JPH06315158A - Delay circuit - Google Patents

Abstract

PURPOSE:To perform the non-adjustment, of delay time and attenuation amount in a delay line delaying a horizontal synchronizing period. CONSTITUTION:A negative feedback system is composed by using a glass delay line 1 as a delay element in a delay route, providing a voltage control phase converter 2 after the delay line 1 and a voltage control amplifier 3 after the voltage control phase converter 2, respectively, taking out each reference signal from the input signal and the output signal of the delay route, comparing the phase and the amplitude of the reference signal, respectively, and transmitting the comparison outputs to the voltage control phase converter 2 and the voltage control amplifier 3, in a delay circuit. Thus, the delay time and the amplification factor of the delay circuit are automatically adjusted and the device having the delay circuit can be made into non-adjustment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a delay circuit, and more particularly to a video signal processing circuit such as a comb filter using a delay line.

[0002]

2. Description of the Related Art FIG. 3 shows a comb filter using a glass delay line in a conventional delay circuit, and FIG. 4 (a) shows an example of a carrier color signal of a television signal which is an input signal to the comb filter. Show. In FIG. 3, 40 is a signal input terminal, 1 is a glass delay line (DL), 2a and 2h are capacitors,
2b, 2c, 2d and 2f are resistors, 2g and 3b are variable resistors, 2e and 3a are NPN transistors, and 3c.
Is a buffer amplifier, 13 is an adder, 50 is a signal output terminal, 20 is a variable phase shifter composed of 2a to 2h, and 30 is a variable gain amplifier composed of 3a to 3c. Then, the glass delay line 1 and the variable phase shifter 2
0 and the variable gain amplifier 30 make one horizontal period (hereinafter, 1
(Referred to as H) constitutes a delay circuit.

Next, the operation will be described. First, a carrier color signal of a television signal as shown in FIG. 4A is input to the signal input terminal 40 and sent to the glass delay line 1 and the adder 13.

The input signal sent to the glass delay line 1 is delayed by 1H in the glass delay line 1 and is output. At this time, the output of the delay circuit is delayed due to variations in the characteristics of the glass delay line 1. There will be a shift in the phase and amplitude of the signal. In order to correct this, a variable phase shifter 20 and a variable gain amplifier 30 are provided, and the output signal of the glass delay line 1 in which the phase and amplitude are deviated is input to the variable phase shifter 20. Variable phase shifter 2
The delay time is adjusted by adjusting the variable resistor 2g within 0, and the variable phase shifter 20 outputs it.

Next, the signal output from the variable phase shifter 20 is input to the variable gain amplifier 30, and the attenuation amount is adjusted by adjusting the variable resistor 3b in the variable gain amplifier 30. It is output from the variable gain amplifier 30.

The input signal thus sent to the glass delay line 1 is accurately delayed by 1H to become an input signal whose amplitude is adjusted and sent to the adder 13.

Next, the input signal delayed by 1H and the input signal directly sent to the adder 13 are added in the adder 13, and the input signal as shown in FIG. Unnecessary frequency components are removed from a certain carrier color signal and output as an output signal.

Conventionally, a 1H comb filter has been constructed as described above.

[0009]

A conventional delay circuit such as a comb filter using a glass delay line is constructed as described above, and since the glass delay line has variations in manufacturing, it is variable. The phase shifter 20 and the variable gain amplifier 30 each have to be adjusted to compensate for variations in the delay time and the variations in the amount of attenuation, and it is necessary to match the comb characteristics with these two adjustments, which is troublesome. It was a thing.

The present invention has been made to solve the above problems, and eliminates the need to adjust the delay time and the amount of attenuation in the delay circuit one by one, that is, a comb filter which does not need adjustment. It is an object of the present invention to provide a delay circuit using the delay line.

[0011]

A delay circuit according to the present invention uses a delay element such as a glass delay line, and a delay element such as the glass delay line and a variable phase for varying the phase of an input signal in its delay path. In the delay circuit having the variable amplifier for amplifying the input signal and the input signal of the delay path, the reference signals are respectively taken out from the input signal and the output signal thereof, the phases of the respective taken out reference signals are compared, and the output thus compared is By sending to the variable phase shifter, a negative feedback system is constructed so as to obtain a predetermined delay time between the input signal and the output signal of the delay path, and the amplitude of each of the extracted reference signals. To form a negative feedback system by sending the compared output to the variable amplifier so as to obtain a predetermined amplification factor between the input signal and the output signal of the delay path. One in which the.

In the delay circuit according to the present invention, the delay time is set to be an integral multiple of the horizontal period of the television signal, and the reference signal used for comparing the phase and the amplitude is the burst signal of the television signal. It was done.

Further, in the delay circuit according to the present invention, the delay time is set to be an integral multiple of the horizontal period of the television signal, and the reference signal used for comparing the phase and the amplitude is set to the delay time of the delay element. The carrier signal color frequency which changes by the same amount as the phase amount of the input signal changed by the above is used as a pilot signal which is inserted in the horizontal erasing period or the vertical erasing period in the input signal.

[0014]

According to the present invention, a delay element such as a glass delay line is used, and a delay element such as the glass delay line, a variable phase shifter for varying the phase of the input signal, and a variable amplifier for amplifying the input signal are used in the delay path. A delay circuit including a reference signal from each of the input signal and the output signal of the delay path, compares the phases of the respective extracted reference signals, and sends the output of the comparison to the variable phase shifter. Since the return ring system is constructed, the amplitudes of the respective extracted reference signals are compared, and the output thus compared is sent to the variable amplifier to form the negative return system. A desired delay time and amplification factor can be obtained between the input signal and the output signal of the path, and the delay circuit can be automatically controlled.

Further, according to the present invention, the delay line of the delay circuit is such that the delay time is an integral multiple of the horizontal period of the television signal, and the reference signal used for the phase and amplitude comparison is a television. The frequency of the carrier color signal, which changes by the same amount as the phase amount of the input signal changed by the burst signal of the signal and the delay time of the delay element, is inserted in the horizontal erasing period or the vertical erasing period in the input signal. Since the pilot signal is used, the delay time in the variable phase shifter becomes an integral multiple of the horizontal period of the television signal, and the variable gain controller automatically controls the delay circuit so that the amplification factor gain becomes a desired value. Can be done.

[0016]

【Example】

Example 1. A first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram for explaining a 1H comb filter according to the first embodiment. 1 is a 1H glass delay line (DL), 2 is a voltage controlled phase shifter (ψ), and 3 is a voltage variable gain amplifier (GCA). ), 4 and 5 are burst gates (BG), 6 are 90 ° phase shifters (90 °), 7 are phase comparators (X), 8 and 9 are peak detectors (PEAKD).
ET), 10 is a comparator, 11 and 12 are integrators, 13
Is an adder, 40 is a signal input end, and 50 is a signal output end. The voltage control phase shifter 2 and the voltage variable gain amplifier 3 correspond to the variable phase shifter 20 and the variable gain amplifier 30 of FIG. To do.

FIG. 4A shows an example of a carrier color signal of a television signal input to the signal input terminal 40,
FIG. 4 (b) shows the output waveforms of the burst gates 4 and 5, and FIG. 4 (c) shows the output waveforms of the peak detectors 8 and 9.

Next, the operation will be described. First, the carrier color signal of the television signal as shown in FIG. 4 (a) inputted to the signal input terminal 40 is sent to the adder 13 through two paths as follows.

That is, one is a path that passes through the 1H glass delay line 1, the voltage control phase shifter 2 and the voltage variable gain amplifier 3 in this order and is sent to the adder 13, and the other is from the signal input terminal 40. This route is directly sent to the adder 13. The 1H glass delay line 1 in the former route has manufacturing variations in its characteristics, as described in the prior art,
The output waveform of the glass delay line 1 has a difference in phase and amplitude as compared with the input waveform as shown in FIG.

Next, a signal having a difference in the phase and amplitude of the waveform of the input signal passing through the glass delay line 1 is passed through the voltage control phase shifter 2 and the voltage variable gain amplifier 3 in this order, and the voltage variable gain amplifier is passed. By sending the signal output from 3 to the burst gate 4 and sending the original input signal to the burst gate 5, only the burst signal is extracted from the respective signals, and the signals output from the burst gates 4 and 5 are Each has a waveform as shown in FIG. At this time, the burst signal output from the burst gate 4 and the burst signal output from the burst gate 5 have different phases and amplitudes.

Next, the burst signal output from the burst gate 5 is sent to the 90 ° phase shifter 6 and the phase thereof is delayed by 90 °. The signal whose phase is delayed by 90 ° and the burst signal The burst signal output from the gate 4 is compared in the phase comparator 7, and the signal output as the phase difference component from the phase comparator 7 is
It is integrated by the integrator 11 to form a DC voltage signal, which is sent to the voltage control phase shifter 2. Then, with the DC voltage signal, the voltage control phase shifter 2 is negatively fed back and automatically controlled so that the phase shift caused by the variation of the glass delay line 1 is accurately delayed by 1H. .

At the same time, the burst signal output from the burst gate 5 is sent to the peak detector 8,
The burst signals output from the burst gate 4 are respectively sent to the peak detector 9, and the signals having the waveforms shown in FIG. 4 (c) are output from the peak detectors 8 and 9, respectively. However, the amplitude of the signal output from the peak detector 9 includes the component of the amplitude shift caused by the variation of the glass delay line 1. The output signal of the peak detector 8 and the output signal of the peak detector 9 are input to the comparator 10 and compared, and the component of the amplitude difference is output as a signal. Then, this output signal is integrated by the integrator 12 to become a DC voltage signal, which is input to the voltage variable gain amplifier 3, whereby the voltage variable gain amplifier is made equal in amplitude to the carrier color signal at the signal input terminal 40. Negative feedback is applied to 3, that is, the amplification gain is automatically controlled to 0 dB.

Next, the carrier color signal input to the signal input terminal 40 and the negative feedback controlled voltage control phase shifter 2 and the voltage variable gain amplifier 3 respectively have the same amplitude and the same delay time. The carrier color signal set to 1H is added in the adder 13, and the carrier color signal obtained by removing unnecessary frequency components from the carrier color signal input to the signal input terminal 40 is output from the signal output terminal 50. Becomes

In the delay circuit using the glass delay line 1 in the delay circuit of the first embodiment, it is not necessary to manually adjust the variable resistor, the delay time and the attenuation amount are automatically adjusted, and unnecessary from the input signal. It is possible to output a signal having a 1H comb filter characteristic from which frequency components have been removed.

In the delay circuit of the first embodiment, the 1H comb filter using the glass delay line 1 is used. However, other than the glass delay line, a delay line using a device such as CCD or a delay time is used. A delay circuit using a delay line of 2H or more, or a delay circuit using a delay line such as a cyclic comb filter or a line type logical comb filter can be configured, and the delay time and the attenuation amount can be automatically adjusted. Is something that can be done.

Example 2. A second embodiment according to the present invention will be described below with reference to the drawings. FIG. 2 shows a first embodiment 1
FIG. 3 is a block diagram for explaining an H comb filter,
4a and 5a are pilot burst gates, 14 is a pilot burst inserter, and 15 is a pilot burst remover. In addition, the same reference numerals as those in FIG. 1 indicate the same parts.

Next, the operation will be described. First, the carrier chrominance signal input from the signal input terminal 40 is added with a pilot burst signal at the carrier chrominance signal frequency in the horizontal erasing period or vertical erasing period in the pilot burst inserter 14.

The carrier color signal to which the pilot burst signal is added is input to the pilot burst gate 5a and the adder 13, and also to the glass delay line 1. Although the carrier color signal including the pilot burst signal input to the glass delay line 1 is delayed by 1H, the phase and amplitude thereof are deviated as in the first embodiment. Then, the carrier chrominance signal including the pilot burst signal having the phase and the amplitude shifted from each other is sent to the voltage control phase shifter 2 and the voltage variable gain amplifier 3 in this order, and the pilot burst gate 4a and the adder 1 are supplied.
3 will be input respectively.

Next, the pilot burst gate 5a outputs only the pilot burst signal, and the pilot burst gate 4a passes through the glass delay line 1 to output only the pilot burst signal having a phase and amplitude shift. Become.

Thereafter, by the same procedure as in the first embodiment,
The carrier chrominance signal including the pilot burst signal whose phase and amplitude are deviated is adjusted in phase by the voltage controlled phase shifter 2 which is negatively fed back, and is amplitude by the voltage variable gain amplifier 3 which is negatively fed back. Is adjusted,
The carrier color signal having the same amplitude and the delay time of 1H is input to the adder 13.

Next, the signal output from the adder 13 is input to the pilot burst remover 15, the added pilot burst signal is removed, and an unnecessary frequency is extracted from the carrier color signal input to the signal input terminal 40. The carrier color signal from which the components have been removed is output from the signal output terminal 50.

In the delay circuit using the glass delay line 1 in the delay circuit according to the second embodiment, it is not necessary to manually adjust the variable resistor, the delay time and the attenuation amount are automatically adjusted, and unnecessary from the input signal. It is possible to output a signal having a 1H comb filter characteristic from which frequency components have been removed. Particularly, in the PAL signal color demodulator, it is necessary to use the 1H delay line, and the phase of the burst of the PAL signal that is the input signal changes every 1H. Therefore, the first embodiment cannot be applied. The second embodiment is effective. Even when the input signal is only the luminance signal, the effect can be obtained by the second embodiment.

Also in the second embodiment, a delay line using a device such as a CCD other than the glass delay line, a delay circuit using a delay line having a delay time of 2H or more, or a cyclic comb type. A delay circuit using a delay line such as a filter or a line-type logical comb filter can also be configured, and the delay time and the amount of attenuation can be automatically adjusted.

[0034]

As described above, according to the delay circuit of the present invention, the delay element such as the glass delay line is used, and the delay element such as the glass delay line and the phase of the input signal are varied in the delay path. In a delay circuit having a variable phase shifter and a variable amplifier for amplifying an input signal, a reference signal such as a burst signal of a television signal is taken out from each of the input signal and the output signal of the delay path, and each taken out reference signal The phases of the above are compared, and the output of this comparison is sent to the variable phase shifter to form a negative feedback system, and the amplitudes of the respective reference signals extracted above are compared,
Since the negative feedback system is constituted by sending the compared output to the variable amplifier, the variable phase shifter automatically sets the delay time to a desired value between the input signal and the output signal of the delay path. In addition, the variable gain controller can automatically set the amplification gain to a desired value, and there is an effect that the adjustment of the delay time and the like in the device using the delay circuit can be eliminated.

According to the present invention, the delay line of the delay circuit is such that the delay time is an integral multiple of the horizontal period of the television signal, and the reference signal used for comparing the phase and the amplitude is used. Since the frequency of the carrier color signal or the like which changes by the same phase amount as the phase amount of the input signal changed by the delay time of the delay element is used as the pilot signal formed by inserting it in the horizontal erasing period or the vertical erasing period in the signal, ,
Even if the phase of the input signal changes every horizontal period of the television signal, the variable phase shifter can automatically set the delay time to a desired value, and the variable gain controller automatically adjusts the amplification gain. It is possible to obtain a desired value, and there is an effect that the adjustment of the delay time and the like in the device using the present delay circuit can be eliminated.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram of a comb filter using a delay line according to an embodiment of the present invention.

FIG. 2 is a circuit configuration diagram of a comb filter using a delay line according to another embodiment of the present invention.

FIG. 3 is a circuit configuration diagram of a conventional comb filter.

FIG. 4 is a diagram for explaining signal processing in a comb filter using a delay line according to an embodiment of the present invention.

[Explanation of symbols]

 1 glass delay line 2 voltage control phaser 3 voltage variable gain amplifier 4,5 burst gate 6 90 ° phase shifter 7 phase comparator 8 and 9 peak detector 10 comparator 11 and 12 integrator 13 adder 14 pilot burst insertion 15 pilot burst eliminator 20 variable phaser 30 variable gain amplifier 40 signal input terminal 50 signal output terminal 2a, 2h capacitors 2b, 2c, 2d, 2f resistors 2e, 3a NPN transistor 2g, 3b variable resistor 3c buffer amplifier

Claims (3)

[Claims] 1. A delay circuit comprising a delay element such as a glass delay line and having the delay element, a variable phase shifter for varying the phase of an input signal, and a variable amplifier for amplifying the input signal in a delay path formed by the delay element. By comparing the phase of each of the reference signals extracted with the reference signal extraction means for extracting the reference signal from the input signal of the delay path and the output signal thereof, and adding the compared output to the variable phase shifter,
The delay time negative feedback system configured to obtain a predetermined delay time between the input signal and the output signal of the delay path is compared with the amplitude of each of the extracted reference signals, and the compared output is changed to the variable value. By adding to the amplifier,
A delay circuit comprising an amplification factor negative feedback system configured to obtain a predetermined amplification factor between an input signal and an output signal of the delay path. 2. The delay circuit according to claim 1, wherein the input signal is a carrier color signal of a television signal, the delay time is an integral multiple of a horizontal period of the television signal, and the phase and amplitude are compared. A delay circuit, wherein the reference signal used is a burst signal of a television signal. 3. The delay circuit according to claim 1, wherein the input signal is a carrier color signal of a television signal, the delay time is an integral multiple of a horizontal period of the television signal, and the phase and amplitude are compared. The reference color signal used has a carrier color signal frequency that changes by the same phase amount as the phase amount of the input signal changed by the delay time of the delay element, and is inserted in the horizontal erasing period or the vertical erasing period in the input signal. A delay circuit, which is a pilot signal.