Electroluminescent storage display with improved intensity driver circuits

• US 4,996,523 A
• Filed: 10/20/1988
• Issued: 02/26/1991
• Est. Priority Date: 10/20/1988
• Status: Expired due to Term

• Current Assignee: Eastman Kodak Company
• Original Assignee: Eastman Kodak Company
• Inventors: Bell, Cynthia S., Gaboury, Michael J.
• Primary Examiner(s): Oberley, Alvin E.
• Application Number:
  US07/260,103
• Time in Patent Office: 859 Days
• Field of Search: 340/781, 340/782, 340/762, 340/767, 340/793
• US Class Current: 345/77
• CPC Class Codes: G09G 2300/0828 forming a digital to analog [D/A] conversion circuit
• CPC Class Codes: G09G 2300/0857 Static memory circuit, e.g. flip-flop
• 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 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 3/3291 in which the data driver supplies a variable data voltage for setting the current through, or the voltage across, the light-emitting elements
• CPC Class Codes: H04N 3/12 by switched stationary formation of lamps, photocells or light relays
• CPC Class Codes: H10K 59/12 Active-matrix OLED [AMOLED] displays

Abstract

In the present invention a matrix array of organic electroluminescent storage display elements along with row and column selection circuitry are used to select the particular display elements within the matrix to be illuminated. Interposed between the column and row selection electronics are a plurality of memory cells receiving as inputs bit values that correspond to the desired intensity requested from a display element. The memory cells output activation signals which drive corresponding MOS switches each of which in turn is parallel connected as part of a current driver source feeding a single display element. Activation of one or more of the MOS switches provides a controlled amount of current to be applied to the display element to in turn provide a related amount of light from the display element.

Claims

1. An electroluminescent storage display with improved intensity driver circuits comprising:

an electroluminescent element;

a plurality of memory elements;

a current source connected in circuit to said electroluminescent element;

a plurality of elements, corresponding in number to said plurality of memory elements, each connected to a respective memory element and responsive to the signals stored therein for causing an incremental current to flow from said current source to said electroluminescent element; and

means for applying signals to said memory elements indicative of the intensity desired from said electroluminescent element.

2. The electroluminescent storage display of claim 1 wherein said plurality of elements are MOS transistors each having a gate electrode connected to a respective memory element.

3. The electroluminescent storage display of claim 1 wherein said means for applying signals to said memory elements is comprised of:

a plurality of binary bits corresponding in number to said plurality of memory elements and an enabling signal source for providing an enabling signal for loading said binary bits into said memory elements.

4. An electroluminescent storage display with improved intensity driver circuits comprising:

a column data register means having an input for serially receiving image signals, and having a plurality of parallel outputs for providing said image signals thereon;

an input/output logic means responsive to an enable signal, and coupled to the plurality of parallel outputs of said column data register means for gating said image signals to respective column outputs;

a row strobe register means responsive to an input signal for sequentially providing an enabling strobe signal on each of a plurality of row outputs;

a plurality of switch means, each connected to a respective one of a plurality of row outputs of said row strobe register means for connecting a respective one of said column outputs of said input/output logic means to a switch output;

a plurality of memory driver circuit means having an input connected to the switch output of a respective switch means and having an output for providing a current as a function of the image signal received on its input;

a plurality of electroluminescent display means each connected to an output of a respective memory driver circuit means for illumination by the provided current therefrom wherein each of said plurality of memory driver circuit means is comprised of;

a plurality of memory elements;

a current source connected in circuit to an electroluminescent display means;

a plurality of elements corresponding in number to said plurality of memory elements, each connected to a respective memory element and responsive to the signals stored therein for causing an incremental current to flow from said current source to said electroluminescent display means; and

means for applying signals to said memory elements indicative of the intensity desired from said electroluminescent display means.

5. The electroluminescent storage display of claim 4 wherein said plurality of elements are MOS transistors each having a gate electrode connected to a respective memory element.

6. The electroluminescent storage display of claim 4 wherein said means for applying signals to said memory elements is comprised of:

a plurality of binary bits corresponding in number to said plurality of memory elements and an enabling signal source for providing an enabling signal for loading said binary bits into said memory elements.

7. An electroluminescent display matrix comprising:

a plurality of electroluminescent elements arranged in a display;

a plurality of storage means for each of said plurality of electroluminescent elements for receiving binary number signals corresponding to the intensity level desired from an associated electroluminescent element;

a plurality of current sources each coupled to a respective plurality of said storage means and an associated electroluminescent element for providing a current as a function of the binary number signals stored in said storage means, and wherein each of said plurality of current sources is comprised of;

a two MOS device current mirror, with the first of said MOS devices connecting said electroluminescent element to a source of power and with the second of said MOS devices connecting said source of power to a selectable current means; and

a selectable current means connected to said plurality of storage means and responsive to the signals stored therein for causing the current in said second MOS device to be a function of the signals stored in said plurality of storage means.