JP3087358B2 - Switching circuit of logical comb filter circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high / low voltage.
The present invention relates to a switching circuit of a logical comb filter circuit in which a logical comb filter circuit and a noise reduction circuit are linked by two signals.

[0002]

2. Description of the Related Art In a conventional television receiver, in order to separate a chrominance signal and a luminance signal, a chrominance signal is 4.43 MHz.
Extracted with a band pass filter, the luminance signal is 4.4
A color signal component was removed by inserting a 3 MHz trap.
However, in such a method, the dot disturbance caused by the color signal component remaining in the luminance signal and the cross color caused by mixing the luminance signal into the color signal have been problems. Therefore, as shown in FIG. 2, a color signal and a luminance signal are completely separated by using a logical comb filter circuit.

Further, a noise reduction circuit is provided for the separated luminance signal so that the noise reduction circuit can be turned on and off according to the user's preference. That is,
A noise reduction circuit 4 is connected to the luminance signal separated by the logical comb filter circuit 1, and is turned on / off by a control signal 3 from a microcomputer.

[0004]

However, in the above-described conventional configuration, the color signal and the luminance signal are separated by the logical comb filter circuit. However, a vertical line noise is generated due to an arithmetic error in the logic circuit. It was outstanding.

[0005] In view of the above problems, the present invention is to pass a logical comb filter circuit according to a user's preference.

[0006]

In order to solve the above-mentioned problems, a logical comb filter circuit switching circuit according to the present invention is configured so as to pass the logical comb filter circuit when a noise reduction circuit is turned on by a signal from a microcomputer. I have.

[0007]

According to the switching circuit of the logical comb filter circuit of the present invention, when the noise on the vertical line is conspicuous due to a calculation error of the logic circuit, the logical comb filter circuit is linked with turning on the noise reduction circuit. This is to make it pass and make noise less noticeable.

[0008]

An embodiment of the present invention will be described below with reference to FIG. In FIG. 1, reference numeral 1 denotes a logical comb filter circuit, which separates a video composite signal into a color signal and a luminance signal. Reference numeral 2 denotes a band pass filter that separates a chrominance signal from a composite signal. A delay line 3 separates a luminance signal from a composite signal. The noise reduction circuit 4 is turned on and off by a control signal from the microcomputer 5. The switch 6 switches between the logical comb filter circuit 1, the band-pass filter 2, and the delay line 3 according to a control signal from the microcomputer.

The operation of the switching circuit of the logical comb filter circuit configured as described above will be described below.

In normal use, it is assumed that the logical comb filter circuit 1 is turned on and the noise reduction circuit 4 is turned off. Here, when the operation error of the logical comb filter circuit 1 is large and the vertical line noise is conspicuous, the user selects the noise reduction circuit 4. As a result, by the signal from the microcomputer,
The logical comb filter circuit 1 is passed by turning on the noise reduction circuit 4 and selecting the band pass filter 2 and the delay line 3.

[0011]

As described above, according to the logical comb filter switching circuit of the present invention, when the vertical line of the logical comb filter is obstructed, the logical comb filter can be passed. Things.

[Brief description of the drawings]

FIG. 1 is a block diagram of a switching circuit of a logical comb filter circuit according to the present invention.

FIG. 2 is a circuit block diagram of a conventional example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 logical comb filter circuit 2 band pass filter 3 delay line 4 noise reduction circuit 5 control signal 6 switch 7 luminance signal 8 color signal 9 composite signal

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-149989 (JP, A) JP-A-1-151389 (JP, A) JP-A-64-60093 (JP, A) JP-A-63-1988 13488 (JP, A) JP-A 2-138359 (JP, U) JP-A 62-129594 (JP, U) JP-B 63-7715 (JP, B2) (58) Fields surveyed (Int. ⁷ , DB name) H03H 17/00-17/08 H04N 9/77-9/78

Claims (1)

(57) [Claims] 1. A method for separating a chrominance signal and a luminance signal from each other.
1 Y / C separation unit and the first Y / C separation unit.
A second Y / C separating means connected to the column,
/ C separating means and the second Y / C separating means.
Switching means for selectively switching the output signal from the stage;
A noise reduction circuit connected to the luminance signal output terminal of the switching means.
Turn on / off the noise reduction circuit and the noise reduction circuit.
A first control unit for performing off control, and the first control unit
The noise reduction controlled by these control signals
Switching control of the switching means in conjunction with ON / OFF of a circuit
And a second control means for performing the first Y / C separation operation.
The step is composed of a logical comb filter, and
Off control of the noise reduction circuit by the first control means
Color signal from the second Y / C separation means in conjunction with
The switching means outputs the second signal so that a luminance signal is output.
A switching circuit for a logical comb filter circuit, wherein the switching is performed by the control means .