JPH0316431A - Phase locked loop device - Google Patents

Abstract

PURPOSE:To suppress the deterioration in the degree of the stereo separation due to the effect of a flyback pulse by storing data when no picture is outputted to a cathode ray tube and applying phase correction at the time of using based on the data. CONSTITUTION:An output to a cathode ray tube is stopped at first (e.g. at plant adjustment) to allow a correction data, that is, the influence of a flyback pulse to be avoided and the output of a low pass filter 9 at that time is held in a data latch 10. The output of the data latch 10 is subtracted from the output of the low pass filter obtained similarly at the adjustment in the actual use by a subtracter 11 and its output is fed to the external input terminal of a VCO 6 via an integration device 12.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention performs carrier regeneration of sub-channels (DSB modulated L-R signals) required for stereo demodulation of audio multiplexing for North American television receivers, for example. The present invention relates to a phase synchronization device for

2. Description of the Related Art A conventional phase synchronization device includes a phase comparator 23 in which an input signal input from an input terminal is connected to one input terminal, and a phase comparator 23 that attenuates the high-frequency components of the output signal of the phase comparator to determine the characteristics of the system. and a VCO that changes the oscillation frequency based on the output of the loop filter and outputs it,
There was a phase synchronizer in which the first output of the VCO was connected to the other input terminal of the phase comparator and the output was taken from the second output terminal of the VCO. FIG. 4 shows the configuration of a conventional phase synchronization device, and the explanation will be given according to the diagram.

In Fig. 4, 21 is an input terminal, 23 is an output terminal, 2
4 is a phase comparator (PC), 25 is a loop filter, 26
is a VCO. When the input signal input from the input terminal 21 is close to or approaching the free running frequency of the VCO 26, according to the characteristics determined by the loop filter 25,
The oscillation signal of the VCO 26 approaches the phase of the input signal and is eventually synchronized. At this time, the low-frequency component (!=F DC) of the output signal of the phase comparator 24 is maintained so as to be output in an amount that corrects the phase error between the free-running frequency and the input signal.

A signal that is synchronized with the input signal but has a different frequency is taken out from the other output terminal of the VCO 26.

Problems to be Solved by the Invention However, in conventional phase synchronization devices, when used in audio multiplex television for North America, for example, a high-voltage flyback pulse having the same frequency component as the pilot signal is converted into an audio composite signal. This has caused a problem in that the phase of the audio pilot signal used for stereo demodulation is disturbed and the degree of stereo separation is deteriorated. That is, when a complex composite signal (only the pilot signal is shown in this figure) as shown in Fig. 5(a) is applied to the input terminal, noise from the flyback transformer as shown in Fig. 5(b) occurs. Let's consider the case where . In this case, for ease of explanation, Figure 5 (
A composite signal of the fundamental wave of the jump signal from the flyback transformer and the input composite signal (5th
Figure (a)) is added to the loop filter 25, and Figure 5 (e) is added to the loop filter 25.
) is output from the VCO 26.

This signal is out of phase with the original carrier signal shown in FIG. 6(f'), and has the drawback of deteriorating the degree of stereo separation.

The present invention has been made in view of the above problems, and provides a phase synchronization device that can improve the degree of separation during stereo demodulation by correcting the influence of flyback pulses in advance.

Means for Solving the Problems In order to achieve this object, a phase synchronization device according to the invention as claimed in claim 1 includes a first phase comparator to which an input signal is applied to one manual terminal; A loop filter that attenuates the high-frequency components of the output signal of the phase comparator and determines the characteristics of the system, and a signal that changes the oscillation frequency based on the output of the loop filter and outputs the signal that is input from another external input terminal. a VCO that changes the phase of an oscillation signal based on the oscillation signal, and a phase synchronization circuit in which a first output of the VCO is connected to the other input terminal of the first phase comparator; an fH signal converter that converts the synchronization pulse into a 50% duty signal having the same fundamental frequency as the synchronization pulse; and a second phase comparator to which the output of the fH signal converter and the output of the CO are respectively given as inputs. a low-pass filter that removes high-frequency components from the output of the second phase comparator; a data latch that holds output data of the low-pass filter at an arbitrary time; and an output of the data latch from the output of the low-pass filter. a subtracter that performs subtraction; an integrator that integrates the output of the subtracter; an output of the integrator is connected to an external input terminal of the VCO;
The configuration is such that the output is taken out from the second output terminal of.

Further, the phase synchronization device according to the invention as claimed in claim 2 has the advantage that the integrator output and the V
A second data latch is provided between the CO external input terminals, and the other features are the same as the phase synchronizer according to the first aspect of the invention.

Effect of the present invention With the above-mentioned configuration, the f is output from the horizontal synchronizing signal input from the input terminal without outputting a flyback pulse, that is, without outputting an image to the cathode ray tube.
A second phase comparator compares the phase of the signal obtained through the H signal converter with the phase of the first output of the VCO synchronized with the input signal, and holds the DC component data. Next, the integrator output is given to the VCO as correction data so that the difference between the DC component data when the flyback pulse is output and the held data becomes zero.

By doing this, the phase of the pilot signal due to the influence of the flyback pulse is corrected, and the degree of stereo separation is improved.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows a configuration diagram of a phase synchronization device according to an embodiment of the invention as claimed in claim 1. In Figure 1, 1 is the first
, 2 is the second input terminal, 3 is the output terminal, 4 is the first phase comparator, 5 is the loop filter, 6 is the VCO 1
7 is an fH signal converter, 8 is a second phase comparator (PC)
, 9 is a low-pass filter, 10 is a data latch, 11 is a subtracter, and 12 is an integrator.

Here, 1 and 4.5 are respectively 2 in the conventional embodiment.
1, 24, and 25, so the explanation will be omitted.

The VCOE is basically the same as the conventional VC026, but it has an external input terminal and the phase of the oscillation signal can be controlled by the signal input from the external input terminal.

A horizontal synchronizing pulse is input from the video signal processing section shown in FIG. 2(a) through the second input terminal 2, and the fH signal converter 7
The signal is converted into a signal with a duty of 50% as shown in FIG. 2(b). This signal is preferably a sine wave, but may also be a square wave or triangular wave. The output of the fH signal converter 7 is input to a second phase comparator 8, and its phase is compared with the first output signal of the vcoe shown in FIG. 2(C).

Since the output of the second phase comparator 8 (FIG. 2(d)) contains unnecessary high-frequency components, only the DC component is extracted through the low-pass filter 9.

In order to create correction data, at first (for example, during factory adjustment) the output to the cathode ray tube is stopped so that it is not affected by the flyback pulse, and the output of the low-pass filter 9 at that time is held in the data latch 10. I'll keep it. This data latch 10 is of a type that does not lose data even when the power is turned on.

During actual use, the output of the data latch 10 is subtracted by the subtracter 11 from the output of the low-pass filter 9 obtained in the same manner as during adjustment, and the output (FIG. 2(f)) is sent to the integrator 1.
2 to the external input terminal of vcoe. In addition, V
The direction of the phase correction of CO6 is the direction in which the output of the subtracter 11 converges to zero.

This will result in Figure 2(e). As shown in (g) showing the input and output of this circuit, the output signal phase of vcoe can be corrected for the influence of the flyback pulse.

Next, FIG. 2 shows a configuration diagram of a phase synchronization device according to an embodiment of the invention as claimed in claim 2 of the present application. In FIG. 2, 1 to 12 are the same as in the first embodiment described above, and 13 is a second data latch.

The basic operation is the same as that of the first embodiment, so the explanation will be omitted.

Now, assuming that the influence of the flyback pulse does not change over time, the output of the integrator 12 may be fixed during factory adjustment. Therefore, in this embodiment, the output of the integrator 12 and the vcoe
A data latch l3 for holding correction data is provided between the external input terminals.

By doing this, on the image receiver side, there is a vc whose phase can be corrected.
By installing only the second data latch 13 in the same phase-locked circuit as the conventional example with OE, and placing the other components outside the receiver, the degree of stereo separation is improved without significantly increasing the cost of the receiver. can do.

Effects of the Invention The phase synchronization device according to the invention according to claim 1 of the present application stores data when not outputting an image to a cathode ray tube,
、． By adding phase correction based on the data during use, it is possible to suppress deterioration of stereo separation due to the influence of flyback pulses.

The phase synchronization device of the invention according to claim 2 significantly increases the cost of the image receiver by installing up to the data latch for storing correction data inside the image receiver, and placing the components necessary for factory adjustment outside the image receiver. It is possible to improve the degree of stereo separation without any interference.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a phase synchronization device in a tth embodiment embodying the invention of claim 1 of the present application, FIG. 2 is a waveform diagram showing waveforms of each part thereof, and FIG. 3 is the invention of claim 2. A configuration diagram of the phase synchronization device in the second embodiment embodying the fourth embodiment.
The figure is a block diagram of a conventional phase synchronization device, and FIG. 5 is a waveform diagram of each part thereof. DESCRIPTION OF SYMBOLS 1... First input terminal, 2... Second input terminal, 3... Output terminal, 4... First phase comparator,
5...Loop filter, 6...VC0,
7...fH signal converter, one-pass filter, 11...subtractor, data latch.

Claims (2)

[Claims] (1) a first phase comparator to which an input signal is given to one input terminal; a loop filter that attenuates high-frequency components of the output signal of the first phase comparator to determine system characteristics; and the loop filter. a VCO that changes the oscillation frequency based on the output of the filter and changes the phase of the oscillation signal based on the signal input from another external input terminal; a phase synchronization circuit connected to the other input terminal of the first phase comparator; and an fH signal converter that converts an externally applied horizontal synchronization pulse into a 50% duty signal having the same fundamental frequency as the horizontal synchronization pulse; a second phase comparator to which the output of the fH signal converter and the output of the VCO are respectively given as inputs; a low-pass filter that removes high-frequency components from the output of the second phase comparator; and any of the low-pass filters. a data latch that holds output data at a time; a subtracter that subtracts the output of the data latch from the output of the low-pass filter; an integrator that integrates the output of the subtracter; and an integrator that integrates the output of the integrator. A phase synchronization device, characterized in that the VCO is connected to an external input terminal of the VCO, and an output is taken out from a second output terminal of the VCO. (2) a first phase comparator to which an input signal is given to one input terminal; a loop filter that attenuates high-frequency components of the output signal of the first phase comparator to determine system characteristics; and the loop filter. a VCO that changes the oscillation frequency based on the output of the filter and changes the phase of the oscillation signal based on the signal input from another external input terminal; a phase synchronization circuit connected to the other input terminal of the first phase comparator; and an fH signal converter that converts an externally applied horizontal synchronization pulse into a 50% duty signal having the same fundamental frequency as the horizontal synchronization pulse; a second phase comparator to which the output of the fH signal converter and the output of the VCO are respectively given as inputs; a low-pass filter that removes high-frequency components from the output of the second phase comparator; and any of the low-pass filters. a first data latch that holds output data at a time; a subtracter that subtracts the output of the first data latch from the output of the low-pass filter; an integrator that integrates the output of the subtracter; a second data latch that holds output data of the VCO, an output of the second data latch is connected to an external input terminal of the VCO, and the output is taken out from a second output terminal of the VCO. A phase synchronization device characterized by: