ACTIVE MATRIX OF AN ORGANIC LIGHT-EMITTING DIODE DISPLAY SCREEN

• US 20080231556A1
• Filed: 03/17/2008
• Published: 09/25/2008
• Est. Priority Date: 03/16/2007
• Status: Active Grant

• Current Assignee: InterDigital Patent Holdings, Inc. (InterDigital, Inc.)
• Original Assignee: Thales SA
• Inventors: Lebrun, Hugues, Chuiton, Elisabeth, Kretz, Thierry
• Granted Patent: US 8,040,299 B2
• Time in Patent Office: Days
• US Class Current: 345/76
• CPC Class Codes: G09G 2300/0426 Layout of electrodes and connections
• CPC Class Codes: G09G 2300/0465 Improved aperture ratio, e.g. by size reduction of the pixel circuit, e.g. for improving the pixel density or the maximum displayable luminance or brightness
• CPC Class Codes: G09G 2300/0852 being a dynamic memory with more than one capacitor
• CPC Class Codes: G09G 2310/0254 Control of polarity reversal in general, other than for liquid crystal displays
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: H10K 59/131 Interconnections, e.g. wiring lines or terminals

Abstract

In an active matrix for an organic light-emitting diode display screen, each pixel is arranged between two row select lines, each line controlling at least a first switching transistor T1, T1′ of the first and second drivers COM and COM′ of this pixel. These two drivers are arranged symmetrically with respect to the pixel electrode E1 of the pixel, each in the space between the pixel electrode and one of the row select lines that flank the pixel. The column data lines are each produced in the interval between two successive columns of pixels, by knitting by means of points of contact ct1, ct2 between the source-drain metal level and the gate metal level, producing the source-drain electrodes and gates, respectively, of the transistors. One source-drain electrode of the control transistors is formed by a supply bus Vdd produced on the source-drain metal level and the other source-drain electrode of the control transistors is formed by at least one finger, formed by an excrescence of the pixel electrode on the same source-drain metal level.

Application to active matrices based on TFT transistors, especially with an amorphous silicon channel.

Claims

1. Active matrix for an organic light-emitting diode display screen, comprising pixels arranged in rows and in columns, each comprising a pixel electrode capable of accommodating an organic light-emitting diode on the surface and first and second current drivers connected to said pixel electrode, each first driver and each second driver comprising a current control transistor connected between a supply voltage Vdd and said pixel electrode and at least a first switching transistor for controlling the gate of said current control transistor, said first switching transistor being connected between a column data line of the matrix and the gate of said current control transistor, and having its gate connected to a row select line of the matrix, the source or drain electrodes of the switching and control transistors and the pixel electrodes being produced on a source-drain metal level, and the gate electrodes of these transistors each being produced by a row select line of the matrix, on a gate metal level, wherein:

each pixel is placed between two row select lines of the matrix, with a driver placed between a first of these two row select lines and its pixel electrode, said first row select line forming the gate of the first switching transistor of this driver and the other driver placed between a second of these two row select lines and the pixel electrode, said second row select line forming the gate of the first switching transistor of this driver;

a source-drain electrode of the control transistors is formed by a supply bus Vdd produced on the source-drain metal level, and the other source-drain electrode of the control transistors is formed by at least one finger, which is an excrescence of the pixel electrode on the same source-drain metal level; and

each column data line is placed between two columns of pixels of the matrix and formed by using said source-drain metal level and said gate metal level, said gate metal level being used along the pixel electrodes and said source-drain metal level being used in the zones between said pixel electrodes where the switching transistors of said drivers are produced.

2. Matrix according to claim 1, in which said supply voltage Vdd is distributed over the matrix by means of a supply bus with a row/column matrixed arrangement.

3. Matrix according to claim 2, in which each interval between two successive columns of pixels comprises a supply bus column conductor Vdd and at least one column data line conductor.

4. Matrix according to claim 2, in which the first switching transistor of the first driver for a pixel and the first switching transistor of a second driver of another pixel are placed back-to-back and on either side of a row select line.

5. Matrix according to claim 4, in which each interval between two successive columns of pixels comprises a supply bus column conductor Vdd and a column data line conductor, and said first switching transistors placed back-to-back have a source-drain electrode formed by a portion of a source-drain metal column conductor of the same column data line.

6. Matrix according to claim 2, in which the control transistor of the first driver of a pixel in a column and the control transistor of the second driver of the preceding or following pixel in the same column are arranged symmetrically on either side of a row select line.

7. Matrix according to claim 2, in which the control transistors of said first and second drivers have interdigitated source-drain electrodes, each source-drain electrode comprising more than one finger.

8. Matrix according to claim 1, in which each first driver and each second driver comprises a second switching transistor connected between the row select line, to which the gate of the first switching transistor of the relevant driver is connected, and the gate of said control transistor, and the gate of which is connected to another row select line, wherein each row select line is divided in the active zone into a first branch and a second branch placed on either side of a corresponding row of pixels.

9. Matrix according to claim 8, in which the supply voltage is distributed by column conductors, with a supply column conductor Vdd in each interval between two columns of pixels, and in which the control transistors of the first and second drivers of a pixel are produced along the pixel electrode, between said pixel electrode and said Vdd supply column conductor which form, respectively, a first source-drain electrode and a second source-drain electrode of said control transistors.

10. Display screen having organic light-emitting diodes, comprising an active matrix according to any one of the preceding claims.