JPS627750B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a ghost removal device, that is, in an image signal such as a television signal, in addition to the original image signal, image signals of positive polarity and reverse polarity that are delayed by a certain period of time are generated. A so-called ghost image occurs. The present invention relates to a device for removing ghost components delayed by a certain period of time.

When a television signal or the like is received, ghosts as shown in FIG. 1 may occur. That is, when an impulse signal with an amplitude of 1 is received, a ghost with an amplitude a ₁ (i=1, 2, . . . ) occurs with a delay of time τ ₁ .

FIG. 2 shows a known feedback type ghost removal device. The impulse response shown in FIG. 1 is determined by the differentiating circuit 2 from the step signal included in the vertical retrace period of the input signal to the terminal 1. Only the ghost component of the impulse response is supplied to the shift register 3, and the amplitude a ₁ is stored in the stage corresponding to the delay time τ ₁ . On the other hand, the signal at the output terminal 4 is supplied to the shift register 5, and the product of the values of each stage of the shift registers 3 and 5 is the multiplication circuit 6J (J=
a, . . . , x, y, z), and the addition circuit 7 obtains the sum. The difference between the input signal and the output of the addition circuit 7 is obtained by the subtraction circuit 8, resulting in an output signal from which ghosts have been removed. In the above-mentioned known example, if the multiplication circuit 6J has non-linear distortion, for example, there is a drawback that ghosts cannot be accurately removed.
Therefore, an object of the present invention is to improve the conventional ghost removal apparatus as described above, and to realize an apparatus that can ultimately correctly remove ghosts even if each circuit has nonlinear distortion.

In order to achieve the above object, the present invention inputs an image signal and a first signal consisting of a ghost component to a ghost removal device, and removes the ghost component from the image signal by combining both signals. and a transversal filter that receives the second image signal and outputs the first signal using the cumulative value of the impulse response of the ghost component included in the signal as a coefficient. It is characterized by what it did.

The present invention will be explained in detail below with reference to Examples. FIG. 3 is a block diagram showing the configuration of one embodiment of the ghost removal device according to the present invention. In this figure, circuits having the same functions as those in FIG. 2 are given the same reference numerals. Unlike the example shown in FIG. 2, an impulse response is obtained by the differentiating circuit 2 from the step signal in the output signal. Of the impulse response, the value of the ghost component at each time is determined by the switch circuit 9 and the accumulation circuit 10J (J=
a, ..., x, y, z). The accumulator circuit uses the sum of the current input value and previous output values as a new output value. The sum of the products of each stage of the output of the accumulation circuit and the output value of the shift register 5 is obtained from a multiplication circuit 6J and an addition circuit 7, and the difference with the input signal is obtained from a subtraction circuit 8, which is used as an output signal. In the present invention, even if the output signal of the multiplication circuit does not correspond to a correct ghost and a ghost remains at the output terminal 4, the impulse response of the residual ghost is given again to the accumulation circuit 10J, so that the final The remaining ghost will be 0. That is, the input to the accumulator circuit is 0, and the output of each stage is _a1 , resulting in a steady state.

In FIG. 3, the output of the accumulation circuit 10J may be supplied once to the shift register 3, and then supplied to the multiplication circuit as shown in FIG. This is because the shift registers 3 and 5, multiplication circuit 6J, and addition circuit 7 are usually called transversal filters and can be easily integrated into one chip.

FIG. 4 is a diagram showing the configuration of another embodiment of the ghost removal device according to the present invention, in which FIG.
Circuits having the same functions as those in FIG. 3 are given the same reference numerals. In this embodiment, the final output of the shift register 3 and the output of the differentiator circuit 2 are added together by an adder circuit 11, and the result is input to the shift register 3. In this case, the cumulative value a ₁ can be obtained in the shift register 3 with one addition circuit, and at the same time, the configuration becomes easy.
It has the advantage of being suitable for integration as described above.

Furthermore, even if the shift register 3 is an analog type and the held value attenuates after a long period of time, if the shift register 3 is circulated as shown in the embodiment of FIG.
Another advantage is that a value that further corrects attenuation is automatically supplied.

The circuit of the above embodiment can be converted into an analog circuit by converting the signals of input/output terminals 1 and 4 into analog signals.
Moreover, if it is converted into a digital signal, it becomes a digital circuit.

Also, even if the input/output signals are analog signals,
In order to lengthen the holding time of the shift register 3, the accumulation circuit 10, etc., it is also possible to make only these parts digital circuits and install A/D or D/A converters before and after them.

As described above, according to the present invention, it is possible to reduce the accuracy of the nonlinear circuit in the ghost removal device.

[Brief explanation of the drawing]

Figure 1 is a waveform diagram for explaining the ghost signal.
FIG. 2 is a circuit diagram showing the configuration of a conventional ghost removal device, and FIGS. 3 and 4 are both circuit diagrams showing the configuration of an embodiment of the ghost removal device according to the present invention. 1...Input terminal, 4...Output terminal, 2...Differentiating circuit, 3, 5...Shift register, 6...Multiplier, 7, 8...Adder, 8...Subtractor, 9...Switch Circuit, 10...cumulative circuit.

Claims (1)

[Claims] 1. A second signal from which the ghost component has been removed from the image signal by inputting an image signal and a first signal consisting of a ghost component and combining both signals.
It is characterized by comprising means for outputting an image signal, and a transversal filter that receives the second image signal and outputs the first signal using the cumulative value of the impulse response of the ghost component included in the signal as a coefficient. Ghost removal device. 2. In claim 1, the transversal filter includes a shift register that inputs the second image signal and outputs the value at each stage, and an impulse of a ghost component included in the second image signal. a first circuit that outputs a response;
a second circuit that accumulates and outputs the values at each time of the impulse response from the circuit for each stage; a third circuit that outputs the product of the values of each stage of the shift register and the second circuit; and a fourth circuit that outputs the sum of the outputs of the three circuits as the first signal. 3. In claim 2, the accumulation circuit includes a shift register that inputs the cumulative value of the impulse response at each time and outputs the value at each stage, and a final stage of the shift register. A ghost removal device comprising: an addition circuit that adds the value and the value of the impulse response from the first circuit and outputs the cumulative value.