Electroluminescent display brightness compensation

• US 5,075,596 A
• Filed: 10/02/1990
• Issued: 12/24/1991
• Est. Priority Date: 10/02/1990
• Status: Expired due to Fees

• Current Assignee: Siemens Rail Automation Ltd. (Siemens AG)
• Original Assignee: United Technologies Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Young, Edward L., Rebeschi, Thomas J.
• Primary Examiner(s): LaRoche, Eugene R.
• Assistant Examiner(s): DINH, TAN X
• Application Number:
  US07/591,995
• Time in Patent Office: 448 Days
• Field of Search: 315/169.3, 315/167, 340/713, 340/781
• US Class Current: 315/169.3
• CPC Class Codes: G09G 2310/027 Details of drivers for data electrodes, the drivers handling digital grey scale data, e.g. use of D/A converters
• CPC Class Codes: G09G 2320/0209 Crosstalk reduction, i.e. to reduce direct or indirect influences of signals directed to a certain pixel of the displayed image on other pixels of said image, inclusive of influences affecting pixels in different frames or fields or sub-images which constitute a same image, e.g. left and right images of a stereoscopic display
• CPC Class Codes: G09G 2320/0223 Compensation for problems related to R-C delay and attenuation in electrodes of matrix panels, e.g. in gate electrodes or on-substrate video signal electrodes
• CPC Class Codes: G09G 3/2011 by amplitude modulation
• CPC Class Codes: G09G 3/30 using electroluminescent panels

Abstract

The luminosity of electroluminescent display pixels arranged at intersection regions between row and column electrodes is controlled so as to compensate for the effect of interelectrode coupling by reducing the voltage differentials applied between the row electrode being addressed and the column electrodes relative to those coresponding to initial pixel luminosity data contained in an incoming data stream, as a direct function of total row luminosity information extracted from that segment of the incoming data stream which pertains to the respective row.

Claims

1. A method of controlling the luminosity of electroluminescent display pixels each arranged at an intersection region between an individually addressable associated row electrode of a row electrode array and an individually addressable associated column electrode of a column electrode array, the luminosity of any of the pixels of any row addressed at any given time being determined by a voltage differential established on the basis of desired pixel luminosity data for such pixel, which is contained in an incoming data stream segment pertaining to the pixels of such row, between a row voltage applied to the associated row electrode and a column voltage applied to the associated column electrode, comprising the steps of

extracting total row luminosity information indicative of the total desired luminosity for all of the pixels of a respective pixel row to be addressed from the incoming data stream segment pertaining to such row, and generating a correction signal representative of such total row luminosity information;

establishing corrected voltage differentials to be applied to all of the pixels of the respective row, including providing for each respective row an initial row voltage and for each respective one of the columns an initial column voltage pertaining to the pixel of the respective row, and modifying at least one of the initial row voltage, and all of the initial column voltages for the pixels of the respective row, to the extent needed to compensate for interelectrode coupling, in proportion to the value of the correction signal and in a sense of reducing the voltage differentials established between the row and column electrodes associated with the pixels of that row relative to those corresponding to the pixel luminosity data contained in the incoming data stream segment pertaining to such row; and

subjecting all of the pixels of the respective row to the thus corrected voltage differentials that have been established for such row.

2. The method as defined in claim 1, wherein said establishing step includes individually reducing the absolute value of the initial row voltage for each of the rows correspondingly to the correction signal applicable to that row to form a modified row voltage for application to the respective row electrode during said subjecting step.

3. The method as defined in claim 2 for use in a situation where the incoming data stream segment consists of digital data, wherein said extracting step includes converting the digital data of the segment into corresponding analog data, and integrating such analog data to present the correction signal as a correction voltage.

4. The method as defined in claim 2 for use in a situation where the incoming data stream segment consists of analog data, wherein said extracting step includes integrating such analog data to present the correction signal as a correction voltage.

5. The method as defined in claim 4, wherein said establishing step further includes converting the analog data of the segment into corresponding initial digital data for use in establishing the individual initial column voltages to be applied to the respective column electrodes during said subjecting step.

6. The method as defined in claim 1, wherein said establishing step includes reducing the absolute value of each of the initial column voltages in correspondence with the correction signal applicable to that row to form a modified column voltage for application to the respective column electrode during said subjecting step.

7. A method of controlling the luminosity of electroluminescent display pixels each arranged at an intersection region between an individually addressable associated row electrode of a row electrode array and an individually addressable associated column electrode of a column electrode array, the luminosity of any of the pixels of any row addressed at any given time being determined by a voltage differential established on the basis of desired pixel luminosity data for such pixel, which is contained in an incoming data stream segment consisting of analog data pertaining to the pixels of such row, between a row voltage applied to the associated row electrode and a column voltage applied to the associated column electrode, comprising the steps of

extracting total row luminosity information indicative of the total desired luminosity for all of the pixels of a respective pixel row to be addressed from the incoming data stream segment pertaining to such row and generating a correction signal representative of such total row luminosity information, including integrating said analog data to present a correction voltage, and converting such correction voltage into a corresponding digital correction signal;

establishing corrected voltage differentials to be applied to all of the pixels of the respective row, including modifying all of the column voltages for the pixels of the respective row to the extent needed to compensate for interelectrode coupling, in proportion to the value of the digital correction signal and in a sense of reducing the voltage differentials established between the row and column electrodes associated with the pixels of that row relative to those corresponding to the pixel luminosity data contained in the incoming data stream segment pertaining to such row, including converting the analog data of the segment into corresponding initial digital signals each individually applicable to a different one of the columns, providing the same row voltage for all of the rows, and a plurality of individual initial column voltages each in association with the respective row for a different one of the columns, and reducing the absolute value of each of the initial column voltages in correspondence with the digital correction signal applicable to that row to form a modified column voltage for the respective column electrode, including digitally subtracting the digital correction signal from each of the initial digital signals to form a modified digital signal for each of the columns, and using the thus modified digital signals for forming the modified column voltages; and

subjecting all of the pixels of the respective row to the thus corrected voltage differentials that have been established for such row.

8. An arrangement for controlling the luminosity of electroluminescent display pixels each arranged at an intersection region between an individually addressable associated row electrode of a row electrode array and an individually addressable associated column electrode of a column electrode array, the luminosity of any of the pixels of any row addressed at any given time being determined by a voltage differential established on the basis of desired pixel luminosity data for such pixel, which is contained in an incoming data stream segment pertaining to the pixels of such row, between a row voltage applied to the associated row electrode and a column voltage applied to the associated column electrode, comprising

means for extracting total row luminosity information indicative of the total desired luminosity for all of the pixels of a respective pixel row to be addressed from the incoming data stream segment pertaining to such row, and for generating a correction signal representative of such total row luminosity information;

means for establishing corrected voltage differentials to be applied to all of the pixels of the respective row, including means for providing for each respective row an initial row voltage and for each respective one of the columns an initial column voltage pertaining to the pixel of the respective row, and means for modifying at least one of the initial row voltage, and all of the initial column voltages for the pixels of the respective row, to the extent needed to compensate for interelectrode coupling, in proportion to the value of said correction signal and in a sense of reducing the voltage differentials established between the row and column electrodes associated with the pixels of that row relative to those corresponding to the pixel luminosity data contained in the incoming data stream segment pertaining to such row; and

means for subjecting all of the pixels of the respective row to the thus corrected voltage differentials that have been established for such row.

9. The arrangement as defined in claim 8, wherein said establishing means includes means for individually reducing the absolute value of the initial row voltage for each of the rows correspondingly to the correction signal applicable to that row to form a modified row voltage for application by said subjecting means to the respective row electrode.

10. The arrangement as defined in claim 9 for use in a situation where the incoming data stream segment consists of digital data, wherein said extracting means includes means for converting the digital data of the segment into corresponding analog data, and means for integrating such analog data to present the correction signal as a correction voltage.

11. The arrangement as defined in claim 9 for use in a situation where the incoming data stream segment consists of analog data, wherein said extracting means includes means for integrating such analog data to present the correction signal as a correction voltage.

12. The arrangement as defined in claim 11, wherein said establishing means further includes means for converting the analog data of the segment into corresponding initial digital data for use in establishing the individual initial column voltages to be applied by said subjecting means to the respective column electrodes.

13. The arrangement as defined in claim 8, wherein said establishing means includes means for reducing the absolute value of each of the initial column voltages in correspondence with the correction signal applicable to that row to form a modified column voltage for application by said subjecting means to the respective column electrode.

14. An arrangement for controlling the luminosity of electroluminescent display pixels each arranged at an intersection region between an individually addressable associated row electrode of a row electrode array and an individually addressable associated column electrode of a column electrode array, the luminosity of any of the pixels of any row addressed at any given time being determined by a voltage differential established on the basis of desired pixel luminosity data for such pixel, which is contained in an incoming data stream segment consisting of analog data pertaining to the pixels of such row, between a row voltage applied to the associated row electrode and a column voltage applied to the associated column electrode, comprising

means for extracting total row luminosity information indicative of the total desired luminosity for all of the pixels of a respective pixel row to be addressed from the incoming data stream segment pertaining to such row and generating a correction signal representative of such total row luminosity information, including means for integrating said analog data to present a correction voltage, and means for converting such correction voltage into a corresponding digital correction signal;

means for establishing corrected voltage differentials to be applied to all of the pixels of the respective row, including means for modifying all of the column voltages for the pixels of the respective row to the extent needed to compensate for interelectrode coupling, in proportion to the value of the digital correction signal and in a sense of reducing the voltage differentials established between the row and column electrodes associated with the pixels of that row relative to those corresponding to the pixel luminosity data contained in the incoming data stream segment pertaining to such row, including means for converting the analog data of the segment into corresponding initial digital signals each individually applicable to a different one of the columns, means for providing the same row voltage for all of the rows, and a plurality of individual initial column voltages each in association with the respective row for a different one of the columns, and means for reducing the absolute value of each of the initial column voltages in correspondence with the digital correction signal applicable to that row to form a modified column voltage for the respective column electrode, including means for digitally subtracting the digital correction signal from each of the initial digital signals to form a modified digital signal for each of the columns for use of the thus modified digital signals in forming the modified column voltages; and

means for subjecting all of the pixels of the respective row to the thus corrected voltage differentials that have been established for such row.