ORGANIC ELECTROLUMINESCENT DISPLAY

• US 20090096725A1
• Filed: 04/27/2007
• Published: 04/16/2009
• Est. Priority Date: 04/28/2006
• Status: Active Grant

• Current Assignee: InterDigital CE Patent Holdings SAS (InterDigital, Inc.)
• Original Assignee: Thales SA
• Inventors: Kretz, Thierry, Lebrun, Hugues, Chuiton, Elisabeth
• Granted Patent: US 9,224,331 B2
• Time in Patent Office: Days
• US Class Current: 345/82
• CPC Class Codes: G09G 2300/0417 Special arrangements specific to the use of low carrier mobility technology
• CPC Class Codes: G09G 2300/0439 Pixel structures
• CPC Class Codes: G09G 2300/0823 used to establish symmetry in driving, e.g. with polarity inversion
• 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 2320/0233 Improving the luminance or brightness uniformity across the screen
• 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

Abstract

In an organic light-emitting display screen, each picture dot includes an organic diode (OLED) and first and second current driver circuits for the diode. Each driver circuit includes: a driving transistor connected between a reference voltage and one electrode of the said diode, a switching transistor for switching a gate voltage onto the gate of the said driving transistor, and a capacitor connected to the gate of the said driving transistor, to maintain the gate voltage. The gate voltage of a driving transistor is alternately a video voltage controlling a display phase, or a turn-off voltage, controlling a recovery phase. The driving transistors are controlled alternately, one in recovery phase, the other in display phase, and vice versa.

Claims

1-7. -7. (canceled)

8. An organic light-emitting display screen comprising:

n·

m picture dots organized in a matrix with m rows and n columns, each picture dot comprising an organic diode and first and second driver circuits for the diode, each comprising;

a driving transistor connected between a reference voltage and one electrode of the said diode,

a switching transistor for switching a gate voltage onto the gate of the driving transistor,

a capacitor connected to the gate of the driving transistor, to maintain the gate voltage;

wherein a circuit for addressing the n·

m picture dots, to control alternately and simultaneously a recovery phase on one driver circuit and a display phase on the other driver circuit of a picture dot, comprises as row select lines, only m row select lines, one per row of picture dots, and/or as data lines, only n data lines, one per column of picture dots.

9. A display screen according to claim 8, wherein the addressing circuit comprises only the m row select lines, and 2·

n data lines, two lines per picture dot column, and to each picture element are made to correspond a respective select line connected to the gates of the switching transistors of the associated first and second driver circuits, a first data line connected to the switching transistor of one of the two driver circuits and a second data line connected to the switching transistor of the other of the two driver circuits, and wherein during one video frame, one of the first and second data lines delivers a video voltage and the other a turn-off voltage, and during another video frame, the reverse occurs.

10. A display screen according to claim 8, wherein the addressing circuit comprises only the m row select lines, and 2·

n data lines, two lines per column of picture dots, and to each picture element are made to correspond a first select line and a second select line, the first being connected to the gate of the switching transistor of one of the two driver circuits, the second being connected to the gate of the switching transistor of the other driver circuit, a first data line being connected to the switching transistor of one of the two driver circuits and a second data line being connected to the switching transistor of the other driver circuit, and wherein during one video frame, one of the first and second data lines delivers a video voltage, and the other a turn-off voltage, and during another video frame, the reverse occurs.

11. A display screen according to claim 8, wherein the addressing circuit comprises only the m row select lines and n data lines, and to each picture element are made to correspond a respective data line connected to the switching transistors of the two associated driver circuits, and a first select line and a second select line, the first being connected to the gate of the switching transistor of one of the two driver circuits, the second being connected to the gate of the switching transistor of the other driver circuit, and wherein in each of the two driver circuits, an additional transistor is provided, connected between the gate of the driving transistor of the driver circuit in question and the select line associated with it, and is controlled on its gate by the select line associated with the other driver circuit, the order of the sequential selection of the select lines of the display screen being alternately reversed at each frame.

12. A display screen according to claim 8, wherein the addressing circuit comprises 2·

m row select lines, two select lines per row of picture dots and n data lines, and to each picture element are made to correspond a respective data line connected to the switching transistors of the two associated driver circuits, and a first select line and a second select line, the first select line being connected to the gate of the switching transistor of one of the two driver circuits, the second select line being connected to the gate of the switching transistor of the other driver circuit, and wherein during one video frame, during the selection of the first select line, video voltages are applied to the columns whereas during the selection of the second select line, recovery voltages are applied to the columns, and during another video frame, the reverse occurs.

13. A display screen according to claim 9, each column of pixels having an associated first and second data line, further comprising a column driver capable of alternately delivering, at a first output connected to the first data line and at a second output connected to the second data line, a video voltage or a turn-off voltage being a function of the video voltage.

14. A display screen according to claim 8, wherein the addressing circuit comprises row and/or column drivers used in liquid crystal displays for controlling the select lines and/or data lines.

15. A display screen according to claim 10, each column of pixels having an associated first an second data line, further comprising a column driver configured to alternately deliver, at a first output connected to the first data line and at a second output connected to the second data line, a video voltage or a turn-off voltage being a function of the video voltage.