JPH05115056A - Television signal transmission system - Google Patents

Abstract

PURPOSE:To prevent the occurrence of uneven brightness due to a baked cathode ray tube by superimposing an auxiliary signal of a luminance signal onto a non-picture part. CONSTITUTION:When a wide television signal whose aspect ratio is 16:9 is sent while upper and lower portions of a screen of the NTSC system are set to be non-picture portions, a video signal (Y signal) on a scanning line at upper or lower end of a wide picture B is fetched in a line memory 23 based on a counter output from a synchronizing signal generator 22. An averaging circuit 24 of a next stage obtains an average by one scanning line. The signal is arranged to positions A, C on a pattern at the upper and lower portions of the wide picture B in a positioning memory 17 and a picture whose aspect ratio is 4:3 is formed together with the wide picture B. An IQ signal outputted from positioning memories 15, 16 is converted into an IQ modulation signal by a modulator 20, added to the Y signal at an adder 21 and the result is led from an output terminal T as the NTSC signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television signal transmission system, and more particularly to a second generation EDTV television signal transmission system compatible with a current television system.

[0002]

2. Description of the Related Art A so-called wide image (b) having an aspect ratio of 16: 9 is transmitted by setting the upper and lower parts of an NTSC system screen having an aspect ratio of 4: 3 into non-image parts a and c as shown in FIG. When a letterbox type signal is reproduced by a current NTSC type receiver, blackness is displayed in the upper and lower parts (a and c) of the screen having an aspect ratio of 4: 3.

[0003]

In the above-mentioned conventional device, when a wide signal having an aspect ratio of 16: 9 is displayed on an NTSC screen having an aspect ratio of 4: 3, the phosphor does not emit light above and below the screen. Margins occur. When it is used for a long time in such a state, the phosphor in the image display portion deteriorates, and the phosphor that did not emit light deteriorates in luminance. As a result, for example, the aspect ratio is 4: 3.
There is a problem that uneven brightness occurs when an image of the NTSC system is displayed.

[0004]

In order to solve the above problems, the present invention provides means for detecting the average value of the brightness signals of the scanning lines at the upper end or the lower end of the wide screen on the transmitting side, and the means for detecting the average value of the brightness signals. A first means for superimposing a signal on a non-image portion generated at the upper end or the lower end of the wide screen, or a means for detecting the average value of the luminance signals of the scanning lines at the upper and lower ends of the wide screen, and an average for both scanning lines. A means for comparing the values and a second means for superimposing a signal having a higher comparison result on the non-image part
Means, or means for detecting the frequency distribution of the luminance signal of the scanning line at the upper or lower end of the wide screen, third means for superimposing the signal having the highest frequency distribution on the non-image part, or the luminance signal for the wide screen. Means for detecting the average value of
Fourth means for superimposing this signal on the non-image part, or means for detecting the frequency distribution of the luminance signal of the wide screen, and fifth means for superimposing the signal with the highest frequency distribution on the non-image part.
Or a means for generating a signal divided into several steps from a black level to a 100% white level, and a sixth means for appropriately switching each level signal according to time and superimposing it on the non-image portion.

[0005]

According to the above construction, when a wide television signal having an aspect ratio of 16: 9 is transmitted with the upper and lower parts of the screen of the NTSC system being a non-picture part, the non-picture part has scanning lines at the upper end or the lower end. , Or the average value of the luminance signals of the wide screen is compared, or the average value of the luminance signals of the scanning lines at the upper and lower ends of the wide screen is compared, and the higher average value signal is multiplexed, or the scanning lines at the upper or lower end of the wide screen. The frequency distribution of the luminance signal is detected, the highest signal of the frequency distribution is multiplexed, or the average value of the luminance signal of the wide screen is multiplexed, or the frequency distribution of the luminance signal of the wide screen is detected, and The signal with the highest frequency distribution is multiplexed, or the signals divided into several stages from the black level to the 100% white level are switched by time and multiplexed.

[0006]

1 is a block diagram of the first embodiment of the present invention. In FIG. 1, 525 scanning lines / aspect ratio 1
The RGB signal output from the wide camera 1 having a 6: 9 / interlace ratio of 1: 1 is converted into a luminance signal Y and color signals IQ by the matrix converter 2. Next, each IQY signal is 0 to 360 by the vertical low-pass filters 3, 4, and 5.
After the band is limited to cph, it is compressed 3/4 times by the vertical compression circuits 6, 7, and 8. As a result, the effective scanning lines after compression are converted from 480 TV lines to 360 TV lines.

Next, the above IQY signals are output from 0 to 360/2 cp by the 2: 1 sub-sampling circuits 9, 10 and 11.
After being converted into h, it is input to the frame delay circuits 12, 13, 14 and the line memory 23 (Y signal only). Above I
The QY signals are delayed by one frame in the frame delay circuits 12, 13 and 14, and then the positioning memory 1
It is input to 5, 16, and 17. Positioning memory 1
In 5, 16, and 17, the IQY signals are arranged at the position of the center portion B of the NTSC screen (4: 3), as shown in FIG.

In the line memory 23, the video signal (Y signal) of the upper or lower scanning line of the wide image B is fetched by the counter output from the synchronizing signal generator 22, as shown in FIG. The average value calculation circuit 24 in the next stage calculates the average value of the video signal (Y signal) for one scanning line. This signal is arranged at positions A and C in FIG. 2 in the positioning memory 17, and together with the wide image B forms an image having an aspect ratio of 4: 3.

Further, the positioning memories 15 and 1 are
The IQ signals output from 6 are 0 through horizontal low-pass filters (hereinafter referred to as H-LPF) 18 and 19, respectively.
The band is limited to 1.5 MHz and 0 to 0.5 MHz, and converted into an IQ modulated signal in the modulator 20. The IQ modulated signal is added to the Y signal output from the positioning memory 17 in the adder 21, and is derived from the output terminal T as an NTSC signal.

Next, a second embodiment of the present invention is shown in FIG. In FIG. 3, parts other than the dotted line parts are common to those in FIG. 1, and corresponding parts are designated by the same reference numerals and description thereof is omitted. In FIG. 3, the Y signal output from the 2: 1 sub-sampling circuit 11 is input to the line memories 30 and 31. In the line memories 30 and 31, the synchronization signal generator 22
As shown in FIG. 2, the video signals (Y signals) of the scanning lines at the upper end and the lower end of the wide image B are respectively captured by the counter output from the.

The average value calculation circuit 32 at the next stage calculates the average value of the video signal (Y signal) for one scanning line at the upper end, and the average value calculation circuit 33 calculates the video signal for one scanning line at the lower end ( The average value of (Y signal) is calculated. The average value calculation circuit 3
The output signals from 2 and 33 are input to the switch circuit 34 and the comparator 35, and the higher average value signal is output from the switch circuit 34 based on the output from the comparator 35. This signal is placed in the positions A and C in FIG. 2 in the positioning memory 17, and the wide image B is displayed.
Together with this, an image having an aspect ratio of 4: 3 is formed.

The second embodiment is different from the first embodiment in that
Since the average value of the video signal is obtained on the scanning lines at the upper and lower ends of the wide image and the average value signal of a high level is superimposed as the auxiliary signal, it is advantageous when the upper and lower scanning lines of the wide image have variations in brightness.

Next, a third embodiment of the present invention is shown in FIG. In FIG. 4, portions other than the dotted line portions are common to those in FIG. 1, and corresponding portions will be denoted by the same reference numerals and description thereof will be omitted. In FIG. 4, the Y signal output from the 2: 1 sub-sampling circuit 11 is input to the line memory 40.
In the line memory 40, the video signal (Y signal) of the scanning line at the upper end or the lower end of the wide image B is fetched by the counter output from the synchronizing signal generator 22, as shown in FIG.

In the frequency distribution calculation circuit 41 in the next stage, as shown in FIG. 5, the frequency distribution (vertical axis) with respect to the luminance level (horizontal axis) of each pixel in the video signal (Y signal) for one scanning line at the upper end or the lower end is shown. Axis) to detect the most frequently occurring luminance level. This signal is used for positioning memory 1
7, the images are arranged at positions A and C in FIG. 2, and together with the wide image B, an image having an aspect ratio of 4: 3 is formed.

In the above invention, the frequency distribution with respect to the brightness level of each pixel in both the upper and lower scanning lines of the wide image B shown in FIG. 2 is obtained, and the level having the highest frequency of occurrence is stored in the positioning memory 17 in FIG. Of A
The method of superimposing at positions C and C can also be used in the same manner.

In the third embodiment, the frequency distribution of the brightness levels in the upper and lower scanning lines of the wide image is obtained, and the brightness level with the highest frequency of occurrence is superimposed as an auxiliary signal. It is possible to superimpose a signal close to, and it is very effective against uneven brightness due to burn-in.

Next, a fourth embodiment of the present invention is shown in FIG. In FIG. 6, portions other than the dotted line portions are common to those in FIG. 1, and corresponding portions will be denoted by the same reference numerals and description thereof will be omitted. In FIG. 6, the Y signal output from the 2: 1 sub-sampling circuit 11 is input to the frame memory 60. In the frame memory 60, the video signal (Y signal) of the wide image B is fetched as shown in FIG. 2 by the counter output from the synchronization signal generator 22. Next-stage average value calculation circuit 6
1, the video signal (Y signal) for one screen of the wide image
Calculate the average value of. This signal is used for positioning memory 1
7, the images are arranged at positions A and C in FIG. 2, and together with the wide image B, an image having an aspect ratio of 4: 3 is formed.

The average value of the brightness level of the wide image may be obtained over several frames, and this signal may be superimposed on the positioning memory 17 at the positions A and C in FIG. it can. The above-mentioned fourth embodiment is advantageous when the average value of the video signals of the entire wide image is obtained and the signal is superimposed as an auxiliary signal, so that the wide image has variations in brightness.

Next, a fifth embodiment of the present invention is shown in FIG. In FIG. 7, parts other than the dotted line parts are common to those in FIG. 1, and corresponding parts are assigned the same reference numerals and explanations thereof are omitted. In FIG. 7, the Y signal output from the 2: 1 sub-sampling circuit 11 is input to the frame memory 70. In the frame memory 70, the video signal (Y signal) of the wide image B is fetched as shown in FIG. 2 by the counter output from the synchronization signal generator 22.

In the frequency distribution calculation circuit 71 in the next stage, as shown in FIG. 5, the video signal (Y
The frequency distribution with respect to the brightness level of each pixel in the signal) is calculated, and the brightness level with the highest frequency of occurrence is detected. This signal is stored in the positioning memory 17 as indicated by A in FIG.
Are arranged at positions C and C, and together with the wide image B, an image having an aspect ratio of 4: 3 is formed.

A method of calculating the frequency distribution for the brightness level of the wide image over several frames and superimposing the most frequently occurring brightness level at the positions A and C in FIG. 2 in the positioning memory 17. However, it can be implemented similarly.

Next, FIG. 8 shows a sixth embodiment of the present invention. In FIG. 8, portions other than the dotted line portions are common to those in FIG. 1, and corresponding portions will be denoted by the same reference numerals and description thereof will be omitted. In FIG. 8, from the signal generators 80 to 84, the black level, the 25% white level, the 50% white level, the 75% white level, and the 100% white are respectively displayed in the areas excluding the synchronizing signal by the synchronizing signal generator 22. A level signal is generated.

The above signals are input to the switch circuit 85. The switch circuit 85 appropriately switches the input signal based on the switching output from the timer 86. This output signal is arranged in positions A and C in FIG. 2 in the positioning memory 17, and together with the wide image B forms an image with an aspect ratio of 4: 3. The sixth embodiment is advantageous in terms of cost because it has a large effect despite its simple circuit configuration.

[0024]

Since the present invention has the above-mentioned structure, the NT
While maintaining compatibility with the SC system, it becomes possible to transmit a wide television signal including an auxiliary signal for preventing burn-in of the current receiver. In addition, in the above transmission method, even if a wide TV signal having an aspect ratio of 16: 9 is reproduced by a current NTSC receiver and used for a long time, uneven brightness due to a burn-in phenomenon of a cathode ray tube is effectively prevented. .. Also, since the auxiliary signal for preventing the seizure is multiplexed on the transmitting side,
The receiver side does not require the above-mentioned hardware for preventing the image sticking, which is advantageous in terms of cost.

[Brief description of drawings]

FIG. 1 is a block diagram of a first embodiment of the present invention.

FIG. 2 is an operation explanatory diagram of the present invention.

FIG. 3 is a block diagram of a second embodiment of the present invention.

FIG. 4 is a block diagram of a third embodiment of the present invention.

FIG. 5 is an operation explanatory diagram of the embodiment of the present invention.

FIG. 6 is a block diagram of a fourth embodiment of the present invention.

FIG. 7 is a block diagram of a fifth embodiment of the present invention.

FIG. 8 is a block diagram of a sixth embodiment of the present invention.

FIG. 9 is an explanatory diagram of a conventional example.

[Explanation of symbols]

 17 Positioning Memory 24, 32, 33, 61 Average Value Operation Circuit 34, 85 Switch Circuit 35 Comparator 41, 71 Frequency Distribution Operation Circuit 80, 81, 82, 83, 84 Signal Generator 86 Timer

Claims (6)

[Claims] 1. A means for detecting an average value of luminance signals of scanning lines at an upper end or a lower end of a wide screen in a television signal transmission system for transmitting a television signal of a wide aspect with an upper and lower portion of an NTSC screen being a non-picture part. A television signal transmission system comprising means for superimposing a signal of this average value on the non-picture portion. 2. A television signal transmission system for transmitting a television signal of a wide aspect with the upper and lower portions of the NTSC screen being a non-picture portion, and means for detecting the average value of the luminance signals of the scanning lines at the upper and lower ends of the wide screen. A television signal transmission system comprising means for comparing the average values of the two scanning lines and means for superimposing a signal having a higher comparison result on the non-picture area. 3. A means for detecting a frequency distribution of luminance signals of scanning lines at an upper end or a lower end of a wide screen in a television signal transmission system for transmitting a television signal of a wide aspect with the upper and lower parts of the NTSC screen being a non-picture part. A television signal transmission system comprising means for superimposing the signal having the highest frequency distribution on the non-picture portion. 4. A means for detecting an average value of a luminance signal of a wide screen in a television signal transmission system for transmitting a television signal of a wide aspect with an upper and lower portion of an NTSC screen being a non-image portion, and the non-image portion for detecting the average value. A television signal transmission system, characterized in that it has means for superimposing on a section. 5. A television signal transmission system for transmitting a television signal of wide aspect with the upper and lower portions of the NTSC screen being a non-picture portion, and means for detecting the frequency distribution of the luminance signal of the wide screen, and the highest frequency distribution. A television signal transmission system comprising means for superimposing a signal on the non-picture portion. 6. A television signal transmission system for transmitting a wide aspect television signal in which the upper and lower portions of the NTSC screen are non-picture areas, and means for generating a signal divided into several steps from a black level to a 100% white level. A television signal transmission system comprising means for appropriately switching each level signal according to time and superimposing it on the non-picture portion.