JPH02261273A - High definition television receiver - Google Patents

Abstract

PURPOSE:To confirm an existing input picture through a slave pattern even when a request of a freeze picture comes by using normally a low frequency replacement circuit and switching a selection circuit to a prescribed position upon the request of the freeze picture. CONSTITUTION:In the case of applying normal decoding of a high definition TV signal, selection circuits 18, 19, 20 are connected to the position of an input terminal (a). When a freeze request is given, the selection circuit 2 is switched to the position of the input terminal (a) and a signal from an inter-frame interpolation circuit 5 is always outputted and the circuit 18 is switched to the position of the input terminal (b). Then a signal received at present subjected to reduction processing is led out. Moreover, the circuit 19 is switched to the position of the input terminal (b) for the master pattern period and switched to the position of the input terminal (a) for the slave pattern period and the circuit 26 is thrown to the position of the input terminal (a) for the master pattern period and switched to the position of the input terminal (b) for the slave pattern period. Thus, the existing input video image is displayed on the slave screen even for the freeze picture period.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) This invention is a high-definition television signal reception method that demodulates a band-compressed high-definition television signal into the original wideband high-definition television signal. In particular, the decoder circuit for obtaining frozen images has been improved.

(Prior Art) As a method of compressing a broadband high-definition television signal to a practical level for transmission, MUSE (MUSE) is a method of applying subsampling to the original high-definition television signal in a cycle of four fields. MultlpleSub-Nyqu
lsut Sampling Encoding) method (“New transmission method for high-definition television - MUSE-NHK
(Giken Monthly Report, written by Ninomiya, Volume 27, No. 7, 1981).

FIG. 6 is an example of a decoder for demodulating a band-compressed high-definition television signal (hereinafter referred to as a MUSE signal) into the original wide-band high-definition television signal.

1 is a MUSE signal input terminal, and the MUSE signal 101 (sample rate I B ,
2MIIz) is first input to the interframe interpolation unit 5. In the interframe interpolation section 5, the input signal 101 is input to an input switching circuit 2 (hereinafter referred to as NR circuit).

The NR circuit 2 alternately selects the signal 101 and the signal 104, performs interpolation processing, and supplies the output to the first field memory 3. The first field memory 3 outputs the signal 101 one field before and the signal three fields before as a signal 103 interpolated between frames. This signal 103 is supplied to the second field memory 4. Therefore, the second field memory 4 outputs a signal 2 fields before the signal 101 and a signal 4 fields before the signal 101 as a signal 104 interpolated between frames.

Therefore, in the NR circuit 2, processing is performed to replace the signal 104 four fields earlier with the signal 101.
The resulting signal 102 (sample rate 32.4
MHz) is output.

Field/interpolation processing circuit 6 to which signal 102 is supplied
First, only the data of the current field is extracted from the signal 102, and the signal 105 subjected to intra-field interpolation from the data of the current field is output, and this is input to the sample frequency conversion circuit 7.

In the sample frequency conversion circuit 7, the sample rate is 32
．． Signal 10f converted from 4MHz to 48.6MHz
i is obtained and supplied to one input terminal of the mixing circuit 12.

Further, the signal 102 is input to the prefilter 8, output as a signal 107, and supplied to the sample frequency conversion circuit 9. This frequency conversion circuit 9 converts the sample rate of the signal 107 from 32.4 MHz to 48.6 Mz), and the output signal 10g is sent to the interfield interpolation circuit 10.
Enter. The interfield interpolation circuit 10 uses the input signal 108 to generate a signal 109 by interpolating data for four fields, and this signal is sent to the mixing circuit 12.
is supplied to the other input terminal of the

The mixing circuit 12 adjusts the mixing ratio of the signals 10B and 109 according to the motion detection signal 110 from the motion detection circuit 11, derives the mixed signal as a decoded output signal ill, and further outputs the mixed signal as a decoded output signal ill. is supplied to one input end of the

The motion detection circuit 15 detects image motion using the signal 102 and obtains the motion detection signal 110 mentioned above.

The output signal from the frequency conversion circuit 20 is connected to the other input terminal of the above-mentioned low frequency replacement circuit 28! 17 are supplied. The frequency conversion circuit 20 receives the derived signal 11 from the selection circuit 19.
B (sample rate 32.4MHz) to 48.8MHz
This is a circuit that converts to a sample rate of z. Selection circuit 1
9 selects and derives either the signal 107 guided to the input terminal A or the signal 101 guided to the input terminal a. During normal decoding processing, the signal of the input terminal a is selected and the frozen image is When requested, the signal 107 on the input terminal side is selected.

The low frequency replacement circuit 28 replaces the low frequency portion of the signal 111 with the signal 111.
This is a circuit that replaces the low frequency part of 7. The purpose of this replacement is to make the switching between the moving image and still image parts less noticeable, to compensate for the image quality deterioration caused by the signal processing of the N1 circuit 2, and to compensate for the vertical resolution deteriorated due to interfield interpolation. be.

The low frequency substitution circuit 28 includes a subtracter 21 that subtracts the signal 111 from the signal 117, and a low pass filter (LPF) 22 that removes the high frequency component of the output signal 11g of the subtracter 21. The output signal (low frequency part of signal 117) 119 of low-pass filter 22 is multiplied by multiplier signal 127 from input terminal 24 in multiplier 23 and output as signal 120. Multiplying by the multiplier signal 127 in this way controls the degree of substitution. Signal 120 is added to signal 111 in adder 27 and is derived as signal 123.

The above-mentioned decoder has a frozen image processing function as disclosed in Japanese Utility Model Application No. 61-121083, and when there is a request for a frozen image, for example, N
1 circuit 2 is set to stop input switching and always select signal 104. Therefore, since the signal 102 is not replaced with a newly received signal, the signal 102 whose contents do not change is repeatedly used to obtain a frozen image. Further, when a frozen image is requested, the selection circuit 19 selects the signal 107 at the input end to obtain a signal for low frequency replacement, so that the low frequency replacement can be performed normally even when the image is frozen. I'm trying to make it happen.

However, in the above decoder, no newly received television signal is input to the decoder circuit from the time the frozen image is requested until the frozen image is released.

(Problems to be Solved by the Invention) As explained above, in the conventional MUSE signal decoder circuit, when a frozen image is requested, what kind of video is sent until the frozen image is released? The problem is that I don't understand.

Therefore, the present invention is capable of displaying what kind of video is currently being sent even during the period when a frozen image is being obtained in a circuit that reproduces the MUSE signal.
Another object of the present invention is to provide a high-definition television receiver that realizes the means for achieving this with a simple configuration.

[Structure of the Invention] (Means for Solving the Problems) This invention is interlaced and goes around in n fields. The high-definition television signal band-compressed by the sub-sampling method is demodulated to the original wide-band high-definition television signal, and the low-frequency portion of the demodulated signal is further converted to the band-compressed signal by a low-frequency replacement section. In a decoder circuit of a high-definition television receiver that replaces a low-frequency part signal of a high-definition television signal with a low-frequency signal, means for obtaining a video signal for a sub-screen by reducing the screen size of video signals currently being sent sequentially; When the image is requested, using the holding circuit output video signal using field memory.

means for obtaining a video signal for a main screen for a frozen image; during a period of obtaining the video signal for the main screen, the replacement section introduces the band-compressed signal to perform low frequency replacement; and means for introducing the video signal for the child screen into the replacing section during a period for obtaining the video signal for the sub-screen, and causing the replacing section to replace not only the low-frequency signals but also the signals of the entire frequency band. It is something.

(Function) With the above means, the replacement unit normally used for low frequency replacement is effectively used, and even if there is a request for a frozen image, it is possible to check what kind of image the currently sent video signal is. can be known through the child screen.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. Input terminal 1 has M
A USE signal is supplied, and this MUSE signal is supplied to the interframe interpolation circuit 5 and the screen reduction circuit 17.

The frame interpolation circuit 5 has N
R circuit 2. The NR circuit 2 is composed of a first field memory 3 and a second field memory 4, and when the received signal is processed in the normal mode, the NR circuit 2 receives the signal 1 from the terminal a.
01 and the signal 104 from the terminal S are alternately switched to perform a process of replacing the data four fields before with the input data. However, when a freeze image is requested, the NR circuit 2 is switched to the terminal side and held.

The output signal 102 of the NR circuit 2 is supplied to the intra-field interpolation circuit 6, the prefilter 8, and the motion detection circuit 11.

The intra-field interpolation circuit 6 extracts data corresponding to the current field from the signal 102, performs intra-field interpolation using the data of the current field, and obtains the signal 105. This signal 105 is input to the sample frequency conversion circuit 7.

In the sample frequency conversion circuit 7, the sample rate is 32
．． Signal 10B converted from 4MHz to 48.6MHz
is obtained and supplied to one input terminal of the mixing circuit 12.

Further, the signal 102 is input to the prefilter 8, output as a signal 107, and supplied to the sample frequency conversion circuit 9. This frequency conversion circuit 9 converts the sample rate of the signal 107 from 32.4Mtlz to 4L8MIrz, and outputs the output signal 10g to the interfield interpolation circuit 10.
Enter. The interfield interpolation circuit 10 uses the input signal 107 to generate a signal 109 by interpolating data for four fields, and this signal is sent to the mixing circuit 12.
is supplied to the other input terminal of the

The mixing circuit 12 adjusts the mixing ratio of the signals 10B and 109 according to the motion detection signal 110 from the motion detection circuit 11, derives the mixed signal as a decoded output signal llt, and further outputs the mixed signal to the low frequency replacement circuit 28. is supplied to one input end of the

The motion detection circuit 15 detects image motion using the signal 102 and derives the motion detection signal 110 mentioned above.

The output signal 117 from the frequency conversion circuit 20 is supplied to the other input terminal of the low frequency replacement circuit 28. The frequency conversion circuit 20 receives the derived signal 11B from the selection circuit 19.
(sample rate 32.4MIIZ) to 48.6M
This is a circuit that converts to a tlz sample rate.

The selection circuit 19 selects and derives either the signal 107 guided to the input terminal A or the signal 115 guided to the input terminal a, and is used during normal decoding processing and when a frozen image is required. During the sub-screen period, the signal 115 guided to the input terminal a is selected.

By the way, the above signal 115 is derived from the selection circuit 18, and this selection circuit 18 receives the signal 10■ from the input terminal 1 (input terminal a side) or the signal 114 from the image reduction unit 17 (input terminal Select one of the two sides) and derive it.

The image reduction unit 17 is a circuit that performs image reduction processing on the signal 101 at the input terminal 1. The signal 101 is supplied to the interpolation filter 13 and derived as a signal tt2 from which the aliasing component has been removed, and is input to the sampling circuit 14. As shown in FIG. 5, the sub-sampling circuit 14 thins out every three samples in the horizontal direction and every three lines in the vertical direction, and outputs a signal 113 for the reduced screen. FIG. 5 shows a sampling pattern of the MUSE signal, and the black circle portion is data sampled for the reduced screen. The reduced screen signal 113 is alternately written to the field memories 15 and 16 for each field, and when one is in the writing state, the other is in the reading state.

The read signal is supplied to the input terminal of the selection circuit 18 as an image reduction signal 114.

The selection circuits 18 and 19 each select the input terminal a side in the normal decoding state of the MUSE signal. As a result, the signal Ill decoded from the mixing circuit 12 is inputted to one input terminal of the low frequency replacement circuit 28, and the signal 101 is input to the frequency conversion circuit 20 at the other input terminal.
A signal 117 converted to a sample rate of 8 MHz is input.

The low frequency replacement circuit 28 converts the low frequency portion of the signal Ut into a signal 117.
and a function to replace not only the low frequency portion of the signal 111 from the mixing circuit 12 but the entire frequency band with the signal 117 during the child screen period. The purpose of replacing low-frequency components is to make the switching between the moving image and still image parts less noticeable, to compensate for the image quality deterioration caused by the signal processing of N1 circuit 2, and to compensate for the vertical resolution deteriorated by interfield interpolation. It is.

The low frequency substitution circuit 28 includes a subtracter 21 that subtracts the signal 111 from the signal 117, and a low pass filter (LPF) 22 that removes the high frequency component of the output signal 11g of the subtracter 21. The output signal (low frequency part of the signal 117) 119 of the low-pass filter 22 is multiplied by a multiplier signal 127 from the input terminal 24 in the multiplier 23 and output as a signal 120. This signal 120 is derived as a signal 122 via the selection circuit 26 and is supplied to the adder 27. Multiplying by the multiplier signal 127 in this way controls the degree of substitution. Signal 122 is added to signal 111 in adder 27 and is derived as signal 123.

Further, the low-pass substitution circuit 28 is provided with a delay circuit 25 that delays the output signal 11g from the subtracter 21 by the same amount of delay as the low-pass filter 22.
The output signal 121 is configured to be supplied to the input terminal of the selection circuit 26.

The selection circuit 26 selects the input terminal side when a frozen image is requested by the system and the child screen period begins. At this time, all frequency band components of the signal 111 are replaced with the signal 117 and output.

The above system has a selection circuit 2.26 and a selection circuit 1.
By controlling 8.19, normal MUSE signal decoding can be performed, and when a frozen image is requested, an image of the frozen main screen and a sub-screen that is a reduced version of the currently sent image are displayed. can be displayed.

That is, when performing normal decoding of the MUSE signal,
The selection circuits 18, 19, and 26 are respectively switched to and maintained at the input terminal a side. The operation at this time is the same as that described for the conventional circuit.

Next, if a frozen image is requested, the selection circuit 1
8.19 is controlled as follows. That is, selection circuit 2
is switched to the input terminal a side and maintained. As a result, the interframe interpolation circuit 5 always outputs a signal 102 with no change in content. The selection circuit 18 is switched and maintained at the input end. Therefore, the signal 115 is derived as a signal obtained by reducing the size of the currently received MUSE signal. Next, the selection circuit 19 selects the input terminal A during the main screen period, and switches to the input terminal a side during the child screen period (a period in which the signal 115 is output as a signal for display). Further, the selection circuit 26 selects the input terminal a during the main screen period, and is switched to the input terminal a during the child screen period.

If the low-pass replacement circuit 28 does not include the delay circuit 25 and the selection circuit 26, the signal 111i passes through the low-pass filter 22, thereby reducing the resolution of the child screen. Furthermore, the high frequency components of the parent screen will be mixed into the high frequency components of the child screen. In order to avoid this, in this example,
A delay circuit 25 and a selection circuit 26 are provided so that the image reduction data of the latest field becomes the output signal 123 as it is without being band-limited during the child screen period.

Furthermore, during the child screen period, the color signal is set to a predetermined level to prevent the color signal of the parent screen from being mixed into the child screen.

That is, normally the color signal is extracted from the signal 102, decoded by the color signal processing circuit 31, and supplied to the matrix circuit 33, but in this invention, the color signal processing circuit 3
A switch 32 is provided at the output stage of 1, and during the main screen period, the switch 32 is set to side a to supply the color signal output from the 1 color signal processing circuit 31 to the matrix circuit 33, and during the child screen period, the switch 32 is is set to b@ so that the color signal supplied to the matrix circuit 33 is set to a predetermined value.

FIG. 2 shows another embodiment of the invention. Components having the same functions as those in the embodiment shown in FIG. 1 are given the same reference numerals as in FIG.

The embodiments shown in FIGS. 1 and 2 differ from each other in the location where the sampling frequency of data for the reduced screen is converted and the location where the signal leading to the input terminal of the selection circuit 19 is extracted. That is, in this embodiment, a signal LQ& of a rate of 4B, flMHz is introduced to the input terminal of the selection circuit 19, and a signal 115 for the reduced screen is converted to a rate of 48.6Hz by the sampling frequency conversion circuit 2o. The signal 128 is converted into a rate and supplied to the input terminal a of the selection circuit 19 as a signal 128.

In the above embodiment as well, the switching operations of the selection circuits 2, 18, 19 and 26 are the same as in the previous embodiment, and when a freeze image is requested, the currently sent video data is transferred to the sub screen. It can be converted into data for use in frozen images and included in the data for frozen images. Note that the color system is the same as the embodiment shown in FIG.

FIG. 3 shows yet another embodiment of the invention. Components having the same functions as those in the embodiment shown in FIG. 2 are given the same reference numerals as in FIG. 2.

The differences between the embodiments shown in FIGS. 2 and 3 are that the sample frequency of data for the reduced screen is converted, and that the sample frequency of the signal 101 for low frequency replacement is changed during normal MUSE signal decoding. This is the place to convert.

That is, the sample frequency conversion circuit 20 converts the signal 101
After converting the data rate to 48.8 M) Iz, the data is supplied to the input terminal a of the selection circuit 18. On the other hand, selection circuit 1
The image reduction signal 114 supplied to the input terminal of No. 8 already has a data rate of 41+, 8 MHz. This is because the image reduction unit 17 can set the data rate based on the clock frequency when performing subsampling.

In this embodiment as well, selection circuits 2, 18, 19 and 2
The switching operation in step 6 is the same as in the previous embodiment, and when a frozen image is requested, the currently sent video data is converted to data for the sub-screen, and then converted into data for the frozen image. Contains LS. This embodiment also has the same color system as the previous embodiment.

FIG. 4 shows yet another embodiment of the invention.

Parts that perform the same functions as those in the above embodiment are given the same reference numerals.

In this example, the part that obtains the frozen image data is
This is the same circuit as shown in FIG. Then, the output of the low frequency permutation circuit 28 (adder 23) is supplied to the input terminal of the selection circuit 30. Further, the output signal 114 of the image reduction section 17 is supplied to the input terminal a of the selection circuit 30 via the sample frequency conversion circuit 29. The selection circuit 3o is switched to select input terminal A during the main screen period and to select input terminal A during the child screen period. Furthermore, signal 1
14 is obtained at a data rate of 48.8 MHz as in the embodiment of FIG. 3, the sample frequency conversion circuit 29 may be omitted. The color system in this embodiment is also the same as in the previous embodiment.

[Effects of the Invention] As explained above, according to the present invention, even during the period when a frozen image is being obtained, it is possible to display what kind of video is currently being sent on a sub-screen; Means for this can be realized with a simple configuration.

[Brief explanation of drawings]

FIG. 1 is a circuit block diagram showing one embodiment of the present invention, FIGS. 2 to 4 are circuit block diagrams showing other embodiments of the invention, and FIG. 5 is a sub-ring pattern of the MUSE signal. The explanatory diagram, FIG. 6, is a circuit block diagram showing the configuration of a conventional MUSE decoder. 5... Inter-frame interpolation circuit, 2... Intra-field interpolation circuit, 7.9.20... Sample frequency conversion circuit,
8... Prefilter, 10... Interfield interpolation circuit, 11... Motion detection circuit, 12... Mixing circuit, 1
7... Image reduction unit, 18.19.26... Selection circuit, 25... Delay circuit, 28... Low frequency replacement circuit.

Claims (2)

[Claims] (1) Demodulate a high-definition television signal that is band-compressed using the sub-sampling method, which is interlaced and goes around in n fields, to the original wide-band high-definition television signal, and signal the low frequency part of the demodulated signal. In the decoder circuit of the high-definition television receiver, which further replaces the low-frequency part of the band-compressed high-definition television signal in the low-frequency replacement section, the screen of the video signal that is currently being sent sequentially is reduced. means for obtaining a video signal for a sub-screen, and means for obtaining a video signal for a parent screen for a frozen image by using an output video signal of a holding circuit using a field memory when a frozen image is requested; In the period for obtaining the video signal for the main screen, the band-compressed signal is introduced into the replacing unit to perform low frequency replacement, and during the period for obtaining the video signal for the sub-screen, the video signal for the sub-screen is A high-definition television receiver comprising: a means for introducing a signal into the replacing section, and causing the replacing section to replace not only the low-frequency signals but also signals in the entire frequency band. (2) In a decoder circuit of a high-definition television receiver that demodulates a high-definition television signal that has been band-compressed using subsamples that are interlaced and circulate in n fields to the original wide-band high-definition television signal, a first field memory that stores (n/2) fields of compressed high-definition television signals;
/2) a first means having a second field memory for storing fields, and performing interframe interpolation processing on the n fields worth of high-definition television signals; and an output signal from the interframe interpolation means. a second means for performing inter-field interpolation processing on the signal and outputting an inter-field interpolation signal; and performing intra-field interpolation processing on the output signal from the inter-frame interpolation means and outputting an intra-field interpolation signal. a third means for detecting a motion image signal portion of the signal using the output signal from the interframe interpolation means; and a ratio based on the motion detection output from the fourth means. in,
fifth means capable of mixing the inter-field interpolated signal supplied to one input and the intra-field interpolated signal supplied to the other input; fed to the end,
A sixth means for replacing the low frequency portion of the output signal with the low frequency portion of the band-compressed high-definition television signal supplied to the other input terminal, and a frozen image is required. In some cases, a seventh means for retaining the contents of a field memory in the interframe interpolation processing section and obtaining a video signal for a freeze image; and sub-sampling and extracting the band-compressed high-definition television signal; eighth means for accumulating this extracted signal in a field memory to obtain a video signal for a reduced screen; 8, and a ninth means for switching the sixth means to replace not only the low frequency band but also the entire frequency band. Quality television receiver.