JPH05308661A - Chrominance signal processor - Google Patents

Abstract

PURPOSE:To reduce the circuit scale of a counter by converting the frequency of the output of a voltage controlled oscillator by a reference frequency to reduce the frequency. CONSTITUTION:A side lock detector 111 is provided with a frequency converter 11 which multiplies the oscillation signal of a voltage controlled oscillator VCO 5 and the frequency of a quartz oscillator 10 to convert the frequency of the oscillation signal of the VCO 5, a low pass filter 12 which filters the low band of the output of the frequency converter 11 to output a signal having the same frequency as a low-band color signal, and a counter which counts the output of the low pass filter 12. The quartz oscillator 10 outputs the oscillation signal having the same frequency as a carrier chrominance signal frequency component to a phase comparator 4 and the frequency converter 11. In this case, the output of the VCO 5 is not directly counted but has the frequency converted, and thereby, the error component is sufficiently secured and only the frequency is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television signal processing device, particularly a television signal magnetic recording / reproducing device (hereinafter referred to as V
The present invention relates to a color signal processing device in TR) in which the side lock detection device is improved.

[0002]

2. Description of the Related Art A conventional VTR color signal processing device is shown in FIG. In FIG. 3, reference numeral 100 is an APC (automatic phase control) loop for converting a low-frequency reproduction color signal input from the outside to a frequency equal to that of the internal crystal precision signal and outputting the same.

In this APC loop 100, 1 is a main frequency converter for converting the frequency of an input signal by multiplying a low-frequency reproduction color signal input from the outside by an output of a second band pass filter 8, and 2 is a main frequency. A first band-pass filter 3 for extracting only the carrier color signal frequency component from the signal frequency-converted by the converter 1, 3 is a first band-pass filter 2
Of the burst gate for selectively passing only the burst component in the output of 4 is a phase comparator for phase comparing the output of the burst gate 3 and the output of the crystal oscillator 10, and 30 is a phase comparison current value of the phase comparator 4. Output from the counter 9,
An adder that adds a DC current according to the count value,
Reference numeral 5 denotes a voltage controlled oscillator (VCO) whose oscillation frequency is controlled according to the output voltage of the adder 30. In this conventional example, an integer multiple (e.g., 8 times) of the low-frequency conversion color signal frequency is set to its center frequency. It oscillates as. Reference numeral 6 divides the oscillation signal of the voltage controlled oscillator 5 by a predetermined division ratio, outputs a frequency equal to the low-pass conversion color signal frequency to the sub-frequency converter 7, and outputs an integral multiple of the low-pass conversion color signal frequency (for example, Frequency divider, which outputs a signal having a frequency equal to 4 times) to the counter 9,
Is a sub-frequency converter that multiplies the frequency-divided output of the frequency divider 6 and the output of the crystal oscillator 10 and frequency-converts the frequency-divided output of the frequency divider 6, and 8 is band-filtering the output of the sub-frequency converter 7. The second bandpass filter 10 for extracting the frequency component of the sum of the low-pass conversion color signal frequency and the carrier color signal frequency is a crystal oscillator (reference oscillator) that oscillates at a frequency equal to the carrier color signal.

Further, 110 is a side lock detection circuit for detecting whether or not the APC (automatic phase control) loop 100 is in a side lock state.

The side lock detection circuit 110 comprises the voltage controlled oscillator 5, the frequency divider 6, the adder 30 and the counter 9. The counter 9 counts the output of the frequency divider 6 and the count value thereof. And the internal comparison reference value are compared to determine whether the side lock state has been reached,
In the side lock state, a direct current corresponding to the count value is output.

Next, the operation of the color signal processing device according to this conventional technique will be described with reference to FIG. A low-frequency reproduction color signal that has entered from the outside, such as an electromagnetic conversion system of a VTR, is input from the second band-pass filter 8 by the main frequency converter 1 and is transmitted between the carrier color signal frequency and the low-frequency signal frequency. A continuous wave having a sum frequency is multiplied and the frequency is converted.

From the frequency-converted signal, only the carrier color signal frequency component is extracted by the first bandpass filter 2 and output to the outside, and only the burst is extracted by the burst gate 3, and the phase comparator 4 Phase comparison with the output of the crystal oscillator 10 is performed, and the voltage-controlled oscillator 5 is controlled by the comparison output.

The output of the voltage-controlled oscillator 5 whose frequency is equal to an integer multiple of the low-pass conversion color signal frequency is divided by the frequency divider 6 into a frequency equal to the low-pass conversion color signal, and then by the sub-frequency converter 7. , Multiplied by the output of the crystal oscillator 10,
Frequency conversion is performed, and the bandpass filter 8 extracts only the component of the sum of the carrier color signal frequency and the low-pass color signal frequency, which is necessary for the main frequency conversion, and outputs it to the frequency converter 1.

As a result, the main frequency converter 1, the first band pass filter 2, the burst gate 3, the phase comparator 4, the voltage controlled oscillator 5, the frequency divider 6, the sub frequency converter 7,
An APC (automatic phase control) loop 100 including the second bandpass filter 8 is formed, and the bandpass filter 2
Has the same frequency as the output of the crystal oscillator 10.

However, in the configuration of the APC loop 100, the output of the second bandpass filter 8 deviates from the sum of the carrier color signal frequency and the low-pass color signal frequency, which is a predetermined frequency, by an integral multiple of the horizontal frequency. AP at different frequencies
The C loop 100 may be locked.

This phenomenon is called side lock, which is called APC.
This is a malfunction that occurs because the loop 100 performs phase comparison only once in one horizontal cycle. That is, at the timing of executing the phase comparison, the phase of the sum of the carrier color signal frequency and the low band color signal frequency and the frequency that is deviated by an integer multiple of the horizontal frequency from each other match, so that they cannot be distinguished. Because.

In order to detect the occurrence of the side lock, the output of the VCO 5 or the frequency divider 6 is counted by the counter 9 for a predetermined period (usually 6 to 10 horizontal periods), and the discrimination circuit inside the counter is counted. It is determined whether the number is a predetermined number or not by detecting whether or not it is in the side lock state. At this time, if the frequency division ratio is large, an error component cannot be sufficiently secured. Therefore, the frequency divider 6 outputs to the counter 9 a signal having a frequency division ratio lower than that output to the sub frequency converter 7, that is, to the counter 9 to the sub frequency. A signal having a frequency that is an integral multiple of the low-pass color signal frequency that is output to the converter 7 is output, and the counter 9 detects an error thereby.

With this detection output, the counter 9 outputs a direct current corresponding to the count value, and the adder 30 outputs the VCO 5 according to the control voltage corresponding to the sum of the direct current and the phase comparison output current of the phase comparator 4. It is configured to control and return from the side lock state to the normal lock state.

[0014]

The side lock detection circuit of the color signal processing device in the conventional configuration is configured as described above, and in order to ensure sufficient detection accuracy, the VC
O5 output or frequency divider 6 output for a sufficiently long time (6 ~
Since it is necessary to count 10 horizontal periods), the number of counts becomes large, which causes a problem that the counter becomes large in scale.

The circuit shown in FIG. 3 is mounted on a one-chip IC. However, since the counter originally has a large circuit scale, this conventional circuit configuration causes an increase in the chip size. There was also.

The present invention has been made to solve the above problems, and an object thereof is to provide a color signal processing device capable of detecting side lock without using a large-scale counter.

[0017]

A color signal processing apparatus according to the present invention frequency-converts an incoming low-frequency converted color signal into a carrier color signal by a frequency converter, and a burst signal and carrier color of this carrier color signal. A voltage whose phase is compared with the output of a reference oscillator that oscillates at a frequency equal to the signal, and which oscillates at the frequency of the sum of the low-pass conversion color signal and the carrier color signal and whose oscillation frequency is controlled according to the output of the phase comparator. Automatic phase control means for operating the frequency converter with the output of the controlled oscillator,
Frequency conversion is performed using the output of the voltage controlled oscillator and the output of the reference oscillator, the frequency converted output is counted for a predetermined period, and the automatic phase control means is in a normal stable state depending on whether the count value is a predetermined value or not. And a means for controlling the voltage controlled oscillator based on the determination result.

The color signal processing device according to the present invention is
The incoming low-pass conversion color signal is frequency-converted into a carrier color signal by a frequency converter, and the burst signal of this carrier color signal is phase-compared with a reference oscillator oscillating at a frequency equal to the carrier color signal, and the above low-pass conversion is performed. The frequency of the first frequency-divided output of the voltage-controlled oscillator, which oscillates at a frequency that is an integral multiple of the color signal and whose oscillation frequency is controlled according to the output of the phase comparator, and the frequency of the sum of the carrier color signal, An automatic phase control means for operating a frequency converter, and a second of the above voltage controlled oscillator
Frequency conversion is performed by the frequency division output and the output of the reference oscillator, the frequency conversion output is counted for a predetermined period, and the automatic phase control means is in a normal stable state depending on whether or not the count value is at a predetermined value. And a means for controlling the voltage controlled oscillator based on the determination result.

Further, as the reference oscillator for performing the frequency conversion, the same frequency oscillator as that input to the phase comparator is used.

[0020]

In the color signal processing apparatus according to the present invention, as described above, the voltage controlled oscillator output is frequency-converted by the reference frequency and the frequency thereof is lowered, so that the circuit scale of the counter can be reduced.

Further, in the color signal processing device according to the present invention,
As described above, since the frequency divider output is frequency-converted by the reference frequency and the frequency is lowered, the circuit scale of the counter can be reduced.

Further, in the color signal processing apparatus according to the present invention, as described above, the reference oscillator for frequency conversion and the frequency oscillator input to the phase comparator are the same. As compared with the case where a separate oscillator is prepared, the oscillator can be saved and the circuit scale can be reduced.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a color signal processing apparatus according to an embodiment of the present invention. In the figure, reference numeral 101 denotes an APC circuit (automatic phase adjustment circuit) that converts a low-frequency converted color signal into a carrier color signal and outputs the carrier color signal.

In this automatic phase adjustment circuit 101, 1
Is a main frequency converter for converting the frequency of the low frequency conversion color signal by multiplying the low frequency conversion color signal input from the outside by the output of the voltage controlled oscillator 5, and 2 is a signal frequency-converted by the main frequency converter 1. A band pass filter for band-pass filtering the carrier color signal and extracting a carrier color signal frequency component, 3 is a burst gate for selectively passing a burst component in the output of the band pass filter 2, and 4 is an output of the burst gate 3 and a crystal oscillator 10. A phase comparator for phase comparison with the output, 30 is an adder for adding the phase comparison output of the phase comparator 4 and the count output of the counter 9, and 5 is voltage control for oscillating at a frequency according to the output voltage of the adder 30. It is an oscillator (VCO).

Reference numeral 111 is a side lock detecting device for detecting that the APC circuit 101 is in the side lock state.

In this side lock detecting device 111, 11 is an oscillation signal of the voltage controlled oscillator 5 and the crystal oscillator 1.
A frequency converter that multiplies the output of 0 and frequency-converts the oscillation signal of the voltage controlled oscillator 5, and 12 is a low-pass filter that low-pass filters the output of the frequency converter 11 and outputs a signal whose frequency is equal to the low-frequency color signal. Filter, 9 is a low-pass filter 12
Is a counter that counts the output of.

Reference numeral 10 is a crystal oscillator that outputs the oscillation signal oscillating at a frequency equal to the frequency component of the carrier color signal to the phase comparator 4 and the frequency converter 11.

Next, the operation of the embodiment of the present invention will be described with reference to FIG. The low-pass conversion color signal coming from the outside is frequency-converted by the output of the voltage-controlled oscillator 5 which oscillates by the main frequency converter 1 with the sum signal of the low-pass color signal frequency and the carrier color signal frequency, and the band pass filter 2 Thus, only the carrier color signal frequency component is extracted and output as a carrier color signal to the outside.

Further, the burst gate 3 extracts only the burst of the carrier color signal from the output of the band pass filter 2, and the phase comparator 4 compares the phase with the output of the crystal oscillator 10.

Then, the adder 30 generates a sum signal of the output of the phase comparator 4 and the output of the counter 9, and a voltage is generated to oscillate with the frequency of the sum of the carrier color signal frequency and the low band color signal frequency as the center frequency. The controlled oscillator 5 is controlled to form an APC loop 101 including the main frequency converter 1, the bandpass filter 2, the burst gate 3, the phase comparator 4, and the VCO 5. In addition, the APC loop 101
In order to detect the side lock of, the VCO 5 output and the output of the crystal oscillator 10 are frequency-converted by the frequency converter 11,
The low pass filter 12 extracts only the low frequency component. As a result, the output frequency becomes equal to the low-pass color signal frequency.

Further, the counter 9 counts the low frequency component for a predetermined period to detect whether or not the side lock state is present.

In the present embodiment, the output of the VCO 5 is not directly counted, but the frequency of this is converted so that only the frequency is lowered while sufficiently securing the error component. The frequency to be counted falls from the sum of the carrier color signal frequency and the low-pass color signal frequency, which is the output frequency of the VCO 5, to the frequency equal to the low-pass color signal frequency.

This is 1/6 to 1/7 of the sum of the carrier color signal frequency and the low-pass color signal frequency in the NTSC system and 1/8 in the PAL system, but in any case, the error to be detected. Since they are the same, it is sufficient to count for the same period. Therefore, in the present embodiment, the counter can be downsized because the frequency is lower. Further, since the limit frequency of the counter circuit can be lowered, its power consumption can be reduced.

Further, in this embodiment, since the output of the crystal oscillator 10 is supplied to the phase comparator 4 and the third frequency oscillator 11, the circuit scale is smaller than that when they are driven by separate oscillators. It has the effect of being small.

FIG. 2 shows a side lock detecting device according to another embodiment of the present invention. In FIG. 2, 100 is an APC loop similar to the conventional example of FIG. This APC loop 1
In 00, 1 is a main frequency converter for frequency-converting the low-pass conversion color signal by multiplying the low-pass conversion color signal input from the outside by the output of the second band-pass filter 8, and 2 is the main frequency converter 1 A band pass filter for extracting the signal of the same frequency as the carrier color signal by band-filtering its output, 3 is a burst gate for selectively passing the burst component in the output of the band pass filter 2, and 4 is a burst gate 3. Is added to the output of the crystal oscillator 10, and 30 is an adder for adding the output of the phase comparator 4 and the output of the counter 9, and 5 is a component for dividing the output of the adder 30. A frequency divider, 7 is a sub-frequency converter that multiplies the output of the frequency divider 6 and the output of the crystal oscillator 10, and frequency-converts the output of the frequency divider 6, and 8 is a band of the output of the sub-frequency converter 7. Second bandpa to limit It is a filter.

Reference numeral 112 denotes a side lock detecting device for detecting whether or not the APC loop 100 is in the side lock state.

In the side lock detecting device 112, 11 is a third frequency converter for multiplying the frequency divider 6 output and the crystal oscillator 10 output to frequency-convert the frequency divider 6 output.
Reference numeral 12 is a low-pass filter that extracts low-frequency components of the output of the third frequency converter 11, and 9 is a counter that counts the output of the low-pass filter 12.

Next, the operation of the side lock detector according to the present invention will be described with reference to FIG. The incoming low-frequency conversion color signal is transferred to the crystal oscillator 1 by the APC loop similar to the conventional example.
It is frequency-converted into a carrier color signal having the same frequency as the output of 0, and is output from the first bandpass filter 2. Since the phase comparison is performed only once in one horizontal period only with the APC loop, side lock is performed as in the conventional example. In order to detect this, the output of the VCO 5 that oscillates at an integer multiple (e.g., 8 times) of the low-pass color signal frequency is divided by the frequency divider 6 (e.g., divided by 2), and the frequency is the carrier color signal frequency. After performing frequency conversion with the output of the crystal oscillator 10 equal to, the low-pass filter 12 extracts only the low-frequency component and the counter 9 counts only the low-frequency component.

As a result, the frequency limit can be further reduced as compared with the first embodiment, so that the configuration of the counter can be further reduced and the power consumption thereof can be further reduced.

Further, in this embodiment, the output of the crystal oscillator 10 is supplied to the phase comparator 4, the sub-frequency converter 7 and the third frequency converter 11, so that these are generated by separate oscillators. There is an effect that the circuit scale can be reduced as compared with the case of driving.

[0041]

As described above, according to the color signal processing device of the present invention, the frequency conversion of the incoming low-frequency conversion color signal is carried out by the frequency converter into the carrier color signal, and the burst signal of the carrier color signal is obtained. And the output of a reference oscillator that oscillates at the same frequency as the carrier color signal are phase-compared, and the oscillation frequency is controlled at the sum frequency of the low-pass conversion color signal and the carrier color signal, and the oscillation frequency is controlled according to the output of the phase comparator. Frequency conversion is performed by the automatic phase control means for operating the frequency converter with the output of the voltage controlled oscillator, the output of the voltage controlled oscillator and the output of the reference oscillator, and the frequency converted output is counted for a predetermined period, and the count is performed. A means for judging whether or not the automatic phase control means is in a normal stable state based on whether or not the value is a predetermined value, and a means for controlling the voltage controlled oscillator based on the judgment result. By providing the means for reducing the frequency input to the counter constituting the side lock detector by using the frequency converter based on the reference frequency, the circuit scale of the counter can be reduced and the frequency to be counted is low. Therefore, the power consumption can be reduced.

Further, the color signal processing device according to the present invention is
The incoming low-pass conversion color signal is frequency-converted into a carrier color signal by a frequency converter, and the burst signal of this carrier color signal is phase-compared with a reference oscillator oscillating at a frequency equal to the carrier color signal, and the above low-pass conversion is performed. The frequency of the first frequency-divided output of the voltage-controlled oscillator, which oscillates at a frequency that is an integral multiple of the color signal and whose oscillation frequency is controlled according to the output of the phase comparator, and the frequency of the sum of the carrier color signal, An automatic phase control means for operating a frequency converter, and a second of the above voltage controlled oscillator.
Frequency conversion is performed by the frequency division output and the output of the reference oscillator, the frequency conversion output is counted for a predetermined period, and the automatic phase control means is in a normal stable state depending on whether or not the count value is at a predetermined value. And a means for controlling the voltage-controlled oscillator based on the result of the determination are used, so that the frequency input to the counter that constitutes the side lock detector is a frequency converter using the reference frequency. Therefore, the circuit scale of the counter can be reduced, and since the counting frequency is low, the power consumption can be reduced.

Further, the color signal processing device according to the present invention uses the same frequency oscillator as the frequency oscillator input to the phase comparator as the reference oscillator for performing the frequency conversion, and therefore these are separately provided. Compared with the case of driving with the oscillator of, there is an effect that the circuit scale can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing a color signal processing device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a color signal processing device according to another embodiment of the present invention.

FIG. 3 is a diagram showing a conventional color signal processing device.

[Explanation of symbols]

 1 Main Frequency Converter 2 First Band Pass Filter 3 Burst Gate 4 Phase Comparator 5 Voltage Controlled Oscillator 6 Frequency Divider 7 Sub Frequency Converter 8 Band Pass Filter 9 Counter 10 Crystal Oscillator 11 Third Frequency Converter 12 Low Pass Filter

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[Procedure amendment]

[Submission date] September 9, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 1

[Correction method] Change

[Correction content]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location H04N 9/83 C 7916-5C

Claims (3)

[Claims] 1. A frequency converter for converting an incoming low-frequency conversion color signal into a carrier color signal, a reference oscillator oscillating at a frequency equal to the carrier color signal, a burst signal of the carrier color signal and the reference oscillator. A phase comparator for comparing the phases of the outputs, and a voltage controlled oscillator that oscillates at the frequency of the sum of the low-pass conversion color signal and the carrier color signal and whose oscillation frequency is controlled according to the output of the phase comparator. Automatic phase control means for operating the frequency converter with the output of the voltage controlled oscillator, means for frequency conversion with the output of the voltage controlled oscillator and the output of the reference oscillator, and counting the frequency converted output for a predetermined period. Means for determining whether the automatic phase control means is in a normal stable state based on whether the count value is a predetermined value, and the determination result. Color signal processing apparatus characterized by comprising a means for controlling the serial voltage controlled oscillator. 2. A frequency converter for converting an incoming low-pass conversion color signal into a carrier color signal, a reference oscillator oscillating at a frequency equal to the carrier color signal, a burst signal of the carrier color signal and the reference oscillator. It has a phase comparator for phase comparing outputs, and a voltage controlled oscillator that oscillates at a frequency that is an integral multiple of the low-pass conversion color signal and whose oscillation frequency is controlled according to the output of the phase comparator. Automatic phase control means for operating the frequency converter at the frequency of the first divided output of the controlled oscillator and the frequency of the sum of the carrier color signals; and the second divided output of the voltage controlled oscillator and the reference oscillator. A means for performing frequency conversion with the output, a means for counting the frequency conversion output for a predetermined period, and a means for the automatic phase control means to be in a normal stable state depending on whether or not the count value is a predetermined value. And means for determining whether a color signal processing apparatus characterized by with a said determination result and a means for controlling the voltage controlled oscillator. 3. The color signal processing device according to claim 1, wherein the reference oscillator for performing the frequency conversion is the same as the frequency oscillator input to the phase comparator.