JPH01236891A - High definition television receiver - Google Patents

Abstract

PURPOSE:To simplify circuit constitution by extracting high definition information by a 1st filter, reproducing it by frequency shift, extracting the vertical high frequency by a 2nd filter, amplifying it and adding the result to a luminance signal. CONSTITUTION:Sub-sampling is not applied at the receiver side, the 1st filter means 452 extracts high definition information and it is reproduced by applying frequency shift. Moreover, the vertical high frequency component is extracted by the 2nd filter means 453, the result is amplified, added to a luminance signal and a signal compensating the reduction in the vertical resolution is obtained. In this case, the 1st and 2nd filter means 452, 453 are constituted by using a vertical filter 451 in common. Thus, the deterioration in the vertical resolution is compensated with small sized circuit constitution.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a high-definition television that receives a television signal in which high-definition information is multiplexed within a frequency-limited band of the NTSC standard television system. Regarding the receiver.

(Prior Art) The standard television system currently adopted in Japan is the NTSC system. In the NTSC system, the horizontal frequency band of the luminance signal is limited to 4.2 MHz, and the theoretical limit value of the horizontal resolution is 320 to 350 TV lines. The theoretical limit value of the other vertical resolution is 450 TV lines, and the fineness of the image quality is determined by the lower of the horizontal or vertical resolution.

Therefore, in order to increase the sense of definition, it is necessary to improve the horizontal resolution.

Therefore, on the transmitting side, high-definition information, which is a high-frequency luminance signal exceeding the limited band (4.2 MH2), is transmitted to the NTS.
A method has been proposed in which the horizontal resolution is improved by inserting the signal into the gap between the frequency bands of the C method and reproducing the high-definition information on the receiving side.

One such method is to remove diagonal high-frequency components of a wideband television signal (luminance signal) that contains high-definition information.
By further sub-numbering, the high-definition information is
A system that fits within the limited band of the TSC system, multiplexes a color modulation signal separably with the high-definition information in the horizontal and vertical spatial frequency regions to configure a high-definition television signal, and transmits this. There is.

An example of such a transmitter is shown in FIG.

Non-internary race R, G, and B signals are input to input terminals 101, 102, and 103.

The input R signal, G signal, and B signal are input to the matrix circuit 104, and are converted into Y signal, ■ signal, and Q signal. The Y signal is input to the A/D converter 105 and converted into a digital signal. The converted Y signal is
The band of the oblique component is limited by the low-pass filter 108 in the vertical spatial frequency domain.

On the other hand, the digitally converted Y signal is simultaneously input to the odd/even field determining circuit 120 and the burst generating circuit 12.
1 is input. The odd/even field determining circuit 120 is
The sub-sampling circuit 109 and the interlace conversion circuit 111.11 determine whether the television signal currently being processed is an odd field or an even field.
3 outputs a control signal shown by a broken line.

Further, the burst generation circuit 121 generates a sub-sampling clock frequency-divided waveform 801 having a basic clock 8r. This frequency-divided waveform 801 is processed by the adder 122.
Leading edge 802 within the horizontal retrace period of the transmitted television signal
(See FIG. 7) Or multiplexed within the vertical retrace period.

Now, the output signal of the low-pass filter 108 is input to an offset sub-sampling circuit 109. Based on the control signal output from the odd/even field determination circuit 120, the offset sub-sampling circuit 109 determines, for example, that in an even field, the phase is the same as that of the burst signal, and in the odd field, it is in phase with the burst signal. Determine the subsample phase so that it is, and perform offset subsampling.

The output of the sub-sampling circuit 109 is band-limited by a horizontal Naigi low-pass filter 110.

Thereafter, in accordance with the control signal of the odd/even field determination circuit 120, the interlace conversion circuit 111 converts the signal into an interlace signal having an inter-field offset subsampling structure.

On the other hand, the I signal and C signal outputted from the matrix circuit 104 are band-limited by a low-pass filter 112 in the horizontal and vertical frequency domains, and then converted into an interlace signal by an interlace conversion circuit 113. The converted I, C signals are converted into quadrature 2 by balanced modulator 114.
It is phase modulated and converted into a C signal. This C signal is multiplexed onto the luminance signal by an adder 115. The high-definition television signal thus obtained is converted into an analog signal by the D/A converter 116, outputted from the output terminal 117, and transmitted.

Next, based on FIG. 5, the principle of multiplexing high-definition information by the above-described operation will be described.

The A/D converter 105 on the transmission shore performs grid sampling as shown in FIG. 5(b) using a clock of 2 and -fi1 (where k is an integer), where the horizontal scanning frequency is fll [Hzl]. Let's do it. Hereinafter, as an example, a case will be described in which the sub-sampling frequency is selected to be 8M, near H2, and the high-definition information is set to 4.2MH7 to 6MH7.

First, the oblique component is removed by the low-pass filter 108 shown in FIG. 4, and as shown in FIG.
25/2 cph (cycle per hig.
ht) respectively. The band-limited signal 301 is
The high-definition information 303 of 4.2M1-1z or more is folded back into the horizontal low frequency band, as shown in FIG. 5(C).

A point 302 in the figure indicates a turning point.

Furthermore, the sampled signal is filtered by a horizontal Nyquist [l-pass filter 110 with the characteristics shown in FIG.
Components of 4.2MH2 or higher are removed. Thereafter, by multiplexing the color signals, the spectrum shown in FIG. 5(e) is obtained. In FIG. 5(e), 304 is 4.2MHz ~
Although this is high-definition information having a frequency component of 6 MHz, this high-definition information 304 is multiplexed into the high frequency range of the color signal 305 in the vertical direction, so that there is little leakage into the color signal 305.

306 is a component of the Y signal up to 4.2 MHz.

Incidentally, if the vertical band of the high-definition information is strictly limited by the low-pass filter 108, the amount of leakage can be further reduced by η', as shown in FIG. 5(f).

Multiplexing of high-definition information using this method is performed at a vertical frequency of 525/
2 cph, time frequency OHz. As with the current system, transmission is performed using signals after interlace conversion. Time frequency 3 in interlaced drawing
It has a turning point at 0 Hz and a vertical frequency of 525/2 cph. Therefore, it can be said that the multiplexing of high-definition information according to the present invention is effective for still images with a temporal spatial frequency of 15t-(z or less) and moving images with very slow movement.However, television cameras carry moving images. In actuality, the present invention can be used without any problem for moving pictures at normal speeds, since the resolution sometimes decreases.

Now, in the example described above, when obtaining the sample clock or carrier, a newly inserted burst signal is used in the leading edge 802 of the horizontal synchronizing signal 803 or in the vertical synchronizing signal, as shown in FIG. ing. The reason for using the burst signal 801 will be explained below.

In order to demodulate signals multiplexed in the horizontal and vertical spatial frequency domains on the receiving side, it is necessary to use a sample clock or a carrier that is phase-synchronized with the sample clock used for signal processing on the transmitting side.

The most stable signal available with current receivers is the color subcarrier fsc. However, in order to minimize interference to current receivers and obtain maximum effectiveness in high-definition receivers, it is desirable to be able to set the multiplexing position of high-definition information without being constrained by the color subcarrier frequency.

For example, set the sample clock on the transmitting side to the horizontal periodic frequency f
A conceivable method is to set it to m times H and use m f It on the receiver side as well. At this time, on the receiver side, by inputting the horizontal synchronizing signal 803 in FIG. 7 and using horizontal FC, a clock with a stable frequency nflll can be obtained.

However, in reality, it is not possible to accurately define the mfH signal phase due to the slope of the edge of the horizontal synchronization signal 803 and ghost interference.

Therefore, as shown in FIG. 7, a burst signal 8 having a frequency component of mfH/n is sent to the leading edge 802 within the horizontal retrace period.
By newly inserting 01, this burst signal 8
The continuous signal of m f 11 can be easily reproduced using 01 as the phase reference.

Note that the frequency component of mfll/n to be inserted into the leading edge portion 802 can be selected to be a high frequency component of about 4MH2.
There is little possibility that this will adversely affect the 2111 playback of current receivers.

Next, FIG. 8 shows an example of a receiver according to this method.

A high-definition television signal on which the above-described high-definition information is multiplexed is input to an input terminal 401 . The input signal is Y
/C separation circuit 402 separates the signal into a Y signal and a C signal. The separated Y signal is converted into a non-interlace signal by a non-interlace conversion circuit 404, and is input to a sub-sampling circuit 4o5.

On the other hand, the input signal is also input to a burst reproduction circuit 420 and an odd/even field determination circuit 421. The burst reproducing circuit 420 reproduces a sampling clock phase synchronized with the burst 1-signal 801 multiplexed on the leading edge portion 802 of the horizontal blanking period shown in FIG. 7, and outputs it to the sub-sampling circuit 405.

Further, the odd/even field determination circuit 421 determines whether the field currently being processed is an odd field or an even field, and outputs a determination signal to the sub-sampling circuit 405. The sub-sampling circuit 405 uses a signal output from the odd/even field determining circuit 421 to determine whether the field is odd or even.
The sampling phase of the sampling clock output from 0 is switched for each field, and the input signal is changed as shown in Figure 5 (
The signal has the sample structure shown in d). in this case,
The sampling phase is pre-arranged on the sending side,
For example, it is determined based on conditions such as the phase being in phase with the burst signal 801 in even fields, and the phase being opposite to the phase of the burst signal 801 in odd fields.

Next, the output signal of the sub-sampling circuit 405 is processed by a horizontal/vertical frequency domain interpolation filter 4 having the same characteristics as the low-pass filter 108 that performs band-limiting on the transmitting side.
06, the sample structure is converted into the sample structure shown in FIG. 5(b). At this time, the spectrum of the signal is a wideband telephony signal with a horizontal frequency band of 6 HMz, as shown in FIG. 5(a), which makes it possible to restore a high-definition image.

On the other hand, the C signal separated by the Y/C separation circuit 402 is input to the IQ demodulation circuit 403, and the ■ signal and the C signal are output. The matrix circuit 407 has Y, 1. Converts C signal to R, G, B signals and outputs terminals 408, 409.4
Output to 10.

As described above, the receiver according to this method performs non-interlaced conversion. This non-interlaced conversion performs interpolation between fields in the case of still images to achieve the vertical resolution limit of 450 TV lines in the NTSC format, and in the case of moving images, interpolates scanning lines within fields to This detects the active component and switches the interpolation method for the active and static scanning lines. Therefore, one receiver according to this method is
In the case of still images, the vertical resolution is obtained by non-interlace conversion, and the horizontal resolution is obtained by high-definition information, so that in principle, a resolution close to 450 TV lines can be obtained both horizontally and vertically.

However, when performing such non-interlaced conversion, it is necessary to generate 525 scanning lines on the picture tube surface in one vertical synchronization period. Current interlaced scanning receivers use 262.5 scanning lines in one vertical synchronization period, so in non-interlaced scanning the spacing between electron beams to construct an image is twice as long as in interlaced scanning. It is necessary to have a density of In such a case, the picture tube uses an electron beam controlled by a video signal to cause the phosphor to emit light to reproduce an image, but the emitted bright spot has a wide spread, resulting in a reduction in vertical resolution.

FIG. 9 is a diagram for explaining the deterioration of vertical resolution due to spot spread. The horizontal axis is the vertical direction, and the vertical axis is the brightness level. As shown in FIG. 9, each scanning line 1, 2, 3 As a result, the bright spot spreads out (not shown by the solid line) with respect to the brightness level that should originally be displayed (indicated by the O mark t), and overlaps from the upper and lower scanning lines. As a result, the brightness level displayed on the picture tube (indicated by the broken line) differs from the brightness level shown by the O mark due to the spread of the spot. This phenomenon occurs because the spacing between electron beams is narrower in non-interlaced scanning than in interlaced scanning, so the amount of overlap due to spot spread increases.

Therefore, in non-interlaced conversion, an image whose vertical resolution is significantly lower than the original one will be reproduced due to the spread of the spot.

(Problems to be Solved by the Invention) As mentioned above, in the conventional high-definition television receiver,
There has been a problem in that the vertical resolution is significantly reduced due to non-interlaced scanning.

Therefore, the present invention is intended to eliminate the above problems.
An object of the present invention is to provide a high-definition television receiver capable of compensating for deterioration in vertical resolution due to non-interlaced scanning.

[Structure of the Invention] (Means for Solving the Problems) The high-definition television receiver of the present invention removes oblique high-frequency components of a wideband television signal (luminance signal) containing high-definition information, and By subsampling, the high-definition information is kept within the limited band of the NTSC system, and
A color modulation signal is separably multiplexed with the high-definition information in the horizontal and vertical spatial frequency domains to form a high-definition television signal, and the high-definition television signal is transmitted from a high-definition television transmitter that transmits the high-definition television signal. means for receiving a high-definition television signal; signal separating means for separating a luminance signal and a color signal from the high-definition television signal; and color demodulation for demodulating the color signal from the signal separating means to obtain a color difference signal. means, non-interlace conversion means for converting the first luminance signal obtained from the signal separation means and the color difference signal from the color demodulation means into non-interlace scanning; and converting the first luminance signal by the non-interlace conversion means. Extracting vertical high-frequency components and horizontal high-frequency components from the second luminance signal obtained by the conversion; 1 first filter means; extracting vertical high-frequency components and horizontal low-frequency components from the second luminance signal; a second filter means, and a high-definition information demodulation means for frequency-shifting the signal extracted by the first filter means in a predetermined main frequency and demodulating high-definition information through a band-pass filter; The vertical resolution is compensated for by subtracting the signal extracted by the first filter means from the luminance signal of and adding a signal obtained by amplifying the signal from the second filter means to the subtracted signal. vertical resolution compensating means for obtaining a third luminance signal, and adding high-definition information from the high-definition information demodulating means to the third luminance signal from the vertical resolution compensating means; and adjustment means for outputting a fourth luminance signal with vertical resolution compensation.

(Operation) In the present invention, high-definition information is extracted by the first filter means and frequency shifted to reproduce the high-definition information without performing sub-rimple on the receiver side. Further, a high frequency component in the vertical direction is extracted by the second filter means, amplified, and then added to the luminance signal to obtain a signal that compensates for the decrease in vertical resolution. In this case, the above 1. Since the second filter means can be configured by sharing a vertical filter,
Deterioration in vertical resolution can be compensated for with a small-scale circuit configuration.

<Examples> The present invention will be described below based on examples shown in the drawings.

FIG. 1 is a block diagram showing an embodiment of a high-definition television receiver of the present invention. However, the same components as those of the conventional example shown in FIG. 8 will be described with the same reference numerals.

The difference between FIG. 1 and FIG. 8 is that the conventional sub-sampling circuit 405 and horizontal/vertical interpolation filter 406, which are arranged on the Y signal path from the non-interlace conversion circuit 404 to the matrix circuit 407, are replaced with vertical resolution compensation. This is because a high-definition demodulator 400 capable of A high-definition 118-degree television signal input to an input terminal 401 and multiplexed with high-definition information is separated into a Y signal and a C signal by a Y/C separation circuit 402 . The separated Y signal is converted into a non-interlace signal by a non-interlace conversion circuit 404 and input to a high-definition information demodulator 400. On the other hand, the high-definition television signal supplied through the above-mentioned inputs is also input to the burst reproduction circuit 420 and the odd/even field determination circuit 421. The burst reproducing circuit 420 reproduces a sampling clock that is phase synchronized with the burst signal multiplexed at the leading edge of the horizontal retrace period of the television signal, and outputs it to the high-definition information demodulator 400. Further, the odd/even field determination circuit 421 determines whether the field currently being processed is an odd field or an even field, and outputs a determination signal to the high-definition information demodulator 400. High definition information demodulator 400
does not perform subsampling, uses horizontal and vertical filters to extract high-definition information, and further performs frequency shift using the sampling clock from the burst reproducing circuit 420 and the judgment signal from the odd/even field judgment circuit 421. While having the ability to perform and reproduce high-definition information,
The horizontal and vertical filters have a function of extracting high-frequency components in the vertical direction and adding them to the Y signal to compensate for a decrease in vertical resolution. Y containing high-definition information output from the high-definition information demodulator 400 and subjected to vertical resolution compensation
The signal is provided to matrix circuit 407.

On the other hand, the C signal separated by the Y/C separation circuit 402 is
The IQ demodulation circuit 403 demodulates the ■ signal and Q signal (8) and outputs them.
1.42 to the matrix circuit 407. The matrix circuit 407 has Y, 1. C signal to R, G,
It is converted into a B signal and output to output terminals 408, 409, and 410.

FIG. 2 is a block diagram showing an embodiment of the high-definition information demodulator 400.

A non-interlaced Y signal is input from an input terminal 450. The input Y signal is sent to the delay circuit 45.
4. Input to vertical bypass filter (vertical [''PF) 4'51. Here, the vertical fi HP F451 passes vertical high frequency components of the image. The output signal of the vertical HPF 451 is passed through the horizontal bypass filter (horizontal 1-IPF) 45'
2,453.

Since the output of the horizontal HPF 452 is horizontal and vertical high frequency components, high definition information is output. Horizontal 1-I PF45
The output of 2 is reduced from the input Y signal that has passed through the 'cn extension circuit 454 to the adder 455. On the other hand, horizontal HPF452
The output signal of is subjected to frequency shift in a transducer 460. Here, the input terminal 463 receives the odd/even field determination signal output from the odd/even field determination circuit/1.21 shown in FIG. The kitt7 rear of the frequency of kfH output from the reproduction circuit 420 is input. The inverting circuit 461 uses the odd/even field determination signal to set the carrier of frequency k f H to a value determined in advance on the transmitting side, for example, in the even field, the same phase as the burst phase 801 shown in FIG. 801 and is further inverted between lines and output to the multiplier 460.

The output signal from the multiplier 460 is passed through a horizontal bandpass filter (
4.2MH7~6M by horizontal BPF) 459
Only the components in the Hz frequency band are passed, and the adder 458
is input. The adder 458 has been added to the adder 45 in advance.
4, the high-definition information is subtracted and added to the Y signal passing through the delay circuit 457 and the high-definition information of 4.2 MHz to □ 6 fvl Hz, and outputted from the output terminal 465.

On the other hand, the output signal of the horizontal LPF 453 is vertical high frequency and horizontal low frequency components that are not multiplexed with high-definition information.

The output of the horizontal LPF 453 is amplified by a coefficient multiplier 470 and added to the T signal from an adder 455 by an adder 456.

Next, the demodulation operation shown in FIG. 2 will be explained in detail with reference to FIG. 3. Since the output signal of the horizontal HPF 452 has vertical and horizontal high frequency components, only the region C is passed through from FIG.
Output high-definition information y +4.

The output carrier (demodulated carrier) of the inversion circuit 461 is k
Since the carrier of the frequency f I+ is line inverted, the position is 525/2 [cph] in the vertical direction. , Therefore, the high-definition information YH is frequency shifted by the carrier of the inverting circuit 461 and becomes 4.2MH7~6MH
7, and other components are removed by the horizontal E3PF459.

In addition, the output signal of the horizontal LPF 453 (the M number is a horizontal low frequency band and a vertical high frequency band, so it is in the area A shown in FIG. 3. Therefore, the output signal of the horizontal LPF 453 is amplified and added to the input Y signal. ri, it is possible to lift the vertical high frequency components and compensate for the vertical resolution.
-(Since the PF 451 is shared with the function of reproducing high-definition information and the function of compensating for vertical resolution, the hardware configuration can be small-scale.

[Effects of the Invention] As described above, according to the present invention, it is possible to compensate for the deterioration in vertical resolution due to non-interlaced scanning with small-scale hardware.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the high-definition television receiver of the present invention, FIG. 2 is a block diagram showing an embodiment of the high-definition information demodulator in FIG. 1, and FIG. FIG. 2 is an explanatory diagram illustrating the demodulation operation, FIG. 4 is a block diagram illustrating an example of a conventional high-definition television transmitter, FIG. 5 is an explanatory diagram illustrating the principle of multiplexing high-definition information, and FIG. is a characteristic diagram showing the characteristics of the horizontal low-pass filter in Fig. 4, and Fig. 7 is a characteristic diagram showing the characteristics of the horizontal low pass filter.
The figure is an explanatory diagram explaining the burst signal used to multiplex high-definition information, Figure 8 is a block diagram showing an example of a conventional high-definition television receiver, and Figure 9 is the vertical resolution due to the spread of the spot. It is an explanatory diagram explaining deterioration of. 400... High-definition information demodulator, 401... High-definition television signal input terminal, 40
2... Y/C separation circuit, 403... IQ demodulation circuit, 404... Non-interlace conversion circuit, 407...
・Matrix circuit, 408.409.410...R, G, B output terminal, 4
11.412...Delay circuit, 420...Burst reproduction circuit, 421...Odd/even field determination circuit, 450...
Non-interlaced Y signal input terminal, 451...Vertical HPF. 452.453...Horizontal LPF, 454.457...Delay circuit, '1.55,456.458...Adder, 459...
・Horizontal BPF, 460... Multiplier, 461... Inverting circuit, 463... Input terminal for odd/even field determination circuit output, 464... Input terminal for burst regeneration circuit output, 465
. . . Output terminal of Y signal from which high-definition information is demodulated; 470 . . . Coefficient unit. Agent Patent Attorney Susumu Ito Figure 1 Figure 2 Figure 3 (a) (b) (
c) (d) (6
) (f) W&5 Figure 6 Figure 7

Claims (1)

[Claims] A wideband television signal having a horizontal frequency band wider than the limited band limited by the NTSC standard television system and containing high-definition information is input, and from this signal, its horizontal frequency components μ, vertical The frequency component ν is μν_0+μ_0ν>μ_0ν_0 μ_0: highest horizontal frequency of the wideband television signal ν_0: highest vertical frequency of the wideband television signal by removing at least a diagonal high frequency component signal to form a first band-limited signal. and a first band-limiting means for outputting the first band-limited signal as a first band-limited signal; sub-sampling means for multiplexing the high-definition information in a horizontal frequency domain above the limited band into the frequency domain from which the diagonal high-frequency components have been removed and onto the first band-limited signal; a second band limiting means for limiting the horizontal frequency band of the multiplexed signal outputted by the controller to the limiting band and outputting a second band limiting signal; modulation means for obtaining a color modulation signal by vertically band-limiting the signal so that the signal is in a frequency region closer than the frequency region, and then modulating the signal using a color subcarrier; and multiplexing the color modulation signal onto the second band-limiting signal. and multiplexing means for obtaining a subsampled high-definition television signal containing the high-definition information within the limited band, and transmitting the high-definition television signal. means for receiving the high-definition television signal transmitted by the high-definition television transmitter; signal separating means for separating a luminance signal and a color signal from the high-definition television signal; color demodulation means for demodulating to obtain a color difference signal; non-interlace conversion means for converting the first luminance signal obtained from the signal separation means and the color difference signal from the color demodulation means into non-interlace scanning; and this non-interlace conversion. a first filter means for extracting a vertical high frequency component and a horizontal high frequency component from a second luminance signal obtained by converting the first luminance signal with a means; and a first filter means for extracting a vertical high frequency component and a horizontal high frequency component from the second luminance signal. and high-definition information demodulation for frequency-shifting the signal extracted by the first filter means using a predetermined carrier and demodulating high-definition information through a band-pass filter. and subtracting the signal extracted by the first filter means from the second luminance signal, and adding to the subtracted signal a signal obtained by amplifying the signal from the second filter means. , vertical resolution compensating means for obtaining a third luminance signal with vertical resolution compensated; and adding high-definition information from the high-definition information demodulating means to the third luminance signal from the vertical resolution compensating means, A high-definition television receiver comprising: an adding means for outputting a fourth luminance signal that includes high-definition information and is vertically resolution compensated.