KR20070012005A - Method for adjusting focus of projection television - Google Patents

Abstract

A method for adjusting a focus of a projection television is provided to perform focusing adjustment by moving the focus to a specific portion when a user wants to clearly watch the specific portion of a PRT screen, thereby providing a user with convenience. A method for adjusting a focus of a projection television comprises the following steps of: separating a vertical sync signal from a video signal by control of a microcomputer when a specific portion for focusing is selected from a PRT(Projection Ray Tube) screen(S10,S20); converting the vertical sync signal into a pulse of a parabola type having a convex middle portion at vertical periods(S30); amplifying the pulse of the parabola type through an amplifier(S40); generating parabola voltage for compensation by converting the pulse of parabola type according to a portion selected from the PRT screen before a focusing process(S50); and changing focusing voltage by mixing the parabola voltage for compensation with the focusing voltage(S60).

Description

Focus adjustment method of projection television {METHOD FOR ADJUSTING FOCUS OF PROJECTION TELEVISION}

1 is a block diagram for explaining a conventional projection television dynamic focus adjusting apparatus.

2 is a flowchart for explaining a focus adjustment method of a projection television according to the present invention;

3 is a graph for explaining a parabolic pulse generation process for correction according to the present invention.

<Description of the symbols for the main parts of the drawings>

10: deflection control unit 20: signal amplification unit

30: focus signal output unit 40: PRT

50: micom

The present invention relates to a focus adjustment method of a projection television, and more particularly, when a projection TV employing a PRT (Projection Ray Tube) is desired to clearly see a specific part of a PRT screen, the focus is moved to that part. A focus adjustment method of a projection television that adjusts focusing.

At present, with the development of electronic technology, large-scale image display apparatuses with various functions are being used, and a representative one of them is a projection TV. Projection TV refers to a TV that displays an image by reflecting and refracting light emitted from a cathode ray tube using a mirror or the like to project on a screen. With the advent of projection TV, users can watch various broadcast signals on a larger screen.

However, the projection TV has a problem that the focus of the image displayed at the center and the edge of the screen is blurred by using the large screen. For example, in a projection TV using a PRT, the signal projected from the PRT will focus on the center of the screen. Therefore, the projection distance of the light transmitted to the center and the edge on the screen is different, and as a result, the diameter of the electron beam emitted from the PRT increases toward the periphery of the screen, so that the focus at the edge is compared to the focus at the center of the monitor. Spreads widely and loses sharpness at the edges. This problem may also occur in conventional flat CRT TVs, but is more problematic in current projection TVs using large screens.

In order to solve this problem, a dynamic focus function has been developed and applied to a projection TV.

1 is a block diagram showing a dynamic focus adjusting apparatus of a conventional CRT projection TV.

In the conventional dynamic focus adjustment apparatus of a CRT projection TV, the image display apparatus includes a deflection control unit 10, a signal amplifier 20, a focus signal output unit 30, a CRT 40, and a microcomputer 50.

The deflection control unit 10 generates and outputs a horizontal focus signal and a vertical focus signal under the control of the microcomputer 50. The horizontal focus signal is a parabola-shaped signal in which the center part is convex in the horizontal period. It is a signal for compensating the left and right edges of the screen. The vertical focus signal is a parabola-shaped signal in which the center part is convex in the vertical period. It is a signal for. Meanwhile, the deflection controller 10 may also generate and output a horizontal phase signal for adjusting the phase of the horizontal focus signal so that the focus at the left and right edges is equalized.

The signal amplifier 20 amplifies each of the horizontal and vertical focus signals into a signal having a predetermined size under the control of the microcomputer 50. In detail, the deflection control unit 10 may generate and output a horizontal focus signal having a peak voltage of about 3VP-P and a vertical focus signal having a peak voltage of about 1VP-P. In this case, if the signal amplifier 20 has a voltage gain of 150, the horizontal focus signal is a parabolic waveform signal in which the center portion generated by the horizontal period 1H is concave and amplified to a voltage having a peak value of about 450 VP-P. The vertical focus signal is amplified by a voltage having a peak value of about 150VP-P as a parabolic waveform signal in which the center portion generated in the vertical period (1V) is concave. Voltage crest values of the horizontal focus signal and the vertical focus signal may be set differently according to the size of the screen. The amplified horizontal focus signal, the vertical focus signal, and the like are synthesized by the focus signal output unit 30 and then applied to the CRT 40.

However, since the dynamic focus has a structure that focuses the entire PRT screen, the entire screen is focused, but the entire screen is not equally good, and there is a problem that only a specific part of the PRT screen cannot be focused. .

The present invention was devised to solve the above problems of the prior art, and when there is a part of a projection TV employing a PRT that wants to clearly see a certain part of the PRT screen, the focus is moved to that part to adjust focusing. A method of adjusting focus of a projection television is provided.

According to another aspect of the present invention, there is provided a method of separating a vertical sync signal from a video signal by controlling a microcomputer when a specific portion to be focused on a PRT screen is selected; Converting the vertical sync signal into a parabolic pulse having a central convex at a vertical period; Amplifying the parabolic pulse through an amplifier; Generating a parabolic voltage for correction by converting a parabola-type pulse according to a position selected for focusing on the PRT screen; And changing the focusing voltage of the corresponding point by mixing the correcting parabola voltage and the focusing voltage.

In the present invention, the generation of the correction parabola voltage is characterized by generating a correction parabola voltage for focusing a specific portion of the PRT screen using a bias or RC circuit of the OP-AMP.

As described above, the present invention provides convenience for the user since the focusing can be adjusted by moving the focus to the portion of the projection TV employing the PRT to clearly see a certain portion of the PRT screen.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in detail.

2 is a flowchart illustrating a focus adjustment method of a projection television according to the present invention, and FIG. 3 is a graph for explaining a process for generating a parabolic pulse for correction according to the present invention.

As shown in FIGS. 2 and 3, when a specific portion to be focused on a PRT screen is selected, a vertical sync signal is separated from a video signal under the control of a microcomputer, and the vertical sync signal is vertically centered at a vertical period. Converting a parabolic pulse into a convex parabolic pulse, amplifying the parabola pulse through an amplifier, and converting a parabolic pulse according to a position selected for focusing on the PRT screen to generate a parabolic voltage for correction. And changing the focusing voltage of the corresponding point by mixing the correcting parabola voltage and the focusing voltage.

First, when the projection TV enters the partial focusing mode by the user (S10) and a specific part to be focused on the PRT screen is selected, the microcomputer separates the vertical sync signal from the video signal (S20).

Subsequently, as shown in FIGS. 2 and 3, the microcomputer converts the vertical sync signal into a parabolic pulse having a convex portion at a vertical period in a vertical period (S30).

Amplifying the converted parabolic pulse through an amplifier (S40), and converting the parabola-shaped pulse according to the position selected for focusing on the PRT screen to generate a correction parabola voltage (S50). At this time, the generation of the correction parabola voltage converts the parabola pulse amplified using the bias or RC circuit of the OP-AMP to a correction parabola voltage for focusing a specific portion of the PRT screen.

Then, the focusing voltage of the point selected by the user is changed by mixing the above-mentioned correction parabola voltage and the focusing voltage.

In this way, the focusing voltage of the specific point is mixed with the correction parabola voltage to correct the specific point of the PRT screen.

As described above, the present invention provides convenience for the user since the focusing can be adjusted by moving the focus to the portion of the projection TV employing the PRT to clearly see a certain portion of the PRT screen.

As described above, the present invention has an advantage of providing convenience to the user since the projection TV employing the PRT can adjust the focusing by moving the focus to the specific part of the PRT screen to clearly see a certain part of the PRT screen. .

Claims (2)

Separating a vertical sync signal from an image signal under the control of a microcomputer when a specific portion to be focused on the PRT screen is selected; Converting the vertical sync signal into a parabolic pulse having a central convex at a vertical period; Amplifying the parabolic pulse through an amplifier; Generating a parabolic voltage for correction by converting a parabola-type pulse according to a position selected for focusing on the PRT screen; Changing a focusing voltage of a corresponding point by mixing the correcting parabola voltage and a focusing voltage; Focus adjustment method of a projection television comprising a. The method of claim 1, The generation of the correction parabola voltage is a focus adjustment method of a projection television, characterized in that for generating a correction parabola voltage for focusing a specific portion of the PRT screen using a bias of the OP-AMP or RC circuit.

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