TWI460705B - 顯示裝置及其調光方法 - Google Patents

顯示裝置及其調光方法 Download PDF

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TWI460705B
TWI460705B TW101133965A TW101133965A TWI460705B TW I460705 B TWI460705 B TW I460705B TW 101133965 A TW101133965 A TW 101133965A TW 101133965 A TW101133965 A TW 101133965A TW I460705 B TWI460705 B TW I460705B
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Taiwan
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voltage
threshold
switch circuit
emitting diode
compensation
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TW101133965A
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TW201413685A (zh
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Cheng Chung Yang
Liang Lu Chen
Chun Yu Chen
Hong Ru Guo
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Innocom Tech Shenzhen Co Ltd
Innolux Corp
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Priority to TW101133965A priority Critical patent/TWI460705B/zh
Priority to US14/013,997 priority patent/US9076372B2/en
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    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09GARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G5/00Control arrangements or circuits for visual indicators common to cathode-ray tube indicators and other visual indicators
    • G09G5/10Intensity circuits
    • 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
    • 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]
    • GPHYSICS
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    • 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]
    • G09G3/3275Details of drivers for data electrodes
    • G09G3/3283Details 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
    • 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]
    • G09G3/3275Details of drivers for data electrodes
    • G09G3/3291Details of drivers for data electrodes in which the data driver supplies a variable data voltage for setting the current through, or the voltage across, the light-emitting elements
    • 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
    • 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
    • G09G2320/00Control of display operating conditions
    • G09G2320/02Improving the quality of display appearance
    • G09G2320/0233Improving the luminance or brightness uniformity across the screen
    • 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
    • G09G2320/02Improving the quality of display appearance
    • G09G2320/029Improving the quality of display appearance by monitoring one or more pixels in the display panel, e.g. by monitoring a fixed reference pixel
    • G09G2320/0295Improving the quality of display appearance by monitoring one or more pixels in the display panel, e.g. by monitoring a fixed reference pixel by monitoring each display pixel
    • 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
    • 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
    • G09G2320/06Adjustment of display parameters
    • G09G2320/0626Adjustment of display parameters for control of overall brightness
    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09GARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2360/00Aspects of the architecture of display systems
    • G09G2360/14Detecting light within display terminals, e.g. using a single or a plurality of photosensors
    • G09G2360/145Detecting light within display terminals, e.g. using a single or a plurality of photosensors the light originating from the display screen
    • G09G2360/147Detecting light within display terminals, e.g. using a single or a plurality of photosensors the light originating from the display screen the originated light output being determined for each pixel

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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)
  • Control Of El Displays (AREA)
  • Electroluminescent Light Sources (AREA)

Description

顯示裝置及其調光方法
本發明係關於一種顯示裝置及其調光方法,特別是關於可以改變驅動電晶體的臨界電壓的一種顯示裝置及其調光方法。
隨著電腦、手機、電視機等各種影音媒體設備的普及,用來呈現影像畫面的顯示裝置也越來越廣泛地應用於生產及生活中。於一般有機發光二極體(Organic Light Emission Diode,OLED)顯示裝置中,利用多個電晶體來控制與驅動發光二極體,使得每一個發光二極體能夠發射出適當的亮度。
舉例來說,圖1係繪示了習知技術之OLED顯示裝置的電路示意圖。如圖1所示,顯示裝置9具有開關電晶體90、電容92、驅動電晶體94以及發光二極體96。開關電晶體90受控於掃描線Scan而選擇性地將資料線Data上的灰階電壓儲存至電容92中,藉以調整驅動電晶體94所輸出的驅動電流。然而,不同的電晶體於出廠時的半導體特性(例如臨界電壓)都存在著誤差,儘管可以提供相同的灰階電壓至驅動電晶體94,但驅動電晶體94用以驅動發光二極體96的驅動電流不會完全相同。
從顯示畫面來看,驅動電流的差異會使畫面亮度分布不均勻(mura),而影響著使用者的觀影品質。為了因應畫面亮度分布不均問題,需要增加每個畫素組內的電路架構以補償驅動電流差異,但是額外的電路架構會導 致畫素開口率降低。因此,業界需要一種新的顯示裝置,而所述顯示裝置不需大量增加每個畫素組內的如何以簡單的電路架構,即可根據顯示畫面的亮度分布情況而調整其中平均化的發光二極體的驅動電流是未來的設計趨勢。
有鑑於此,本發明在於提出一種顯示裝置,所述顯示裝置中的驅動電晶體係改成四端元件,使得驅動電晶體可以依據補償電壓的大小以調變臨界電壓的數值,藉此調整輸出的驅動電流以改變發光二極體的亮度。
本發明實施例提供一種顯示裝置,所述顯示裝置具有發光二極體以及驅動模組。所述驅動模組用以驅動發光二極體,且驅動模組包括第一開關電路、第二開關電路以及驅動電晶體。第一開關電路選擇性地將灰階電壓寫入第一電容,第二開關電路選擇性地將補償電壓寫入第二電容。驅動電晶體分別耦接發光二極體、第一電容與第二電容,且驅動電晶體受控於灰階電壓與補償電壓,據以調整輸出給發光二極體的驅動電流。其中,灰階電壓調整驅動電晶體的閘極與源極電壓差,且補償電壓調整驅動電晶體的臨界電壓。
於本發明一實施例中,當發光二極體的亮度低於第一門限值時,補償電壓係用以降低驅動電晶體的臨界電壓,據以增加驅動電流,而當發光二極體的亮度高於第二門限值時,補償電壓係用以提高驅動電晶體的臨界電壓,據以減少驅動電流。在此,所述多組畫素組係以影像擷取裝置拍攝畫面,並經由處理裝置判斷於影像擷取 裝置拍攝到的畫面中,每一組畫素組中的發光二極體的亮度是否低於第一門限值或者高於第二門限值。另外,第一開關電路與第二開關電路為開關電晶體,第二開關電路耦接補償資料線,補償資料線係用以傳輸補償控制模組所輸出的補償電壓,且補償控制模組依據處理裝置的判斷結果調整補償電壓。其中,第一開關電路耦接灰階資料線,灰階資料線係用以傳輸灰階控制模組所輸出的灰階電壓,且第一開關電路與第二開關電路受控於同一掃描線而同時導通或截止。
於本發明另一實施例中,第一開關電路與第二開關電路為開關電晶體,第一開關電路與第二開關電路耦接同一資料線,所述資料線分別耦接灰階控制模組與補償控制模組,且所述資料線分時地傳送灰階電壓或補償電壓。其中,第一開關電路與第二開關電路分別受控於第一掃描線與第二掃描線,當第一掃描線控制第一開關電路導通時,資料線傳輸灰階控制模組所輸出的灰階電壓,當第二掃描線控制第二開關電路導通時,資料線傳輸補償控制模組所輸出的補償電壓。
本發明在於提出一種顯示裝置的調光方法,可判斷顯示畫面的亮度,適應性地調變驅動電晶體的臨界電壓的數值,藉此調整驅動電晶體輸出的驅動電流以改變發光二極體的亮度。
本發明實施例提供一種顯示裝置的調光方法,所述顯示裝置具有複數個畫素組,每一組畫素組具有發光二極體與驅動模組,驅動模組具有第一開關電路、第二開關電路以及驅動電晶體,且驅動電晶體受控於灰階電壓 與補償電壓,據以調整輸出給發光二極體的驅動電流。所述方法包括下列步驟:判斷發光二極體的亮度是否低於第一門限值或者高於第二門限值;當發光二極體的亮度低於第一門限值時,調整補償電壓以降低驅動電晶體的臨界電壓,據以增加驅動電流;當發光二極體的亮度高於第二門限值時,調整補償電壓以提高驅動電晶體的臨界電壓,據以減少驅動電流。
綜上所述,本發明實施例提供之顯示裝置及其調光方法,可根據顯示畫面的亮度而調整輸出給驅動電晶體的補償電壓,使得驅動電晶體可以依據補償電壓的大小以調變臨界電壓的數值,藉此調整驅動電晶體輸出的驅動電流以改變發光二極體的亮度。如此一來,所述顯示裝置的顯示畫面可以減少或避免亮度不均的問題,從而改善使用者的觀影品質。
為使能更進一步瞭解本創作之特徵及技術內容,請參閱以下有關本創作之詳細說明與附圖,但是此等說明與所附圖式僅係用來說明本創作,而非對本創作的權利範圍作任何的限制。
請一併參見圖2A與圖2B,圖2A係繪示依據本發明一實施例之顯示裝置的局部電路示意圖,圖2B係繪示依據本發明一實施例之顯示裝置的局部剖面示意圖。如圖所示,顯示裝置1具有複數個畫素組,每一個畫素組中至少具有發光二極體20以及驅動模組(包括元件符號10、12、14、16、18),使得驅動模組可以驅動發光二極體20。詳細來說,驅動模組裡的第一開關電路 10分別耦接灰階資料線D1、第一電容14以及驅動電晶體18,第二開關電路12分別耦接補償資料線D2、第二電容16以及驅動電晶體18。驅動電晶體18為四端元件,驅動電晶體18的第一閘極端分別耦接第一開關電路10與第一電容14,驅動電晶體18的第二閘極端分別耦接第二開關電路12與第二電容16,驅動電晶體18的汲極端耦接高電壓端Vdd,而驅動電晶體18的源極端經過發光二極體20耦接低電壓端Vss。以下分別就顯示裝置1中的各部元件做更進一步地說明。
第一開關電路10係受控於掃描線S1而選擇性地導通或截止,當第一開關電路10被導通時,灰階資料線D1上承載的灰階電壓便可以順利寫入第一電容14。於實務上,掃描線S1可以連接到顯示裝置1中的閘極驅動器(未繪示),並由閘極驅動器決定是否導通第一開關電路10。在此,雖然圖2A係以電晶體為例子描繪出第一開關電路10的一種可能的實施方式,但是本發明之第一開關電路10不應以電晶體為限。舉例來說,第一開關電路10可以由多個電晶體所組成或者選用其他的開關元件來替代開關電晶體,於所屬技術領域具有通常知識者可以視需要自由設計。
請繼續參見圖2A,第二開關電路12同樣受控於掃描線S1而選擇性地導通或截止,當第二開關電路12被導通時,補償資料線D2上承載的補償電壓便可以順利寫入第二電容16。在此實施例中,掃描線S1上所承載的控制信號同時控制著第一開關電路10與第二開關電路12,即閘極驅動器(未繪示)同時控制是否寫入灰階電 壓與補償電壓,但本發明並不應以此為限。請注意,本實施例僅繪示了一種可能的電路連接關係,然而只要驅動電晶體18仍可由灰階電壓與補償電壓調整驅動電流,於所屬技術領域具有通常知識者也可以適當改變成其他等效的電路連接關係。
為了更清楚驅動電晶體18的實體結構與元件特性,請參見圖2B所繪示的驅動電晶體18的剖面示意圖。首先,基板302可以是玻璃或塑膠材質,且基板302上會設置有附著層304以利於在基板302上設置其他功能層。驅動電晶體18的閘極層306係設置在附著層304上,並且閘極層306以及附著層304上再設置絕緣層308。通道層310係設置在絕緣層308上,且部分的絕緣層308與通道層310上更具有蝕刻終止層312,以避免蝕刻終止層312下方的結構於蝕刻過程中損壞。閘極層306可以是單層或多層的銅、鋁、鉬、鈦等金屬/合金所構成。附著層304、絕緣層308及蝕刻終止層312可以是單層或多層的矽的氧化物(SiOx)或氮化物(SiNx)結構。
接著,電極層314設置在蝕刻終止層312上,並且接觸部分的通道層310。於實務上,於圖2B中接觸通道層310左側的電極層314可視為圖2A中的驅動電晶體18的汲極,即左側的電極層314會電性連接至高電壓端Vdd。另外,於圖2B中接觸通道層310右側的電極層314可視為圖2A中的驅動電晶體18的源極。於電極層314上方設置保護層316之後,為了使接下來的製程更順利,於實務上還會設置一層平坦層318,以形成一個較為平整的平面。電極層314可以是單層或多層的銅、 鋁、鉬、鈦等金屬/合金所構成。平坦層318材料可以是有機樹脂。
一般來說,圖2A中的發光二極體20係為圖2B中右側電極層320、發光二極體層324以及電極層326直接層疊起來的區域(也就是面板上的發光區域),而圖2B中左側電極層320上方還具有絕緣層322(也就是面板上的非發光區域)。在此,發光二極體層324可以是有機發光二極體材料所製成,而電極層320以及電極層326分別是發光二極體層324的陽極與陰極。換句話說,發光二極體20實際上可以為一種有機發光二極體(OLED),且電極層320以及電極層326可以由透明導電材料(例如ITO)或者其他適當的材料製成。絕緣層322材料可以是有機樹脂。
請注意,圖2B中分別繪示有兩個區塊的電極層320,於右側的電極層320係接觸通道層310右側的電極層314(即驅動電晶體18的源極),而左側的電極層320係位於通道層310之上。從半導體的原理可知,當左側的電極層320提供正電壓時,電子較易聚集而形成電流通道,使得驅動電晶體18的臨界電壓將會降低,而驅動電晶體18輸出的驅動電流會隨之提高。相反的,當左側的電極層320提供負電壓時,電子不較易聚集成電流通道,使得驅動電晶體18的臨界電壓將會提高,而驅動電晶體18輸出的驅動電流會隨之降低。
據此,藉由本實施例中的驅動電晶體18的設計,使得顯示裝置1中每個畫素組不需大幅增加電晶體的數量,也可以簡易地藉由儲存於第二電容16中的補償電 壓調整驅動電晶體18的臨界電壓,從而調整了驅動電晶體18輸出給的發光二極體20的驅動電流。
為了舉出顯示裝置1其他的等效電路連接關係,本發明更揭露了另一種可能的實施方式。請參見圖3,圖3係繪示依據本發明另一實施例之顯示裝置的局部電路示意圖。如圖3所示,顯示裝置4同樣可具有複數個畫素組,每一個畫素組中至少具有發光二極體50以及驅動模組(包括元件符號40、42、44、46、48),使得驅動模組可以驅動發光二極體50。與前一實施例相同的是,電容44、電容46、驅動電晶體48以及發光二極體50的電路連接關係與作動方式,本實施例在此不予贅述。與前一實施例不同的是,第一開關電路40與第二開關電路42係連接到同一條資料線D3,並且分別受控於不同的掃描線S2、S3。
詳細來說,資料線D3會分時地傳送灰階電壓與補償電壓,而傳送灰階電壓或補償電壓的時段應恰好對應掃描線S2、S3控制第一開關電路40或第二開關電路42導通的時段。舉例來說,第一開關電路40係受控於掃描線S2而選擇性地導通或截止,當第一開關電路40被導通時,資料線D3應恰好傳送著灰階電壓,使得灰階電壓便可以順利寫入電容44。另一方面,當灰階電壓寫入電容44後且第二開關電路42被導通時,資料線D3可以轉而傳送補償電壓,使得補償電壓便可以順利寫入電容46。在此,本實施例並不限制傳送灰階電壓與補償電壓的順序或者傳送時間長短,於所屬技術領域具有通常知識者可以視需要自由設計。
當然,雖然圖3同樣以電晶體為例子描繪出第一開關電路40與第二開關電路42的一種可能的實施方式,但是本發明之第一開關電路40與第二開關電路42同樣不應以電晶體為限。
以圖3實際的例子來說,為了判斷顯示裝置4是否產生畫面亮度分布不均勻(mura效應)的問題,於進行品管或是檢測時,更可以先利用一組影像擷取裝置(未繪示)拍攝顯示裝置4於發光時的畫面,所述影像擷取裝置例如可以選用CCD攝影機或其他適當的攝影器材。接著,更可經由處理裝置(未繪示)觀察或判斷於影像擷取裝置拍攝到的畫面中,每一組畫素組中的發光二極體50的亮度是否符合標準,例如亮度是否低於第一門限值(即太暗)或是否高於第二門限值(即太亮)。當然,第一門限值與第二門限值可預先由使用者自行選定,第一門限值與第二門限值可以相等,或是分別為一個範圍區間內的下限與上限,本實施例在此不加以限制。
於實務上,第一門限值與第二門限值可以預先被設置在一個查找表中,所述查找表可以記錄著亮度對應補償電壓的關係。舉例來說,當處理裝置判斷某一個畫素組中的發光二極體50太暗或太亮時,可以藉由查找表找出適於補償驅動電晶體48的補償電壓,並經由第二開關電路42儲存在電容46中。據此,驅動電晶體48的臨界電壓可以被動態地調整,所述畫素組的亮度於補償後均在一個可接受的範圍內。
從實際測量的數據來看,請一併參見圖4A、圖4B以及圖4C,圖4A係繪示依據本發明一實施例之驅動電 晶體的電路示意圖,圖4B係繪示依據本發明一實施例之驅動電流、灰階電壓與補償電壓的關係曲線圖,圖4C係繪示依據本發明一實施例之驅動電晶體的臨界電壓與補償電壓的關係曲線圖。驅動電晶體6具有第一閘極端VG、第二閘極端VG’、源極端VS與閘極端VD,第一閘極端VG係用以耦接前一實施例的第一開關電路與儲存灰階電壓的電容,而第二閘極端VG’係用以耦接前一實施例的第二開關電路與儲存補償電壓的電容。
由圖4B的實際數據可知,在灰階電壓不變的情況下(例如VG為8V時),第二閘極端VG’收到的補償電壓越高,則驅動電流Id明顯會隨著提高。此外,由圖4C的實際數據可知,第二閘極端VG’收到的補償電壓愈高,則驅動電晶體6的臨界電壓Vth會越低,從電晶體的基礎電流公式可知,臨界電壓Vth越低則驅動電流Id必然會越高,而臨界電壓Vth越高則驅動電流Id會隨著越低。藉此,本實施例提供的驅動電晶體6可以輕易地用不同的補償電壓調整輸出給發光二極體的驅動電流。
為了使所屬技術領域具有通常知識者能了解本發明之精神,以下將本發明之顯示裝置搭配顯示裝置之調光方法做更清楚地說明。
請一併參見圖3與圖5,圖5係繪示依據本發明一實施例之顯示裝置的調光方法的流程圖。如圖所示,於步驟S70中,本實施例會先利用一組影像擷取裝置(未繪示)拍攝顯示裝置4於發光時的畫面,並由處理裝置(未繪示)判斷於影像擷取裝置拍攝到的畫面中,每一組畫素組中的發光二極體50的亮度是否低於第一門限值(即太 暗)或是否高於第二門限值(即太亮)。
於步驟S72中,當處理裝置判斷某一個畫素組中的發光二極體50太暗時,會將輸出給電容46的補償電壓提高,據以降低驅動電晶體48的臨界電壓,使得流經發光二極體50的驅動電流提高,從而增加發光二極體50的亮度。於步驟S74中,當處理裝置判斷某一個畫素組中的發光二極體50太亮時,會將輸出給電容46的補償電壓降低,據以提高驅動電晶體48的臨界電壓,使得流經發光二極體50的驅動電流降低,從而減少發光二極體50的亮度。
綜上所述,本發明實施例提供之顯示裝置及其調光方法,可根據顯示畫面的亮度而調整輸出給驅動電晶體的補償電壓,使得驅動電晶體可以依據補償電壓的大小而調變臨界電壓的數值,藉此調整驅動電晶體輸出的驅動電流以改變發光二極體的亮度。如此一來,所述顯示裝置的顯示畫面可以減少或避免亮度不均的問題,從而改善使用者的觀影品質。
藉由以上較佳具體實施例之詳述,係希望能更加清楚描述本發明之特徵與精神,而並非以上述所揭露的較佳具體實施例來對本發明之範疇加以限制。相反地,其目的是希望能涵蓋各種改變及具相等性的安排於本發明所欲申請之專利範圍的範疇內。
1‧‧‧顯示裝置
10‧‧‧第一開關電路
12‧‧‧第二開關電路
14‧‧‧第一電容
16‧‧‧第二電容
18‧‧‧驅動電晶體
20‧‧‧發光二極體
S1‧‧‧掃描線
D1‧‧‧灰階資料線
D2‧‧‧補償資料線
Vdd‧‧‧高電壓端
Vss‧‧‧低電壓端
302‧‧‧玻璃基板
304‧‧‧附著層
306‧‧‧閘極層
308‧‧‧絕緣層
310‧‧‧通道層
312‧‧‧蝕刻終止層
314‧‧‧電極層
316‧‧‧保護層
318‧‧‧平坦層
320‧‧‧電極層
322‧‧‧絕緣層
324‧‧‧發光二極體層
326‧‧‧電極層
4‧‧‧顯示裝置
40‧‧‧第一開關電路
42‧‧‧第二開關電路
44‧‧‧電容
46‧‧‧電容
48‧‧‧驅動電晶體
50‧‧‧發光二極體
S2‧‧‧掃描線
S3‧‧‧掃描線
D3‧‧‧資料線
6‧‧‧驅動電晶體
VG‧‧‧第一閘極端
VG’‧‧‧第二閘極端
VS‧‧‧源極端
VD‧‧‧閘極端
Id‧‧‧驅動電流
S70~S74‧‧‧步驟流程
9‧‧‧顯示裝置
90‧‧‧開關電晶體
92‧‧‧電容
94‧‧‧驅動電晶體
96‧‧‧發光二極體
Scan‧‧‧掃描線
Data‧‧‧資料線
圖1係繪示了習知技術之顯示裝置的電路示意圖。
圖2A係繪示依據本發明一實施例之顯示裝置的局部電路示意圖。
圖2B係繪示依據本發明一實施例之顯示裝置的局部剖面示意圖。
圖3係繪示依據本發明另一實施例之顯示裝置的局部電路示意圖。
圖4A係繪示依據本發明一實施例之驅動電晶體的電路示意圖。
圖4B係繪示依據本發明一實施例之驅動電流、灰階電壓與補償電壓的關係曲線圖。
圖4C係繪示依據本發明一實施例之驅動電晶體的臨界電壓與補償電壓的關係曲線圖。
圖5係繪示依據本發明一實施例之顯示裝置的調光方法的流程圖。
1‧‧‧顯示裝置
10‧‧‧第一開關電路
12‧‧‧第二開關電路
14‧‧‧第一電容
16‧‧‧第二電容
18‧‧‧驅動電晶體
20‧‧‧發光二極體
S1‧‧‧掃描線
D1‧‧‧灰階資料線
D2‧‧‧補償資料線
Vdd‧‧‧高電壓端
Vss‧‧‧低電壓端

Claims (8)

  1. 一種顯示裝置,具有複數個畫素組,每一該畫素組至少包括:一發光二極體;以及一驅動模組,用以驅動該發光二極體,該驅動模組包括:一第一開關電路,選擇性地將一灰階電壓寫入一第一電容;一第二開關電路,選擇性地將一補償電壓寫入一第二電容;以及一驅動電晶體,分別耦接該發光二極體、該第一電容與該第二電容,受控於該灰階電壓與該補償電壓,據以調整輸出給該發光二極體的一驅動電流;其中該灰階電壓調整該驅動電晶體的一閘極與源極電壓差,且該補償電壓調整該驅動電晶體的一臨界電壓;其中當該發光二極體的亮度低於一第一門限值時,該補償電壓係用以降低該驅動電晶體的該臨界電壓,據以增加該驅動電流;當該發光二極體的亮度高於一第二門限值時,該補償電壓係用以提高該驅動電晶體的該臨界電壓,據以減少該驅動電流。
  2. 如申請專利範圍第1項所述之顯示裝置,其中該些畫素組係以一影像擷取裝置拍攝畫面,並經由一處理裝置判斷於該影像擷取裝置拍攝到的畫面中,每一該畫素組中的該發光二極體的亮度是否低於該第一門限值或者高於該第二門限值。
  3. 如申請專利範圍第2項所述之顯示裝置,其中該第一開關電路與該第二開關電路為開關電晶體,該第二開關電路耦接一補償資料線,該補償資料線係用以傳輸一補償控制模組所輸出的該補償電壓,且該補償控制模組依據該處理裝置的判斷結果調整該補償電壓。
  4. 如申請專利範圍第3項所述之顯示裝置,其中該第一開關電路耦接一灰階資料線,該灰階資料線係用以傳輸一灰階控制模組所輸出的該灰階電壓,且該第一開關電路與該第二開關電路受控於同一掃描線而同時導通或截止。
  5. 如申請專利範圍第2項所述之顯示裝置,其中該第一開關電路與該第二開關電路為開關電晶體,該第一開關電路與該第二開關電路耦接同一資料線,該資料線分別耦接一灰階控制模組與一補償控制模組,且該資料線分時地傳送該灰階電壓或該補償電壓。
  6. 如申請專利範圍第5項所述之顯示裝置,其中該第一開關電路與該第二開關電路分別受控於一第一掃描線與一第二掃描線,當該第一掃描線控制該第一開關電路導通時,該資料線傳輸該灰階控制模組所輸出的該灰階電壓,當該第二掃描線控制該第二開關電路導通時,該資料線傳輸該補償控制模組所輸出的該補償電壓。
  7. 一種顯示裝置的調光方法,所述顯示裝置具有複數個畫素組,每一該畫素組具有一發光二極體與一驅動模組,該驅動模組具有一第一開關電路、一第二開關電路以及一驅動電晶體,且該驅動電晶體受控於一灰階電壓與一補償電壓,據 以調整輸出給該發光二極體的一驅動電流,所述方法包括下列步驟:判斷發光二極體的亮度是否低於一第一門限值或者高於一第二門限值;當該發光二極體的亮度低於該第一門限值時,調整該補償電壓以降低該驅動電晶體的該臨界電壓,據以增加該驅動電流;以及當該發光二極體的亮度高於該第二門限值時,調整該補償電壓以提高該驅動電晶體的該臨界電壓,據以減少該驅動電流。
  8. 如申請專利範圍第7項所述之顯示裝置的調光方法,其中於判斷發光二極體的亮度是否低於該第一門限值或者高於該第二門限值的步驟中,更包括下列步驟:拍攝包含該些畫素組的畫面;以及判斷於拍攝到的畫面中,每一該畫素組中的該發光二極體的亮度是否低於該第一門限值或者高於該第二門限值。
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