TWI546794B - Circuitry of organic light emitting diode - Google Patents

Description

Organic light emitting diode circuit

The present invention relates to an organic light emitting diode circuit, and more particularly to an organic light emitting diode circuit using a thin film transistor process.

The organic light-emitting diode has the advantages of small volume, high luminous efficiency, and can be applied to a flexible panel, and thus can be applied to a display device as a backlight element or a pixel. When an organic light-emitting diode is used as a pixel of a display device, a so-called "thin-film transistor" (TFT) is usually applied. The threshold voltage (V _th ) of the transistor switch in the thin film transistor process is quite different from that of the transistor switch in the general process. In addition, the threshold voltage of the transistor switch in the thin film transistor process also varies with the time the transistor switch is used. Even if the two thin film transistor switches have the same threshold voltage at the factory, the threshold voltage of the two thin film transistor switches varies with the use time, and finally the two thin film transistor switches have different threshold voltages. . Such a characteristic causes uneven brightness of the screen, and the reason is briefly described below.

Please refer to FIG. 1A and FIG. 1B. FIG. 1A is a general organic light emitting diode circuit, and FIG. 1B is a timing chart of signals in the circuit of FIG. 1A. The organic light emitting diode driving circuit 100 as shown in FIG. 1A is generally called The "two-transistor-one-capacitor circuit" includes a transistor 101, a transistor 103, a capacitor 105, and an organic light-emitting diode 107. The negative terminal of the organic light emitting diode 107 is connected to the first driving voltage terminal VSS. One end of the transistor 101 is connected to the second driving voltage terminal VDD, and the other end of the transistor 101 is connected to the positive terminal of the organic light emitting diode 107. One end of the transistor 103 is connected to the data voltage terminal DATA, the other end of the transistor 103 is connected to the control terminal of the transistor 101, and the control terminal of the transistor 103 is connected to the scan voltage terminal SCAN. A capacitor 105 is further connected between the control terminal of the transistor 101 and the second driving voltage terminal VDD. As shown in the figure, in Fig. 1A, a P-type thin film transistor process is exemplified.

As shown in FIG. 1B, the voltage level of the scan voltage VSCAN received at the beginning of the scan voltage terminal SCAN is the high voltage VH, and then at the first time point T1, the voltage level of the scan voltage VSCAN is converted to the low voltage VL. Therefore, the transistor 103 is turned on so that the voltage level V101 of the control terminal of the transistor 101 is equal to the voltage level of the data voltage VDATA. Then, at the second time point T2, the voltage level of the scan voltage VSCAN is converted to the high voltage VH, so the transistor 103 forms an open circuit. Since the capacitor 105 can store the charge, the voltage level is within a period of time after the second time point T2. The quasi-V101 can remain unchanged, so the current I101 flowing through the transistor 101 can be determined by the voltage level VDD of the second driving voltage terminal VDD, the voltage level V101, and the threshold voltage VTH1 of the transistor 101. The voltage-current relationship of the transistor 101 can be described as the following equation (1): I101 = K101 × (VDD - V101 - | VTH1 |) ² (1) where K101 is a characteristic coefficient with respect to the transistor 101, which is related to the process and The size of the transistor 101 is related. It can be seen from the above equations (1) and 1A that even if the same voltage level V101 (that is, the material voltage VDATA) is given, the current I101 for driving the organic light-emitting diode 107 to emit light will follow the threshold of the transistor 101. The voltage VTH1 changes.

Since the threshold voltage VTH1 of the transistor 101 in the organic light emitting diode circuit in the adjacent or adjacent two pixels in the display device may be different, even in one frame, because two pixels are to be displayed The colors are the same. When the driving chip of the display device gives the same data voltage VDATA to two pixels, the colors displayed by the two pixels may still be different. For example, the red light intensity in the pixel on the left may be greater than the red light intensity in the pixel on the right. Further, when the display device is used for a while, the color of the screen displayed by the display device also changes due to the threshold voltage variation of the transistor in the organic light-emitting diode. How to solve the non-ideal effect caused by the variation of threshold voltage is an urgent problem to be overcome.

In view of the above problems, the present invention provides an organic light emitting diode circuit, by which the current used to drive the organic light emitting diode is independent of the threshold voltage of the transistor in the circuit, thereby avoiding the transistor. Non-ideal effects caused by threshold voltage variations.

An organic light emitting diode circuit according to one or more embodiments of the present invention includes a driving switch, an organic light emitting diode, a capacitor, a data reading circuit, a first enabling switch, a second enabling switch, and a data Read the switch. Wherein, the driving switch has a first end, a second end and a control end. Organic light-emitting diode has The first end of the organic light emitting diode is electrically coupled to the first driving voltage end of the organic light emitting diode circuit. The capacitor is electrically coupled between the control end of the drive switch and the second drive voltage terminal of the organic light emitting diode circuit. The data reading circuit is electrically coupled between the first end of the driving switch and the second end of the driving switch, and the data reading circuit drives the switch in a first time interval in an illumination period of the organic light emitting diode circuit The second end provides a reset voltage, a data voltage is supplied to the first end of the driving switch in a second time interval in the lighting period, and no voltage is supplied to the driving switch in a third time interval in the lighting period. The first uniformity switch is electrically coupled between the first end of the driving switch and the second driving voltage end, and the first enabling switch is turned on in the third time interval in the lighting period. The second enabling switch is electrically coupled between the second end of the driving switch and the second end of the organic light emitting diode, and the second enabling switch is turned on during the third time interval in the lighting period. The data reading switch is electrically coupled between the second end of the driving switch and the control end of the driving switch, and the data reading switch is turned on in the first time interval and the second time interval in the lighting period.

An organic light emitting diode circuit according to another embodiment of the present invention includes a driving switch, an organic light emitting diode, a capacitor, a data reading circuit, a first enabling switch, a second enabling switch, and a data reading switch. Wherein, the driving switch has a first end, a second end and a control end. The organic light emitting diode has a first end and a second end. The first end of the organic light emitting diode is electrically coupled to the first driving voltage end of the organic light emitting diode circuit. The capacitor is electrically coupled between the control end of the drive switch and the second drive voltage terminal of the organic light emitting diode circuit. The data reading circuit is electrically coupled between the first end of the driving switch and the control end of the driving switch, and the data is read. The circuit provides a reset voltage to the control terminal of the driving switch in a first time interval in one lighting cycle of the organic light emitting diode circuit, and supplies a data voltage to the first terminal of the driving switch in a second time interval in the lighting cycle, and The drive switch is not supplied with a voltage during a third time interval in the lighting cycle. The first enable switch is electrically coupled between the first end of the drive switch and the second drive voltage terminal, and the first enable switch is turned on in the third time interval. The second enabling switch is electrically coupled between the second end of the driving switch and the second end of the organic light emitting diode, and the second enabling switch is turned on in the third time interval. The data read switch is electrically coupled between the second end of the drive switch and the control end of the drive switch, and the data read switch is turned on in the second time interval.

According to some embodiments of the invention, the organic light emitting diode circuit further includes a data circuit. The data circuit is electrically coupled to the data voltage end of the data reading circuit, and the data circuit outputs a reset voltage to the data voltage end according to the data voltage in the first time interval, and outputs the data voltage to the data voltage end in the second time interval. In addition, the data circuit can generate a reset voltage according to the data voltage and a look-up table (LUT).

In the various organic light-emitting diode circuits disclosed in one or more embodiments of the present invention, the driving transistor is connected by electrically connecting one end of the driving transistor in the organic light-emitting diode circuit to the control terminal. It is diode-connected and gives a data voltage to the other end of the drive transistor. Thus, the potential difference between the control terminal and the driving voltage terminal of the driving transistor is equal to the sum of the data voltage and the threshold voltage of the driving transistor. Then, when the driving transistor drives the organic light emitting diode to emit light, the current drawn by the driving transistor from the driving voltage terminal and the driving electron crystal The threshold voltage of the body itself is irrelevant. Thus, the variation of the threshold voltage will not affect the luminous intensity of the organic light emitting diode.

The above description of the present invention and the following description of the embodiments of the present invention are intended to illustrate and explain the spirit and principles of the invention.

100, 200, 300, 500, 600‧‧‧ organic light-emitting diode circuits

101, 103‧‧‧Optoelectronics

105, 230, 330, 630, 630‧‧ ‧ capacitor

107‧‧‧Organic Luminescent Diodes

210, 310, 510, 610‧‧‧ drive switches

211, 311, 511, 611‧‧‧ first end

213, 313, 513, 613‧‧‧ second end

215, 315, 515, 615‧‧ ‧ control end

220, 320, 520, 620‧‧‧ Organic Light Emitting Diodes

221, 321, 521, 621‧‧‧ first end

223, 323, 523, 623‧‧ second end

240, 340, 540, 640‧‧‧ data reading circuit

241A, 241B, 541, 641‧‧‧ first scan switch

243A, 243B, 543, 643‧‧‧ second scan switch

243B1‧‧‧ first end

243B2‧‧‧ second end

243B3‧‧‧Control terminal

245, 545, 645‧‧‧ data voltage terminals

250, 350, 550, 650‧ ‧ first enable switch

260, 360, 560, 660‧‧‧ second enable switch

270, 370, 570, 670‧‧‧ data read switch

280, 380, 580, 680‧‧‧ first drive voltage terminal

290, 390, 590, 690‧‧‧ second drive voltage terminal

400‧‧‧Digital Analog Converter

401‧‧‧First switch

403‧‧‧second switch

VRST‧‧‧Reset voltage

VDATA‧‧‧ data voltage

VC, VD2, V541, V543‧‧‧ voltage

VREAD‧‧‧ data reading voltage

VTH1‧‧‧ threshold voltage

VDD‧‧‧second drive voltage terminal

VSS‧‧‧First drive voltage terminal

VSS2, VDD3‧‧‧ first drive voltage

VDD2, VSS3‧‧‧second drive voltage terminal

VDDL‧‧‧ first high voltage end

VDDH‧‧‧second high voltage end

VH‧‧‧High voltage

VL‧‧‧low voltage

GNDL‧‧‧first ground

GNDH‧‧‧Second ground

P1~P3‧‧‧ time interval

Figure 1A is a general organic light emitting diode circuit.

Fig. 1B is a timing chart of signals in the circuit of Fig. 1A.

2A is a schematic diagram of an organic light emitting diode circuit in accordance with an embodiment of the present invention.

Fig. 2B is a timing chart of a plurality of voltages in the organic light emitting diode circuit of Fig. 2A.

3A is a schematic diagram of an organic light emitting diode circuit in accordance with an embodiment of the present invention.

Fig. 3B is a timing chart of a plurality of voltages in the organic light emitting diode circuit of Fig. 3A.

Figure 4 is a schematic diagram of a data reading circuit in accordance with an embodiment of the present invention.

Figure 5 is a schematic diagram of a data circuit in accordance with an embodiment of the present invention.

Figure 6 is a schematic diagram of a data reading circuit in accordance with an embodiment of the present invention.

FIG. 7A is a schematic diagram of an organic light emitting diode circuit according to an embodiment of the invention.

Fig. 7B is a timing chart of a plurality of voltages in the organic light emitting diode circuit of Fig. 7A.

FIG. 8A is a schematic diagram of an organic light emitting diode circuit according to an embodiment of the invention.

Fig. 8B is a timing chart of a plurality of voltages in the organic light emitting diode circuit of Fig. 8A.

The detailed features and advantages of the present invention are set forth in the Detailed Description of the Detailed Description of the <RTIgt; </ RTI> <RTIgt; </ RTI> </ RTI> </ RTI> <RTIgt; The objects and advantages associated with the present invention can be readily understood by those skilled in the art. The following examples are intended to describe the present invention in further detail, but are not intended to limit the scope of the invention.

In view of the problems already existing in the prior art, the present invention proposes an organic light emitting diode circuit. The circuit provided by the present invention is suitable for a thin film transistor process, and the organic light emitting diode circuit of the present invention can be used to make the current driving the organic light emitting diode independent of the threshold voltage of the transistor in the circuit. Thereby, the non-ideal effect caused by the variation of the threshold voltage of the transistor can be avoided.

For an organic light-emitting diode circuit according to an embodiment of the present invention, please refer to FIGS. 2A and 2B, wherein FIG. 2A is a schematic diagram of an organic light-emitting diode circuit according to an embodiment of the present invention, and FIG. 2B is a schematic diagram of FIG. A timing diagram of a plurality of voltages in the organic light emitting diode circuit of Fig. 2A. As shown in Figure 2A, organic light-emitting diodes The body circuit 200 includes a driving switch 210, an organic light emitting diode 220, a capacitor 230, a data reading circuit 240, a first enabling switch 250, a second enabling switch 260, and a data reading switch 270. The driving switch 210 has a first end 211, a second end 213 and a control end 215. The organic light emitting diode 220 has a first end 221 and a second end 223. The first end 221 of the organic light emitting diode 220 is electrically coupled to the first driving voltage terminal 280 in the organic light emitting diode circuit 200. A driving voltage terminal 280 is used to provide a first driving voltage VSS2 of the organic light emitting diode circuit 200. The capacitor 230 is electrically coupled between the control terminal 215 of the driving switch 210 and the second driving voltage terminal 290 of the organic light emitting diode circuit 200. The second driving voltage terminal 290 is used to provide the organic light emitting diode circuit 200. The second driving voltage VDD2, and the second driving voltage VDD2 is greater than the first driving voltage VSS2. The data reading circuit 240 is electrically coupled between the first end 211 of the driving switch 210 and the second end 213 of the driving switch 210. The first uniformity switch 250 is electrically coupled between the first end 211 of the driving switch 210 and the second driving voltage terminal 290. The second enable switch 260 is electrically coupled between the second end 213 of the drive switch 210 and the second end 223 of the organic light emitting diode 220. The data read switch 270 is electrically coupled between the second end 213 of the drive switch 210 and the control end 215 of the drive switch 210. Although each of the switches in this embodiment is a P-type transistor, the switches in this embodiment can also be realized by an N-type transistor, and the circuit configuration thereof will be described later.

As shown in FIG. 2B, the data reading circuit 240 supplies the reset voltage VRST to the second terminal 213 of the driving switch 210 in the first time interval P1 in one lighting period of the organic light emitting diode circuit 200, and thus One time interval P1 The voltage level of the voltage VD2 of the second terminal 213 of the middle drive switch 210 is equal to the reset voltage VRST. At the same time, the voltage level of the control terminal of the data reading switch 270, that is, the data reading voltage VREAD, is a low voltage VL in the first time interval P1 and the second time interval P2 in the lighting period, so the data reading switch 270 The first time interval P1 and the second time interval P2 are turned on, so that the voltage level of the control terminal 215 of the driving switch 210, that is, the voltage VC, is equal to the voltage level of the voltage VD2, and is also equal to the reset voltage VRST. The data reading circuit 240 supplies the data voltage VDATA to the first terminal 211 of the driving switch 210 in the second time interval P2, and does not supply the voltage to the driving switch 210 in the third time interval P3 in the lighting period.

In this embodiment, if the reset voltage VRST provided by the data reading circuit 240 is much lower than the data voltage VDATA, in the second time interval P2, the driving switch 210 is substantially turned on by the data reading switch 270. Connected to a diode-connected state, in this state, if the second time interval P2 is long enough, the voltage level of the second end 213 and the control terminal 215 of the driving switch 210 will eventually be raised to The data voltage VDATA is subtracted from the threshold voltage VTH1 of the drive switch 210 (absolute value).

Then, in the third time interval P3 in one illumination period of the organic light emitting diode circuit 200, the first enable switch 250 and the second enable switch 260 are turned on, the data read switch 270 is not turned on, and the data is read. Circuit 240 does not provide a voltage to drive switch 210. In the third time interval P3, the charge stored in the capacitor 230 can ideally maintain the voltage level of the control terminal 215 of the drive switch 210 equal to the absolute value of the data voltage VDATA minus the threshold voltage VTH1 of the drive switch 210. Therefore, the current I210 drawn by the driving switch 210 from the second driving voltage terminal 290 can be roughly described by the following equation (2): I210=K210×[VDD2-(VDATA-| VTH1 |)-| VTH1 |] ² (2) Where K210 is the characteristic coefficient of the drive switch 210. And the equation (2) can be organized into the following equation (3): I210=K210×[VDD2-VDATA] ² (3) Therefore, the driven switch 210 is drawn from the second driving voltage terminal 290 for driving the organic light emitting diode 220. The current I210 is no longer related to the threshold voltage VTH1 of the drive switch 210.

For an organic light emitting diode circuit according to an embodiment of the present invention, please refer to FIGS. 3A and 3B, wherein FIG. 3A is a schematic diagram of an organic light emitting diode circuit according to an embodiment of the present invention, and FIG. 3B is a schematic diagram of the organic light emitting diode circuit according to an embodiment of the present invention. A timing diagram of a plurality of voltages in the organic light emitting diode circuit of Fig. 3A. As shown in FIG. 3A, the organic light emitting diode circuit 300 includes a driving switch 310, an organic light emitting diode 320, a capacitor 330, a data reading circuit 340, a first enabling switch 350, a second enabling switch 360, and a data. The switch 370 is read. The driving switch 310 has a first end 311, a second end 313 and a control end 315. The organic light emitting diode 320 has a first end 321 and a second end 323. The first end 321 of the organic light emitting diode 320 is electrically coupled to the first driving voltage terminal 380 in the organic light emitting diode circuit 300. A driving voltage terminal 380 is used to provide a first driving voltage VDD3 of the organic light emitting diode circuit 300. The capacitor 330 is electrically coupled between the control terminal 315 of the driving switch 310 and the second driving voltage terminal 390 of the organic light emitting diode circuit 300. The second driving voltage terminal 390 is used to The organic light emitting diode circuit 300 is supplied with a second driving voltage VSS3, and the second driving voltage VSS3 is smaller than the first driving voltage VDD3. The data reading circuit 340 is electrically coupled between the first end 311 of the driving switch 310 and the second end 313 of the driving switch 310. The first uniformity switch 350 is electrically coupled between the first end 311 of the drive switch 310 and the second drive voltage terminal 390. The second enable switch 360 is electrically coupled between the second end 313 of the drive switch 310 and the second end 323 of the organic light emitting diode 320. The data read switch 370 is electrically coupled between the second end 313 of the drive switch 310 and the control end 315 of the drive switch 310.

As shown in FIG. 3B, the data reading circuit 340 supplies the reset voltage VRST to the second terminal 313 of the driving switch 310 in the first time interval P1 in one lighting period of the organic light emitting diode circuit 300, and thus The voltage level of the voltage VD2 of the second terminal 313 of the drive switch 310 in a time interval P1 is equal to the reset voltage VRST. At the same time, the voltage level of the control terminal of the data reading switch 370, that is, the data reading voltage VREAD, is a low voltage VL in the first time interval P1 and the second time interval P2 in the lighting period, so the data reading switch 370 The first time interval P1 and the second time interval P2 are turned on, so that the voltage level of the control terminal 315 of the driving switch 310, that is, the voltage VC, is equal to the voltage level of the voltage VD2, and is also equal to the reset voltage VRST. The data reading circuit 340 supplies the data voltage VDATA to the first terminal 311 of the driving switch 310 in the second time interval P2, and does not supply the voltage to the driving switch 310 in the third time interval P3 in the lighting period.

In this embodiment, if the reset voltage VRST provided by the data reading circuit 340 is much higher than the data voltage VDATA, then in the second time interval P2, The driving switch 310 is substantially diode-connected due to the conduction of the data reading switch 370. In this state, if the second time interval P2 is long enough, the second end of the driving switch 310 is driven. The voltage level of 313 and control terminal 315 will eventually be pulled down to the data voltage VDATA plus the threshold voltage VTH1 of the drive switch 310.

Then, in the third time interval P3 in one illumination period of the organic light emitting diode circuit 300, the first enable switch 350 and the second enable switch 360 are turned on, the data read switch 370 is not turned on, and the data is read. Circuit 340 does not provide a voltage to drive switch 310. In the third time interval P3, the charge stored in the capacitor 330 can be maintained to maintain the voltage level of the control terminal 315 of the drive switch 310 equal to the data voltage VDATA plus the threshold voltage VTH1 of the drive switch 310. Therefore, the current I310 flowing through the driving switch 310 to the second driving voltage terminal 390 can be roughly described by the following equation (4): I310=K310×[VDATA+VTH1-VSS3-VTH1] ² (4) where K310 is the driving switch 310 Characteristic coefficient. And Equation (4) can be organized into the following equation (5): I310 = K310 × [VDATA - VSS3] ² (5) Therefore, the current I310 for driving the organic light-emitting diode 320 and the threshold voltage VTH1 of the driving switch 310 are not There is a relationship.

In an embodiment of the present invention, please refer to FIG. 2A and FIG. 4 together, wherein FIG. 4 is a schematic diagram of a data reading circuit according to an embodiment of the present invention. As shown in FIG. 4, the first scan switch may be included in the data reading circuit 240. 241A and second scan switch 243A. The first scan switch 241A is electrically coupled between the data voltage terminal 245 and the first end 211 of the drive switch 210, and the first scan switch 241A is turned on in the second time interval P2. The second scan switch 243A is electrically coupled between the data voltage terminal 245 and the second end 213 of the drive switch 210, and the second scan switch 243A is turned on during the first time interval P1. The data voltage terminal 245 is also electrically connected to a signal source, which provides a reset voltage VRST in the first time interval P1 and a data voltage VDATA in the second time interval.

In an embodiment of the invention, the aforementioned signal source is a data circuit. In one implementation, the data circuit can provide a reset voltage VRST to the data voltage terminal 245 in the first time interval P1, and the reset voltage VRST is a fixed voltage (eg, 0V or any much lower) A constant voltage of the data voltage VDATA). In another implementation manner, when receiving the data voltage VDATA to be supplied to the data voltage terminal 245, the data circuit can find a reset corresponding to the data voltage VDATA according to the data voltage VDATA and a comparison table of the above table 1. The voltage VRST is then supplied to the data voltage terminal 245. The first table described in the above table assumes that the threshold voltage VTH1 of the drive switch 210 is less than 1 volt. However, how to design a comparison table can be based on the knowledge of those in the field. The invention is not limited by the spirit of the invention.

In another implementation, please refer to FIG. 5, which is a schematic diagram of a data circuit in accordance with an embodiment of the present invention. As shown in FIG. 5, the data circuit may include a digital-to-analog converter (DAC), a first switch 401, and a second switch 403. After receiving a set of digital signals representing the brightness of the organic light emitting diode circuit 200 to be illuminated, in the first time interval P1, the first switch 401 electrically connects the high voltage end of the digital analog converter 400 to the first high voltage. The terminal VDDL, and the second switch 403 electrically connects the ground of the digital analog converter to the first ground GNDL. In the second time interval P2, the first switch 401 electrically connects the high voltage terminal of the digital analog converter 400 to the second high voltage terminal VDDH, and the second switch 403 electrically connects the ground terminal of the digital analog converter to the first Two ground terminals GNDH. The voltage level provided by the first high voltage terminal VDDL is lower than the voltage level provided by the second high voltage terminal VDDH, and the voltage level provided by the first ground terminal GNDL is lower than the voltage provided by the second ground terminal GNDH. Level. The voltage difference between the second high voltage terminal VDDH and the first high voltage terminal VDDL, and the voltage difference between the second ground terminal GNDH and the first ground terminal GNDL are both slightly larger than the absolute value of the threshold voltage VTH1 of the driving switch 210. As such, the voltage level output by the digital analog converter 400 in the first time interval P1 can be used as the reset voltage VRST, and the voltage level output by the digital analog converter 400 in the second time interval P2 can be used as the data voltage VDATA.

In an embodiment of the present invention, please refer to FIG. 2A and FIG. 6 together, wherein FIG. 6 is a schematic diagram of a data reading circuit according to an embodiment of the present invention. Figure. As shown in FIG. 6, the data reading circuit 240 may include a first scan switch 241B and a second scan switch 243B. The first scan switch 241B is electrically coupled between the data voltage terminal 245 and the first end 211 of the drive switch 210, and the first scan switch 241B is turned on during the second time interval P2. The second scan switch 243B has a first end 243B1, a second end 243B2 and a control end 243B3. The first end 243B1 of the second scan switch 243B is electrically coupled to the second end 213 of the drive switch 210. The second scan switch 243B The second end 243B2 and the control end 243B3 are electrically coupled to the data voltage terminal 245. The data voltage terminal 245 is also electrically connected to a signal source, which provides a control voltage (below the reset voltage VRST) in the first time interval P1 to drive the voltage of the second terminal 213 of the switch 210. The bit is ready to be pulled down to the reset voltage VRST, and this signal is derived from the supply of the data voltage VDATA in the second time interval P2.

In an embodiment of the present invention, please refer to FIG. 7A and FIG. 7B together, wherein FIG. 7A is a schematic diagram of an organic light emitting diode circuit according to an embodiment of the present invention, and FIG. 7B is an organic A timing diagram of multiple voltages in a light-emitting diode circuit. As shown in FIG. 7A, the organic light emitting diode circuit 500 can include a driving switch 510, an organic light emitting diode 520, a capacitor 530, a data reading circuit 540, a first enabling switch 550, and a second enabling switch 560. The data read switch 570. The driving switch 510 has a first end 511, a second end 513 and a control end 515. The organic light emitting diode 520 has a first end 521 and a second end 523. The first end 521 of the organic light emitting diode 520 is electrically coupled to the first driving voltage terminal 580 of the organic light emitting diode circuit 500. A driving voltage terminal 580 is used to provide an organic light emitting diode circuit 500 a first driving voltage VSS2. The capacitor 530 is electrically coupled between the control terminal 515 of the driving switch 510 and the second driving voltage terminal 590 of the organic light emitting diode circuit 500. The second driving voltage terminal 590 is used to provide the organic light emitting diode circuit 500. The second driving voltage VDD2, and the second driving voltage VDD2 is greater than the first driving voltage VSS2. The data reading circuit 540 is electrically coupled to the first end 511 of the driving switch 510 and the control end 515 of the driving switch 510. The first uniformity switch 550 is electrically coupled between the first end 511 of the driving switch 510 and the second driving voltage terminal 590. The second enable switch 560 is electrically coupled between the second end 513 of the drive switch 510 and the second end 523 of the organic light emitting diode 520. The data read switch 570 is electrically coupled between the second end 513 of the drive switch 510 and the control end 515 of the drive switch 510.

More specifically, the data reading circuit 540 may include a first scan switch 541 and a second scan switch 543. The first scan switch 541 is electrically coupled between the data voltage terminal 545 and the first end 511 of the drive switch 510. As shown in FIG. 7B, the voltage V541 of the control terminal of the first scan switch 541 is in the first time interval. P1 and the second time interval P2 are low voltage VL, and the first scan switch 541 is turned on in the first time interval P1 and the second time interval P2. The second scan switch 543 is electrically coupled between the first end 511 of the drive switch 510 and the control end 515 of the drive switch 510, and as shown in FIG. 7B, the voltage V543 of the control end of the second scan switch 543 is first. The low voltage VL is in the time interval P1, so that the second scan switch 543 is turned on in the first time interval P1. The data voltage terminal 545 can be electrically connected to a signal source, which provides a reset voltage VRST in the first time interval P1 and a data voltage VDATA in the second time interval P2.

Therefore, as shown in FIG. 7B, the material reading circuit 540 supplies the reset voltage VRST to the control terminal 515 of the driving switch 510 in the first time interval P1 in one lighting period of the organic light emitting diode circuit 500, and thus The voltage level of the voltage VC of the control terminal 515 of the drive switch 510 in the first time interval P1 is equal to the reset voltage VRST. Meanwhile, as shown in the circuit structure of FIG. 7A, the control terminal of the data read switch 570 is substantially connected to the control terminal of the first scan switch 541, so the data read switch 570 is also in the first time interval P1 and the second time. Conducted in the interval P2. The data reading circuit 540 supplies the data voltage VDATA to the first end 511 of the driving switch 510 in the second time interval P2, and does not supply the voltage to the driving switch 210 in the third time interval P3 in the lighting period.

In this embodiment, if the reset voltage VRST provided by the data reading circuit 540 is much lower than the data voltage VDATA, in the second time interval P2, the driving switch 510 is essentially turned on by the data reading switch 570. The diode VC is diode-connected. In this state, if the second time interval P2 is long enough, the voltage VC of the second terminal 513 and the control terminal 515 of the driving switch 510 is finally raised to the data. The voltage VDATA is subtracted from the absolute value of the threshold voltage VTH1 of the drive switch 510.

Then, in the third time interval P3 in one illumination period of the organic light emitting diode circuit 500, the first enable switch 550 and the second enable switch 560 are turned on, the data read switch 570 is not turned on, and the data is read. Circuit 540 does not provide a voltage to drive switch 510. In the third time interval P3, the charge stored in the capacitor 530 is ideally maintained to maintain the voltage level of the control terminal 515 of the drive switch 510 equal to the absolute value of the data voltage VDATA minus the threshold voltage VTH1 of the drive switch 510. Therefore, the current I510 drawn from the second driving voltage terminal 590 by the driving switch 510 can be roughly described by the following equation (6): I510=K510×[VDD2-(VDATA-| VTH1 |)-| VTH1 |] ² (6) Where K510 is the characteristic coefficient of the drive switch 510. And equation (6) can be organized into the following equation (7): I510 = K510 × [VDD2-VDATA] ² (7)

Therefore, the current I510 drawn by the driven switch 510 from the second driving voltage terminal 590 for driving the organic light emitting diode 520 is no longer related to the threshold voltage VTH1 of the driving switch 510.

In another embodiment of the present invention, please refer to FIG. 8A and FIG. 8B together, wherein FIG. 8A is a schematic diagram of an organic light emitting diode circuit according to an embodiment of the present invention, and FIG. 8B is a diagram of FIG. 8A. A timing diagram of multiple voltages in an organic light emitting diode circuit. As shown in FIG. 8A, the organic light emitting diode circuit 600 can include a driving switch 610, an organic light emitting diode 620, a capacitor 630, a data reading circuit 640, a first enabling switch 650, and a second enabling switch 660. The data read switch 670. The drive switch 610 has a first end 611, a second end 613 and a control end 615. The organic light emitting diode 620 has a first end 621 and a second end 623. The first end 621 of the organic light emitting diode 620 is electrically coupled to the first driving voltage terminal 680 of the organic light emitting diode circuit 600. The capacitor 630 is electrically coupled between the control terminal 615 of the driving switch 610 and the second driving voltage terminal 690 of the organic light emitting diode circuit 600. The data reading circuit 640 is electrically coupled to the first end 611 of the driving switch 610 and the driving switch 610 Between the control terminals 615. The data read switch 670 is electrically coupled between the second end 613 of the drive switch 610 and the control end 615 of the drive switch 610. The first enabler switch 650 is electrically coupled between the first end 611 of the drive switch 610 and the second drive voltage terminal 690, and the second enable switch 660 is electrically coupled to the second end 613 of the drive switch 610. Between the second ends 622 of the organic light emitting diodes 620.

The data reading circuit 640 includes a first scan switch 641 and a second scan switch 643. The first scan switch 641 is electrically coupled between the data voltage terminal 645 and the first end 611 of the drive switch 610, and the control terminal voltage V641 of the first scan switch 641 is a low voltage VL in the second time interval P2, thereby The first scan switch 641 is turned on in the second time interval P2. The second scan switch 643 is electrically coupled between the data voltage terminal 645 and the control terminal 615 of the drive switch 610, and the control terminal voltage V643 of the second scan switch 643 is a low voltage VL in the first time interval P1, thereby The second scan switch 643 is turned on in the first time interval P1. The data voltage terminal 645 is electrically coupled to a voltage source that provides a reset voltage VRST in the first time interval P1 and a data voltage VDATA in the second time interval P2.

Therefore, as shown in FIG. 8B, the material reading circuit 640 supplies the reset voltage VRST to the control terminal 615 of the driving switch 610 in the first time interval P1 in one lighting period of the organic light emitting diode circuit 600, and thus at the first In the time interval P1, the voltage level of the voltage VC of the control terminal 615 of the drive switch 610 is pulled down to the reset voltage VRST. And the data reading circuit 640 supplies the data voltage to the first end 611 of the driving switch 610 in the second time interval P2 in the lighting period. VDATA, at the same time, the voltage level of the control terminal of the data read switch 670, that is, the data read voltage VREAD, is the low voltage VL in the second time interval P2, so that the data read switch 670 is turned on in the second time interval P2. Therefore, the driving switch 610 is diode-connected, so in the second time interval, the voltage VC of the control terminal 615 of the driving switch 610 is gradually pulled up to the data voltage VDATA minus the driving switch 610. Threshold voltage VTH1 (absolute value). The data read switch 640 does not supply a voltage to the drive switch 610 during the third time interval P3 in the lighting period. The first coincidence switch 650 and the second enable switch 660 are turned on in the third time interval P3.

In this embodiment, if the reset voltage VRST provided by the data reading circuit 640 is much lower than the data voltage VDATA, in the second time interval P2, the driving switch 610 is substantially driven by the conduction of the data reading switch 670. Connected to a diode-connected state, in this state, if the second time interval P2 is long enough, the voltage VC of the control terminal 615 of the drive switch 610 is finally raised to the data voltage VDATA minus the drive. The absolute value of the threshold voltage VTH1 of the switch 210.

Then, in the third time interval P3 in one illumination period of the organic light emitting diode circuit 600, the first enable switch 650 and the second enable switch 660 are turned on, the data read switch 670 is not turned on, and the data is read. Circuit 640 does not provide a voltage to drive switch 610. In the third time interval P3, the charge stored in the capacitor 630 ideally maintains the voltage VC of the control terminal 615 of the drive switch 610 equal to the absolute value of the data voltage VDATA minus the threshold voltage VTH1 of the drive switch 610. Therefore, the current I610 drawn from the second driving voltage terminal 690 by the driving switch 610 can be roughly described by the following equation (8): I610=K610×[VDD2-(VDATA-|VTH1|)-|VTH1|] ² (8) Where K610 is the characteristic coefficient of the drive switch 610. And equation (8) can be organized into the following equation (9): I610 = K610 × [VDD2-VDATA] ² (9)

Therefore, the current I610 drawn by the driven switch 610 from the second driving voltage terminal 690 for driving the organic light emitting diode 620 is no longer related to the threshold voltage VTH1 of the driving switch 610. Although each of the switches in this embodiment is a P-type transistor, the switches in this embodiment can also be implemented with an N-type transistor.

In some embodiments of the present invention, in the various embodiments of the foregoing FIGS. 2A-8A, each switch is made of a transistor, and wherein the width of the first enable switch and/or the second enable switch The width-over-length ratio (W/L) is greater than the aspect ratio (W/L) of the drive switch. The aspect ratio of the first uniform switch is greater than the width to length ratio of the drive switch, and the voltage change caused by the first enable switch can be prevented from affecting the magnitude of the current used to drive the organic light emitting diode. The width-to-length ratio of the second enable switch is greater than the width-to-length ratio of the drive switch, which can prevent the drive switch from entering the triode region and causing current variation.

With the at least one organic light emitting diode circuit disclosed in the present invention, since the voltage of the control terminal of the driving switch is modulated to be substantially equal to the data voltage minus (or plus, depending on the process), the threshold voltage of the driving switch is absolute. The value, so in fact the current value through the drive switch is almost independent of the threshold voltage of the drive switch, and is related to the data voltage value. In this way, the threshold voltage of the drive switch can be avoided. The non-ideal effect of the light caused by the variation.

Although the present invention has been disclosed above in the foregoing embodiments, it is not intended to limit the invention. It is within the scope of the invention to be modified and modified without departing from the spirit and scope of the invention. Please refer to the attached patent application for the scope of protection defined by the present invention.

200‧‧‧Lighting diode circuit

210‧‧‧Drive Switch

211‧‧‧ first end

213‧‧‧ second end

215‧‧‧ third end

220‧‧‧Lighting diode

221‧‧‧ first end

223‧‧‧ second end

230‧‧‧ Capacitance

240‧‧‧ data reading circuit

250‧‧‧First enable switch

260‧‧‧Second enable switch

270‧‧‧ data reading switch

280‧‧‧First drive voltage terminal

290‧‧‧second drive voltage terminal

Claims (16)

An organic light emitting diode circuit includes: a driving switch having a first end, a second end and a control end; an organic light emitting diode having a first end and a second end, the organic light emitting The first end of the diode is electrically coupled to a first driving voltage terminal; a capacitor is electrically coupled between the control terminal of the driving switch and a second driving voltage terminal; Between the first end of the driving switch and the second end of the driving switch, the second end of the driving switch is provided with a reset voltage in a first time interval of an illumination period. a second time interval of the illumination period provides a data voltage of the first end of the driving switch, and does not provide a voltage to the driving switch in a third time interval of the lighting period; a first enabling switch, electrical And being coupled between the first end of the driving switch and the second driving voltage terminal for conducting in the third time interval; a second enabling switch electrically coupled to the second end of the driving switch Between the second ends of the organic light emitting diodes Three conduction time interval; and a data read switch electrically coupled between the second terminal and the control terminal of the drive switch of the drive switch for the first time interval to the second time interval is turned on. The organic light emitting diode circuit of claim 1, wherein the driving switch, The first enabling switch, the second enabling switch and the data reading open relationship P-type transistor, the voltage level of the first driving voltage terminal is smaller than the voltage level of the second driving voltage terminal, and the reset voltage The voltage value is less than the voltage value of the data voltage. The OLED circuit of claim 1, wherein the driving switch, the first enabling switch, the second enabling switch and the data reading open relationship N-type transistor, the first driving voltage end The voltage level is greater than the voltage level of the second driving voltage terminal, and the voltage value of the reset voltage is greater than the voltage value of the data voltage. The OLED circuit of claim 1, wherein the first enable switch has a width to length ratio greater than a width to length ratio of the drive switch. The OLED circuit of claim 1, wherein the data reading circuit comprises: a first scan switch electrically coupled between a data voltage terminal and the first end of the drive switch; And the second scan switch is electrically coupled between the data voltage end and the second end of the drive switch for conducting in the first time interval; wherein the data voltage is The reset voltage is provided in the first time interval, and the data voltage is provided in the second time interval. The OLED circuit of claim 5, further comprising a data circuit electrically coupled to the data voltage terminal, wherein the data circuit outputs the reset voltage to the data according to the data voltage in the first time interval Voltage terminal, and the second The time interval outputs the data voltage to the data voltage terminal. The organic light emitting diode circuit of claim 6, wherein the data circuit generates the reset voltage according to the data voltage and a comparison table. The OLED circuit of claim 1, wherein the data reading circuit comprises: a first scan switch electrically coupled between a data voltage terminal and the first end of the drive switch; And the second scan switch has a first end, a second end, and a control end, and the first end of the second scan switch is electrically coupled to the second end of the drive switch The second end of the second scan switch and the control end of the second scan switch are electrically coupled to the data voltage end; wherein the data voltage terminal provides a control voltage in the first time interval to provide The second end of the drive switch resets the voltage and provides the data voltage in the second time interval. The OLED circuit of claim 1, wherein the data reading circuit comprises: a first scan switch electrically coupled between a data voltage terminal and the first end of the drive switch; The first time interval is electrically connected to the second time interval; and a second scan switch is electrically coupled between the first end of the drive switch and the control end of the drive switch for the first time Interval conduction; wherein the data voltage terminal provides the reset power in the first time interval Pressing and providing the data voltage in the second time interval. An organic light emitting diode circuit includes: a driving switch having a first end, a second end and a control end; an organic light emitting diode having a first end and a second end, the organic light emitting The first end of the diode is electrically coupled to a first driving voltage terminal; a capacitor is electrically coupled between the control terminal of the driving switch and a second driving voltage terminal; The first end of the driving switch is coupled to the control end of the driving switch to provide a reset voltage of the control terminal of the driving switch during a first time interval of an illumination period. a second time interval of the driving switch is provided with a data voltage of the first end of the driving switch, and no voltage is supplied to the driving switch in a third time interval of the lighting period; a first enabling switch is electrically coupled Between the first end of the driving switch and the second driving voltage terminal for conducting in the third time interval; a second enabling switch electrically coupled to the second end of the driving switch and the organic Between the second ends of the light emitting diodes for Three conduction time interval; and a data read switch electrically coupled between the second terminal and the control terminal of the drive switch of the drive switch for the second time interval in conduction. The OLED circuit of claim 10, wherein the driving switch, the first enabling switch, the second enabling switch, and the data reading open relationship are P-type In the transistor, the voltage value of the first driving voltage is less than the voltage value of the second driving voltage, and the voltage value of the reset voltage is less than the voltage value of the data voltage. The OLED circuit of claim 10, wherein the driving switch, the first enabling switch, the second enabling switch, and the data reading open relationship N-type transistor, the first driving voltage The voltage value is greater than the voltage value of the second driving voltage, and the voltage value of the reset voltage is greater than the voltage value of the data voltage. The OLED circuit of claim 10, wherein the first enable switch has a width to length ratio greater than a width to length ratio of the drive switch. The OLED circuit of claim 10, wherein the data reading circuit comprises: a first scan switch electrically coupled between a data voltage terminal and the first end of the drive switch; And the second scan switch is electrically coupled between the data voltage end and the control end of the drive switch for conducting in the first time interval; wherein the data voltage end The reset voltage is provided in the first time interval, and the data voltage is provided in the second time interval. The OLED circuit of claim 14 further comprising a data circuit electrically coupled to the data voltage terminal, wherein the data circuit outputs the reset voltage to the data according to the data voltage in the first time interval And the voltage terminal outputs the data voltage to the data voltage terminal in the second time interval. The organic light emitting diode circuit of claim 15, wherein the data circuit generates the reset voltage according to the data voltage and a comparison table.