JP2609657B2 - Television receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an IDTV capable of receiving a signal that does not accurately meet a current broadcasting system such as a VTR, and more particularly, to detecting a non-standard signal, The present invention relates to a television receiver suitable for performing analog Y / C separation at the time of a standard signal.

[Conventional technology]

Hitherto, the specification of Japanese Patent Application No. 61-143019 has discussed the IDTV technology for improving the image quality even for a non-standard signal such as a VTR. In this patent application specification, a non-standard signal is detected, Y / C separation is performed by an analog comb filter when determined to be a non-standard signal, and digital motion adaptive Y / C is determined when determined to be a standard signal. An arrangement for performing C separation is shown in FIG.

However, as shown in FIG. 8, in a configuration in which a signal that is simply passed through the analog comb and a signal that is not passed are switched by a switch between the standard signal and the non-standard signal, the DC level between the two signals is changed. Is different, there is a possibility that the black level changes when the standard / non-standard signal is switched, but this has not been mentioned.

[Problems to be solved by the invention]

In the above-mentioned prior art, when a standard signal and a non-standard signal are frequently determined, for example, when a normal reproduction and a still image reproduction of a video disc player are repeatedly performed, a standard signal and a non-standard signal are obtained, respectively. However, there is a problem that the black level changes to give an unnatural impression to the user, despite the fact that the user is watching the input signal of the image.

SUMMARY OF THE INVENTION An object of the present invention is to provide a television receiver in which a change in black level does not occur as in the related art even if the determination between a standard signal and a non-standard signal is switched.

[Means for solving the problem]

The object is to provide a comb filter for obtaining a luminance signal and a carrier chrominance signal at the output by adding and subtracting the composite video signal and its 1H delay output with a composite video signal as an input, and a color demodulation circuit for demodulating the carrier chrominance signal into a color difference signal. A / D converters for converting the luminance and chrominance signals into digital signals, respective motion adaptive spatio-temporal processing circuits for processing the luminance and chrominance signals converted to digital signals, and input signals In a television receiver comprising a determination circuit for determining whether or not a signal of
Stop means for stopping the addition / subtraction of the delayed output to / from the composite video signal is provided.When the determination circuit determines that the input signal is not a proper signal, the stop means is turned off and the signal passed through the line comb filter is turned off. A /
The signal is guided to a D converter and a color demodulation circuit, and when the input signal is determined to be a normal signal by the determination circuit, the stop means is turned on and a signal that does not pass through the line comb filter is used as the A / A signal for the luminance signal. This is achieved by controlling to lead to a D converter and a color demodulation circuit.

[Action]

When the determination circuit determines that the input signal is not a legitimate signal, it turns off the addition / subtraction stop means. Then, addition and subtraction of the composite video signal and the 1H delay output are performed in the comb filter, and a luminance signal and a carrier chrominance signal that have been subjected to the comb filter are obtained as outputs. On the other hand, when the determination circuit determines that the input signal is normal, the addition stopping means is turned on. Then, since the 1H delay output is not added to or subtracted from the composite video signal in the comb filter, the original composite video signal is obtained. Instead of switching between the two signals with a switch,
For one signal path, add or subtract an AC signal delayed by 1H according to the standard / non-standard signal, or not,
The comb filter is turned ON / OFF. Therefore, there is no change in the DC between the standard signal and the non-standard signal, that is, no change in the black level.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to FIG. First, the configuration of FIG. 1 will be described. In FIG. 1, 10
1 is an input video signal, 102 is an analog comb filter,
103 is a luminance signal, 104 is a carrier color signal, 105 is a color demodulation circuit, 1
06 and 107 are color difference signals, 108 to 110 are LPFs, 111 is a non-standard signal detection circuit, 112 is a non-standard signal detection output, 113 to 115 are A / D converters, and 116 to 118 are motion adaptive space-time processing circuits.

Next, the operation of FIG. 1 will be described. First, consider a case where a signal such as a VTR reproduction signal that has not been subjected to accurate frequency management is input. In this case, the non-standard detection circuit 111 detects the non-standard state and outputs a non-standard signal detection output 112 so as to turn on the comb filter. In this state, the input video signal 101 is first sent to the comb filter 102. Then, the luminance signal 103 and the carrier chrominance signal 104 are generated by the comb filter 102.
And separated. Further, the carrier chrominance signal 104 is sent to a color demodulation circuit 105, and a chrominance signal RY106 and a BY signal 107 are output. The luminance signal 103 and these color difference signals 10
A / D converters 113- are passed through husband and wife LPFs 108-110 for 6,107.
A / D conversion is performed by 115. Thereafter, processing such as motion adaptive YC separation and scanning line interpolation are performed by the motion adaptive spatiotemporal processing circuits 116 to 118, further converted into RGB signals, and transmitted to the cathode ray tube. This motion adaptive spatio-temporal processing is omitted because it does not directly relate to the description of the present invention. For details, refer to the specification of Japanese Patent Application No. 61-143019.

On the other hand, consider a case in which a signal that is accurately subjected to frequency management, such as that transmitted from a normal broadcasting station, is input. In this case, the non-standard detection circuit 111 does not detect the non-standard state, and outputs a non-standard detection output 112 so as to turn off the comb filter. Then, the comb filter operation is not performed in the comb filter 102 and the composite video signal 101
Are output as a luminance signal 103, and a signal subjected to only horizontal band limitation is output as a carrier chrominance signal 104. Then, the same processing as that for the non-standard signal detection described above is performed from the carrier color signal 104 and the luminance signal 103.

Here, the configuration of 102 in FIG. 1 will be described in more detail. FIG. 2 (a) is a detailed explanatory view of the comb filter 102. In FIG. 2A, components having the same functions as those in FIG. 1 are denoted by the same reference numerals, 201 is a trap circuit, 202 is a buffer, 203 is a 1H delay circuit, and 204 is 1
An H delay element, 205 is an amplification circuit, 206 is a subtraction circuit, 207 is an AC addition circuit, and 208 is a BPF.

Next, the operation of FIG. 2A will be described. Input video signal
101 is sent to the trap circuit 201. This trap circuit 20
The characteristic of 1 is shown in FIG. 4 (a), and the characteristic is different at the time of standard signal judgment and at the time of non-standard signal judgment. As shown in the figure, when the standard signal is determined, the frequency characteristic is uniform with respect to the frequency axis.
Shows the trap-type filter characteristics with a 6 dB gain drop. Actual hardware showing this frequency characteristic is shown in FIG. In FIG. The constant is chosen so that the relationship of is satisfied. Here, when the non-standard signal detection output 112 is at the “H” level indicating the non-standard signal state, the Tr ₄₀₆ is turned on, and the collector potential of the Tr ₄₀₆ is substantially at the ground potential. Then, because it resonates in sc, L ₄₀₃
And the series impedance of C ₄₀₄ is zero. Therefore, the input signal is divided at the output by R ₄₀₁ and R ₄₀₂ Becomes

On the other hand, when the non-standard signal detection output 112 is at the “L” level indicating the standard signal state, the Tr ₄₀₆ is turned off, and if the impedance of the R ₄₀₅ is set to be large, the collector of the Tr ₄₀₆ is opened AC. . Therefore, the input video signal 101 appears at the output as it is.

Next, returning to FIG. 2, the case of non-standard signal determination will be described. After passing through the trap circuit 201 having the above-described characteristics,
The signals are sent to one input of each of the subtraction circuit 206 and the addition circuit 207 via the buffer 202. At the same time, it is input to the 1H delay circuit 203. The 1H delay circuit 203 includes a 1H delay element 204 and an amplifier circuit 205 having a gain that cancels the loss. As the 1H delay element 204, for example, a glass delay line may be used. Then, the signal delayed by 1H by the 1H delay circuit 203 is sent to the other input of the subtraction circuit and the addition circuit 207.
Then, since the carrier color signal component is inverted every 1H period, the carrier signal can be extracted if it is subtracted by the subtraction circuit 206 and band-limited by the BPF 208. Addition circuit
When the addition is performed by 207, the carrier color signal component is inverted every 1H as described above, so that the carrier color signal is deleted, and the luminance signal is output.

Next, a description will be given of the time of the standard signal determination. The non-standard detection output 112 stops the output of the 1H delay circuit 203 from being supplied to the subtraction circuit 206 and the addition circuit 207. A specific stop means may be a switch as shown in FIG. Sixth
Figure (a) shows a method of connecting signals in series,
(B) shows a method of connecting signals in parallel. The stop means stops the output of the 1H delay circuit 20 from being supplied to the subtraction circuit 206 and the addition circuit 207. Then, at the time of the standard signal determination, the input video signal 101 which is not trapped is directly input to one input of the subtraction circuit 206 and the addition circuit 207, and the other input is 0. The input video signal 101 appears at the output of the adding circuit 207 as it is. After that, the output of the subtraction circuit 206 is band-limited by the BPF 208.

From the above description, it can be seen that a signal not subjected to comb filtering can be output to the A / D converter for a standard signal and a signal subjected to comb filtering for a non-standard signal. Also,
As a specific example of the addition circuit 207, an AC addition circuit having a configuration as shown in FIG. 2B is used. Then, the operation of stopping or not supplying the output of the 1H delay circuit 203 to the subtraction circuit 206 and the addition circuit 207 determines whether the comb filter should be applied or not. The DC level does not change regardless of the determination.

Further, another specific example of FIG. 102 will be described with reference to FIG. FIG. 3 has almost the same configuration as FIG.
The input of the delay circuit 203 is not the output of the buffer 202, but the input video signal 101. In the case of this configuration, there is no 6 dB decrease in sc due to the trap 201, and accordingly, the amplification circuit 20
The same operation as in FIG. 2 can be performed by lowering the amplification degree of 5 by 6 dB with respect to the amplification circuit 205 of FIG.

FIG. 5 is an explanatory diagram illustrating the configuration of FIG. 111.
In FIG. 5, reference numeral 501 denotes a burst extraction circuit for extracting a color burst signal; 502, a synchronization separation circuit for separating and extracting a horizontal synchronization signal; 503, an APC circuit which receives a color burst signal and outputs a continuous color subcarrier; Denotes an AFC circuit which forms a PLL circuit with a horizontal synchronization signal as input, 505 and 506 denote frequency dividers, 507 denotes a comparison circuit, and 508 denotes an integration circuit.

The frequency of the signal transmitted from the broadcasting station is accurately controlled. Relationship is satisfied. FIG. 5 shows the detection of a non-standard signal depending on whether or not this relationship is satisfied. The principle is that the frequency of the frequency of the color burst signal is reduced to the field frequency and the frequency is reduced to the field frequency, and the frequency of the horizontal synchronization signal that is frequency divided and reduced to the field frequency is equal or not equal. Is measured, the non-standard signal can be detected. In FIG. 5, a signal of frequency sc is obtained by the burst extraction circuit 501 and the APC circuit 503, and a signal of frequency _H is obtained by the synchronization separation circuit 502 and the AFC circuit 504. And the frequency divider circuits 505 and 506
To make the signal of the field frequency. If the frequency is a standard signal whose frequency is managed, the cycle of the two counted down field frequencies is the same, but if the signal is a non-standard signal, the cycle of the two field frequencies is different.
The non-standard signal can be detected by integrating with the integration circuit 508.

〔The invention's effect〕

According to the present invention, the change in the DC level between the standard signal and the non-standard signal in the above-described conventional technique can be eliminated, so that the black level changes even when the normal reproduction and the still image reproduction are repeated by a video disc player or the like. Without
There is an effect of not giving unnaturalness to the user.

[Brief description of the drawings]

FIG. 1 is a system block diagram of one embodiment of the present invention, FIG. 2 is a detailed explanatory diagram of the comb filter 102 of FIG. 1, FIG. 3 is another detailed explanatory diagram of the comb filter 102, and FIG. a) is a characteristic diagram of the trap circuit 201 of FIG.
FIG. 5B is a circuit diagram showing a specific example of the trap, FIG. 5 is a block diagram showing a specific example of the non-standard signal detecting circuit 111 of FIG. 1, and FIG. Figure,
It is. 101: Input video signal, 102: Comb filter, 105: Color demodulation circuit, 113 to 115: A / D converter, 116 to 118: Motion adaptive spatio-temporal processing circuit, 111: Non-standard signal Detection circuit, 112 ... Non-standard signal detection output.

 ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Mutual Isshiki 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Within Hitachi Video Engineering Co., Ltd. (56) References JP-A 64-89791 (JP, A) JP-A 63 -1284 (JP, A)

Claims (3)

(57) [Claims] 1. A luminance signal / color signal separation means having an addition / subtraction means for performing addition or subtraction by analog processing between an input composite video signal and its delayed output, and said luminance signal / color signal separation. Analog / digital conversion means for inputting a luminance signal as a means output, converting the signal into a digital signal, and outputting the signal; and processing means for receiving the output of the analog / digital conversion means, performing motion adaptive spatio-temporal processing, and outputting the result. A television receiver, comprising: a determination unit that determines whether the composite video signal is a regular video signal that meets a predetermined method; and a stop unit that stops addition or subtraction in the addition / subtraction unit. When the determination circuit determines that the video signal is a regular video signal, the stop circuit stops addition or subtraction, and the video signal is not a regular video signal. A television receiver that does not operate the stop circuit when it is determined that the television receiver has been activated. 2. The attenuating means for attenuating a high frequency component of a horizontal frequency of an input signal, a delay means for delaying an output of the attenuating means by a horizontal time, and an output of the attenuating means. 2. The television receiver according to claim 1, further comprising an adding unit that performs addition with the output of the delay unit or a subtracting unit that performs subtraction. 3. The luminance signal / color signal separation means includes: first attenuation means for attenuating a high frequency component of a horizontal frequency of an input signal; delay means for delaying the input signal by a horizontal time; and output of the delay means. Second attenuating means for attenuating the first
2. The television receiver according to claim 1, further comprising an adding unit for adding the output of the second attenuating unit and the subtracting unit for performing a subtraction.