KR20020091310A - A Circuit for compensating focus of monitor - Google Patents

Abstract

PURPOSE: A focus correction circuit of a monitor is provided to correct a voltage level of a dynamic focus waveform according to horizontal frequencies by resolutions to maintain the voltage level uniform. CONSTITUTION: A focus correction circuit of a monitor having the first coil(LY) for receiving high voltage to deflect electron beams and the second coil for compensating the signal output from the first coil such that the interval between horizontal lines of the signal becomes uniform includes a condenser(C11), a transformer(T11), and a signal level connection unit(10). The condenser passes AC voltage of the signal transmitted through the second coil. The transformer receives the AC voltage through its primary side and induces the AC voltage to its secondary side according to a predetermined turn ratio. The signal level correction unit corrects the level of the AC voltage applied to the primary side of the transformer to a predetermine level.

Description

A circuit for compensating focus of monitor

The present invention relates to a monitor, and more particularly to a focus correction circuit of a monitor.

In general, a monitor is a device that displays a video signal of a predetermined format transmitted from an internal video card on a screen through a series of signal processing such as digital sampling and scaling.

Hereinafter, a focus correction circuit of a monitor according to the prior art will be described with reference to the accompanying drawings.

1 is a view showing a focus correction circuit of a monitor according to the prior art, Figures 2a and 2b is a diagram showing the voltage waveform appearing on the primary side and secondary side of the transformer shown in Figure 1, Figures 3a and 3b A diagram illustrating a dynamic focus waveform according to screen focus.

As shown in FIG. 1, a focus correction circuit of a monitor according to the related art is provided with a first coil LY for deflecting an electron beam by applying a high voltage B +, and a signal output through the first coil LY. A second coil HL for compensating for the constant horizontal line spacing, a first capacitor C1 passing only an AC waveform of a signal output from the second coil HL, and the second linear horizontality. A second capacitor C2 for equally adjusting the horizontal line of the signal output from the HL, and a transformer T1 for inducing a voltage value output through the first capacitor C1 according to the turns ratio. .

The focus correction circuit of the monitor configured as described above operates as follows.

First, the first coil LY receives a voltage from a voltage input unit (not shown) to deflect the electron beam, and the second coil HL has a horizontal line spacing of the signal deflected through the first coil LY. Compensating this to be constant to generate a waveform having a predetermined voltage level Vcs, that is, an amplitude, as shown in FIG. 2A at the point 'A'.

Here, the first capacitor C1 is a coupling capacitor and passes only an AC component excluding a DC component of a signal transmitted through the second coil HL.

In addition, the second condenser C2 is adjusted to equalize the horizontal line spacing compensated by the second coil HL according to one or more connected horizontal frequencies f _h .

Subsequently, the transformer T1 induces the AC voltage waveform output through the first capacitor C1 to the secondary side according to the ratio of the primary winding and the secondary winding to the secondary side, as shown in FIG. 2B. A waveform having a predetermined voltage level, that is, a dynamic focus waveform, is generated and transmitted to the dynamic focus circuit unit (not shown).

In this case, the dynamic focus circuit unit (not shown) receives a waveform transmitted from the transformer T1 and focuses an image on the screen.

In this case, as shown in FIG. 3A, the dynamic focus waveform focuses on a half point of the screen to focus the image on the screen. In this case, the relationship between the amplitude (Vcs) and the screen length of the corresponding waveform according to the reference horizontal frequency is As shown in FIG. 3B, the 'A1' region of FIG. 3A is enlarged.

That is, as shown in Figure 3b, it can be seen that the amplitude of the dynamic focus waveform according to the reference horizontal frequency input is maintained at a constant voltage level (Vcs) for a predetermined screen length.

However, the focus correction circuit of the monitor according to the related art described above performs positive focusing because the voltage level (ie, amplitude) of the dynamic focus waveform induced on the secondary side of the transformer is not constant when the horizontal frequency is input differently for each resolution. There is a problem.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is possible to correct the voltage level (that is, amplitude) of the dynamic focus waveform according to the horizontal frequency for each resolution and maintain the corresponding voltage level so that the focusing can be achieved. The purpose is to provide a focus correction circuit.

1 is a view showing a focus correction circuit of a monitor according to the prior art;

2A and 2B show voltage waveforms appearing on the primary and secondary sides of the transformer shown in FIG.

3A and 3B illustrate dynamic focus waveforms according to screen focus.

4 illustrates a focus correction circuit of the monitor according to the present invention.

5A to 5C are diagrams for calculating the voltage level of the waveform generated at the point 'A11' shown in FIG.

In order to achieve the above object, a focus correction circuit of a monitor according to the present invention includes a first coil LY for deflecting an electron beam by applying a high voltage B +, and a horizontal line spacing of a signal output through the first coil. In a monitor having a second coil (HL) that compensates for this to be constant, a first capacitor for passing an alternating voltage of a signal transmitted through the second coil and an alternating voltage transmitted through the first capacitor are input to the primary side. A signal level correction unit for correcting the level of the alternating voltage applied to the primary side of the transformer by operating in conjunction with the transformer according to the predetermined frequency inputted with the transformer to receive the secondary to the secondary side according to the predetermined turns ratio. It is configured to include its features.

Hereinafter, a focus correction circuit of a monitor according to the present invention will be described with reference to the accompanying drawings.

4 is a diagram illustrating a focus correction circuit of a monitor according to the present invention, and FIGS. 5A to 5C are diagrams for calculating a voltage level of a waveform generated at point 'A' shown in FIG. 4.

As shown in FIG. 4, the focus correction circuit of the monitor according to the present invention includes a first coil LY for deflecting an electron beam by applying a high voltage B +, and a signal output through the first coil LY. In the monitor having a second coil (HL) to compensate for the horizontal line spacing of the constant, the first condenser (C11) for passing the alternating voltage of the signal transmitted through the second coil (HL), and the first The transformer T11 receives the AC voltage transmitted through the first capacitor C11 to the primary side and induces the secondary voltage according to the predetermined winding ratio to the secondary side, and operates in conjunction with the first capacitor C11 according to the input frequency. And a signal level correction unit 10 for correcting the level of the AC voltage applied to the primary side of the transformer T11 to a preset level.

And a second condenser C12 connected in parallel to the first condenser C11 to equally adjust a horizontal line of a signal output through the second coil HL.

In addition, the signal level correction unit 10 is connected to the third capacitor (C13) and the third capacitor (C13) connected in parallel to the first capacitor (C11), one end is connected to the other end, the transformer (T11) And a transistor Q11 connected to the primary side of the C1 and determining whether to be driven according to a predetermined frequency.

An embodiment of the focus correction circuit operation of the monitor according to the present invention configured as described above is as follows.

First, the first coil LY is applied with a high voltage B + from a voltage input unit (not shown) to deflect the electron beam, and the second coil HL is a horizontal line interval of the waveform deflected through the first coil LY. Compensate this so that it is constant.

Here, in order to calculate the voltage level of the waveform generated at the point 'A11' through the second coil HL, first, the current Iy flowing through the first coil LY with reference to FIG. The value is calculated as follows.

Here, ton / 2 indicates a point in time when the voltage level Vcs of the waveform generated at the point 'A11' through the second coil HL becomes Peak To Peak, and Idyop As shown in FIG. 5C, a current value corresponding to the ton / 2 time point is shown.

Subsequently, the voltage Vcs applied to the capacitor Cs shown in FIG. 5A is calculated based on the current Idy (t) defined in Equation 1 as follows.

At this time, the capacitor (Cs) shown in Figure 5a represents the values of the first to third condensers (C11 ~ C13) shown in Figure 4, the ton and Ts has a relationship of Ts = 2ton, as shown in Figure 5b, This is summarized as ton = Ts / 2.

Here, the first capacitor C11 is a coupling capacitor and passes only an AC component excluding a DC component of a signal transmitted through the second coil HL.

In addition, the second condenser C12 is a switching condenser, and is adjusted so that the horizontal line interval compensated by the second coil HL is equalized according to one or more connected horizontal frequencies.

Subsequently, by replacing the ton value in Equation 2 with the above ton = Ts / 2, it can be arranged as defined below.

Here, Ts is Th-Tr and Th is 1 / fs. Thus, Equation 3 can be summarized as follows.

As a result, the voltage level Vcs of the waveform generated at the point 'A11' shown in FIG. 4 is the horizontal frequency f _h input as defined in Equation 4 and the first to third capacitors C11 to parallel connected. It can be seen that it is changed in proportion to C13).

For example, when the horizontal frequency f _h is increased above the reference horizontal frequency, the voltage level Vcs of the waveform generated at the point 'A11' is decreased.

At this time, the microcomputer (not shown) determines whether the input horizontal frequency f _h is greater than or equal to the reference horizontal frequency, and if the horizontal frequency f _h is greater than or equal to the reference horizontal frequency, the signal level correction unit shown in FIG. The predetermined frequency FS is transmitted so that the transistor Q11 of (10) becomes conductive.

Subsequently, the transistor Q11 receives the frequency FS transmitted from the microcomputer as a base and is turned on to generate a current Idy according to the voltage level Vcs of the waveform generated at the point 'A11'. Via.

In addition, since the third capacitor C13 is operated in parallel with the first capacitor C11 according to the conduction of the transistor Q11, the capacitor Cs defined in Equation 4 is Becomes

As a result, the waveform voltage level Vcs reduced at the point 'A11' according to the input of the horizontal frequency f _{h that} is equal to or greater than the reference horizontal frequency is increased due to the sum of the first and third capacitors C11 and C13. Corrected to the set voltage level, i.e., amplitude.

Subsequently, the corrected voltage waveform is applied to the primary side of the transformer T11 to induce a voltage waveform of a predetermined level toward the secondary side of the transformer T11 in proportion to the primary winding ratio and the secondary winding ratio.

The voltage waveform induced on the secondary side of the transformer T11 is applied to a dynamic focus circuit unit (not shown) as a dynamic focus waveform having a predetermined voltage level to focus the image on the screen.

Similarly, when the horizontal frequency f _h is less than or equal to the reference horizontal frequency, the voltage level Vcs of the waveform generated at the point 'A11' shown in FIG. 4 is increased by a predetermined level according to the definition of Equation 4.

At this time, the microcomputer (not shown) determines whether the input horizontal frequency f _h is less than or equal to the reference horizontal frequency, and if the horizontal frequency f _h is less than or equal to the reference horizontal frequency, the signal level corrector 10 Transmits the frequency FS for 'off' the transistor Q11.

Subsequently, the transistor Q11 receives the frequency FS transmitted from the microcomputer as a base and is 'off' to not operate the third capacitor C13.

As a result, since the third capacitor C13 is not operated, the capacitor Cs shown in Equation 4 is represented only by the first capacitor C11, thereby increasing the waveform voltage level Vcs at the 'A11' point. Is reduced and corrected to a predetermined voltage level, i.e., amplitude.

Subsequently, the corrected voltage waveform is applied to the primary side of the transformer T11, and the transformer T11 induces the voltage input to the primary side to the secondary side in proportion to the primary winding ratio and the secondary winding ratio.

The voltage waveform induced on the secondary side of the transformer T11 is applied to a dynamic focus circuit unit (not shown) as a dynamic focus waveform having a predetermined voltage level to focus the image on the screen.

In this case, the signal level correction unit 10 including the third condenser C13 and the transistor Q11 may be formed of at least one, and as a result, the voltage level of the dynamic focus waveform according to image focusing of the screen may be further refined. Can be corrected.

As described above, the present invention improves the quality according to the image focus of a screen by correcting and maintaining a constant amplitude, that is, a voltage level, of a dynamic focus waveform that varies according to an input horizontal frequency.

As described above, the focus correction circuit of the monitor according to the present invention can provide better image focus by correcting a voltage level (ie, amplitude) of a dynamic focus waveform according to a change in horizontal frequency for each resolution and maintaining the amplitude constant. This may have the effect of improving the reliability of the product quality.

Claims (3)

In a monitor having a first coil (LY) for deflecting an electron beam by applying a high voltage (B +) and a second coil (HL) for compensating for a constant horizontal line spacing of a signal output through the first coil, A first condenser for passing an alternating voltage of a signal transmitted through the second coil, A transformer that receives the AC voltage transmitted through the first capacitor to the primary side and induces it to the secondary side according to a predetermined winding ratio, And a signal level correction unit configured to operate in conjunction with the first capacitor according to a predetermined frequency to correct the level of the AC voltage applied to the primary side of the transformer to a predetermined level. . The method of claim 1, And a second capacitor connected in parallel to the first capacitor to equally adjust a horizontal line of a signal output through the second coil. The method of claim 1, The signal level correction unit A third capacitor connected in parallel with the first capacitor; And a transistor having one end connected to the third capacitor and the other end connected to the primary side of the transformer and configured to be driven according to a predetermined frequency input thereto.