Video signal compensation apparatus

• US 5,359,342 A
• Filed: 02/01/1993
• Issued: 10/25/1994
• Est. Priority Date: 06/15/1989
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Kubota, Masashi, Nakai, Seiji
• Primary Examiner(s): Oberley, Alvin E.
• Assistant Examiner(s): Liang, Regina
• Application Number:
  US08/011,828
• Time in Patent Office: 631 Days
• Field of Search: 340/703, 340/721, 340/767, 340/782, 340/784, 340/793, 340/805, 340/811, 340/812, 358/29, 358/32, 345/147, 345/87, 345/89, 345/199, 345/112
• US Class Current: 345/89
• CPC Class Codes: G09G 2310/0221 with use of split matrices G09G3/3644 and G09G3/3666 take precedence
• CPC Class Codes: G09G 2320/02 Improving the quality of display appearance
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0276 for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction
• CPC Class Codes: G09G 2320/0285 using tables for spatial correction of display data
• CPC Class Codes: G09G 2320/041 Temperature compensation
• CPC Class Codes: G09G 3/36 using liquid crystals
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers

Abstract

In a dot matrix type display represented by a liquid crystal television receiver, as the use of a large screen display screen size progresses, display non-uniformity becomes significant at some screen position attributed to the combination of the property of display panel with the characteristic of the optical system and the like. According to the present invention, by splitting the display screen and converting the video signal by using the different correction data by the split region, display can be performed with composite correction of the display non-uniformity.

Claims

1. A display apparatus comprising a dot matrix type display apparatus for displaying a video signal on a pixel by pixel basis by a dot clock and horizontal and vertical synchronous signals, and a video signal compensation apparatus for compensating the video signal, wherein said video signal compensation apparatus comprises:

a dot counter for counting the dot clock and outputting a first count signal indicative of a horizontal screen position;

a line counter for counting said the horizontal synchronous signal and outputting a second count signal indicative of a vertical screen position;

a screen split control means for producing an output signal according to said first and second count signals which is indicative of a screen split region, said split screen region being one of a plurality of screen split regions; and

a correction processing means for correcting an input video signal according to said output signal from said screen split control means and for outputting a corrected video signal to said dot matrix type display apparatus;

and wherein said correction processing means comprises;

an analog-to-digital converter for converting the input video signal to a digital signal;

a look-up-table memory means including therein a plurality of tables each of which has stored therein correction data for a corresponding one of said plurality of screen split regions, said look-up-table memory means being responsive to said output signal from said screen split control means for selecting one of said plurality of tables corresponding to a screen split region indicated by said signal outputted from said screen split control means and for correcting said digital signal from said analog-to-digital converter according to the correction data stored in the selected one of said plurality of tables; and

a digital-to-analog converter for converting a corrected digital signal outputted from said look-up-table memory means to an analog signal, said analog signal from said digital-to-analog converter being outputted as said corrected video signal from said correction processing means;

wherein the correction data stored in each look-up-table is data prepared by measuring a video signal level versus screen brightness characteristic curve of the dot matrix display apparatus for each of three primary colors in a corresponding one of the plurality of screen split regions and computing an inverse conversion curve to said characteristic curve;

and wherein said screen split control means comprises a horizontal split bit selection circuit connected to said dot counter for selecting from bits of said first count signal a bit which is renewed by every horizontal split position and bits which are higher order than said bit, and a vertical split bit selection circuit connected to said line counter for selecting from bits of said second count signal a bit which is renewed by every vertical split position and bits which are higher order bits than said bit, the selected bits of said first and second cut signals being outputted as said signal indicative of a screen split region.

2. A display apparatus comprising a dot matrix type display apparatus for displaying a video signal on a pixel by pixel basis by a dot clock and horizontal and vertical synchronous signals, and a video signal compensation apparatus for compensating the video signal, wherein said video signal compensation apparatus comprises:

a dot counter for counting the dot clock and outputting a first count signal indicative of a horizontal screen position;

a line counter for counting said the horizontal synchronous signal and outputting a second count signal indicative of a vertical screen position;

a screen split control means for producing an output signal according to said first and second count signals which is indicative of a screen split region, said split screen region being one of a plurality of screen split regions; and

a correction processing means for correcting an input video signal according to said output signal from said screen split control means and for outputting a corrected video signal to said dot matrix type display apparatus;

and wherein said correction processing means comprises;

an analog-to-digital converter for converting the input video signal to a digital signal;

a look-up-table memory means including therein a plurality of tables each of which has stored therein correction data for a corresponding one of said plurality of screen split regions, said look-up-table memory means being responsive to said output signal from said screen split control means for selecting one of said plurality of tables corresponding to a screen split region indicated by said signal outputted from said screen split control means and for correcting said digital signal from said analog-to-digital converter according to the correction data stored in the selected one of said plurality of tables; and

a digital-to-analog converter for converting a corrected digital signal outputted from said look-up-table memory means to an analog signal, said analog signal from said digital-to-analog converter being outputted as said corrected video signal from said correction processing means;

wherein the correction data stored in each look-up-table is data prepared by measuring a video signal level versus screen brightness characteristic curve of the dot matrix display apparatus for each of three primary colors in a corresponding one of the plurality of screen split regions, computing a minimum level among maximum screen brightness levels in said plurality of screen split regions.

3. A display apparatus according to claim 2, wherein said screen split control means comprises a horizontal split bit selection circuit connected to said dot counter for selecting from bits of said first count signal a bit which is renewed by every horizontal split position and bits which are higher order than said bit, and a vertical split bit selection circuit connected to said line counter for selecting from bits of said second count signal a bit which is renewed by every vertical split position and bits which are higher order bits than said bit, the selected bits of said first and second cut signals being outputted as said signal indicative of a screen split region.

4. A display apparatus according to claim 2, wherein said screen split control means comprises a horizontal split position memory connected to said dot counter for generating from said first count signal a signal which is indicative of a horizontal screen split position, and a vertical split position memory connected to said line counter for generating from said second count signal a signal which is indicative of a vertical screen split position, said signals generated by said horizontal split position memory and said vertical split position memory being outputted as said signal indicative of a screen split region.

5. A display apparatus according to claim 2, wherein said screen split control means comprises a horizontal split position memory connected to said dot counter for generating from said first count signal a signal which is indicative of a horizontal screen split position, a vertical split position memory connected to said line counter for generating from said second count signal a signal which is indicative of a vertical screen split position, and a block address memory connected to said horizontal split position memory and said vertical split position memory for generating said signal indicative of a screen split region from said signals generated by said horizontal split position memory and said vertical split position memory.

6. A display apparatus comprising a dot matrix type display apparatus for displaying a video signal on a pixel by pixel basis by a dot clock and horizontal and vertical synchronous signals, and a video signal compensation apparatus for compensating the video signal, wherein said video signal compensation apparatus comprises:

a dot counter for counting the dot clock and outputting a first count signal indicative of a horizontal screen position;

a line counter for counting said the horizontal synchronous signal and outputting a second count signal indicative of a vertical screen position;

a screen split control means for producing an output signal according to said first and second count signals which is indicative of a screen split region, said split screen region being one of a plurality of screen split regions; and

a correction processing means for correcting an input video signal according to said output signal from said screen split control means and for outputting a corrected video signal to said dot matrix type display apparatus;

and wherein said correction processing means comprises;

an analog-to-digital converter for converting the input video signal to a digital signal;

a look-up-table memory means including therein a plurality of tables each of which has stored therein correction data for a corresponding one of said plurality of screen split regions, said look-up-table memory means being responsive to said output signal from said screen split control means for selecting one of said plurality of tables corresponding to a screen split region indicated by said signal outputted from said screen split control means and for correcting said digital signal from said analog-to-digital converter according to the correction data stored in the selected one of said plurality of tables; and

a digital-to-analog converter for converting a corrected digital signal outputted from said look-up-table memory means to an analog signal, said analog signal from said digital-to-analog converter being outputted as said corrected video signal from said correction processing means;

wherein the correction data stored in each look-up-table is data prepared by measuring a video signal level versus screen brightness characteristic curve of the dot matrix display apparatus for each of three primary colors in a corresponding one of the plurality of screen split regions, computing a normalization level at which mixture of three primary colors of maximum screen brightness levels in the corresponding screen split region becomes white color, and computing an inverse conversion curve to a part of said characteristic curve from zero level to said normalization level.

7. A display apparatus according to claim 6, wherein said screen split control means comprises a horizontal split bit selection circuit connected to said dot counter for selecting from bits of said first count signal a bit which is renewed by every horizontal split position and bits which are higher order than said bit, and a vertical split bit selection circuit connected to said line counter for selecting from bits of said second count signal a bit which is renewed by every vertical split position and bits which are higher order bits than said bit, the selected bits of said first and second cut signals being outputted as said signal indicative of a screen split region.

8. A display apparatus according to claim 6, wherein said screen split control means comprises a horizontal split position memory connected to said dot counter for generating from said first count signal a signal which is indicative of a horizontal screen split position, and a vertical split position memory connected to said line counter for generating from said second count signal a signal which is indicative of a vertical screen split position, said signals generated by said horizontal split position memory and said vertical split position memory being outputted as said signal indicative of a screen split region.

9. A display apparatus according to claim 6, wherein said screen split control means comprises a horizontal split position memory connected to said dot counter for generating from said first count signal a signal which is indicative of a horizontal screen split position, a vertical split position memory connected to said line counter for generating from said second count signal a signal which is indicative of a vertical screen split position, and a block address memory connected to said horizontal split position memory and said vertical split position memory for generating said signal indicative of a screen split region from said signals generated by said horizontal split position memory and said vertical split position memory.