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CA2490848A1 - Pixel circuit and driving method for fast compensated programming of amoled displays - Google Patents

Pixel circuit and driving method for fast compensated programming of amoled displays Download PDF

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Publication number
CA2490848A1
CA2490848A1 CA002490848A CA2490848A CA2490848A1 CA 2490848 A1 CA2490848 A1 CA 2490848A1 CA 002490848 A CA002490848 A CA 002490848A CA 2490848 A CA2490848 A CA 2490848A CA 2490848 A1 CA2490848 A1 CA 2490848A1
Authority
CA
Canada
Prior art keywords
voltage
pixel circuit
oled
programming
driving method
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
CA002490848A
Other languages
French (fr)
Inventor
Arokia Nathan
Chaji G. Reza
Servati Peyman
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ignis Innovation Inc
Original Assignee
Ignis Innovation Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ignis Innovation Inc filed Critical Ignis Innovation Inc
Priority to CA002490848A priority Critical patent/CA2490848A1/en
Priority to US11/274,957 priority patent/US7889159B2/en
Priority to EP05807905A priority patent/EP1825455A4/en
Priority to PCT/CA2005/001730 priority patent/WO2006053424A1/en
Priority to CA002523841A priority patent/CA2523841C/en
Priority to EP11175225.9A priority patent/EP2383721B1/en
Priority to CN2005800464787A priority patent/CN101111880B/en
Priority to JP2007541598A priority patent/JP2008521033A/en
Priority to TW094140360A priority patent/TWI389085B/en
Publication of CA2490848A1 publication Critical patent/CA2490848A1/en
Priority to US12/952,951 priority patent/US8319712B2/en
Abandoned legal-status Critical Current

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Classifications

    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09GARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/22Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
    • G09G3/30Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels
    • G09G3/32Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED]
    • G09G3/3208Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED]
    • G09G3/3225Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED] using an active matrix
    • G09G3/3233Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED] using an active matrix with pixel circuitry controlling the current through the light-emitting element
    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09GARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2300/00Aspects of the constitution of display devices
    • G09G2300/08Active matrix structure, i.e. with use of active elements, inclusive of non-linear two terminal elements, in the pixels together with light emitting or modulating elements
    • G09G2300/0809Several active elements per pixel in active matrix panels
    • G09G2300/0819Several active elements per pixel in active matrix panels used for counteracting undesired variations, e.g. feedback or autozeroing
    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09GARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2300/00Aspects of the constitution of display devices
    • G09G2300/08Active matrix structure, i.e. with use of active elements, inclusive of non-linear two terminal elements, in the pixels together with light emitting or modulating elements
    • G09G2300/0809Several active elements per pixel in active matrix panels
    • G09G2300/0842Several active elements per pixel in active matrix panels forming a memory circuit, e.g. a dynamic memory with one capacitor
    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09GARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2300/00Aspects of the constitution of display devices
    • G09G2300/08Active matrix structure, i.e. with use of active elements, inclusive of non-linear two terminal elements, in the pixels together with light emitting or modulating elements
    • G09G2300/0809Several active elements per pixel in active matrix panels
    • G09G2300/0842Several active elements per pixel in active matrix panels forming a memory circuit, e.g. a dynamic memory with one capacitor
    • G09G2300/0852Several active elements per pixel in active matrix panels forming a memory circuit, e.g. a dynamic memory with one capacitor being a dynamic memory with more than one capacitor
    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09GARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2300/00Aspects of the constitution of display devices
    • G09G2300/08Active matrix structure, i.e. with use of active elements, inclusive of non-linear two terminal elements, in the pixels together with light emitting or modulating elements
    • G09G2300/0809Several active elements per pixel in active matrix panels
    • G09G2300/0842Several active elements per pixel in active matrix panels forming a memory circuit, e.g. a dynamic memory with one capacitor
    • G09G2300/0861Several active elements per pixel in active matrix panels forming a memory circuit, e.g. a dynamic memory with one capacitor with additional control of the display period without amending the charge stored in a pixel memory, e.g. by means of additional select electrodes
    • G09G2300/0866Several active elements per pixel in active matrix panels forming a memory circuit, e.g. a dynamic memory with one capacitor with additional control of the display period without amending the charge stored in a pixel memory, e.g. by means of additional select electrodes by means of changes in the pixel supply voltage
    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09GARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00Control of display operating conditions
    • G09G2320/04Maintaining the quality of display appearance
    • G09G2320/043Preventing or counteracting the effects of ageing

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Control Of Indicators Other Than Cathode Ray Tubes (AREA)
  • Electroluminescent Light Sources (AREA)

Abstract

Disclosed is a technique for driving a column of pixels implemented using light emitting elements, in particular, OLEDs. The technique includes a driving method to generate a gate-source voltage independent of the driver threshold voltage and OLED
voltage.

Description

FIELD OF THE INVENTION
The present invention generally relates to a light emitting device display, and more particularly.
to a driving technique of the active matrix organic light emitting diode (AMOLED), and for enhancement of OLED brightness stability by using compensation.
SUMMARY OF INVENTION
The invention provides a hybrid programming technique, suitable for use in AMOLED. Each pixel has a driving thin film transistor (TFT) whose overdrive voltage is generated independent from its threshold voltage and the OLED voltage.
Advantages The present invention provides a stable current independent of the threshold voltage shift of the driving TFT and the OLED degradation under prolonged display operation, so as to efficiently improve the display product quality. Moreover, because of its simplicity, it provides higher yield, lower fabrication cost and higher resolution than its counterparts. Most importantly, since the settling time of new pixel is much smaller than the present pixels, it is suitable for large-area display such as high definition TV.

DETAILED DESCRIPTION OF THE INVENTION
The present invention involves a technique for driving a column of pixels to provide stable OLED operation.
FIG. 1 (a-c) shows a pixel circuit along with its control signals. This method is valid with complementary (p-type transistor) device as well.
The pixel circuit comprises three transistors T1, T2 and T3, a storage capacitor 12 and an organic light-emitting diode (OLED) 10. The pixel circuit is connected to two select lines (SELI and SEL2), a signal line (VDATA), a bias line (IBIAS), a voltage line (VDD), and a common ~,~round.
Transistors Tl, T2 and T3 can be amorphous silicon, poly silicon, or organic thin-film transistors (TFT) or standard MOSFETs in CMOS technology.
The source terminal of driving transistor Tl is connected to the anode electrode of the OLED 10. The drain terminal of T1 is connected to VDD, and the gate terminal of Tl is connected to the signal line (VDATA) through T2. The storage capacitor is connected between the source and gate of Tl.
Transistor T2 is a switch. The gate terminal of T2 is connected to the first select line (SEL1). The drain terminal of TZ is connected to the signal line (VDATA), and the source terminal is connected to the gate terminal of Tl.
Transistor T3 is a switch. The gate terminal of T3 is connected to the second select line (SEL2). The source terminal of T3 is connected to the bias line (IB1AS), and the drain terminal is connected to the anode terminal of the OLED 10. The cathode electrode of the OLED 10 is connected to the common ground.
The operation of pixel presented in Fig 1 (b and c) consists of two cycles:
programming and driving cycles. In the programming cycles node B is charged to negative of the threshold voltage of Tl and node A is charged to programming voltage (VP) resulting in the gate-source voltage of T1 as:
YGS = VP - (-YT ) = YP + YT .
With reference to the waveform shown on FIG.1 (b) we describe the following operating cycles.

The first operating ~cle: Both select lines are high. A bias current (IB) flows through the IBIAS, and VDATA goes to a bias voltage (VB), resulting in the voltage of node B as:
V ~~me-a = VB - ~I ~ Y~ , Where VT is the threshold voltage of Tl, and ~ is the coefficient is current-voltage (I-V) characteristics of the TFT given by Ibs = (i (VGS - VT)z, The second operatic cycle: While SEL2 is low, and SELL is high, VDATA goes to a programming voltage (VP). Because the OLED capacitance 11 is large, the voltage of node B generated in the previous cycle stays intact. Therefore, the gate-source voltage of TI can be found as:
VGS=VP+AVB+VT, where VGS is the gate-source voltage of Tl, and OVB = ~ -VB (if VB is chosen properly, ~VB will be zero).
The third operating~cycle: SELI goes to zero, and a current independent of the threshold voltage flows through the OLED 10.
The operation of the waveform shown in Fig 1 (c) is exactly the same as above except that in the second operating cycle, T3 is on but ttte bias current (IB) is zero. Because both select lines (SELL and SEL2) have the same timing, they can be connected to a common select line.
FIG. 2 shows the simulation result for the circuit and waveform shown in the FIG.1 (a) and (b). The result shows that the change in the OLED current due 2-volt VT-shift in Tl is almost zero percent for most of the programming voltage.
FIG. 3 (a-c) shows a pixel circuit along with its control signals. This method is valid with complementary (p-type transistor) device as well.
The pixel circuit comprises three transistors T1, T2, T3 and T4, two storage capacitors 32-33, and an organic light-emitting diode (OLED) 30. The pixel circuit is connected to a select line (SEL), a signal line (VDATA), a bias line (IBIAS), a voltage line (VDD), and a common ground.

Transistors T1, T2, T3 and T4 can be amorphous silicon, poly silicon, or organic thin-film transistors (TFT) or standard MOSFETs in CMOS technology.
The source terminal of the driving transistor TI is connected to the cathode electrode of the OLED 30. The drain terminal of TI is connected to the ground, and the gate terminal of Tl is connected to its drain terminal through T2. The storage capacitors 32-33 are in series and connected between the source of T1 and ground.
Transistor T2 is a switch. The gate terminal of T2 is connected to the select line (SEL).
The drain terminal of T2 is connected to the drain terminal of TI, and the source terminal is connected to the gate terminal of TI.
Transistor T3 is a switch. The gate terminal of T3 is connected to the select line (SEL).
The drain terminal of T3 is connected to the signal line (VDATA), and the source terminal is connected to the connected tenminal of the storage capacitors 32-33.
Transistor T4 is a switch. The gate terminal of T4 is connected to the select line (SEL).
The drain terminal of T4 is connected to bias line (IBIAS), and the source terminal is connected to the cathode terminal of the OLED 30. The anode electrode of the is connected to common ground.
The operation of the pixel presented in Fig 3 (b) consists of two operating cycles:
programming cycles and driving cycle. In the programming cycles, the first storage capacitor 32 is charged to a programming voltage plus the threshold voltage (VT) of TI, and the second storage capacitor 33 is charged to zero, resulting in a gate-source voltage ofTl as: VGS=-YP+VT.
With reference to the waveform shown on FIG. 3 (b) we describe the following operating cycles.
The first operating cycle: Both select lines are high. A bias current (IB) flows through the IBIAS, and VDATA goes to a programming voltage (VP), resulting in the stored voltage in the first storage capacitor 32 as:
YCl = R -VP+VT , where VCI is the stored voltage in the first storage capacitor 32, and (i is the coefficient in current-voltage (I-V) characteristics of the TFT given by Ips = p (VGS -VT)Z, The second operating cycle: While SEL is high, VDATA is zero, and IBIAS goes to zero. Because the OLED capacitance 31 and the parasitic capacitance of the bias line (IBIAS) are large, the voltage of node B (and node A) generated in the previous cycle stays untouched. Therefore, the gate-source voltage of Tl can be found as:
VCl = VB-VP+VT, where VGS is the gate-source voltage of Tl, and ~B = IB .
The third operatinyycle: SEL goes to zero, and a current independent of the threshold voltage flows through the OLED 30.

BRIEF DESCRIPTION OF THE DRAWINGS
FIG.1 (a-c) shows the draft diagram of an embodiment of a pixel circuit and its corresponding waveforms.
FIG. Z shows the current stability of the pixel after 2 V VT shift in the driving TFT.
FIG. 3 (a-b) shows the circuit diagram of an embodiment of a pixel circuit and its corresponding waveform.

Claims

CA002490848A 2004-11-16 2004-11-16 Pixel circuit and driving method for fast compensated programming of amoled displays Abandoned CA2490848A1 (en)

Priority Applications (10)

Application Number Priority Date Filing Date Title
CA002490848A CA2490848A1 (en) 2004-11-16 2004-11-16 Pixel circuit and driving method for fast compensated programming of amoled displays
EP11175225.9A EP2383721B1 (en) 2004-11-16 2005-11-15 System and Driving Method for Active Matrix Light Emitting Device Display
EP05807905A EP1825455A4 (en) 2004-11-16 2005-11-15 System and driving method for active matrix light emitting device display
PCT/CA2005/001730 WO2006053424A1 (en) 2004-11-16 2005-11-15 System and driving method for active matrix light emitting device display
CA002523841A CA2523841C (en) 2004-11-16 2005-11-15 System and driving method for active matrix light emitting device display
US11/274,957 US7889159B2 (en) 2004-11-16 2005-11-15 System and driving method for active matrix light emitting device display
CN2005800464787A CN101111880B (en) 2004-11-16 2005-11-15 System and driving method for active matrix light emitting device display
JP2007541598A JP2008521033A (en) 2004-11-16 2005-11-15 System and driving method for active matrix light emitting device display
TW094140360A TWI389085B (en) 2004-11-16 2005-11-16 System and driving method for active matrix type light-emitting device display
US12/952,951 US8319712B2 (en) 2004-11-16 2010-11-23 System and driving method for active matrix light emitting device display

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CA002490848A CA2490848A1 (en) 2004-11-16 2004-11-16 Pixel circuit and driving method for fast compensated programming of amoled displays

Publications (1)

Publication Number Publication Date
CA2490848A1 true CA2490848A1 (en) 2006-05-16

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Application Number Title Priority Date Filing Date
CA002490848A Abandoned CA2490848A1 (en) 2004-11-16 2004-11-16 Pixel circuit and driving method for fast compensated programming of amoled displays

Country Status (2)

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CA (1) CA2490848A1 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10192485B2 (en) 2016-01-04 2019-01-29 Boe Technology Group Co., Ltd. Pixel compensation circuit and AMOLED display device
CN110827767A (en) * 2014-08-06 2020-02-21 精工爱普生株式会社 Electro-optical device

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100939211B1 (en) * 2008-02-22 2010-01-28 엘지디스플레이 주식회사 Organic light emitting diode display and its driving method
CN104299566B (en) 2008-04-18 2017-11-10 伊格尼斯创新公司 System and driving method for light emitting device display
JP5310244B2 (en) * 2009-05-12 2013-10-09 ソニー株式会社 Display device and display method
CN101847365B (en) * 2010-04-13 2013-01-23 友达光电股份有限公司 Pixel circuit, driving method thereof, and applied display panel and display
US9322869B2 (en) * 2014-01-03 2016-04-26 Pixtronix, Inc. Display apparatus including dummy display element for TFT testing
CN110930947A (en) * 2019-11-28 2020-03-27 武汉华星光电半导体显示技术有限公司 Pixel compensation circuit, driving method thereof and display device
KR102773247B1 (en) * 2020-07-23 2025-02-28 삼성디스플레이 주식회사 Pixel and display device having the same
CN114170966B (en) * 2021-12-09 2023-09-08 南京国兆光电科技有限公司 Image display device and display method thereof

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001147659A (en) * 1999-11-18 2001-05-29 Sony Corp Display device
US6414661B1 (en) * 2000-02-22 2002-07-02 Sarnoff Corporation Method and apparatus for calibrating display devices and automatically compensating for loss in their efficiency over time

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110827767A (en) * 2014-08-06 2020-02-21 精工爱普生株式会社 Electro-optical device
CN110827767B (en) * 2014-08-06 2022-06-24 精工爱普生株式会社 Electro-optical device
US10192485B2 (en) 2016-01-04 2019-01-29 Boe Technology Group Co., Ltd. Pixel compensation circuit and AMOLED display device

Also Published As

Publication number Publication date
CN101111880B (en) 2013-01-02
CN101111880A (en) 2008-01-23

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