Classifications

• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
  • G09G3/20—Control 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
  • G09G3/22—Control 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
  • G09G3/30—Control 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
  • G09G3/32—Control 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]
  • G09G3/3208—Control 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]
  • G09G3/3275—Details of drivers for data electrodes
  • G09G3/3283—Details of drivers for data electrodes in which the data driver supplies a variable data current for setting the current through, or the voltage across, the light-emitting elements
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
  • G09G3/20—Control 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
  • G09G3/22—Control 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
  • G09G3/30—Control 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
  • G09G3/32—Control 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]
  • G09G3/3208—Control 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]
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
  • G09G3/20—Control 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
  • G09G3/22—Control 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
  • G09G3/30—Control 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
  • G09G3/32—Control 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]
  • G09G3/3208—Control 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]
  • G09G3/3225—Control 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
  • G09G3/3233—Control 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
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K50/00—Organic light-emitting devices
  • H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
  • H10K50/11—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
  • H10K59/10—OLED displays
  • H10K59/12—Active-matrix OLED [AMOLED] displays
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G2300/00—Aspects of the constitution of display devices
  • G09G2300/04—Structural and physical details of display devices
  • G09G2300/0404—Matrix technologies
  • G09G2300/0408—Integration of the drivers onto the display substrate
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G2310/00—Command of the display device
  • G09G2310/02—Addressing, scanning or driving the display screen or processing steps related thereto
  • G09G2310/0243—Details of the generation of driving signals
  • G09G2310/0248—Precharge or discharge of column electrodes before or after applying exact column voltages
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G2310/00—Command of the display device
  • G09G2310/02—Addressing, scanning or driving the display screen or processing steps related thereto
  • G09G2310/0262—The addressing of the pixel, in a display other than an active matrix LCD, involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependent on signals of two data electrodes
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G2320/00—Control of display operating conditions
  • G09G2320/02—Improving the quality of display appearance
  • G09G2320/0223—Compensation for problems related to R-C delay and attenuation in electrodes of matrix panels, e.g. in gate electrodes or on-substrate video signal electrodes

Definitions

• This invention generally relates to active matrix displays and to related display driving methods. More particularly the invention relates to additional driving circuitry for active matrix driven Organic Light Emitting Diode (OLED) displays employed to improve the performance characteristics of the device.
• OLED Organic Light Emitting Diode
• Displays fabricated using OLEDs provide a number of advantages over LCD and other flat panel technologies. They are bright, stylish, fast-switching (compared to LCDs), provide a wide viewing angle and are easy and cheap to fabricate on a variety of substrates.
• Organic (which here includes organometallic) LEDs may be fabricated using materials including polymers, small molecules and dendrimers, in a range of colours which depend upon the materials employed. Examples of polymer-based organic LEDs are described in WO 90/13148, WO 95/06400 and WO 99/48160; examples of dendrimer- based materials are described in WO 99/21935 and WO 02/067343; and examples of so called small molecule based devices are described in US 4,539,507.
• a typical OLED device comprises two layers of organic material, one of which is a layer of light emitting material such as a light emitting polymer (LEP), oligomer or a light emitting low molecular weight material, and the other of which is a layer of a hole transporting material such as a polythiophene derivative or a polyaniline derivative.
• a layer of light emitting material such as a light emitting polymer (LEP), oligomer or a light emitting low molecular weight material
• a hole transporting material such as a polythiophene derivative or a polyaniline derivative.
• Organic LEDs may be deposited on a substrate in a matrix of pixels to form a single or multi-colour pixellated display.
• a multicoloured display may be constructed using groups of red, green, and blue emitting pixels.
• So-called active matrix (AM) displays have a memory element, typically a storage capacitor and a transistor, associated with each pixel whilst passive matrix displays have no such memory element and instead are repetitively scanned to give the impression of a steady image. Examples of polymer and small- molecule active matrix display drivers can be found in WO 99/42983 and EP 0,717,446A respectively.
• a display may be either bottom-emitting or top-emitting. In a bottom-emitting display light is emitted through the substrate on which the active matrix circuitry is fabricated; in a top-emitting display light is emitted towards a front face of the display without having to pass through a layer of the display in which the active matrix circuitry is fabricated.
• Top-emitting OLED displays are less common than bottom-emitting displays because, typically, the upper electrode comprises the cathode and this must be at least partially transparent, as well as having sufficient conductivity and, preferably, providing a degree of encapsulation of the underlying organic layers. Nonetheless a large variety of top-emitting structures has been described, including in the applicant's published PCT application WO 2005/071771 (hereby incorporated by reference in its entirety) which describes a cathode incorporating an optical interference structure to enhance the amount of light escaping from the OLED pixel.
• An OLED display conventionally displays an image built from a rectilinear matrix of picture elements (or pixels).
• An Active Matrix OLED display conventionally has a row data line and a column data line for each colour of each pixel.
• One such data line 102 is shown in Figure 1. Referring to Figure 1 , a drive circuit 101 is connected to the data line 102 which is connected to a plurality of pixel circuits 103. Each pixel circuit 103 corresponds to one pixel display element and contains a memory element (not shown). Each data line 102 will typically be connected to many hundred pixel circuits 103.
• the data lines 102 utilise either a voltage driving method or a current driving method.
• the pixel circuits 103 may be used as either a current source or a current sink.
• Figure 2 which is taken from our application WO 03/038790, shows an example of a current-controlled pixel driver circuit. In this circuit the current through an OLED 152 is set by setting a drain source current for OLED driver transistor 158 using a reference current sink 166 and memorising the driver transistor gate voltage required for this drain-source current.
• the brightness of OLED 152 is determined by the current, lcol, flowing into reference current sink 166, which is preferably adjustable and set as desired for the pixel being addressed.
• reference current sink 166 which is preferably adjustable and set as desired for the pixel being addressed.
• a further switching transistor 164 is connected between drive transistor 158 and OLED 152.
• one current sink 166 is provided for each column data line.
• a problem shared by current driven active matrix pixel circuits is that where, as is often the case, the pixel "programming" currents are small leakage and/or data line capacitance may dominate, particularly in large displays.
• conventional current-driven active matrix OLED displays must overcome the resistor-capacitor constant of the data line 102.
• the drive circuit 101 must overcome the inherent resistance and capacitance of the data line 102 in addition to supplying sufficient current to the pixel circuits 103 to achieve the desired light output.
• an active matrix OLED display comprising a data line, a plurality of pixel circuits connected to the data line, a drive circuit connected towards one end of the data line for writing display data to the pixel circuits, and a programmable drive boost circuit connected towards another end of the data line from the drive circuit.
• the invention preferably provides a programmable drive boost circuit connected to the data line at an opposite end to which the drive circuit is connected.
• a programmable drive boost circuit can be a voltage controlled circuit or a current controlled circuit.
• the programmable drive boost circuit is a current source or current sink. Using the programmable drive boost circuit as a current source or current sink reduces the current required to overcome the resistor-capacitor coefficient of the data line.
• the benefits of the present invention include increased device power efficiency and lower time to display an image and consequential higher image display refresh rates.
• the programmable drive boost circuit comprises a select or enable circuit. More preferably, the drive circuit is connected to the enable circuit by a data bus. This allows the drive circuit to control the programmable drive boost circuit by transmitting an enable data bit and/or one or more program data bits.
• the programmable drive boost circuit is a current copier.
• the current copier can be controlled as a variable current sink with a duty programmed enable signal or by a most significant bit of a programmed data signal or the copier can be enabled for a fixed period of time.
• the programmable drive boost circuit can be n-channel or a p-channel depending upon circuit design requirements.
• the programmable drive boost circuit and the drive circuit are located on the same substrate.
• a suitable substrate or backplane can be one fabricated from amorphous silicon (a-Si).
• a method of programming an active matrix OLED display having a current programmed data line, a plurality of pixel circuits connected to the data line, a drive circuit connected towards one end of the data line to write display data to the pixel circuits, and a programmable drive boost circuit connected towards another end of the data line from the drive circuit; the method comprising a first addressing period including programming the programmable drive boost circuit with a first current; and a second addressing period including writing display data to the pixels and supplying the first current to the data line.
• a current is programmed onto the data line by the programmable booster circuit.
• This method substantially reduces the charge time and charging the data line from both ends reduces the resistor-capacitor constant by around 75%.
• the method of programming comprises, in the first addressing period activating the programmable drive boost circuit with an enable data bit and one or more program data bits to provide a current biased with respect to the current provided to the data line from the drive circuit.
• the first addressing period comprises the programmable drive boost circuit being enabled for a fixed time period.
• the programmable drive boost circuit being enabled for a fixed time period.
• the first addressing period comprises the programmable drive boost circuit being enabled and providing a current corresponding to the most significant bit of the digital signal information transmitted by the driver circuit.
• the maximum current provided by the programmable booster circuit and the drive circuits is reduced.
• the first addressing period comprises the programmable booster circuit being programmed to vary according to a duty cycle.
• the duty cycle may be selected, for example to overcome physical impurities in the material of the data line, to achieve an optimal display time or electrical efficiency, for example dependant upon the information content of the image to be displayed, or to follow a fixed duty cycle, for example to minimise the numerical calculations required to achieve the desired image display.
• Figure 1 is a schematic diagram of a row or column display layout as is known in the art
• Figure 2 is a schematic diagram of an active matrix pixel driver circuit as is known in the art
• Figure 3 is a schematic diagram of a row or column display layout according to an embodiment of the present invention.
• Figures 4a to 4d are schematic diagrams of four sample circuits for use as a programmable circuit booster circuit according to an embodiment of the present invention.
• a schematic diagram of a row or column display layout comprises an active matrix OLED display 200.
• the display 200 comprises a programmable booster circuit, showing drive chip circuit 201 , data line 202, pixel circuits 203 and programmable drive boost circuit 204.
• the programming of the display 200 has two stages due to the active matrix arrangement of the pixel circuits 203.
• drive circuit 201 identifies from the digital signal information the required current or range of current to be supplied to the pixel circuits 203 and supplies current to a plurality of pixel circuits 203 which store current in memory cells (not shown). Additionally, programmable booster circuit 204 is engaged during this first stage of programming.
• the drive circuit 201 ceases to supply current and the pixel circuits 203 drive an OLED (not shown) within the pixel circuit to illuminate a portion of the intended display image corresponding to the digital signal data supplied.
• the drive circuit 201 is assisted by the programmable drive boost circuit 204 in the task of supplying current to charge the memory cells of the pixel circuits 203 and also to supply enough current to overcome the resistor-capacitor constant of the data line 202.
• the programmable drive boost circuit 204 can function as a current copier in cooperation with the drive circuit 201 wherein both circuits 201 , 204 source or sink current to the pixel circuits 203.
• the programmable booster circuit 204 may function in opposition to the drive circuit 201 , wherein the programmable booster circuit 204 sinks current while the drive circuit 201 sources current or the programmable booster circuit 204 sources current while the drive circuit 201 sinks current.
• the programmable booster circuit 204 can be enabled only during a pre-charge portion of the first stage of programming the display 200. Additionally, the programmable drive boost circuit 204 can be programmed to a level of current associated with the most significant bit of the digital signal information against which fixed level the drive circuit 201 programs the pixel circuits 203 during a first stage of programming the display 200. Additionally, the programmable drive boost circuit 204 can be programmed to follow a variable duty program, for example to optimise the current delivered according to the content of the intended display image.
• Figures 4a to 4d are schematic diagrams of four sample circuits for use as a programmable circuit booster circuit 204 according to an embodiment of the present invention. Common in parts (a), (b), (c) and (d) of Figure 4 are voltage source V D D 301 , program data 302, enable data 303 and circuit ground 304.
• Figure 4(a) shows a typical layout for an example programmable booster circuit 204 using n-type transistors to provide a current source programmable booster circuit.
• Figure 4(b) shows a typical layout for an example programmable booster circuit 204 using n-type transistors to provide a current sink programmable booster circuit.
• Figure 4(c) shows a typical layout for an example programmable booster circuit 204 using p-type transistors to provide a current source programmable booster circuit.
• Figure 4(d) shows a typical layout for an example programmable booster circuit using p-type transistors to provide a current sink programmable booster circuit.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Computer Hardware Design (AREA)
• General Physics & Mathematics (AREA)
• Theoretical Computer Science (AREA)
• Optics & Photonics (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Control Of Indicators Other Than Cathode Ray Tubes (AREA)
• Electroluminescent Light Sources (AREA)
• Control Of El Displays (AREA)

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Applications Claiming Priority (2)

Publications (1)

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Cited By (1)

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• 2008
  • 2008-05-07 GB GB0808178.8A patent/GB2460018B/en not_active Expired - Fee Related
• 2009
  • 2009-03-31 CN CN200980123786.3A patent/CN102067202B/zh not_active Expired - Fee Related
  • 2009-03-31 KR KR1020107027514A patent/KR20110003583A/ko not_active Ceased
  • 2009-03-31 US US12/991,334 patent/US20110096066A1/en not_active Abandoned
  • 2009-03-31 WO PCT/GB2009/000866 patent/WO2009136134A1/en not_active Ceased
  • 2009-03-31 JP JP2011507978A patent/JP2011529195A/ja active Pending
  • 2009-03-31 DE DE112009001143T patent/DE112009001143T5/de not_active Withdrawn

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