KR20080062307A - Organic light emitting diode display device and method of driving the same - Google Patents
Organic light emitting diode display device and method of driving the same Download PDFInfo
- Publication number
- KR20080062307A KR20080062307A KR1020060137922A KR20060137922A KR20080062307A KR 20080062307 A KR20080062307 A KR 20080062307A KR 1020060137922 A KR1020060137922 A KR 1020060137922A KR 20060137922 A KR20060137922 A KR 20060137922A KR 20080062307 A KR20080062307 A KR 20080062307A
- Authority
- KR
- South Korea
- Prior art keywords
- thin film
- film transistor
- voltage
- driving
- storage capacitor
- Prior art date
Links
Images
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]
- G09G3/3225—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
- G09G3/3258—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 voltage across the light-emitting element
-
- 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
- G09G2310/0251—Precharge or discharge of pixel before applying new pixel voltage
-
- 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
- G09G2320/0233—Improving the luminance or brightness uniformity across the screen
-
- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G2330/00—Aspects of power supply; Aspects of display protection and defect management
- G09G2330/02—Details of power systems and of start or stop of display operation
- G09G2330/028—Generation of voltages supplied to electrode drivers in a matrix display other than LCD
Abstract
The present invention provides an organic light emitting diode display device and a driving method thereof capable of ensuring luminance uniformity regardless of a characteristic variation of a thin film transistor.
To this end, the present invention provides an organic light emitting diode comprising: an organic light emitting diode; Disclosed are an organic light emitting diode display including a pixel driver that adjusts an emission time of the organic light emitting diode according to a data voltage, and a driving method thereof.
Description
1 is an equivalent circuit diagram of a basic pixel of an organic light emitting diode display according to a first exemplary embodiment of the present invention.
FIG. 2 is a driving waveform diagram of the pixel driver shown in FIG. 1. FIG.
FIG. 3 is a graph illustrating light emission time according to the gradation of the pixel illustrated in FIG. 1.
4 is an equivalent circuit diagram of a basic pixel of an organic light emitting diode display according to a second exemplary embodiment of the present invention.
5 is an equivalent circuit diagram of a basic pixel of an organic light emitting diode display according to a third exemplary embodiment of the present invention.
6 is an equivalent circuit diagram of a basic pixel of an organic light emitting diode display according to a fourth exemplary embodiment of the present invention.
FIG. 7 is a driving waveform diagram of the pixel driver shown in FIG. 6; FIG.
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic light emitting diode (OLED) display device, and more particularly, to an OLED display device and a driving method thereof capable of preventing luminance unevenness due to differences in characteristics of thin film transistors.
The OLED display is a self-luminous device that emits an organic light emitting layer by recombination of electrons and holes, and is expected to be a next generation display device because of its high brightness, low driving voltage, and ultra-thin film.
Each of the pixels constituting the OLED display device includes an organic light emitting diode composed of an organic light emitting layer between an anode and a cathode, and a pixel driver for independently driving the organic light emitting diode. The pixel driver mainly includes a switch thin film transistor and a capacitor, and a driving thin film transistor. The switch thin film transistor charges the data signal to the capacitor in response to the scan pulse, and the driving thin film transistor adjusts the magnitude of the current supplied to the OLED according to the magnitude of the data voltage charged in the capacitor to implement the gray scale. At this time, when the uniformity of the threshold voltage of the driving thin film transistor is not constant, the current flowing through the driving thin film transistor is not uniform, resulting in uneven luminance and unevenness.
In order to solve this problem, a digital driving method for realizing grayscales by adjusting the emission period of the OLED according to data has been proposed. The digital driving method divides one frame into first to sixth subframes SF1 to SF6 when it is desired to display a plurality of subframes corresponding to each bit of data, that is, 6 bits of video data. Each of the first to sixth subframes SF1 to SF6 includes a scan period and a light emission period, and different weights are assigned to the light emission periods of each subframe, so that each of the first to sixth subframes SF1 to SF6 is assigned. The ratio of the light emission periods is 1: 2: 4: 8: 16: 32. In addition, the digital driving method causes the OLED to emit or not emit light in each subframe according to the video data, and implements gradation by combining the emission time of the subframe in which the OLED is emitted.
However, the digital driving method requires high speed driving by dividing one frame into a number of subframes by the number of bits of data. Therefore, the mobility of the thin film transistor must be large and the resistance of the signal line must be small. There is a problem that is difficult to apply. In addition, since the light emission time is insufficient due to the division of a plurality of subframes, the voltage applied to the OLED needs to be increased in order to maintain the same brightness, thereby increasing the power consumption of the OLED and reducing its lifespan.
Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide an OLED display device and a driving method thereof capable of ensuring luminance uniformity regardless of characteristics variation of a thin film transistor.
In addition, the present invention provides an OLED display device and a driving method thereof using amorphous silicon or polysilicon thin film transistors and applicable to high resolution.
In addition, the present invention is to provide an OLED display device and a driving method thereof that can reduce power consumption and extend a lifespan.
To this end, the OLED display device according to the present invention comprises: each of the plurality of pixels includes an organic light emitting diode; And a pixel driver configured to adjust a light emission time of the organic light emitting diode according to the data voltage.
The pixel driver may include a switch thin film transistor configured to output a data voltage of a data line in response to a gate voltage of a gate line; A storage capacitor charging the data voltage from the switch thin film transistor; A driving thin film transistor for driving the organic light emitting diode; A control thin film transistor configured to adjust an on time of the driving thin film transistor in proportion to a magnitude of the data voltage charged in the storage capacitor; A resistor connected between a power line and said storage capacitor; And an auxiliary capacitor connected between the power supply line and the gate electrode of the driving thin film transistor.
The storage capacitor charges a negative data voltage, and the control thin film transistor adjusts an on time of the driving thin film transistor in proportion to a discharge time of the data voltage charged in the storage capacitor. The power line supplies a low power supply voltage during a data charging period during which the storage capacitor charges the data voltage, a high power supply voltage during a period during which the storage capacitor discharges the charged data voltage, and the data voltage is charged. The low power supply voltage is supplied in the previous reset period. The control thin film transistor is turned on when the gate voltage reaches the threshold voltage due to the discharge of the storage capacitor, thereby turning off the driving thin film transistor.
The source electrode of the driving thin film transistor is connected to the anode of the organic light emitting diode, and the drain electrode is connected to the power line. The source electrode of the control thin film transistor is connected to the source electrode of the driving thin film transistor.
The present invention further includes a low potential voltage line connected to the source electrode of the control thin film transistor and supplying a low potential voltage lower than the source voltage of the driving thin film transistor.
As the switch, control, and driving thin film transistor, an amorphous silicon or polysilicon thin film transistor is applied.
The present invention further includes a DC power supply line connected to a drain electrode of the driving thin film transistor or an anode of the organic light emitting diode to supply a DC power supply voltage different from the power supply voltage. The organic light emitting diode is connected to a source electrode or a drain electrode of the driving thin film transistor.
The pixel driver may include a first switch thin film transistor configured to output a data voltage of a data line in response to a gate voltage of a gate line; A first storage capacitor charging the data voltage from the switch thin film transistor; A driving thin film transistor for driving the organic light emitting diode; A control thin film transistor configured to adjust an on time of the driving thin film transistor in proportion to a magnitude of the data voltage charged in the storage capacitor; A resistor connected between a first power line and said storage capacitor; A second switch thin film transistor connecting a first power supply line to a gate electrode of the driving thin film transistor in response to the gate voltage; A second storage capacitor configured to charge a first power supply voltage from the first power supply line via the second switch thin film transistor; And a second power supply line connected to the anode of the organic light emitting diode.
The storage capacitor charges a negative data voltage, and the control thin film transistor adjusts an on time of the driving thin film transistor in proportion to a discharge time of the data voltage charged in the storage capacitor. The second power line supplies a negative voltage to the anode of the organic light emitting diode only during a data charging period in which the first and second switch thin film transistors are turned on, and supplies a positive voltage in the remaining period. The control thin film transistor is turned on when the gate voltage reaches the threshold voltage due to the discharge of the storage capacitor, thereby turning off the driving thin film transistor. The source electrode of the control thin film transistor is connected to the source electrode of the driving thin film transistor.
According to another aspect of the present invention, there is provided a method of driving an organic light emitting diode display, the method comprising: charging a data voltage to a storage capacitor of each pixel driver; And adjusting an emission time of the organic light emitting diode according to the magnitude of the data voltage of the charged data voltage. The storage capacitor charges a negative voltage with the data voltage through a switch thin film transistor in a data charge period; Driving the organic light emitting diode by turning on a driving thin film transistor in a light emitting period; The driving time of the driving thin film transistor, which determines the emission time, is controlled by switching a control thin film transistor according to the discharge voltage of the storage capacitor.
According to another aspect of the present invention, a method of driving an organic light emitting diode display includes driving a first switch thin film transistor to charge a data voltage to a first storage capacitor and simultaneously driving a second switch thin film transistor to provide a second storage capacitor. Charging a power supply voltage; Driving a driving thin film transistor with a first power voltage charged in the second storage capacitor to emit an organic light emitting diode to which a second power voltage is supplied; And controlling a light emitting time of the organic light emitting diode by controlling a driving time of the driving thin film transistor by switching a control thin film transistor according to a discharge voltage of the first storage capacitor. The second power supply voltage supplies a positive voltage to the organic light emitting diode, and provides a negative voltage only during a period when the first power supply voltage is charged to the second storage capacitor.
Other features and advantages of the present invention in addition to the features of the present invention will become apparent from the description of the preferred embodiment of the present invention with reference to the accompanying drawings.
Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to FIGS. 1 to 7.
FIG. 1 is an equivalent circuit diagram of a basic pixel of an OLED display according to a first exemplary embodiment of the present invention, and FIG. 2 is a driving waveform diagram of a pixel driver shown in FIG. 1.
The pixel shown in FIG. 1 includes an OLED, a switch thin film transistor TS, a control thin film transistor TC, a storage capacitor C1 and an auxiliary capacitor C2, a resistor R, and a driving thin film transistor to drive the OLED. And a pixel driver including TD).
The gate electrode of the switch thin film transistor TS is connected to the gate line GL, the source electrode is connected to the data line DL, and the drain electrode is connected to the first node N1. The gate electrode of the control thin film transistor TC is connected to the first node N1, the drain electrode to the second node N2, and the source electrode to the third node N3 connected to the OLED. The gate electrode of the driving thin film transistor TD is connected to the second node N2, the drain electrode is connected to the power supply line, and the source electrode is connected to the OLED. The storage capacitor C1 is between the first node N1 and the third node N3, the auxiliary capacitor C2 is between the power line and the second node N2, and the resistor R is the power line and the first node. It is connected between the nodes N1.
The switch thin film transistor TS receives the negative data voltage VD of the data line DL in response to the high gate voltage VG of the gate line GL in the data charging period B shown in FIG. 2. Supply to node N1 to charge storage capacitor C1. The control thin film transistor TC controls on / off of the driving thin film transistor TD and turns on the driving thin film transistor TD according to the magnitude of the data voltage VD (that is, the amount of charge) charged in the storage capacitor C1. Adjust the time For this purpose, the control thin film transistor TC is turned off in the data charging period B and the light emitting period C shown in FIG. 2, and turned on in the reset period A and the non-light emitting period. The driving thin film transistor TD is turned on in the light emission period C to supply the power supply voltage VP to the OLED to drive the OLED. The resistor R delays the voltage of the second node N2 to gradually converge toward the power supply voltage VP from the negative data voltage VD. The resistor R may be formed of a polysilicon layer, an amorphous silicon layer, a doped polysilicon layer, a doped amorphous silicon layer, or the like. The auxiliary capacitor C2 stabilizes the voltage of the second node N2.
Referring to FIG. 2, it can be seen that the pixel driver is driven including the reset period A, the data charging period B, the light emission period C, and the non-light emission period during one
In the reset period A, the power supply voltage VP of the power supply line PL is changed from high to low so that the second node N2 maintains a certain low state so that the driving thin film transistor TD remains in an off state. . This is to prevent the driving thin film transistor TD from malfunctioning due to the high state of the second node N2 due to the high voltage of the power supply voltage VP. At this time, since the control thin film transistor TC maintains the same on state as the previous non-emission period, the second node N2 maintains the same low state as the voltage of the third node N3. As shown in FIG. 2, the voltage of the second node N2 temporarily drops through the auxiliary capacitor C2 when the power supply voltage VP drops from high to low, and then maintains the low state.
In the data charging period B of one
In the light emission period C, the switch thin film transistor TS is turned off by the low gate voltage VG and the power supply voltage VP is changed to a high state. Accordingly, since the second node N2 is turned high through the auxiliary capacitor C2 and the driving thin film transistor TD is turned on, the power supply voltage VP is supplied to the anode of the OLED and the OLED emits light. In addition, as the power supply voltage VP becomes high, as the current flows through the resistor R, the voltage of the first node N1 gradually increases toward the high power supply voltage VP over time. When the voltage of the first node N1 increases to reach the threshold voltage of the control thin film transistor TC, the control thin film transistor TC is turned on and the voltage of the second node N2 is changed to that of the third node N3. Equal to voltage. Accordingly, the driving thin film transistor TD is turned off due to the same voltage between the gate electrode and the source electrode, and the OLED does not emit light for the remaining period of one
As described above, the OLED display according to the present invention implements grayscale by adjusting the emission time of the OLED according to the data voltage (charge amount) stored in the storage capacitor C1 of the pixel driver, so that the threshold voltage of the driving thin film transistor TD is variable. Uniform brightness can be obtained without affecting the brightness. In other words, the OLED display device according to the present invention corresponds to a linear region in which an operating region of the driving thin film transistor operates in a region where the gate voltage is higher than the drain voltage, as in general digital driving, and thus the threshold voltage variation of the driving thin film transistor is changed. As a result, the current variation can be reduced, and thus more uniform luminance can be obtained. In addition, although the gray scale is realized by adjusting the light emission time of the OLED, it is not necessary to divide one frame into a plurality of subframes as in a digital driving method, thereby sufficiently securing the OLED light emission time in one frame. Accordingly, the amorphous silicon thin film transistor having low mobility can be applied not only to the pixel driver but also to a high resolution display device. In addition, it is not necessary to increase the power supply voltage applied to the OLED, thereby reducing power consumption and extending the life of the OLED.
4 is an equivalent circuit diagram of a basic pixel of an OLED display according to a second exemplary embodiment of the present invention.
In contrast to the pixel driver shown in FIG. 1, the pixel driver shown in FIG. 4 has a first power supply voltage VP having a power supply voltage equal to the power supply voltage VP shown in FIG. 2, and a second power supply voltage supplied to the OLED. Since the same components are provided except those separated by VDD, detailed descriptions of the components duplicated with FIG. 1 will be omitted. The driving waveforms shown in FIG. 2 are equally applied to the pixel driver illustrated in FIG. 4, and a positive DC voltage is supplied to the second power supply voltage VDD line connected to the anode of the OLED. The OLED is connected between the second power supply voltage VDD line and the drain electrode of the driving thin film transistor TD as shown in FIG. 4, or the P point as shown in FIG. 1, that is, the source electrode and the base voltage line of the driving thin film transistor TD. Can be connected between.
In the reset period A, the first power supply voltage VP is changed from high to low, and the voltages of the second and third nodes N2 and N3 are the same by the control thin film transistor TC maintaining the on state. Therefore, the driving thin film transistor TD maintains the off state. In the data charging period B, the switch thin film transistor TS is turned on to charge the storage capacitor C1 with the negative data voltage VD of the data line DL, and the control thin film transistor TC is negative. It is turned off by the data voltage VD. In the light emission period C, the switch thin film transistor TS is turned off and the first power supply voltage VP and the second node N2 are changed to a high state so that the driving thin film transistor TD is turned on. Accordingly, the OLED emits light because the cathode of the OLED is connected to the base voltage line through the driving thin film transistor TD and a forward current flows through the OLED from the second power supply voltage VDD line. In addition, as the first power supply voltage VP becomes high, as the current flows through the resistor R, the voltage of the first node N1 gradually increases as time passes, thereby causing the threshold of the control thin film transistor TC. When the voltage is reached, the control thin film transistor TC is turned on and the driving thin film transistor TD is turned off, so that the OLED does not emit light for the remaining period of one
As described above, the pixel driver according to the present invention uses the power supply voltage as the first power supply voltage VP supplied to the second node N2 via the resistor R and the second power supply voltage VPDD supplied to the OLED. Separation facilitates driving of the driving thin film transistor TD in the light emission period C, which is a linear region. Accordingly, when the polysilicon thin film transistor is applied, laser streaks according to the scan position of the laser in the laser crystallization process may be removed.
5 is an equivalent circuit diagram of a basic pixel of an OLED display according to a third exemplary embodiment of the present invention.
5, except that the low-potential voltage VL is supplied to the third node N3 to which the source electrode of the control thin film transistor TC is connected as compared to the pixel driver shown in FIG. 1. Since the same components are provided, detailed descriptions of the components duplicated with those of FIG. 1 will be omitted.
When an amorphous thin film transistor is used as the switch thin film transistor TS, the control thin film transistor TC, and the driving thin film transistor TD shown in FIG. 5, the threshold voltage is shifted when a bias stress is applied to the gate electrode, and thus compensation is required. Done. To prevent this, the low potential is supplied through the control thin film transistor TC by supplying the low potential voltage VL to the source electrode of the control thin film transistor TC, which remains on for the period during which the driving thin film transistor TD is turned off. The voltage VL is applied to the gate electrode of the driving thin film transistor TD. In this case, the low potential voltage VL is set to be lower than the source voltage of the driving thin film transistor TD. Accordingly, since the bias stress is reduced by keeping the gate voltage VL of the off driving thin film transistor TD lower than the source voltage, the threshold voltage shift may be alleviated or the shifted threshold voltage may be compensated.
FIG. 6 is an equivalent circuit diagram of a basic pixel of an OLED display according to a fourth exemplary embodiment of the present invention, and FIG. 7 is a driving waveform diagram of a pixel driver shown in FIG. 6.
In contrast to the pixel driver shown in FIG. 1, the pixel driver shown in FIG. 6 is divided into first and second power voltages VP and VDD, and the gate driver VG is used instead of the auxiliary capacitor C2. A second switch thin film transistor TS2 is controlled and includes the same components except that a second storage capacitor C2 is further connected between the gate electrode and the source electrode of the driving thin film transistor TD. Detailed descriptions of the components duplicated with 1 will be omitted. Here, the first power supply voltage VP maintains a high voltage and is changed to a low voltage only in the data charging period B, and the second power supply voltage VDD maintains a positive DC voltage.
The second switch thin film transistor TS2 shown in FIG. 6 is turned on only during the data charging period B shown in FIG. 7 together with the first switch thin film transistor TS1 to convert the second power voltage VDD into the second storage capacitor. Charge to (C2). At this time, the driving thin film transistor TD is turned on by the second power supply voltage VDD supplied to the second node N2 to connect the cathode of the OLED and the base voltage line, but the anode of the OLED has a first power supply as shown in FIG. 7. Since the negative voltage is supplied to the voltage VP, the OLED does not emit light. Subsequently, in the emission period C, the driving thin film transistor TD is kept on by the second power supply voltage VDD charged in the second storage capacitor C2, and the first power supply voltage VP is applied to the anode of the OLED. As a positive voltage is supplied, the OLED emits light. When the negative data voltage charged in the first storage capacitor C1 is discharged through the resistor R to reach the threshold voltage, the driving thin film transistor TD is turned off by the turned-on control thin film transistor TC. OLEDs stop emitting light. As the second switch thin film transistor TS2 eliminates the need for the reset period A for resetting the second node N2 to the low state as shown in FIG. 2, the emission period C may be more secured to improve luminance. Can be.
In the data charging period B illustrated in FIG. 7, the first switch thin film transistor TS1 is turned on in response to the high gate voltage VG, so that the negative data voltage VD of the data line DL is stored in the storage capacitor C1. ) And the control thin film transistor TC is turned off by the negative data voltage VD. At the same time, the second switch thin film transistor TS2 is turned on in response to the high gate voltage VG, and a positive second power supply voltage VDD is supplied to the second node N2 to charge the second storage capacitor C2. The driving thin film transistor TD is turned on. Accordingly, although the cathode of the OLED is connected to the base voltage line through the turned-on driving thin film transistor TD, the OLED does not emit light because the negative first power supply voltage VP is supplied to the anode of the OLED.
Subsequently, in the emission period C, the first and second switch thin film transistors TS1 and TS2 are turned off and the driving thin film transistor TD is kept on by the voltage charged in the second storage capacitor C2. A positive first power supply voltage VP is supplied to the anode of the OLED. Accordingly, the OLED emits light because a forward current flows. When the current flows through the resistor R, the voltage of the first node N1 gradually increases toward the second power voltage VDD as time passes to reach the threshold voltage of the control thin film transistor TC. Since the control thin film transistor TC is turned on and the driving thin film transistor TD is turned off, the OLED stops emitting light and does not emit light for the remaining period of one
As described above, the OLED display device according to the present invention implements grayscale by adjusting the light emission time of the OLED in proportion to the data voltage (charge amount) charged in the storage capacitor of the pixel driver, so that the luminance is changed even when the threshold voltage of the driving thin film transistor is variable. It is possible to obtain a uniform brightness without affecting.
In addition, the grayscale is realized by adjusting the emission time of the OLED, but since one frame is not divided into a plurality of subframes as in the digital driving method, one frame time can be sufficiently used as the OLED emission time. Accordingly, the amorphous silicon thin film transistor having low mobility can be applied not only to the pixel driver but also to a high resolution display device. In addition, it is not necessary to increase the power supply voltage applied to the OLED, thereby reducing power consumption and extending the life of the OLED.
Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.
Claims (21)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1020060137922A KR20080062307A (en) | 2006-12-29 | 2006-12-29 | Organic light emitting diode display device and method of driving the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1020060137922A KR20080062307A (en) | 2006-12-29 | 2006-12-29 | Organic light emitting diode display device and method of driving the same |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| KR20080062307A true KR20080062307A (en) | 2008-07-03 |
Family
ID=39814450
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| KR1020060137922A KR20080062307A (en) | 2006-12-29 | 2006-12-29 | Organic light emitting diode display device and method of driving the same |
Country Status (1)
| Country | Link |
|---|---|
| KR (1) | KR20080062307A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR101056302B1 (en) * | 2009-03-26 | 2011-08-11 | 삼성모바일디스플레이주식회사 | Organic light emitting display |
| US8654041B2 (en) | 2008-11-26 | 2014-02-18 | Samsung Display Co., Ltd. | Organic light emitting display device having more uniform luminance and method of driving the same |
| KR20140056697A (en) * | 2012-10-31 | 2014-05-12 | 엘지디스플레이 주식회사 | Organic light emitting diode display and method of driving the same |
| WO2014197198A1 (en) * | 2013-06-06 | 2014-12-11 | Intel Corporation | Thin film transistor display backplane and pixel circuit therefor |
-
2006
- 2006-12-29 KR KR1020060137922A patent/KR20080062307A/en not_active Application Discontinuation
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8654041B2 (en) | 2008-11-26 | 2014-02-18 | Samsung Display Co., Ltd. | Organic light emitting display device having more uniform luminance and method of driving the same |
| KR101056302B1 (en) * | 2009-03-26 | 2011-08-11 | 삼성모바일디스플레이주식회사 | Organic light emitting display |
| US8531358B2 (en) | 2009-03-26 | 2013-09-10 | Samsung Display Co., Ltd. | Organic light emitting display device having improved brightness |
| KR20140056697A (en) * | 2012-10-31 | 2014-05-12 | 엘지디스플레이 주식회사 | Organic light emitting diode display and method of driving the same |
| WO2014197198A1 (en) * | 2013-06-06 | 2014-12-11 | Intel Corporation | Thin film transistor display backplane and pixel circuit therefor |
| US9773443B2 (en) | 2013-06-06 | 2017-09-26 | Intel Corporation | Thin film transistor display backplane and pixel circuit therefor |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| KR101157979B1 (en) | Driving Circuit for Organic Light Emitting Diode and Organic Light Emitting Diode Display Using The Same | |
| KR101186254B1 (en) | Organic Light Emitting Diode Display And Driving Method Thereof | |
| JP5218879B2 (en) | Electroluminescence display device and driving method thereof | |
| KR102053444B1 (en) | Organic Light Emitting Display And Mobility Compensation Method Thereof | |
| KR100606416B1 (en) | Driving Apparatus And Method For Organic Light-Emitting Diode | |
| JP5844525B2 (en) | Pixel, organic light emitting display device and driving method thereof | |
| KR100592644B1 (en) | Light emitting display and driving method thereof | |
| KR101040893B1 (en) | Pixel and Organic Light Emitting Display Device Using the Same | |
| US7609234B2 (en) | Pixel circuit and driving method for active matrix organic light-emitting diodes, and display using the same | |
| KR102367483B1 (en) | Organic light emitting diode display devece | |
| US20110084993A1 (en) | Oled display panel with pwm control | |
| KR101474024B1 (en) | Organic light emitting diode display device | |
| JP4435233B2 (en) | Active matrix display device | |
| KR102024240B1 (en) | Pixel and organic light emitting display device using the smme and drving method thereof | |
| KR20090069939A (en) | Display device and driving method thereof | |
| US20060043371A1 (en) | Active matrix organic electroluminescent display device | |
| KR20080062307A (en) | Organic light emitting diode display device and method of driving the same | |
| KR20080113528A (en) | Organic light emitting device | |
| KR100583124B1 (en) | Light emitting display | |
| KR20200080206A (en) | Display device and driving method thereof | |
| KR100602357B1 (en) | Light emitting display and driving method thereof | |
| KR100595108B1 (en) | Pixel and Light Emitting Display and Driving Method Thereof | |
| KR101390316B1 (en) | AMOLED and driving method thereof | |
| KR20080048831A (en) | Organic light emitting diode display and driving method thereof | |
| KR100511787B1 (en) | Apparatus and method for driving electro-luminescence display panel |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WITN | Withdrawal due to no request for examination |