JP3408667B2 - Luminance / color signal separation circuit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a luminance / color signal for separating a luminance signal and a chrominance signal from a video signal in a television receiver.
The present invention relates to a color signal separation circuit. 2. Description of the Related Art In recent years, as television receivers have become larger and demands for higher image quality have been increased, a charge-coupled device (hereinafter abbreviated as CCD) delay line has been used as a method for addressing the problems of dot disturbance and cross color. A luminance signal and a chrominance signal are separated from a video signal by a comb filter (hereinafter, referred to as a CCD comb filter) that uses a color filter. Hereinafter, a conventional luminance / color signal separation circuit will be described. FIG. 5 shows a block diagram of a conventional luminance / color signal separation circuit. In FIG. 5, reference numeral 12 denotes a television broadcast signal 1
1 is a detection circuit for detecting a video signal in the video band (0 to 4.2 MHz);
And a CCD comb filter for separating into color signals 20;
Is a voltage controlled oscillator (VCO) for outputting a drive signal (here, a signal of 14.32 MHz is used) for driving the CCD comb filter 14, 16 is a frequency dividing circuit,
7 is a phase comparison circuit, 18 is a reference signal (generally, 3.5
8 MHz is used), 21 is a luminance / color signal separation unit,
19 is a luminance signal, and 20 is a color signal. In the luminance / chrominance signal separation circuit configured as described above, the signal obtained by passing the output of the voltage controlled oscillation circuit 15 through the frequency dividing circuit 16 to divide the frequency by と and 3.58.
MHz reference signal 18 is compared with a phase comparison circuit 17,
By controlling the voltage controlled oscillation circuit 15 based on the comparison result, the output signal of the voltage controlled oscillation circuit 15 is stabilized at 14.32 MHz as a drive signal of the CCD comb filter 14, and the CC driven by the 14.32 MHz drive signal is used.
The D-comb filter 14 separates the video signal detected by the detection circuit 12 from the television broadcast signal 11 into a video band into a luminance signal 19 and a chrominance signal 20. [0005] However, in the above-described conventional luminance / color signal separation circuit, when a radio wave is mixed into the detection output line of the detection circuit, an unnecessary signal due to the mixed radio wave is generated by the luminance signal. When the frequency of the unnecessary signal is input to the color signal separation unit and further propagated to the voltage controlled oscillation circuit, for example, 10.12 MHz to 18.52 MHz, the signal and the CCD which is the output signal of the voltage controlled oscillation circuit are used. By frequency conversion between the signal and the drive signal (14.32 MHz) of the comb filter, spurious (unwanted radio waves) (0 to 4.2 MH) which becomes an obstacle in the video signal in the video band.
z) occurs, and as a result, there is a problem that radio interference such as disturbed images occurs. The present invention solves the above problems,
Provided is a luminance / color signal separation circuit capable of reducing a disturbance generated on a video signal due to an unnecessary signal due to a radio wave mixed into a detection output line in a video band and suppressing a radio wave disturbance in an image. [0007] In order to solve the above object, according to an aspect of, Brightness and color signal separating circuit of the present invention is a comb filter using a charge coupled device delay line, phase controlled voltage A CCD comb filter driven by a drive signal of a constant frequency output from a control oscillation circuit;
The comb filter, the luminance and color signal separating circuit that is configured to separate the video signal output from the detection circuit for detecting a television signal into a video signal of the video band into a luminance signal and a color signal, the voltage controlled oscillator Drive signal from
Signal and remove the signal of the frequency of the video band
A filter having a cut-off frequency for
Receiving the drive signal output from the voltage controlled oscillation circuit,
The drive signal is passed and supplied to the CCD comb filter. [0010] According to this configuration, the filter performs frequency conversion between an unnecessary signal caused by radio waves mixed in from the detection output line and a drive signal of the CCD comb filter output from the voltage controlled oscillation circuit. The generated spurious in the video band is attenuated before being input to the CCD comb filter.
The drive signal of the CCD comb filter output from the voltage controlled oscillation circuit is passed without attenuation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a luminance / color signal separation circuit according to an embodiment of the present invention will be described with reference to the drawings. Note that components having the same functions as those of the conventional example shown in FIG. 5 are denoted by the same reference numerals, and detailed description thereof will be omitted. A first embodiment of the present invention will be described. FIG. 1 shows a configuration of a luminance / color signal separation circuit according to the first embodiment. In FIG. 1, 11 is a television broadcast signal, 12 is a detection circuit, 13 is a first filter, 14 is a CCD comb filter, 15 is a voltage controlled oscillator (VCO), 16 is a frequency divider, 17 is a phase comparator,
18 is a reference signal, 19 is a luminance signal, 20 is a color signal, 21
Denotes a luminance / color signal separation unit. Here, the components other than the first filter 13 are the same as the conventional example shown in FIG. The operation of the luminance / color signal separation circuit composed of the above components will be described below with reference to FIG. Among the frequencies (10.12 MHz to 18.52 MHz) of the mixed radio waves that cause spurious interference that may be an obstacle in the video signal in the conventional luminance / color signal separation circuit shown in FIG. 14.1 for example, spurs that are prone to obstacles
When a radio wave near 8 MHz enters the output line of the detection circuit 12, the television broadcast signal 11 is detected by the detection circuit 12 and becomes a video signal in a video band (0 to 4.2 MHz). The signal is input to a low-pass filter 33 including a first resistor 30 and a first capacitor 31. The low-pass filter 33 has a cut-off frequency set to about 5 MHz or more.
Therefore, the video signal detected from the television broadcast signal 11 passes, but the mixed radio wave near 14.18 MHz is attenuated and removed. On the other hand, the luminance / chrominance signal separation section 21 compares the signal obtained by passing the output of the voltage controlled oscillation circuit 15 through the 1/4 frequency dividing circuit 32 and the 3.58 MHz reference signal 37 with the phase comparison circuit 1.
7 and controls the voltage-controlled oscillation circuit 15 based on the comparison result, so that the output signal of the voltage-controlled oscillation circuit 15 is used as a driving signal of the CCD comb filter 14 by 1
It is stabilized at 4.32 MHz. In this case, the low-pass filter 33
Since the mixed radio wave near 14.18 MHz is not input to the luminance / color signal separation unit 21, 14.32 accompanying the mixing of the radio wave near 14.18 MHz into the voltage controlled oscillator 15.
No spurious around 140 kHz occurs due to frequency conversion to MHz. By providing a low-pass filter having a cut-off frequency of about 5 MHz or more at the front stage of the CCD comb filter by the above operation, an output end of the luminance / color signal separation section can be used in a video band which is an obstacle to a video signal. Spurious generation can be suppressed. Although the cut-off frequency of the low-pass filter 33 is set to 5 MHz or more in the first embodiment, any other cut-off frequency can be used as long as a signal of a frequency to be removed other than the video band can be removed. The cutoff frequency can be similarly implemented. Next, a second embodiment of the present invention will be described. FIG. 3 shows a configuration of a luminance / color signal separation circuit according to the second embodiment. In FIG. 3, 11 is a television broadcast signal, 12 is a detection circuit, 14 is a CCD comb filter, 24 is a second filter, 15 is a voltage controlled oscillator (VCO), 16 is a frequency divider, 17 is a phase comparator, 1
8 is a reference signal, 19 is a luminance signal, 20 is a chrominance signal, and 21 is a luminance / color signal separation unit. Here, the second filter 2
Other than 4 are the same as the conventional example shown in FIG. 5 and the first embodiment shown in FIG. The operation of the luminance / color signal separation circuit composed of the above components will be described below with reference to FIG. In this luminance / color signal separation circuit, a CCD
A second resistor 34 and a second capacitor 35 are provided between the input terminal of the drive signal of the comb filter 14 and the output terminal of the voltage controlled oscillator 15 that supplies the drive signal of the CCD comb filter 14. A high-pass filter 36 having a cutoff frequency of 10 MHz or less is provided. When a radio wave near 14.18 MHz similar to that of the first embodiment enters the output line of the detection circuit 12 when the television broadcast signal 11 is received, the television broadcast signal 1
1 is detected by the detection circuit 12 and detected in the video band (0 to 4.2 M).
Hz), and is input to the luminance / color signal separation section 21 together with the mixed radio wave near 14.18 MHz. On the other hand, the luminance / color signal separating section 21 compares the signal obtained by passing the output of the voltage controlled oscillation circuit 15 through the 1/4 frequency dividing circuit 32 and the 3.58 MHz reference signal 37 with the phase comparison circuit 1.
7 and controls the voltage-controlled oscillation circuit 15 based on the comparison result, so that the output signal of the voltage-controlled oscillation circuit 15 is used as a driving signal of the CCD comb filter 14 by 1
It is stabilized at 4.32 MHz. In this case, the high-pass filter 36
14.32 MHz output from the voltage controlled oscillation circuit 15
The drive signal of the CCD comb filter 14 of FIG.
The spurious near 140 kHz generated by the frequency conversion to 14.32 MHz due to the mixing of the radio wave around 4.18 MHz into the voltage controlled oscillation circuit 15 can be suppressed from entering the CCD comb filter 14. With the above operation, the cut-off frequency of 10 MHz is provided before the input end of the drive signal of the CCD comb filter.
By providing a high-pass filter of a degree or less, it is possible to suppress the output of spurious near 140 kHz to the output terminal of the luminance / color signal separation unit in a video band that becomes an obstacle in a video signal. In the second embodiment, the cut-off frequency of the high-pass filter 36 is set to 10 MHz or less. However, the drive signal of the CCD comb filter 14 output from the voltage-controlled oscillation circuit 15 is passed, and As long as the cutoff frequency can remove the signal of the frequency, the cutoff frequency can be similarly set as another cutoff frequency. In each of the above embodiments, 14.18
One possible example of the possibility of radio wave mixing in the vicinity of MHz is a signal from an amateur radio station legally operated in an amateur band of 14 MHz band using equipment having no technical problem. By the operation of each of the above-described embodiments, it is possible to reduce a disturbance occurring on a video signal due to an unnecessary signal due to a radio wave mixed into a detection output line within a video band, and suppress a radio disturbance in an image. be able to. In each of the above embodiments, 14.18 MH
Although the possibility of radio wave mixing near z has been described using an example of a signal from an amateur radio station, the frequency of a signal that interferes with a video signal is 10.12 MHz to 18.52 MHz.
The same effect can be obtained for a device that emits a signal in a wide range of z, including around 14.18 MHz, or a signal emitted by a wireless station or an illegal wireless station. As described above, according to the present invention, the filter
But unnecessary signals due to radio waves mixed in from the detection output line
Drive of CCD comb filter output from pressure control oscillator
Within the video band generated by frequency conversion with
Before the spurious is input to the CCD comb filter,
Attenuated CCD comb output from voltage controlled oscillator
The filter drive signal can be passed without attenuation
You. Therefore, in the video band, it is possible to reduce a disturbance that occurs on the video signal due to an unnecessary signal due to a radio wave mixed into the detection output line, and it is possible to suppress a radio disturbance in an image.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram of a luminance / color signal separation circuit according to a first embodiment of the present invention; FIG. 2 is a detailed explanatory diagram of a luminance / color signal separation circuit according to the first embodiment; FIG. 3 is a configuration diagram of a luminance / color signal separation circuit according to a second embodiment of the present invention. FIG. 4 is a detailed explanatory diagram of a luminance / color signal separation circuit according to the second embodiment. FIG. Configuration Diagram of Signal Separation Circuit Explanation of Symbols 13 First filter 24 Second filter 30 First resistor 31 First capacitor 33 Low-pass filter 34 Second resistor 35 Second capacitor 36 High-pass filter

Claims (1)

(57) Claims 1. A comb filter using a charge-coupled device delay line, wherein the CCD comb is driven by a constant-frequency drive signal output from a phase-controlled voltage-controlled oscillation circuit. A luminance / color signal separation circuit comprising a filter, wherein the CCD comb filter is configured to separate the video signal output from a detection circuit for detecting a television signal into a video signal in a video band into a luminance signal and a color signal. , the power
The drive signal from the pressure control oscillator circuit is passed and
Cut-off frequency for removing signals in the frequency band
Output from the voltage controlled oscillator circuit
Received by the driving signal , the driving signal is passed, and the luminance and the luminance are arranged to be supplied to the CCD comb filter.
Color signal separation circuit.