JPH0233296A - Split television signal transmitter - Google Patents

Abstract

PURPOSE:To prevent the occurrence of the joint of a pattern center part and a pattern side part caused by a difference of reception S/N of a chrominance signal on a reproduced wide aspect pattern by sending the luminance signal and the chrominance signal of an added signal in a different rate with respect to a main signal. CONSTITUTION:The time base of the main signal S1 outputted from a pattern split filter 12 is expanded by a multiple of 5/4 at a time expansion circuit 21. The added signal S2 is subjected to time expansion by a multiple of 4 at a time expansion circuit 22 and fed to a time division chrominance multiplex circuit 32. Chrominance signals I, Q are subjected to line sequential multiplex by the circuit 32 and also subjected to time division multiplex with the luminance Y. The output of a time division chrominance multiplex circuit 32 is added to the output of an NTSC encoder 27 at an adder circuit 29 via a band compression circuit 33, a level conversion circuit 34 and an additional signal encoder 35. The added output is added to a luminance high frequency signal YH outputted from a YH encoder 25 by an adder circuit 36. The added output becomes a transmission signal.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) This invention, for example, ensures compatibility with the NTSC system for a color television signal that displays a screen with an aspect ratio of 16=9. In order to do this, the present invention relates to a divided television signal transmission device that divides and transmits a main signal for displaying the center portion of the screen and an additional signal for displaying the side portions of the screen excluding the center portion of the screen.

(Prior Art) In recent years, it has been desired to further improve the image quality in television broadcast systems.

As a measure to improve image quality in a television broadcasting system, for example, there is a method of increasing the width of the screen in the horizontal direction. In other words, the current horizontal to vertical ratio (hereinafter referred to as aspect ratio) of the NTSC screen is 4:3, but it is known that setting this to a ratio of 523 or 6:3 improves the image quality. It is being Focusing on this point, adoption of an aspect ratio of 16:9 is being considered in high-definition television broadcasting systems.

By the way, the screen whose aspect ratio has been expanded like this (
Television broadcasting system (hereinafter referred to as wide aspect screen) that displays a wide aspect screen (hereinafter referred to as wide aspect screen)
When realizing this, it is necessary to consider compatibility with the current NTSC system.

As a way to ensure this compatibility, as shown in Figure 8, a color television signal for displaying a wide aspect screen is added to the main signal for displaying the screen center area F1 and the other screen side area F2. divided into signals, and
A method of transmitting the main signal in the form of an NTSC signal has been considered.

According to this method, even in an NTSC color television receiver, it is possible to enjoy the screen in the center portion F1 of the wide aspect television broadcast using the main signal.

However, when the main signal and the additional signal are transmitted in different signal formats in this way, a seam may occur between the screen center portion F1 and the screen side portion F2 in the reproduced wide aspect screen. The cause of this seam is that there is a difference in the signal-to-noise ratio (hereinafter referred to as reception S/N ratio) on the receiving side between the chromaticity signal of the main signal and the chromaticity signal of the additional signal. .

That is, in the current NTSC system, the chromaticity signal is frequency-multiplexed with the luminance signal and transmitted.

In this case, the amplitude of the chrominance signal is set such that the maximum amplitude of the color television signal for transmission (so-called composite color signal) does not exceed 133% of the maximum amplitude of the luminance signal. Under such amplitude settings, a difference occurs between the luminance signal and the chromaticity signal in the interference effects of noise power added in the transmission system.

Experiments have confirmed that the influence of noise power on chromaticity signals is 1/2 times the influence of noise power on luminance signals. The value of k differs depending on the hue and saturation, and the chromaticity signal is 6 d
B. In the case of a highly saturated color image, there is a margin of 3 dB against the influence of noise signals.

Since the NTSC system has the reception S/N ratio characteristics described above, in the wide aspect system, the S/N ratio of the chromaticity signal of the additional signal is lower than the S/N ratio of the chromaticity signal of the main signal. In the reproduced wide aspect screen, a seam occurs between the screen center portion Fl and the screen side portion F2, resulting in a decrease in image quality.

(Problems to be Solved by the Invention) As mentioned above, in order to ensure compatibility with the NTSC system, color television signals for wide aspect screen display are divided into the main signal for displaying the center part of the screen and the side part of the screen. In conventional split television signal transmission equipment that divides and transmits the chromaticity signal of the main signal and the chromaticity signal of the additional signal, the reproduced wide aspect There is a problem in that the screen has a seam between the center portion of the screen and the side portions of the screen, resulting in a reduction in image quality.

SUMMARY OF THE INVENTION Accordingly, the present invention provides a split TV screen that can prevent the generation of seams between the center part of the screen and the side parts of the screen due to the difference in reception S/N ratio of chromaticity signals on the reproduced wide aspect screen. The purpose is to provide a signal transmission device.

[Structure of the Invention] (Means for Solving the Problem) In order to achieve the above object, the present invention transmits a luminance signal and a chromaticity signal as additional signals at different ratios to the main signal. It is.

(Function) According to the above configuration, the margin of the chromaticity signal of the additional signal against the influence of the noise signal can be increased in the same way as the margin of the chromaticity signal of the main signal, so that the reception of the chromaticity signal on the wide aspect screen can be improved. It is possible to prevent seams between the center portion of the screen and the side portions of the screen from occurring due to the S/N ratio.

(Embodiments) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a circuit diagram showing the configuration of an embodiment of the present invention.

In FIG. 1, reference numeral 11 denotes an input terminal to which a color television signal Sl for wide aspect screen display is supplied. This color television signal S1 is divided by a screen division filter 12 into a main signal S2 and an additional signal S3.

The main signal S2 is supplied as is to the transmission processing circuit 13, and the additional signal S3 is sent to the multiplier circuit 14, which increases the amplitude of the chromaticity signal by k(-1
10,75-1,33) and then supplied to the transmission processing circuit 13.

The transmission processing circuit 13 converts the format of the main signal S2 into the transmission format of the NTSC system, and multiplexes both signals S2. Perform multiple processing of S3. The color television signal for transmission thus obtained is output from the output terminal 15.

The structure of multiplexing the additional signal S3 on the main signal S2 in the vicinity of the baseband of the main signal S2 is disclosed in the patent application filed in 1983 by the applicant of this patent on March 10, 1988.
-56843 is described. Here, the configuration of this device will be explained with reference to FIG.

In FIG. 2, the same parts as in FIG. 1 are given the same reference numerals.

In FIG. 2, the television signal Sl supplied to the input terminal 11 has an aspect ratio of 16:9 and a number of scanning lines of 5.
It is a sequential scanning (non-interlaced) signal with 25 lines and a frame frequency of 60 Hz. Hereinafter, such a non-increment signal will be expressed as 525/60. This signal consists of a luminance signal represented by Y and chromaticity signals represented by I and Q.

The television signal SL supplied to the input terminal 11 is divided by the screen division filter 12 into a main signal S2 and an additional signal S2.

The main signal S2 output from the screen division filter 12 is supplied to the time expansion circuit 21, and the time axis is expanded by 574 times. On the other hand, the additional signal s2 is expanded four times by the time expansion circuit 22. Figure 3 shows the state of time dilation. Of the effective horizontal scanning period of 53 μs in terms of interlace, the screen center portion Fl has 42. is assigned and the screen side part F
2 is assigned 11. This relationship is (42 + 11): 42X (3/4) - 5: 3, which basically corresponds to an aspect ratio of 5:3; , assuming an overscan of about 6%,
It can also support an aspect ratio of 16:9. Hereinafter, we will explain using parameters based on the relationship shown in Figure 3.
If you do not want to allow overscanning, you can slightly change the parameters described below.

The main signal S2 is time-expanded by a factor of 5/4, resulting in a band of 0 to 10 MHz. Of this time-expanded main signal S2, the luminance signal Y is supplied to the luminance high frequency separation circuit 23. This brightness high frequency separation circuit 23 receives input signals from 8 to 8.
It is separated into a 10 MHz brightness high band signal YH and a 0 to 8 MHz brightness low band signal YL.

The brightness high frequency signal YH has its level suppressed by a level conversion circuit 24, and then converted by a YH encoder 25 into a signal suitable for multiplexing. On the other hand, the luminance low frequency signal YL is supplied to the NTSC encoder 27 after being subjected to a motion adaptive blur processing circuit 28 to make it a signal suitable for multiplexing with the luminance high frequency signal YH and the side signal. . At this time, the spectrum of the luminance low-frequency component YL is limited to a region as shown in FIG. 4(a).

Of the main signals S2 output from the time expansion circuit 21, the chromaticity signals 1. Q is the NTSC color difference band-limiting filter 28.
After being limited to a band that meets the standard, it is supplied to the NTSC encoder 27. And this NTSC encoder 2
7, the signal is converted into an NTSC color television signal together with the luminance low frequency signal YL, and then sent to the adder circuit 29.
is supplied to

On the other hand, the additional signal S3 is time-expanded four times by the time expansion circuit 22, and is made into a signal with a band of 2.2 MHz. This time-expanded side signal is supplied to a time-division color multiplexing circuit 32. This time-division color multiplexing circuit 32 receives chromaticity signals 1. After band-limiting Q to 0.25M7, line sequential multiplexing is performed. Furthermore, by time-division multiplexing this line-sequential multiplexed signal and the luminance signal Y, the signal shown in FIG. 5 is obtained.

The output of the time-division color multiplexing circuit 32 is outputted by the band compression circuit 33 at 1/30 [second] and 525/4 [in the vertical direction].
c, p, h], and the horizontal direction is compressed to a band of 1 [MHz]. The level of this compressed output is suppressed by a level conversion circuit 34, and then converted by an additional signal encoder 35 into a signal suitable for multiplexing. The spectrum of this converted signal is located in the shaded area in FIGS. 4(a) and (b), and as shown in FIG. 4(a), the main signal S2 is
Horizontal.

Located at separation in the vertical spectral region.

The output of the additional signal encoder 35 is supplied to an adder circuit 29 and added to the output of the NTSC encoder 27. This addition output is sent to the YH encoder 25 by the addition circuit 36.
It is added to the luminance high frequency signal YH output from the . This addition output becomes a transmission signal.

In such a configuration, the chromaticity signal of the additional signal is doubled, for example, at a stage subsequent to the time expansion circuit 22. That is, in the figure, 30 and 31 are multiplication circuits that multiply the chromaticity signals I and Q output from the time expansion circuit 22, respectively.

As described above, in this embodiment, by multiplying the amplitude of the chromaticity signal of the additional signal S3, the amplitude ratio of the luminance signal and the chromaticity signal of the additional signal S3 is changed to the original ratio, that is,
Color television signal S1 supplied to input terminal 11
The amplitude ratios of the luminance signal and chromaticity signal are set to different values.

According to the configuration in which the chromaticity signal of the additional signal is multiplied in the same way as the chromaticity signal of the main signal and time-division multiplexed on the luminance signal, the chromaticity signal of the additional signal S3 is The margin is exactly the same as that of the chromaticity signal of the main signal S2. As a result, the received S/N ratio of the chromaticity signal of the additional signal S3 becomes equal to the received S/N ratio of the chromaticity signal of the main signal S2, and the reproduced wide aspect screen is affected by this received S/N ratio. Screen center part Fl and screen side part F
There will be no seams with 2.

In addition, by setting k to 1633, when multiplying the amplitude of the chromaticity signal by 1/1.33-0.75 on the receiving side, the multiplication can be performed only by bit shifting, reducing the hardware size. can be done.

Note that this invention is not limited to the embodiments described above.

For example, in the previous embodiment, the multiplication coefficient of the multiplication circuit 14 is k
(-1, 33) has been explained, but any value smaller than this may be sufficient as long as it makes the seam between the screen center part Fl and the screen side part F2 less noticeable. .

In the previous embodiment, the present invention was applied to a device that multiplexes the additional signal S3 to the main signal S2 near the baseband of the main signal S2. Of course, the present invention can also be applied to a device that transmits the main signal S2 and the additional signal S3 using a transmission band for two channels, such as a device. Figure 6 shows 5L
It is a frequency characteristic diagram which shows the transmission band in SC system.

Here, the band from 0 to 4.2 MHz is allocated to the transmission of the main signal S2, and the band from 4.9 to 10.1 MHz is allocated to the transmission of the additional signal S2.

Furthermore, in the previous embodiment, the present invention was applied to a device that divides a wide aspect screen into a central screen center portion F1 and screen side portions F2 on both sides, but for example, as shown in FIG. , the present invention may be applied to a device that divides a wide aspect screen into two.

Furthermore, in this embodiment, the present invention is applied to a device that is designed to ensure compatibility with the NTSC system.
Of course, it is also applicable to devices designed to ensure compatibility with the M method.

It goes without saying that the present invention can be modified in various other ways without departing from the spirit thereof.

[Effects of the Invention] As described above, according to the present invention, when performing split-screen transmission to ensure compatibility with the NTSC system, etc., seams due to the reception S/N ratio of chromaticity signals occur. You can avoid it.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the configuration of an embodiment of the present invention, and FIG.
The figure is a circuit diagram showing an example of the specific configuration of FIG. 1, FIGS. 3 to 5 are diagrams for explaining the operation of FIG. 2, and FIG. 6 is a diagram explaining a second embodiment of the invention. FIG. 7 is a diagram for explaining the third embodiment of the present invention, and FIG. 8 is a diagram for explaining the division of a wide aspect screen. 11...Input terminal, 12...Screen division filter, 1
3...Transmission processing circuit, 14, 30.31...Multiplication circuit, 15...Output terminal.

Claims (1)

[Scope of Claims] A divided television signal transmission device that divides and transmits a color television signal into a main signal for displaying a predetermined portion of the screen and an additional signal for displaying a portion other than the predetermined portion. 1. A divided television signal transmission device characterized in that the luminance signal and chromaticity signal are transmitted at different ratios to the main signal during transmission.