Automatic digital convergence correcting method and apparatus therefor

• US 5,497,054 A
• Filed: 08/31/1994
• Issued: 03/05/1996
• Est. Priority Date: 08/31/1993
• Status: Expired due to Term

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Ryu, Kyeong-keol
• Primary Examiner(s): Blum, Theodore M.
• Application Number:
  US08/298,743
• Time in Patent Office: 552 Days
• Field of Search: 315/368.11, 315/368.12, 348/807, 348/745
• US Class Current: 315/368.11
• CPC Class Codes: H04N 9/28 Arrangements for convergence or focusing

Abstract

In an automatic digital convergence correction method and apparatus therefore employing a CRT-type display, the vertical and horizontal convergence with respect to the red and green CRTs are tracked based on the ideal seed point within a test pattern generated via the green CRT so that the vertical and horizontal convergence match, to thereby enhance the accuracy of a correction operation and reduce the correction time.

Claims

1. An automatic digital convergence correction method for correcting a convergence of a display employing red, green and blue CRTs, said method comprising the steps of:

generating a box test pattern via said green CRT;

adjusting a geometrical position between a projector and a screen using said box test pattern as a reference;

generating a predetermined number of seed points within the box test pattern;

generating horizontal and vertical tracking reference patterns that pass through one of the seed points at a predetermined location, said one of the seed points being generated by said green CRT in said seed-point generating step; and

tracking the horizontal and vertical tracking reference patterns generated in said tracking reference pattern generating step by employing a tracking pattern generated via said red CRT and said blue CRT at a seed point corresponding to the green seed point of said predetermined location, wherein said tracking step is performed simultaneously with said generating horizontal and vertical tracking reference patterns step by counting a time interval between a component of one of said horizontal and vertical tracking reference patterns signal and a component of a tracking pattern signal and by comparing the counted values and by making the counted values match each other.

2. An automatic digital convergence correction method according to claim 1, wherein said tracking step is performed for tracking a horizontal tracking pattern and a vertical tracking pattern by employing a charge-coupled device (CCD) type camera.

3. An automatic digital convergence correction method that corrects the convergence of a display employing red, green and blue CRTs, said method comprising the steps of:

(a) generating a box test pattern via said green CRT;

(b) adjusting a geometrical position between a projector and a screen using said box test pattern as a reference;

(c) generating a predetermined number of seed points within the box test pattern;

(d) generating a vertical tracking reference pattern that passes through one of the seed points at a predetermined location;

(e) tracking the vertical tracking reference pattern generated in said vertical tracking reference pattern generating step by employing a tracking pattern generated via said red CRT at the seed point of said predetermined location, said tracking the vertical tracking reference pattern step being performed simultaneously with said generating a vertical tracking reference pattern step, and counting a time interval between a component of said vertical tracking reference pattern and said tracking pattern generated via said red CRT and comparing the counted values and making the counted values match each other;

(f) generating a horizontal tracking reference pattern that passes through the seed point at said predetermined location and which is generated via said green CRT in said seed-point generating step;

(g) tracking the horizontal tracking reference pattern generated in said horizontal tracking reference pattern generating step by employing the tracking pattern generated via said red CRT at the seed point of said predetermined location, said tracking the horizontal tracking reference pattern step being performed simultaneously with said generating a horizontal tracking reference pattern step, and counting a time interval between a component of said horizontal tracking reference pattern and said tracking pattern generated via said red CRT and comparing the counted values and making the counted values match each other;

(h) repeating said steps (d) through (g) while changing the coordinates of a target seed point when the horizontal tracking and vertical tracking of said predetermined seed point are completed; and

(i) repeating steps (d) through (h) with respect to each seed point of a blue CRT when all the seed points generated via said red CRT match all the seed points generated via said green CRT.

4. An automatic digital convergence correction apparatus in a display employing red, green and blue CRTs, said apparatus comprising:

a test pattern memory for generating a green-CRT-based box test pattern for adjusting a geometric position between a screen and said display, horizontal and vertical tracking reference patterns from each of a predetermined number of seed points by employing said box test pattern, and a tracking pattern via red and blue CRTs from a seed point corresponding to said green seed point;

pickup means for picking up the box test pattern, the horizontal and vertical tracking reference patterns and a tracking pattern displayed onto a screen after being output from said test pattern memory;

reference signal generating means for generating a first reference signal of one of the horizontal and vertical tracking reference patterns, and a second reference signal of a tracking pattern, which are output from said pickup means, said first and second references signals being generated simultaneously;

controlling means for counting a time interval between corresponding components of said first and second reference signals output from said reference signal generator; and

convergence correction means for storing convergence correction data generated in response to a comparison result of said controlling means and converting the stored convergence correcting data into an analog signal and for outputting the converted result.

5. An automatic digital convergence correction apparatus according to claim 4, wherein said pickup means is a CCD-type camera.

6. An automatic digital convergence correction apparatus according to claim 4, wherein said reference signal generating means comprises:

first limiting means for outputting only that portion of a signal which is beyond a predetermined level with respect to the horizontal and vertical tracking reference pattern signals and the tracking pattern signal, which are output from said pickup means;

differentiating means for differentiating the reference pattern signal and the tracking pattern signal which are output by said first limiting means; and

second limiting means for outputting only that portion of a signal which is beyond a predetermined level with respect to an output signal of said differentiation means, said output of said second limiting means representing said first and second reference signals.

7. An automatic digital convergence correction apparatus according to claim 4, wherein said controlling means determines that one of said horizontal and vertical tracking reference patterns is identical to said tracking pattern if the interval between the corresponding components of the first reference signal and the second reference signal is near zero.

8. An automatic digital convergence correction apparatus according to claim 4, wherein said convergence correction means includes a first region for storing vertical and horizontal convergence correction data for said red CRT, a second region for storing vertical and horizontal convergence correction data for said green CRT, and a third region for storing vertical and horizontal convergence correction data for said blue CRT.

9. An automatic digital convergence correction apparatus according to claim 8, wherein the vertical and horizontal convergence correction data for said red, green and blue CRTs are interpolated and stored into said correction memory.