 and the output value of the constant generator 20105. The operation of the on-screen display ratio determination device configured as described above will be described below with reference to FIG.

FIG. 3 is a signal waveform diagram for explaining the operation of the on-screen display ratio judging device of FIG. FIG. 9 shows an example of the large-area on-screen display described above.
An example will be described in which the screen is displayed. At this time, as shown in FIG.
Since the period from the dot 40 to the dot 640 is valid in the 30 period, the output of the AND element 2010 in FIG.
As shown in (1), the burst clock is output only during the period when Ys is valid. This burst clock is used as a counter 201
02, first, in the scanning line period of the line 111,
Count 1 to 640, and in the next line 12, 6
Count from 41 to 1280. As a result, before the next vertical synchronization signal is input, in this case, 640 × 2
Count 20 = 140800.

Next, the data flip-flop 20103
Outputs the counter value, in this case, the value “140800”, to the comparator 20104 by the next synchronization signal. The comparator 20104 compares this value with a constant value, in this case, the value 10000, and outputs a valid signal as shown in FIG. 3 because it is larger than the constant value.

Although not shown in FIG. 3, when the screen of FIG. 7 of the above-described small-area on-screen display example is displayed, as shown in FIG. In this case, the counter 20102 counts 1 to 50 in the scanning line period of the line 11 because the burst clock output from the AND element 2010 in FIG. And
In the next line 12, counting is performed from 51 to 100. As a result, 50 × 50 = 250 in this case is counted until the next vertical synchronization signal is input.

Next, the data flip-flop 20103
Outputs the counter value, in this case, the value “250”, to the comparator 20104 by the next synchronization signal.
The comparator 20104 compares this value with a constant value, in this example, the value 10000, and in this case, does not output a valid signal because it is smaller than the constant value. As described above, the on-screen display ratio determination is performed in the vertical period cycle.

Returning to FIG. 1, the operation will be described.
Reference numeral 2020 denotes a logical product device that calculates a logical product of a filter selection by manual selection and an output signal of the on-screen display ratio determining unit 2010. As in the conventional example, the switch 1070 is operated by the user while looking at a display screen such as a conspicuous on-screen screen such as cross-color interference on a television monitor at the subsequent stage to select an optimal filter characteristic. For example, when the Y / C separation system of the TV monitor to be connected is based on a trap filter in which cross-color interference is conspicuous, the switch 1070 is selected to be OFF by the user to reduce the interference. As a result, the H signal is input to the AND device 2020, and at this time, the output signal of the AND device 2020 becomes the output signal of the on-screen display ratio determination means 2010, and the on-screen display area ratio is larger than a certain value. Sometimes, the changeover switch 1050 is controlled so as to be connected to the second Y filter 1020 side, and when the on-screen display area ratio is smaller than a certain value, the first Y filter 1010 is controlled. As a result, the second Y filter 1020 is selected only on the on-screen display screen where cross-color interference is conspicuous, and the luminance is automatically selected on the normal program screen or the like by automatically selecting the first Y filter 1010. The frequency characteristics of the signal Y do not deteriorate unnecessarily.

On the other hand, when the Y / C separation system of the TV monitor to be connected is based on a comb filter or the like in which cross color interference is inconspicuous, the switch 10 is switched by the user.
Since 70 is normally selected as ON, the logical product 2020
In this case, a low (hereinafter simply referred to as L) signal is input. As a result, at this time, the output signal of the AND device 2020 becomes an L signal irrespective of the output signal of the on-screen display ratio determining means 2010, and the changeover switch 1050 is always set to the first Y filter 1010
Connected to.

As described above, the on-screen display area ratio is automatically detected only for the on-screen screen where conspicuous cross-color interference or the like occurs, and only when the display area ratio exceeds a certain value, the luminance signal Y Is switched to the cross-color reduction characteristic, so that a high-quality digital broadcast receiver can be realized without deteriorating the frequency characteristic of the luminance signal Y of the normal program screen.

[0032]

As described above, according to the present invention, the user looks at the cross-colored on-screen display screen,
Since the filter characteristics of the luminance signal Y for reducing this are selected, the display area ratio of the on-screen screen is automatically detected, and the filter characteristics are automatically switched, the connection is made by a simple operation. A high-quality digital broadcast receiver that complements the separation characteristics of the luminance signal Y and the chroma signal C from the composite signal of the television monitor to the maximum can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a main part of a digital broadcast receiver according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a specific configuration example of a main part of the digital broadcast receiver according to the first embodiment of the present invention.

FIG. 3 is a timing chart for explaining an operation of a specific configuration example of a main part of the digital broadcast receiver according to the first embodiment of the present invention;

FIG. 4 is a block diagram showing a configuration example of a conventional digital broadcast receiver.

FIG. 5 is a block diagram showing a configuration of a main part of a conventional digital broadcast receiver.

FIG. 6 is a frequency characteristic diagram showing a Y signal filter characteristic in the digital broadcast receiver.

FIG. 7 is a diagram showing an example of channel number display by on-screen;

FIG. 8 is a timing chart showing main signal waveforms in a case of displaying an on-screen channel number.

FIG. 9 is a diagram showing an example of an on-screen program guide display;

FIG. 10 is a timing chart showing main signal waveforms in a case of displaying an on-screen channel number.

[Explanation of symbols]

 140 video decoder (V decoder) 150 on-screen synthesizing means 160 digital video encoding means 2010 on-screen screen display ratio detecting means 1070 monitor characteristic information input means 1010, 1020 luminance signal filter means 1050 filter characteristic control means 20101 AND device 20102 counting means 20103 Data flip-flop 20104 Comparison means 20105 Constant generator

Claims (3)

[Claims] 1. The frequency characteristic of a luminance signal filter unit to which a luminance signal of an analog video signal encoded from a digital video signal on which on-screen information is multiplexed is input to a monitor, the separation characteristic information of a chrominance signal and the monitor screen. A digital broadcast receiver adapted to change adaptively according to the ratio of the above on-screen information area. 2. A video decoder for reproducing program video from compressed code data, digital on-screen synthesis means for multiplexing on-screen information with program video output from the video decoder, and a composite video signal format or luminance from the digital video signal. A digital video encoding unit for encoding and outputting a signal and an analog video signal format of a color signal separation format, an on-screen screen display ratio detecting unit for detecting a ratio of an on-screen area of a video signal to a normal program screen area, and a monitor connected thereto Monitor characteristic information input means for inputting separation characteristic information of a color signal from an analog video signal, luminance signal filter means capable of changing frequency characteristics, and filter characteristics for controlling change of frequency characteristics of the luminance signal filter means Control means, and the brightness of the connected monitor A digital broadcast receiver characterized by switching frequency characteristics of a luminance signal filter means that outputs adaptively according to a separation characteristic of a degree / color signal component and a display ratio between a normal program screen and an on-screen screen. 3. An AND device for converting a dot clock signal into a burst clock in accordance with an on-screen information selection signal, wherein the on-screen screen display ratio detecting means includes:
Counting means reset by a vertical synchronization signal to count the burst-like clock; a data flip-flop for reading a counter value of the counting means for each vertical synchronization signal; a constant generation device for generating a set constant; 2. The digital broadcast receiver according to claim 1, further comprising comparison means for comparing the magnitude of the output value of the flip-flop with the output value of the constant generator.