TWI281139B - A display pixel compensation circuit and driving method and display apparatus thereof - Google Patents

Abstract

A display pixel compensation circuit includes three transistors, a condenser, and an LED. The gate of the first transistor is coupled to a scan line, the source of the first transistor is coupled to a data line. The gate of the second transistor is coupled to the drain of the second transistor, the drain of the first transistor, one end of the condenser and the gate of the third transistor. The drain of the third transistor is coupled to the other end of the condenser. The source of the third transistor is coupled to the LED. By using the compensation circuit, the problem that non-uniform brightness and poor grayscale accuracy can be solved. Because only three transistors are used to achieve the circuit, a higher open ratio can be obtained and the duty ratio is easy to adjusted.

Description

128 im f.doc/006 IX. Description of the Invention: [Technical Field] The present invention relates to a compensation circuit and a driving method for displaying a pixel, and a display device, and more particularly to an active matrix organic light emitting display The compensation circuit and the driving method of the halogen are displayed. [Prior Art] At present, the organic light-emitting display technology can be classified into a passive matrix and an active matrix driving according to a driving method. The passive driving method is to illuminate the LEDs of the array according to different current values of the respective data lines at the turn-on time when the scan lines are sequentially turned on. Therefore, each diode is operated in a short pulse mode, and only one scan line is lit at each time point, which means that to achieve the average brightness of the display, each light-emitting diode needs to be high. Pulse operation (>1〇〇〇〇Nits) requires higher diode operating voltage and current. However, this will also result in a significant drop in material life and efficiency. Moreover, this problem will become more serious as the size and resolution of the display increase. Therefore, the active driving method can be used to solve the lack of the passive driving method, that is, the switching and driving circuit of the transistor is added to the pixels of each of the light-emitting diodes. Since the organic light emitting diode is a current driving element, the general pixel structure to = two transistors is required, and FIG. 1A shows the pixel structure of the general active driving organic light emitting display H. The pixel structure mainly includes _ Switched TFTs (Switch TFT) l〇〇, - > [Solid Drive Thin Films (Drive Ding) 1〇2 and a Capacitor Reservoir (Do not 〇1# 咽(;叩触〇1>) 1〇4. The function of switching thin film transistor 100 is to enter the storage capacitor 104 I281H.doc/006 as the image data for the switching and addressing. The storage capacitor 104 provides the potential to open the driving thin film transistor 102 and is regulated by the power supply voltage. Vdd provides current for driving the organic light-emitting diode element 106 while controlling the gray scale of the display by modulating different current values. However, the critical electric frequency (threshold voltage) and carrier of the low-temperature polycrystalline silicon driven thin film transistor The mobility (yn or Vp) will cause variation due to the crystal structure of the laser company, and the position difference of the structure of the alizarin without the display device of the ηχη 昼 结构 structure, and the different positions # have different threshold voltages: such as νΛ (1, υ, vt h(1,njV^(^,

Vth(n,n)...·etc. Figure 1C illustrates the change in threshold voltage caused by the difference in position. Therefore, vth = (^ electric = body organic light-emitting diode current Ud = f = extremely KlriJ2, so it is related to the position of the organic light-emitting diode. The brightness coffee / heart is proportional to WK is the application) Therefore, it can be seen that the threshold voltage in different pixel structure levels causes uneven brightness and inaccurate gray levels. Please refer to Figure 2, where % shows the driving view result of a monolithic structure without a compensation circuit. When the threshold voltage is -IV, -2V, and _3V, the current values of the simulation results are also different, so the quality of the kneading surface is unstable. In order to improve the laser crystallization process and space differences caused by the changes, the research unit has proposed the pixel structure of the circuit compensation method, see the picture from ~ guilty. In the general structure, six crystals are used to improve the above variation. However, since the compensation circuit requires at least 4 transistors, the aperture ratio is low, and the working ratio is difficult to adjust. Missing, pending resolution. SUMMARY OF THE INVENTION An object of the present invention is to provide a compensation circuit and a driving method for displaying a pixel and a display device. The use of only three transistors improves the unevenness of the luminance and the inaccuracy of the gray scale due to the critical voltage variation, and has the advantages of a higher aperture ratio and easier adjustment of the work ratio. The present invention provides a compensation circuit for displaying a halogen, the compensation circuit comprising three transistors, a capacitor, and a light emitting diode. Each of the three transistors has a gate, first and second source/drain. The first source/drain surface of the first transistor is connected to the data line, and the gate is connected to the sweeping cat line. The gate of the second transistor is coupled to the second source/drain and coupled to the first source//pole of the first transistor, and the first source/no pole of the second transistor is surface-connected Information line. The second source/drain of the third transistor is coupled to the power supply voltage level, and the gate is lightly coupled to the second source/drain of the second transistor. In addition, the capacitor has two ends, one end of which is coupled to the gate of the second transistor, and the other end of which is coupled to the second source/drain of the third transistor. And a light emitting diode having a p terminal and an N terminal, wherein the P terminal is coupled to the first source/drain of the third transistor, and the N terminal is grounded. In the above compensation circuit, a thin film transistor can be used for the transistor; an organic light emitting diode can be used for the light emitting diode. From another point of view, the present invention also provides a display device comprising a plurality of compensation circuits, wherein each compensation circuit further comprises at least three transistors, a capacitor, and a light-emitting diode. Each of the three transistors has a gate, first and second source/drain. The first source/drain of the first transistor is coupled to the data line, and the gate is coupled to the scan line. The doc/006 1281139 13349 twfj is a gate of the transistor and a second source/drain of the second source/body, and the second electric is coupled to the first transistor. The second source of the third transistor is the same as that of the data pole. The second is closed: two of them: Zhao to P; 5, Long Gan and a light-emitting diode, with W and N, The tP terminal is switched to the third transistor. The display device further includes a data line driving circuit, and the nth and middle data line driving circuits are respectively connected to each of the moving circuits, and the first transistor is disposed on the first transistor. The first source/no pole, and the gate of the first transistor connected to the above-mentioned transistor-selectively selectively pass the electro-ceramic materials. Heart output k The above-mentioned device shows that the light-emitting diode used in each pixel structure is present. From another point of view, the present invention also provides a circuit driving method, which is applicable to The compensation circuit described above first makes the power supply voltage 0' and then causes the voltage value of the data line to be smaller than the threshold voltage value of the second transistor: Ξ== the voltage of the line to open the first transistor, and then change the sweeping power to close the first - After changing the data line to the display device, and changing the power supply voltage level to the operating potential, the current drives the light-emitting diode. The power supply circuit of the present invention is a voltage driving circuit, and can change the brightness unevenness caused by the threshold voltage variation and the gray level is not allowed. ^1281 f.doc/006 Loss: the display picture quality can be more uniform . In addition, it has the advantages of a relatively low aperture ratio and easy adjustment of the work ratio. The above and other objects, advantages, and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments. [Embodiment] Referring to FIG. 4A, there is shown a compensation circuit 1 implemented by three transistors according to a preferred embodiment of the present invention, wherein η, Τ2, Τ3 are three transistors, 400 is a capacitor, 402 It is an organic light-emitting diode (〇rganiciight diode hereinafter referred to as coffee). DAT is the data line, and sct is the sweep. Note that in this embodiment, it is adopted? For example, a type of transistor is familiar to the

The limb of the transistor. I The three transistors T1 and T2^3 have sluice, first- and first-source/record respectively. The first - transistor η is connected to the data line DAT 'gate _ on the broom line SCT 'two: 2 between the pole and the second source, difficult _, the first-electro-crystal: τ Γ! ^ two dirty And the first source __ of the second transistor Τ2 is connected to the position. / gate: the second source/no pole of the electrical upper body 3 is coupled to the power supply voltage level vdd, and the __ is connected to the second transistor τ. In addition, the capacitor 400 has two ends, wherein the gate of the first:=~ The other end is connected to the third transistor T3 and the body pole = the light emitting diode 402, having a p-terminal and a terminal end 'p to the first-source level of the third transistor Τ3, and the terminal is grounded. 1281 LI- Please refer to the clock map of Figure 5. In the first phase, the reset phase, the power supply voltage level is reduced from Vdd to 〇, the voltage value of the data line DAt is reduced to -Vdn' and the voltage value -Vdn is lower than -VthT2 (the threshold voltage of the transistor T2) ). Furthermore, the scan line SCT is reduced to a voltage which is at least -VthT1 (the threshold voltage of the transistor T1) lower than the voltage value of the data line DAT. In this case, the circuit shown in Fig. 4A will be equivalent as shown in Fig. 4B. Among them, since the T1 transistor will be turned on at this time, in the ideal hypothesis state, the & point voltage value Va should be equal to the voltage of the data line DAT and be _Vdn. In the second phase of FIG. 5, that is, during the stylization phase, the voltage value of the data line dAt is returned from -Vdn to the voltage vdata required for the original display, and the potential of the scan line sct is also pulled high to turn off the transistor T1. . In this case, the circuit shown in Fig. 4A will be equivalent as shown in Fig. 4C. Among them, the transistor T1 is turned off, and the original voltage value is a point of ^^, because the transistor is gradually turned on due to conduction, the voltage rise process will continue until the voltage value of point a and Vdata The phase difference is -vthT2 (the threshold voltage of the transistor T2)' and thus causes the transistor T2 to be stopped when it is turned off. Therefore, after the end of the stylization phase, the voltage value at point a will be Vdata-|Vtj^. Next, in the third phase of Figure 5, the illuminating phase, the power supply voltage level is restored by 〇 to Vdd> And other conditions remain unchanged. In this case, the circuit shown in Fig. 4A will be equivalent as shown in Fig. 4D. Among them, the transistor T2 is kept open, and the voltage value at point a (i.e., the gate voltage value of T3) is synchronously increased by about vdd due to the push-up effect of the capacitor 400. In other words, at this time, the voltage value of point a is Va=Vdd+Vdata_|VthT2丨, and the value of the current ioled flowing through the organic light-emitting diode can be obtained by the following formula: 128 Wei_ioled^ |(|^h|^ 3|)2 = I [(Vdd - Fa)^\VthT3\J == Camp [(4)-((5) Cardiac α - -n 1)) 1-n |]2 Among them, due to the industry's general presupposition: in the same 昼Since the transistors in the prime are extremely small, the threshold voltages are almost equal. Therefore, VthT2 = Vth^ can be obtained, then iQled=[[Kcfeta]2 in the above formula. It can be known from the above calculation that the compensation circuit is a voltage driving circuit, and the current flowing through the organic light emitting diode is only related to the input voltage value Vdata of the data line, and the position of the pixel where the organic light emitting diode is located.

Vth(x,y;) has nothing to do. Therefore, the problem of uneven luminance and inaccurate gray scale due to spatial variation of the vth threshold voltage value can be improved. The present invention also provides a display device. Referring to Figure 4E, at least a plurality of the above-described compensation circuits, a data line drive circuit 41A, and a gate drive circuit 412 are included. The data line driving circuit 41 is coupled to the first source/drain of the Τ2, and the gate driving circuit 412 is coupled to the gate of the T1 for outputting a signal to selectively conduct the crystal. The display device of the present invention also has the functions and advantages of the compensation circuit of the present invention by applying the above compensation circuit. ^ To the parameter K if ^ calculate n outside '* can also see the result through simulation. Figure v f shows the simulation results of time vs. voltage. in

Si s? ff VthT2 V^-2V and -3V 'Va paving results are _5V, wish, then," a is all. And [is ten, therefore, when Vdata keeps ^疋, I.丨^ will also be stable, making the brightness of the face. Figure 7 shows the current stability of the compensation circuit compared with Figure 2, it can be seen that when Vth points jam, the result of the current results are close. And; because of 2Τ(/1Τ2), T1; I28iy^doc/006 can be adjusted. The variation of electron mobility in the conventional case can be improved by a higher rate, and the aperture ratio and compensation circuit Inversely proportional to the size, when we use fewer components to implement the compensation circuit, we can get an aperture ratio to improve the electron mobility. In summary, the compensation circuit of the present invention is only used. Three transistors are implemented, so in addition to improving the uncompensated circuit, the uneven brightness, gray scale into the disk and other issues, compared with the conventional compensation circuit, there is a higher rate to improve the electron mobility and reduce the cost. And having the advantage of being comparable to the above. Although the invention has been disclosed above in the preferred embodiment, It also stipulates that any of the inventions of the present invention may be modified and retouched in the spirit of the present invention. Therefore, the protection of the present invention is defined by the definition of the application. [Simple diagram of the diagram] Port: C. The structure of the organic light-emitting device. Figure 1B shows the active organic light-emitting display. Figure 3A to 3D are conventional compensation circuit diagrams. Fig. 4 is a timing diagram of the present invention. Fig. 5 is a timing diagram of the present invention. Fig. 7 is a graph showing the simulation results of the present invention. Fig. 12 128 im f.doc/006 [Description of main component symbols] 100, 102: Transistor 104: Capacitor 106: Organic light emitting diode 400: Capacitor 402: Light emitting diode 410: Data line driving circuit 412: Gate drive circuit ΤΙ, T2, T3: transistor

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Claims (1)

I281m f.doc/〇〇6 X. Patent application scope·· L compensation circuit for displaying pixels, including: 兮 Ϊ Ϊ—transistor 'with gate, first and second source/no-pole, in the basin Two =:! Sweep: a first material line, the first-electro-crystal 兮 two transistor 'has a gate, a first and a second source / secret, of which two - the gate of the crystal _ in the first - transistor a second source/drain, a second source/drain of the second transistor, the first addend and the pole face of the second transistor being connected to the data line; ^ a third transistor having a gate, And a second source/drain, wherein the gate of the three transistors is coupled to the second source/drain of the second transistor, and the second source/no pole of the second transistor is coupled to the first source/drain a voltage level; a capacitor having one end coupled to the gate of the second transistor, the other end coupled to the second source/drain of the third transistor; and a light emitting diode having a ρ And a terminal, wherein the terminal is coupled to the first source/drain of the third transistor, and the terminal is coupled to a ground voltage level. 2. The compensation circuit of claim 1, wherein the light emitting diode is an organic light emitting diode. 3. The compensation circuit of claim 1, wherein the first, second, and third transistors can use a thin film transistor. 4. A display device comprising: a plurality of compensation circuits adapted to a plurality of pixel structures of the display device, wherein each of the compensation circuits further comprises: 1281 13? 42ν£άοο/006 :Ϊ:=' a pole, a first and a second source/drain; the second thunder two P' in A has a gate, first and second source/drain, i, two i rth day ^= The second source of the first-transistor/no brother: the second source/no pole of the electric Japanese body; the basin (four) body' has the - gate, the first and the second source/dippole, the pole; ϊ: the gate is coupled to the second source of the second transistor, and the second source/no pole of the transistor is connected to a power supply voltage level; at the second; one end and the other end Wherein the end is coupled to the second source h, and the other end is reduced from the D mountain*-light emitting diode of the third transistor, having one? And an N-terminal, wherein the first electrode of the third transistor is reduced from a drain circuit to a first source of the first transistor and the first The first source/difference of the two transistors: and the gates of the first transistor are selectively used to conduct the transistors. The display device of the fourth aspect of the invention, wherein the plurality of organic electrodes are a plurality of organic light-emitting diodes. The display device of claim 4, wherein the first and second transistors can use a thin film transistor. The method of the Hi-turn method of the road spoon is suitable for the compensation-compensation circuit, the compensation circuit 14--the transistor has a gate, a first and a second source/no pole, and the source/drain is coupled to a data line. The gate is coupled to a scan of 15 128 m·, d〇c/〇〇6 Ϊ2 second transistor, having a gate, a first and a second source/drain, and an A pole? The second source of the first transistor is coupled to the second source of the first transistor, and the second source of the second transistor is the second source/no pole. The second transistor is lightly connected to the data. a third transistor having a gate, two thunders, a source/drain, wherein the gate of the third transistor is the second and the second transistor a pole shank=the original voltage level; a capacitor having one end and the other end, wherein the second electrode is connected to the gate of the second transistor, the other end is secreted by the first source and the drain of the first body; And a light-emitting diode having a p-terminal end and an N-terminal end, wherein the P-terminal is coupled to the first source of the third transistor, and the N-terminus is coupled to a ground voltage level, the circuit driving method The method includes: a• making the power voltage level 〇; value; b· making the voltage value of the financial line smaller than the critical electric grind of the second transistor, changing the voltage of the broom line to open the first transistor; • Change the voltage of the broom line to turn off the first transistor; f the wire to the desired power when displaying the image; and the voltage level of the power supply Potential.