JPH0529878A - Switching circuit for logical com filter circuit - Google Patents

Abstract

PURPOSE:To avoid cross color generated in the separation process of the chrominance signal and luminance signal of a television receiver by linking a logical COM filter circuit with the turning on/off of a noise reduction circuit so as to execute switching. CONSTITUTION:The logical COM filter circuit 1 is linked with the noise reduction circuit 4 by a signal from a microcomputer so as to be switched in the circuit providing the logical COM filter circuit 1 and the noise reduction circuit 4. When the operation difference of the logical COM filter circuit 1 is large and vertical stripe-shaped noise is conspicuous, a user selects the noise reduction circuit. As a result, the noise reduction circuit 4 is turned on by the signal from the microcomputer and the band-pass filter 2 and the delay line 3 are selected so that the logical COM filter 1 is made to pass.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage High / Low.
The present invention relates to a switching circuit of a logical comb filter circuit that switches a logical comb filter circuit and a noise reduction circuit by using two signals.

[0002]

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

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

[0004]

However, in the above conventional configuration, the color signal and the luminance signal are separated by the logical comb filter circuit, but vertical line noise is generated due to the calculation error in the logic circuit. It was conspicuous.

In view of the above problems, the present invention allows a logical comb filter circuit to pass according to user preference.

[0006]

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

[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 the operation error of the logic circuit, the logical comb filter circuit is operated in conjunction with turning on the noise reduction circuit. It passes it and makes noise less noticeable.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 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. A bandpass filter 2 separates the color signal from the composite signal. A delay line 3 separates the luminance signal from the composite signal. The noise reduction circuit 4 is turned on / off by a control signal from the microcomputer 5. The switch 6 switches between the logical comb filter circuit 1, the bandpass filter 2 and the direct 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 on and the noise reduction circuit 4 is off. Here, when the arithmetic error of the logical comb filter circuit 1 is large and vertical line noise is noticeable, the user selects the noise reduction circuit 4. As a result, the signal from the microcomputer
By turning on the noise reduction circuit 4 and selecting the bandpass filter 2 and the delay line 3, the logical comb filter circuit 1 is passed.

[0011]

As described above, according to the logical comb filter switching circuit of the present invention, when the vertical line interference of the logical comb filter is noticeable, the logical comb filter can be passed, and the effect is great. It is a thing.

[Brief description of drawings]

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

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

[Explanation of symbols]

 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

Claims (1)

Claim: What is claimed is: 1. A circuit comprising a logical comb filter circuit and a noise reduction circuit, wherein the logical comb filter circuit and the noise reduction circuit are interlocked and switched by a signal from a microcomputer. Logical comb filter circuit switching circuit characterized by