JPS6350165A - Horizontal defiecting circuit - Google Patents

Abstract

PURPOSE:To obtain a horizontal deflecting circuit which can stabilize the circuit without providing a correcting circuit, necessitates no adjustment, and has high accuracy, by comparing the frequencies or phases of a horizontal synchronizing signal input and a horizontal output pulse, and controlling a voltage control oscillator, based on its compared output. CONSTITUTION:As for a horizontal synchronizing signal (frequency fy) which has been inputted, and a waveform-shaped horizontal output pulse (frequency fv) being an output of a waveform shaping circuit 11, a difference of frequencies and phases is detected by a phase comparing detector 2. When a difference of phases or phases exists between both of them, an error signal E0 is outputted from the phase comparing detector 2. An operation of a PLL is controlled so that its error signal E0 becomes zero. The error signal E0 is converted to a DC voltage VD by an integrator 3, and varies an output frequency f0 of a voltage control oscillator 4. An output of the f0 is waveform-shaped by the waveform shaping circuit 11 and becomes the fv, but as a result of execution of the PLL operation, the fv draws nearer to the fy. Thereafter, after the same operation is repeated, the loop is balanced in a stable state.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is applicable to C
The present invention relates to horizontal deflection circuits in RT monitors, television receivers, etc., and particularly relates to horizontal deflection circuits in which a horizontal oscillation frequency automatically follows a horizontal synchronization signal in an arbitrary frequency range.

[Conventional technology]

Figure 2 shows a conventional horizontal oscillation frequency automatic tracking CRT.
2 shows a block circuit diagram of the monitor.

In the figure, (1) is F-V (Frequency2-Volt) which converts the frequency of the horizontal synchronizing signal into DC voltage
(age) converter, (2) is a phase comparison detector, (3) is an integrator, (4) is a voltage controlled oscillator, (5) is a horizontal drive circuit, (6) is a horizontal output circuit, (7) is a high voltage In the circuit,
These (2) to (7) constitute a horizontal deflection circuit section. (8) is a horizontal deflection coil, (9) is a CRT, (
10) is a correction circuit.

Next, the operation shown in FIG. 2 will be explained. The input horizontal synchronization signal is converted into a DC voltage by an F-V converter (1) and applied to a correction circuit (10). In the correction circuit (10),
Corrections are made for temperature, aging, variations in circuit components, etc., and the corrected DC voltage is applied to the voltage controlled oscillator (4). The voltage controlled oscillator (4) generates a horizontal oscillation pulse according to the applied voltage, and supplies this horizontal oscillation pulse to the horizontal drive circuit (5). The horizontal output circuit (6) creates a horizontal output pulse, and the obtained horizontal output pulse and
A phase comparison detector (2
) to compare.

If there is a phase difference as a result of the comparison, use a phase comparison detector (
2) outputs a correction pulse corresponding to the difference, and a divider (
3). The integrator (3) averages this correction pulse over a relatively long time and applies it to the voltage controlled oscillator (0) to correct the deviation in the voltage controlled oscillator (0) and output the horizontal synchronization signal and the horizontal output circuit (6). The phase is matched with the horizontal output pulse from.

The oscillation output of the voltage controlled oscillator (0) adjusted in this way is passed through the horizontal drive circuit (5) to the horizontal output circuit (
8), and the horizontal output pulse ' output from the horizontal output circuit (6) is supplied to the horizontal deflection coil (8) to perform a horizontal deflection operation.

On the other hand, the output from the horizontal output circuit (8) is output from the high voltage circuit (7).
The high voltage circuit (7) creates a high voltage pulse from this horizontal output pulse and supplies it to the 7 nodes of the CRT (9).

[Problems to be solved by the invention] Since the conventional horizontal deflection circuit is configured as described above, the stability of the circuit largely depends on the followability of the F-V converter (1) to the horizontal synchronization signal input. Therefore, it is necessary to add a correction circuit (10) and an adjustment mechanism to correct for variations in temperature and aging 9 circuit components as described above, which makes the circuit complex and expensive. There was a problem in that it was difficult to adjust the accuracy.

This invention was made to solve the above-mentioned problems, and provides a highly accurate horizontal deflection circuit that can stabilize the circuit without providing a correction circuit and does not require adjustment. It is intended to.

[Means for Solving the Problems] The horizontal deflection circuit according to the present invention includes a voltage controlled oscillator whose oscillation frequency can be varied by applying an external voltage, and a horizontal output pulse based on the oscillation output from the voltage controlled oscillator. a horizontal output circuit that generates a horizontal output pulse and supplies it to a horizontal deflection coil, and a comparison detector that compares the frequency or phase of the horizontal output pulse of this horizontal output circuit and an input horizontal synchronizing signal and outputs an error signal. , varying the oscillation frequency of the voltage controlled oscillator based on the error signal;
The PLL is characterized in that the PLL is configured so that the error signal becomes zero.

[Function] In the horizontal deflection circuit of the present invention, if there is a frequency or phase difference between the input horizontal synchronizing signal and the horizontal output pulse, the comparison detector outputs an error signal, and this error signal increases the voltage. The output frequency of the controlled oscillator changes.

At this time, since the PLL operation is performed so that the error signal becomes zero, the frequency of the horizontal output pulse becomes equal to the frequency of the input horizontal synchronizing signal, and the loop becomes locked. In this state, the output frequency output from the voltage controlled oscillator becomes equal to the frequency of the input horizontal synchronizing signal and automatically follows this.

[Embodiment] An embodiment of the present invention will be described below with reference to FIG. 1 in FIG.
a phase comparison detector (3) that compares the frequency 9 phase with the waveform-shaped horizontal output pulse from the waveform shaping circuit (11);
) is an integrator consisting of a low-pass filter that integrates the phase detection output that is the output of the phase comparison detector (2) and obtains a DC output according to the phase difference, and (4) is an integrator consisting of a low-pass filter that obtains a DC output according to the phase difference. This is a voltage controlled oscillator that can vary the voltage.

(5) is a horizontal drive circuit that amplifies the horizontal oscillation pulse from the voltage controlled oscillator (4), and (6) is a horizontal drive circuit that generates a horizontal output pulse based on the output pulse from the horizontal drive circuit (5). A horizontal output circuit (7) supplies high voltage pulses to the horizontal deflection coil (8) of the CRT (8) based on the output from the horizontal output circuit (6).
This is a high-voltage circuit that supplies the anode of the As mentioned above (2)
The portions (7) to (7) constitute a horizontal deflection circuit section as in the conventional case.

In Fig. 1, a conventional F-V converter (1) and a correction circuit (lO) are not provided, and instead, a horizontal output circuit (6) and a phase comparison detector (2) are A waveform shaping circuit (11) is added to the. Then, the horizontal synchronization signal input and the frequency 0 phase of the horizontal output pulse of the horizontal output circuit (6) are compared by the phase comparison detector (2), and the voltage controlled oscillator (4) is controlled based on the detected output. P L L to obtain a pulse with the desired horizontal oscillation frequency.
(Phase Locked LOOP) method is adopted.

Next, the operation of the circuit shown in FIG. 1 will be explained. The input horizontal synchronizing signal (frequency is fy) is combined with the waveform-shaped horizontal output pulse (frequency is fy) which is the output of the waveform shaping circuit (11) by the phase comparison detector (2).
A phase difference is detected.

If there is a frequency or phase difference between the two, the one-phase comparison detector (2) outputs an error signal EO.

The operation of the PLL is controlled so that this error signal Eo becomes zero.

The error signal EO is converted into a DC voltage VD by passing through an integrator (3), and this DC voltage VD changes the output frequency fO of the voltage controlled oscillator (4). The output of fo is waveform-shaped by the waveform shaping circuit (11) and becomes fy, but as a result of the PLL operation being performed so that EO becomes zero as described above, fy approaches fy, and fy
The difference between y and fy is detected by the phase comparison detector (2), and after repeating the same operation, fy finally becomes equal to f7, and the loop is balanced in a stable state. This state is called a locked state, and the frequency relationship at this time is f
! =fma, that is, fo=fy.

As a result of the above, the output frequency fO output from the voltage controlled oscillator (0) automatically follows the frequency fy of the input horizontal synchronizing signal, and the oscillation output of this fo is output from the horizontal drive circuit (5). The horizontal output pulse output from the horizontal output circuit (6) is applied to the horizontal deflection coil (8) of the CRT (9) to perform horizontal deflection. The output from the horizontal output circuit (8) is also applied to the high voltage circuit (7).
) creates a high voltage pulse from this horizontal output pulse and
Supplies to 7 nodes of RT(8).

[Effects of the Invention] As described above, according to the present invention, the frequency or phase of the horizontal synchronizing signal input and the horizontal output pulse are compared, and the voltage controlled oscillator is controlled based on the comparison output, thereby achieving a desired horizontal Since it uses a PLL method to obtain the oscillation frequency, it is possible to automatically follow the horizontal oscillation frequency to the horizontal synchronization signal without the need for a correction circuit or adjustment mechanism, resulting in a simple and inexpensive circuit configuration. Moreover, it has the effect of providing a highly accurate horizontal deflection circuit.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram of an embodiment of a CRT monitor using the horizontal deflection circuit of the present invention, and FIG. 2 is a block circuit diagram of a CRT monitor using a conventional horizontal deflection circuit. (2)...Phase comparison detector, (4)...Voltage controlled oscillator, (6)...Horizontal output circuit, (8)...Horizontal deflection coil. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] (1) A voltage-controlled oscillator whose oscillation frequency can be varied by applying an external voltage; a horizontal output circuit that generates horizontal output pulses based on the oscillation output from the voltage-controlled oscillator and supplies them to the horizontal deflection coil; and a comparison detector that compares the frequency or phase of the horizontal output pulse of the horizontal output circuit and the input horizontal synchronizing signal and outputs an error signal, and varies the oscillation frequency of the voltage controlled oscillator based on the error signal. A horizontal deflection circuit characterized in that a PLL is configured such that the error signal becomes zero.