Electroluminescent panel driving system for driving the panel's electrodes only when non-blank data is present to conserve power

• US 4,823,121 A
• Filed: 10/15/1986
• Issued: 04/18/1989
• Est. Priority Date: 10/15/1985
• Status: Expired due to Term

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Sakamoto, Atsushi, Ohba, Toshihiro, Harada, Shigeyuki
• Primary Examiner(s): Caldwell, Sr., John W.
• Assistant Examiner(s): Brier, Jeffery A.
• Application Number:
  US06/918,902
• Time in Patent Office: 916 Days
• Field of Search: 340/781, 340/753, 340/754, 340/825.81, 315/169.1, 315/169.3
• US Class Current: 345/78
• CPC Class Codes: G09G 2310/0267 Details of drivers for scan electrodes, other than drivers for liquid crystal, plasma or OLED displays
• CPC Class Codes: G09G 2310/0275 Details of drivers for data electrodes, other than drivers for liquid crystal, plasma or OLED displays, not related to handling digital grey scale data or to communication of data to the pixels by means of a current
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 3/30 using electroluminescent panels

Abstract

An EL (electroluminescent) panel driving system includes a display control circuit for producing, line by line, an image data. The image data of each line is defined by a combination of a HIGH level signal representing a spot illumination of the EL panel and a LOW level signal representing a non-illumination of a spot on the EL panel. The system further includes a pre-charge circuit and a pull-up charge circuit for providing a first range voltage to the EL panel at the beginning of each line scan operation to make the EL panel ready to illuminate, and a write-in circuit and a source level switching circuit for providing a second range voltage to the EL panel to permit the spot illumination of the EL panel in accordance with the HIGH level signals contained in the image data. These four circuits are turned on by four signals. The driving system also includes a detector that detects when no HIGH level signal are present in the image data of a line, an AND gate array for cutting off the four signals from the pre-charge circuit, pull-up circuit, write-in circuit, and source circuit, the four circuits are prevented from being actuated, thereby cutting off the power normally supplied during the blank line scanning to save power.

Claims

1. An electroluminescent panel display system comprising:

electroluminescent panel means, for displaying information, having a plurality of display lines;

display drive means, operatively connected to said electroluminescent panel means, for producing image data for each display line, said image data for each display line represented by a group of signals, each signal being either a first level or a second level, said first level representing a spot of intended illumination on said electroluminescent panel means, said second level representing a spot of intended non-illumination on said electroluminescent panel means;

said display means providing drive signals, producing at a first instant in time a first voltage in accordance with said drive signals and producing at a second instant in time a second voltage in accordance with said drive signals, said first voltage preparing said electroluminescent panel means to illuminate, said second voltage causing a spot of illumination on said electroluminescent panel means; and

display control means, operatively connected to said display drive means to receive said image data and said drive signals, for detecting when at least one first level is present in said image data;

said display control means permitting the production of said first and said second voltage by said display drive means when at least one first level is present in said image data and preventing the production of said first voltage and said second voltage by said display drive means when at least one first level is not detected in said image data, said display control means thereby preventing power loss when an individual display line contains no intended spots of illumination.

2. The electroluminescent panel display system as claimed in claim 1, wherein said display lines comprise scan lines and data lines.

3. The electroluminescent panel display system as claimed in claim 2, wherein said display drive means comprises:

first scan means, operatively connected to said electroluminescent panel means and responsive to said drive signals, for sequentially providing said first voltage to each scan line of said electroluminescent panel; and

second scan means, operatively connected to said electroluminescent panel means and responsive to said drive signals, for providing said second voltage to each scan line of said electroluminescent panel means in response to said first levels.

4. The electroluminescent panel display system as claimed in claim 3, wherein said display control means comprises:

first switch means, responsive to said image data, for detecting when at least one first level is present in said image data, for producing a present signal when at least one first level is present in said image data and for producing an absent when at least one first level is not present in said image data; and

second switch means, operatively connected to said display drive means and responsive to said present signal and said absent signal produced by said first switch means, for regulating application of said drive signals to said first and second scan means;

said second switch means providing said first and second scan means with said drive signals in response to said present signal and preventing the application of said drive signals to said first and second scan means in response to said absent signal.

5. An electroluminescent panel display system comprising:

electroluminescent panel means, for displaying information having a plurality of display lines, said display lines being scan lines and data lines;

display control means, for producing image data for each display line, for detecting the contents of said image data, and for providing drive signals, said image data for each display line represented by a group of signals, each signal being either a first level or a second level, said first level representing a spot of intended illumination on said electroluminescent panel means, said second level representing a spot of intended non-illumination on said electroluminescent panel means, said drive signals being provided only when at least one first level is present in said image data; and

circuit means, operatively connected to said electroluminescent panel means and said display control means and responsive to said drive signals and said image data, for producing at a first instant in time a first voltage in accordance with said image data only when said drive signals are provided and for producing at a second instant in time a second voltage in accordance with said image data only when said drive signals are provided, said first voltage preparing said electroluminescent panel means to illuminate, said second voltage causing a spot of illumination on said electroluminescent panel means;

said circuit means including,

first scan means, operatively connected to said electroluminescent panel means and responsive to said drive signals, for sequentially providing said first voltage to each scan line of said electroluminescent panel means, and

second scan means, operatively connected to said electroluminescent panel means and said display control means and responsive to said drive signals and said image data, for providing said second voltage to each scan line of said electroluminescent panel means in response to said first levels;

said display control means including,

first switch means, responsive to said image data, for detecting when at least one first level is present, for producing a present signal when at least one first level is present in said image data, and for producing an absent signal when at least one first level is not present in said image data, and

second switch means, operatively connected to said circuit means and responsive to said present signal and said absent signal, for regulating transmission of said drive signals to said first and second scan means,

said second switch means allowing transmission of said drive signals to said first and second scan means in response to said present signal and for preventing transmission of said drive signals to said first and second scan means in response to said absent signal, thereby preventing the functions of said first and second scan means when no first level is detected in said image data.

6. An electroluminescent panel system for displaying information comprising:

an electroluminescent panel having plurality of display lines;

display control means for producing control signals and image data for each display line, said image data for each said display line formed of a group of signals, each signal being either the first level or a second level, said first level representing a spot of intended illumination on said electroluminescent panel, said second level representing a spot of intended non-illumination on said electroluminescent panel;

drive means, operatively connected to said electroluminescent panel and said display control means to receive said image data and responsive to said display control means, for sequentially providing at a first instant in time a first voltage to certain display lines of said electroluminescent panel and for providing a second voltage at a second instant in time to certain display lines of said electroluminescent panel in response to said first level, said first voltage preparing said electroluminescent panel to illuminate, said second voltage selectively causing a spot of a illumination on said electroluminescent panel, said control signals determining when said first voltage and said second voltage are provided to said electroluminescent panel; and

control means, operatively connected to said display control means and said drive means, for detecting at least one first level in said image data;

said control means permitting said control signals to be provided to said drive circuit means when at least one first level is detected and not permitting said control signals to be provided to said drive means when no first levels are detected, thereby preventing the function of said drive means when no first levels are present.

7. The electroluminescent panel system as claimed in claim 6, wherein said displayed lines comprise scan lines and data lines.

8. The electroluminescent panel system as claimed in claim 7, wherein said drive means comprise:

first scan means, operatively connected to said electroluminescent panel and responsive to said control signals, for sequentially providing said first voltage to each scan line of said electroluminescent panel; and

second scan means, operatively connected to said display control means and said electroluminescent panel and responsive to said control signals, for providing said second voltage to each scan line of said electroluminescent panel in response to said first levels.

9. The electroluminescent panel system as claimed in claim 8, wherein said control means comprises:

detetection means, operatively connected to said display control means and responsive to said image data, for detecting at least one first level in said image data, for producing a present signal when at least one first level is present in said image data and for producing an absent signal when at least one first level is not present in said image data; and

switch means, operatively connected to said first and second scan means and said display control means and responsive to said present signal and said absent signal, for regulating transmission of said control signals from said display control means to first and second scan means;

said switch means allowing the transmission of said control signals to said first and second scan means in response to said present signal and preventing the transmission of said control signals to said first and second scan means in response to said absent signal, thererby preventing the function of said first and second scan means when at least one first level is not present in said image data.

10. An electroluminescent panel driving system for driving electroluminescent panel having a plurality of scan lines and data lines comprising:

image data producing means, for sequentially producing image data for each scan line, said image data for each scan line formed of a group of bits, each bit having either a first level or a second level, said first level representing a spot of intended illumination on the electroluminescent panel, said second level representing a spot of intended non-illumination on the electroluminescent panel;

first scan means, operatively connected to the electroluminescent panel, for sequentially providing a first voltage to each scan line of the electroluminescent panel, said first voltage preparing the electroluminescent panel to illuminate;

second scan means, operatively connected to said image data producing means and the electroluminescent panel, for providing a second voltage to each scan line of the electroluminescent panel in response to said first level, said second voltage selectively causing a spot of illumination on the electroluminescent panel;

detecting means, operatively connected to said image data producing means, for detecting the presence of at least one first level in said image data;

said detecting means producing a present signal when at least one first level is present and producing an absent signal when at least one first level is not present in said image data; and

control means, operatively connected to the said first and second scan means and responsive to said present and absent signals of said detecting means, for enabling said first and second scan means when said present signal is received and disabling said first and second scan means when said absent signal is received.

11. An electroluminescent matrix display drive system for supplying drive voltages to elements of an electroluminescent matrix display, the elements being arranged in scan lines, comprising:

a power supply;

display control means, for developing image data representative of an image to be displayed on the display, said image data selectively representing the intended illumination or lack of intended illumination of each element on the display;

display drive means, powered by said power supply, for supplying a net drive voltage across each element to selectively cause the element to illuminate in response to said image data developed by said display control means; and

power conservation means, responsive to said image data, for disconnecting said power supply from said display drive means when the image data for an entire scan line is representative only of the lack of illumination of each scan line element, thereby to substantially reduce power consumption of said drive system.

12. The electroluminescent matrix display drive system as claimed in claim 11, wherein the electroluminescent matrix display further comprises data lines and said driver system further comprising data line drive means for driving said data lines to selectively cause illumination in the elements along the scan lines.

13. The electroluminescent matrix display drive system as claimed in claim 12, wherein said display drive means comprises:

first scan means, operatively connected to the electroluminescent matrix display and responsive to said display control means, for sequentially providing a first voltage to each scan line of the electroluminescent matrix display; and

second scan means, operatively connected to the electroluminescent matrix display and responsive to said display control means, for providing a second voltage to each scan line of the electroluminescent matrix display in response to said image data.

14. The electroluminescent matrix display drive system as claimed in claim 13, wherein said power conservation means comprises:

first switch means, responsive to said image data, for detecting when said image data represents that at least one element in the scan line is intended for illumination and for producing a present signal only when at least one element on the scan line is intended for illumination; and

second switch means, operatively connected to said display drive means and responsive to said present signal produced by said first switch means, for regulating application of said power supply to said first and second scan means;

said second switch means allowing said first and second scan means to connect with said power supply in response to said present signal, thereby preventing the application of said power supply to said first and second scan means when no element on the scan line is intended for illumination.