CN1889161A - Organic light-emitting diode picuture element circuit and its brightness control method - Google Patents
Organic light-emitting diode picuture element circuit and its brightness control method Download PDFInfo
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- CN1889161A CN1889161A CNA2006101059629A CN200610105962A CN1889161A CN 1889161 A CN1889161 A CN 1889161A CN A2006101059629 A CNA2006101059629 A CN A2006101059629A CN 200610105962 A CN200610105962 A CN 200610105962A CN 1889161 A CN1889161 A CN 1889161A
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Abstract
A organic light-emitting diode (OLED) pixel circuit and its control method of the brightness. According to the invention, the both ends of the driving transistor source are fixed by the pace voltage, to control the brightness of OLED by control the control voltage which is added to the grid of the driving transistor in the picture-point circuit, making it to reach the preset brightness in specific gray scale (for example white scale).
Description
Technical field
The present invention relates to a kind of image element circuit of display device, more clearly say it, include OLED (OLED) image element circuit with and brightness control method.
Background technology
Fig. 1 shows the circuit diagram of existing OLED image element circuit.As shown in the figure, this OLED image element circuit includes the first transistor 12, holding capacitor 14, transistor seconds 16 and Organic Light Emitting Diode (OLED) 18.Transistor seconds 16 is as the driving transistors of driving OLED 18, and it can be p type channel transistor.The source electrode of transistor seconds 16 is connected to supply voltage V
DDVoltage source, drain electrode is connected to the anode of this OLED.The negative electrode of this OLED is connected to supply one low-voltage V
SSVoltage source.
The grid of transistor seconds (driving transistors) 16 is connected to an auxiliary voltage source or supply voltage V via a holding capacitor 14
DDSame voltage source.In addition, pixel data data is supplied to the grid of transistor seconds 16 by data line (not shown).And pixel data data is subjected to the control of the first transistor 12 to the supply of the grid of transistor seconds 18.The first transistor 12 is as a switch, and it can be a n type channel transistor.The grid of the first transistor 12 is accepted the sweep signal scan from sweep trace (not shown), according to this sweep signal scan and conducting/shutoff is controlled the supply of pixel data data to the grid of transistor seconds 16 thereby make a choice.
When showing, the sweep signal scan that sweep trace provides is a high level, the first transistor 12 thereby conducting.Under this state, the pixel data data that data line transmitted makes holding capacitor 14 chargings.Then transistor seconds 16 is driven by the voltage corresponding to pixel data data, makes the electric current OLED18 that flows through, thereby makes OLED 18 shinny.
In theory, if when pixel data data is identical, that is under the same GTG, the brightness of each pixel should be identical.For example be all demonstration white rank (white level), the OLED in the different pixels circuit should send same brightness.In other words, the white rank brightness that OLED sent of each image element circuit should be consistent.Yet the brightness of OLED is directly proportional in fact with the electric current of this OLED that flows through, and this electric current is activated the influence of transistor (transistor seconds of Fig. 1) 16 self characters, at identical V
DDAnd V
SSThe voltage supply down may be different.Therefore, along with the difference of drive transistor characteristics, the same GTG brightness that each image element circuit sent may be variant.
In order to overcome this problem, be to utilize to adjust the brightness that the voltage difference of striding driving transistors is adjusted OLED in the prior art.On the actual practice, generally be fixing V
SSSize, and adjust V
DDSize, thereby make the electric current difference of the OLED that flows through reach the purpose of adjusting OLED brightness.If V
SSBe fixed as-9V V
DDAdjustable scope is+3V-+5V that then the design of circuit board just must be satisfied V
DDDemand for 5V.In addition, because V
DDTo V
SSCross-pressure become 14V from 12V, cross-pressure rises and to cause power consumption to increase, and causes inconsistent on the specification.In brief, for the brightness unanimity of OLED under same gray scale states of keeping each image element circuit, the V of each image element circuit
DDJust must be different.
The present invention proposes a kind of novel pixel circuit brightness control method, and it can be as the brightness of required adjustment OLED on specific grey-scale (as white rank), and must not adjust V
DDWith V
SSSize.
Summary of the invention
A purpose of the present invention is to propose a kind of method that is used to control the brightness of OLED image element circuit.Utilize this method can adjust the brightness of the OLED of image element circuit, make it be issued to predetermined luminance, and must not change supply voltage in specific grey-scale.
Another object of the present invention is to propose a kind of OLED image element circuit, and its OLED is adjustable to make it to be issued to predetermined luminance and must not change supply voltage in specific grey-scale.
According to characteristics of the present invention, the method that is used to control the brightness of OLED image element circuit includes sets a control voltage, and will control of the brightness of the driving transistors of the image element circuit that voltage applies with control OLED, wherein, this control voltage can be the reference voltage of a gamma circuit.The setting of this control voltage can be reached by the resistance value of the lowest-order voltage end of adjusting this gamma circuit.
According to another characteristics of the present invention, the OLED image element circuit includes a switch entering in order to control data signal; One OLED; One driving transistors is in order to drive this OLED and a voltage controller.This voltage controller determines a control voltage, and should control voltage and provide to this driving transistors, makes OLED be issued to predetermined brightness in specific grey-scale.This voltage controller can be a gamma circuit, and for example the reference voltage of may command gamma circuit (lowest-order voltage) is so that the brightness of OLED under white rank reaches predetermined value.The reference voltage of this gamma circuit can be controlled by the resistance value of adjusting the lowest-order voltage end.
Description of drawings
Fig. 1 is the circuit diagram that shows existing image element circuit;
Fig. 2 is the circuit diagram that shows according to image element circuit of the present invention;
Fig. 3 is the circuit diagram of voltage controller in the image element circuit of displayed map 2; And
Fig. 4 shows that gamma curve changes and the synoptic diagram of translation with reference voltage.
The reference numeral explanation
12 the first transistors
14 holding capacitors
16 transistor secondses
18 OLED
22 switching transistors
24 holding capacitors
26 driving transistorss
28 OLED
30 voltage controllers
32 resistive device
The R1-R254 resistor
Embodiment
Hereinafter with reference to graphic detailed description technology contents of the present invention.
Fig. 2 shows the synoptic diagram according to image element circuit of the present invention.As shown in the figure, image element circuit of the present invention includes switching transistor 22, holding capacitor 24, driving transistors 26 and OLED 28.The source electrode of driving transistors 26 is connected to supply voltage V
DDVoltage source, drain electrode is connected to the anode of this OLED 28.The negative electrode of this OLED 28 is connected to supply one low-voltage V
SSVoltage source.Image element circuit of the present invention still comprises a voltage controller 30, and it is by the control voltage V of the grid that is applied to driving transistors 26
ControlInfluence drive current, thus the brightness of control OLED.According to embodiments of the invention, the voltage of this voltage controller 30 control pixel data data is as control voltage V
Control, know clearly as described later.
Figure 3 shows that a GTG adjusts circuit, also be called gamma circuit, its be a plurality of resistor R 1, R2 ..., R253, R254 serial connection, in each difference of voltage of different nodes outputs, make also difference of brightness that OLED reaches.In an embodiment of the present invention, this voltage controller 30 is promptly implemented with the gamma circuit of Fig. 3.In this circuit, the voltage at Level 255 places is lowest-order voltage, when lowest-order voltage provides grid to driving transistors 26, makes brightness that OLED reaches for maximum, and these rank (Level 255) are called white rank, and this lowest-order voltage also is called white rank voltage.According to the present invention, in the last resistor R 254 and reference voltage V
REFBetween a resistive device 32 is provided, this resistive device 32 provides a resistance value, offers the reference voltage (that is white rank voltage) of each series resistor device in order to influence, thereby influences the brightness of OLED in each rank.
According to embodiments of the invention, adjust the reference voltage of gamma circuit (ash stage circuit) by resistive device 32.The gamma curve pattern that it should be noted that gamma circuit can't change, just entire curve translation.As shown in Figure 4, when the reference voltage change, gamma curve is along with upper and lower translation, but the curvature of curve can't change.That is to say, the brightness of jumping to another GTG from a GTG change with adjust before identical, but the pairing voltage of each GTG adjust to some extent, thereby the brightness of each GTG also adjust to some extent, this be because reference voltage through adjustment.
As mentioned above, adjust reference voltage by the resistance value that resistive device 32 is provided, the voltage on each rank of gamma circuit just can be different, and for example lowest-order voltage promptly changes and changes along with this resistance value.When lowest-order voltage (white rank voltage) not simultaneously, the brightness that the OLED in the image element circuit is reached under white scalariform attitude will be different.Therefore, can reach by the resistance value of setting or adjust resistive device 32 and adjust the brightness of OLED in white scalariform attitude, therefore, even the difference to some extent on electric characteristics of the driving transistors in each image element circuit still can be reached the purpose of the brightness unanimity that the OLED that makes each image element circuit is issued in white scalariform attitude.
On real the work, the resistance value that resistive device 32 is provided is preferably variable.This resistive device 32 can simply be made of a variohm, perhaps can be combined by a plurality of fixed resisters and Guan Guan, perhaps can comprise a transistor and reach.Preferred embodiment is to make image element circuit be in white scalariform attitude, that is pixel data data is the white rank of indicated number, provides white rank voltage to image element circuit by gamma circuit.Resistance value by adjusting this resistive device 32 makes the white rank brightness of the OLED 28 of image element circuit reach predetermined brightness.So just can overcome because the phenomenon of the OLED brightness irregularities that difference caused of the driving transistors 26 of each image element circuit.
Though the present invention discloses as above with preferred embodiment; right its is not in order to limit the present invention; anyly have the knack of this skill person; without departing from the spirit and scope of the present invention; when can doing various changes and modification, so protection scope of the present invention is as the criterion when looking accompanying the claim person of defining.
Claims (25)
1. method of controlling the shinny degree of organic light-emitting diode pixel circuit, this organic light-emitting diode pixel circuit has an input in order to receive pixel data, one switch is in order to receive the reception of sweep signal with the control pixel data, one Organic Light Emitting Diode and a driving transistors are in order to drive this Organic Light Emitting Diode according to this pixel data, and this method comprises step to be had:
Control is in order to specify the voltage on these pixel data burnt hair rank; And
Apply this voltage to this organic light-emitting diode pixel circuit and send out the control end of driving transistors, so that the brightness of this Organic Light Emitting Diode reaches a predetermined value.
2. the method for claim 1, wherein this control voltage steps is controlled the lowest-order voltage of a gamma circuit.
3. method as claimed in claim 2, wherein, the lowest-order voltage of this gamma circuit is set by the resistance value of the lowest-order end of this gamma circuit of control.
The method of claim 1, wherein this voltage be controlled to be fixed setting.
The method of claim 1, wherein this voltage be controlled to be adjustable adjustment.
6. the method for claim 1, wherein the control end of this driving transistors is a gate terminal.
7. the method for claim 1, wherein the control end of this driving transistors two ends in addition are connected to voltage fixing voltage source and this Organic Light Emitting Diode respectively.
8. the method for claim 1, wherein this control voltage is applied to this control end so that the brightness of this Organic Light Emitting Diode under a specific grey-scale reaches predetermined value.
9. method as claimed in claim 8, wherein, this specific grey-scale is white scalariform attitude.
10. method of controlling the brightness of organic light-emitting diode pixel circuit, this organic light-emitting diode pixel circuit have an Organic Light Emitting Diode and a driving transistors in order to drive this Organic Light Emitting Diode, and this method comprises step to be had:
Set a control voltage; And
Applying the control end of this control voltage to the driving transistors of this organic light-emitting diode pixel circuit, is a predetermined value so that be in the brightness of the Organic Light Emitting Diode of a specific grey-scale.
11. method as claimed in claim 10, wherein, the lowest-order voltage that this control voltage is a gamma circuit.
12. method as claimed in claim 11, wherein, the lowest-order voltage of this gamma circuit is set by the resistance of the lowest-order end of this gamma circuit of control.
13. method as claimed in claim 10, wherein, being set at of this control voltage is fixed.
14. method as claimed in claim 10, wherein, being set at of this control voltage is adjustable.
15. method as claimed in claim 10, wherein, the control end of this driving transistors is a gate terminal.
16. method as claimed in claim 10, wherein, the two ends beyond the control end of this driving transistors are connected to voltage fixing voltage source and this Organic Light Emitting Diode respectively.
17. an organic light-emitting diode pixel circuit comprises:
One switch is in order to the input of control data signal;
One Organic Light Emitting Diode;
One driving transistors has first end, second end and control end, and this first end is connected to a voltage source, and second end and this Organic Light Emitting Diode couple to drive this Organic Light Emitting Diode, and this control end is connected with this switch; And
One voltage controller determines a control voltage, and provides this control voltage this control end to this driving transistors so that the brightness of the specific grey-scale of this Organic Light Emitting Diode is predetermined value.
18. circuit as claimed in claim 17, wherein, this voltage controller is a gamma circuit, and should control voltage be the lowest-order voltage of this gamma circuit.
19. circuit as claimed in claim 18, wherein, this gamma circuit has a resistive device and is coupled to the lowest-order voltage end, and this resistive device provides required resistance to control the lowest-order voltage of this gamma circuit.
20. circuit as claimed in claim 19, wherein, the resistance value of this resistive device is variable.
21. circuit as claimed in claim 20, wherein, this resistive device comprises a variohm.
22. circuit as claimed in claim 20, wherein, this resistive device comprises the combination of fixed resister, and this resistor combination can provide multiple resistance value.
23. circuit as claimed in claim 20, wherein, this resistive device comprises a transistor.
24. circuit as claimed in claim 19, wherein, this resistive device has default fixed resistance value.
25. circuit as claimed in claim 17, wherein, this voltage controller determines this control voltage according to the characteristic of this driving transistors.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA2006101059629A CN1889161A (en) | 2006-07-19 | 2006-07-19 | Organic light-emitting diode picuture element circuit and its brightness control method |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA2006101059629A CN1889161A (en) | 2006-07-19 | 2006-07-19 | Organic light-emitting diode picuture element circuit and its brightness control method |
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| Publication Number | Publication Date |
|---|---|
| CN1889161A true CN1889161A (en) | 2007-01-03 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNA2006101059629A Pending CN1889161A (en) | 2006-07-19 | 2006-07-19 | Organic light-emitting diode picuture element circuit and its brightness control method |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103177693A (en) * | 2013-01-22 | 2013-06-26 | 友达光电股份有限公司 | Organic light emitting diode display device and driving method thereof |
| CN111243493A (en) * | 2018-11-29 | 2020-06-05 | 昆山工研院新型平板显示技术中心有限公司 | Pixel circuit, display device and driving method of pixel circuit |
-
2006
- 2006-07-19 CN CNA2006101059629A patent/CN1889161A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103177693A (en) * | 2013-01-22 | 2013-06-26 | 友达光电股份有限公司 | Organic light emitting diode display device and driving method thereof |
| CN111243493A (en) * | 2018-11-29 | 2020-06-05 | 昆山工研院新型平板显示技术中心有限公司 | Pixel circuit, display device and driving method of pixel circuit |
| US11282436B2 (en) | 2018-11-29 | 2022-03-22 | Chengdu Vistar Optoelectronics Co., Ltd. | Pixel circuit including a storage device connected to a control line, display device and method for driving pixel circuit |
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