ORGANIC LIGHT EMITTING DIODE PIXEL DRIVING CIRCUIT AND DISPLAY APPARATUS OF SAME

• US 20200135094A1
• Filed: 09/10/2018
• Published: 04/30/2020
• Est. Priority Date: 07/20/2018
• Status: Active Grant

• Current Assignee: Shenzhen China Star Optoelectronics Semiconductor Display Technology Co., Ltd.
• Original Assignee: Shenzhen China Star Optoelectronics Semiconductor Display Technology Co., Ltd.
• Inventors: CHEN, Xiaolong, WEN, Yi-chen, JOU, Mingjong
• Granted Patent: US 10,685,602 B2
• Time in Patent Office: Days
• CPC Class Codes: G09G 2300/0819 used for counteracting undesired variations, e.g. feedback or autozeroing
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0295 by monitoring each display pixel
• CPC Class Codes: G09G 2320/045 Compensation of drifts in the characteristics of light emitting or modulating elements
• CPC Class Codes: G09G 3/3241 the current through the light-emitting element being set using a data current provided by the data driver, e.g. by using a two-transistor current mirror
• CPC Class Codes: G09G 3/325 the data current flowing through the driving transistor during a setting phase, e.g. by using a switch for connecting the driving transistor to the data driver
• CPC Class Codes: G09G 3/3258 with pixel circuitry controlling the voltage across the light-emitting element
• CPC Class Codes: G09G 3/3266 Details of drivers for scan electrodes

Abstract

The present disclosure provides an OLED pixel driving circuit and an OLED display apparatus utilizing the circuit scheme of 3T1C. The normal displaying mode and detecting mode of the pixel driving circuit both include two phases by controlling the conductions of different transistors. And, the pixel driving circuit is capable of implementing corresponding data compensation under the displaying mode according to the detected voltage threshold Vth of the driving TFT and the intrinsic conductivity factor value k of the aged OLED. This is capable of improving the uniformity of display and the illuminating efficiency.

Claims

1. An organic light emitting diode (OLED) pixel driving circuit having an operating status including a displaying mode and a detecting mode, said driving circuit comprising:

a first thin film transistor, a gate of said first thin film transistor electrically connecting with a first node, a source of said first thin film transistor electrically connecting with a second node, a drain of said first thin film transistor simultaneously electrically connected to a data current through a first transistor and electrically connected to a power voltage through a second transistor;

a second thin film transistor, a gate of said second thin film transistor electrically connected to a scan signal, a source of said second thin film transistor electrically connected to said first node, a drain of said second thin film transistor electrically connected to a data signal, electrically connected to a data voltage through a fifth transistor during said displaying mode, electrically connected to an initializing voltage through said fifth transistor during said detecting mode and electrically connected to a first analog to digital converter (ADC) through a sixth transistor;

a third thin film transistor, a gate of said third thin film transistor electrically connected to said scan signal, a source of said third thin film transistor electrically connected to said second node, a drain of said third thin film transistor simultaneously electrically connected to a reference voltage through a third transistor and a second ADC through a fourth transistor;

a capacitor, one end of said capacitor electrically connected to said first node, the other end of said capacitor electrically connected to said second node; and

an OLED, an anode of said OLED electrically connected to said second node, a cathode of said OLED electrically connected to a common ground;

wherein said first to said sixth transistors, said first and second ADCs are disposed in a driver chip;

wherein said displaying mode comprises a data writing phase and an illuminating phase;

wherein during said data writing phase of said displaying mode, said scan signal is in a high voltage level so as to enable a conduction of said second thin film transistor and said third thin film transistor, said second transistor, said fifth transistor and said third transistor are conducted under control by corresponding voltage level control signals, said first node is written with said data voltage through said second thin film transistor and said fifth transistor, said second node is written with said reference voltage through said third thin film transistor and said third transistor;

wherein during said illuminating phase of said displaying mode, said scan signal is in a low voltage level so as to disable the conduction of said second thin film transistor and said third thin film transistor, charges stored in said capacitor are attributed to a difference between said data voltage and said reference voltage, and said OLED illuminates;

wherein said detecting mode comprises a voltage level initializing phase and a detecting phase;

wherein during said voltage level initializing phase of said detecting mode, said scan signal is in said high voltage level so as to enable the conduction of said second thin film transistor and said third thin film transistor, said fifth transistor and said third transistor are conducted under control by the corresponding voltage level control signal, said first node is written with said initializing voltage through said second thin film transistor and said fifth transistor, said second node is written with said reference voltage through said third thin film transistor and said third transistor; and

wherein during said detecting phase of said detecting mode, said scan signal is in said high voltage level, said fifth transistor and said third transistor are cut off under control by the corresponding voltage level control signals, said first transistor, said sixth transistor and said fourth transistor are conducted under control by the corresponding voltage level control signals, said second node is charged and discharged by inputting different values of said data current through said first thin film transistor, said first ADC detects a voltage level of said first node through said second thin film transistor and said sixth transistor after said data current is stabilized, said second ADC detects a voltage level of said second node through said third thin film transistor and said fourth transistor, whereby a voltage threshold of said first thin film transistor and an intrinsic conductivity factor value are detected.

2. The driving circuit according to claim 1, wherein during said detecting phase of said detecting mode:

said second node is charged and discharged by inputting a first data current through said first thin film transistor, said first ADC detects said voltage level of said first node through said second thin film transistor and said sixth transistor after said first data current is stabilized, said second ADC detects said voltage level of said second node through said third thin film transistor and said fourth transistor, whereby a first voltage difference between said gate and said source of said first thin film transistor is obtained; and

said second node is charged and discharged by inputting a second data current through said first thin film transistor, said first ADC detects said voltage level of said first node through said second thin film transistor and said sixth transistor after said second data current is stabilized, said second ADC detects said voltage level of said second node through said third thin film transistor and said fourth transistor, whereby a second voltage difference between said gate and said source of said first thin film transistor is obtained;

wherein said voltage threshold of said first thin film transistor and said intrinsic conductivity factor value are obtained according to the simultaneous equations of Idata1=k(Vgs1−

Vth) and Idata2=k(Vgs2−

Vth), in which Idata1 is said first data current, Vgs1 is said first voltage difference, Idata2 is said second data current, Vgs2 is said second voltage difference, Vth is said voltage threshold of said first thin film transistor, and k is said intrinsic conductivity factor value.

3. The driving circuit according to claim 1, wherein said first to said sixth transistors are switching components;

wherein control ends of said first transistor and said second transistor are configured to receive corresponding voltage level control signals, first connecting points of said first transistor and said second transistor are shorted and then electrically connected to said drain of said first thin film transistor, a second connecting point of said first transistor is input by said data current, a second connecting point of said second transistor is input by said power voltage, control ends of said third transistor and said fourth transistor are configured to receive corresponding voltage level control signals, first connecting points of said third transistor and said fourth transistor are shorted and then electrically connected to said drain of said third thin film transistor, a second connecting point of said third transistor is input by said reference voltage, and a second connecting point of said fourth transistor is connected to said second ADC; and

wherein control ends of said fifth transistor and said sixth transistor are configured to receive corresponding voltage level control signals, first connecting points of said fifth transistor and said sixth transistor are shorted then electrically connected to said drain of said second thin film transistor, a second connecting point of said fifth transistor is input by said data voltage during said displaying mode and is input by said initializing voltage during said detecting mode, and a second connecting point of said sixth transistor is connected to said first ADC.

4. The driving circuit according to claim 3, wherein during said data writing phase of said displaying mode, said scan signal is in said high voltage level, said control ends of said first, said fourth and said sixth transistors receive said low voltage level, and said control ends of said second, said third and said fifth transistors receive said high voltage level;

wherein during said illuminating phase of said displaying mode, said scan signal is in said low voltage level, said control ends of said first, said fourth and said sixth transistors receive said low voltage level, and said control ends of said second, said third and said fifth transistors receive said high voltage level;

wherein during said voltage level initializing phase of said detecting mode, said scan signal is in said high voltage level, said control ends of said first, said second, said fourth and said sixth transistors receive said low voltage level, and said control ends of said third and said fifth transistors receive said high voltage level; and

wherein during said detecting phase of said detecting mode, said scan signal is in said high voltage level, said control ends of said first, said fourth and said sixth transistors receive said high voltage level, and said control ends of said second, said third and said fifth transistors receive said low voltage level.

5. The driving circuit according to claim 1, wherein said first to said sixth transistors are metal oxide semiconductor field effect transistors (MOSFET);

wherein said gates of said first transistor and said second transistor are shorted to receive corresponding voltage level control signals, said sources of said first transistor and said second transistor are shorted and electrically connected to said drain of said first thin film transistor, said source of said first transistor is input by said data current, and said source of said second transistor is input by said power voltage;

wherein said gates of said third transistor and said fourth transistor are shorted to receive corresponding voltage level control signals, said sources of said third transistor and said fourth transistor are shorted and electrically connected to said drain of said third thin film transistor, said drain of said third transistor is input by said reference voltage, and said drain of said fourth transistor is connected to said second ADC; and

wherein said gates of said fifth transistor and said sixth transistor are shorted to receive corresponding voltage level control signals, said sources of said fifth transistor and said sixth transistor are shorted and electrically connected to said drain of said second thin film transistor, said drain of said fifth transistor is input by said data voltage during said displaying mode and is input by said initializing voltage during said detecting mode, and said drain of said sixth transistor is connected to said first ADC.

6. The driving circuit according to claim 5, wherein during said data writing phase of said displaying mode, said scan signal is in said high voltage level, said gates of said first transistor and said second transistor receive said low voltage level, and said gates of said third, said fourth, said fifth and said sixth transistors receive said high voltage level;

wherein during said illuminating phase of said displaying mode, said scan signal is in said low voltage level, said gates of said first transistor and said second transistor receive said low voltage level, and said gates of said third, said fourth, said fifth and said sixth transistors receive said high voltage level;

wherein during said voltage level initializing phase of said detecting mode, said scan signal is in said high voltage level, said gates of said first transistor and said second transistor receive said low voltage level, and said gates of said third, said fourth, said fifth and said sixth transistors receive said high voltage level; and

wherein during said detecting phase of said detecting mode, said scan signal is in said high voltage level, said gates of said first transistor and said second transistor receive said high voltage level, and said gates of said third, said fourth, said fifth and said sixth transistors receive said low voltage level.

7. An organic light emitting diode (OLED) pixel driving circuit comprising the operating status of a displaying mode and a detecting mode, said driving circuit comprising:

a first thin film transistor, a gate of said first thin film transistor electrically connected to a first node, a source of said first thin film transistor electrically connected to a second node, a drain of said first thin film transistor electrically connected to a data current through a first transistor and electrically connected to a power voltage through a second transistor;

a second thin film transistor, a gate of said second thin film transistor electrically connected to a scan signal, a source of said second thin film transistor electrically connected to said first node, a drain of said second thin film transistor electrically connected to a data signal, electrically connected to a data voltage through a fifth transistor during said displaying mode, electrically connected to a initializing voltage through said fifth transistor during said detecting mode and electrically connected to a first analog to digital converter (ADC) through a sixth transistor;

a third thin film transistor, a gate of said third thin film transistor electrically connected to said scan signal, a source of said third thin film transistor electrically connected to said second node, a drain of said third thin film transistor simultaneously electrically connected to a reference voltage through a third transistor and a second ADC through a fourth transistor;

a capacitor, one end of said capacitor electrically connected to said first node, the other end of said capacitor electrically connected to said second node; and

an OLED, an anode of said OLED electrically connected to said second node, a cathode of said OLED electrically connected to a common ground;

wherein during said displaying mode, said second transistor, said fifth transistor and said third transistor are conducted under control by the corresponding voltage level control signals;

wherein said displaying mode comprises a data writing phase and an illuminating phase, said scan signal is in a high voltage level during said data writing phase so as to enable the conductions of said second thin film transistor and said third thin film transistor, said data voltage and said reference voltage are input into said driving circuit, said scan signal is in a low voltage level during said illuminating phase so as to disable the conductions of said second thin film transistor and said third thin film transistor, the charges stored in said capacitor illuminate said OLED;

wherein during said detecting mode, said fifth transistor and said third transistor are conducted under control by the corresponding voltage level control signals in the first, and then said fifth transistor and said third transistor are cut off under control by the corresponding voltage level control signals, and, said first transistor, said sixth transistor and said fourth transistor are conducted under control by the corresponding voltage level control signals;

wherein said detecting mode comprises a voltage level initializing phase and a detecting phase, said scan signal is always in said high voltage level, said second thin film transistor and said third thin film transistor are conducted during said voltage level initializing phase, said initializing voltage and said reference voltage are input into said driving circuit, said data current is input into said driving circuit during said detecting mode, said first ADC and said second ADC detect a voltage threshold of said first thin film transistor and an intrinsic conductivity factor value by inputting different values of said data current.

8. The driving circuit according to claim 7, wherein during said data writing phase of said displaying mode:

said scan signal is in said high voltage level so as to enable the conductions of said second thin film transistor and said third thin film transistor, said second transistor, said fifth transistor and said third transistor are conducted under control by the corresponding voltage level control signals, said first node is written with said data voltage through said second thin film transistor and said fifth transistor, said second node is written with said reference voltage through said third thin film transistor and said third transistor;

wherein during said illuminating phase of said displaying mode;

said scan signal is in said low voltage level so as to disable the conductions of said second thin film transistor and said third thin film transistor, the charges stored in said capacitor are attributed to a difference between said data voltage and said reference voltage, and said OLED illuminates;

wherein during said voltage level initializing phase of said detecting mode, said scan signal is in said high voltage level so as to enable the conductions of said second thin film transistor and said third thin film transistor, said fifth transistor and said third transistor are conducted under control by the corresponding voltage level control signals, said first node is written with said initializing voltage through said second thin film transistor and said fifth transistor, said second node is written with said reference voltage through said third thin film transistor and said third transistor;

wherein during said detecting phase of said detecting mode;

said scan signal is in said high voltage level, said fifth transistor and said third transistor are cut off under control by the corresponding voltage level control signals, said first transistor, said sixth transistor and said fourth transistor are conducted under control by the corresponding voltage level control signals, said second node is charged and discharged by inputting different values of said data current through said first thin film transistor, said first ADC detects a voltage level of said first node through said second thin film transistor and said sixth transistor after said data current is stabilized, said second ADC detects a voltage level of said second node through said third thin film transistor and said fourth transistor, whereby said voltage threshold of said first thin film transistor and said intrinsic conductivity factor value are detected.

9. The driving circuit according to claim 8, wherein during said detecting phase of said detecting mode:

said second node is charged and discharged by inputting a first data current through said first thin film transistor, said first ADC detects said voltage level of said first node through said second thin film transistor and said sixth transistor after said first data current is stabilized, said second ADC detects said voltage level of said second node through said third thin film transistor and said fourth transistor, whereby a first voltage difference between said gate and said source of said first thin film transistor is obtained; and

said second node is charged and discharged by inputting a second data current through said first thin film transistor, said first ADC detects said voltage level of said first node through said second thin film transistor and said sixth transistor after said second data current is stabilized, said second ADC detects said voltage level of said second node through said third thin film transistor and said fourth transistor, whereby a second voltage difference between said gate and said source of said first thin film transistor is obtained;

wherein said voltage threshold of said first thin film transistor and said intrinsic conductivity factor value are obtained according to the simultaneous equations of Idata1=k(Vgs1−

Vth) and Idata2=k(Vgs2−

Vth), in which Idata1 is said first data current, Vgs1 is said first voltage difference, Idata2 is said second data current, Vgs2 is said second voltage difference, Vth is said voltage threshold of said first thin film transistor, and k is said intrinsic conductivity factor value.

10. The driving circuit according to claim 7, wherein said first to said sixth transistors are switching components;

wherein the control ends of said first transistor and said second transistor are configured to receive corresponding voltage level control signals, the first connecting points of said first transistor and said second transistor are shorted then electrically connected to said drain of said first thin film transistor, a second connecting point of said first transistor is input by said data current, a second connecting point of said second transistor is input by said power voltage, the control ends of said third transistor and said fourth transistor are configured to receive corresponding voltage level control signals, the first connecting points of said third transistor and said fourth transistor are shorted then electrically connected to said drain of said third thin film transistor, a second connecting point of said third transistor is input by said reference voltage, a second connecting point of said fourth transistor is connected to said second ADC;

wherein the control ends of said fifth transistor and said sixth transistor are configured to receive corresponding voltage level control signals, the first connecting points of said fifth transistor and said sixth transistor are shorted then electrically connected to said drain of said second thin film transistor, a second connecting point of said fifth transistor is input by said data voltage during said displaying mode and is input by said initializing voltage during said detecting mode, a second connecting point of said sixth transistor is connected to said first ADC.

11. The driving circuit according to claim 10, wherein during said data writing phase of said displaying mode:

said scan signal is in said high voltage level, said control ends of said first, said fourth and said sixth transistors receive said low voltage level, said control ends of said second, said third and said fifth transistors receive said high voltage level;

wherein during said illuminating phase of said displaying mode;

said scan signal is in said low voltage level, said control ends of said first, said fourth and said sixth transistors receive said low voltage level, said control ends of said second, said third and said fifth transistors receive said high voltage level;

wherein during said voltage level initializing phase of said detecting mode;

said scan signal is in said high voltage level, said control ends of said first, said second, said fourth and said sixth transistors receive said low voltage level, said control ends of said third and said fifth transistors receive said high voltage level;

wherein during said detecting phase of said detecting mode;

said scan signal is in said high voltage level, said control ends of said first, said fourth and said sixth transistors receive said high voltage level, said control ends of said second, said third and said fifth transistors receive said low voltage level.

12. The driving circuit according to claim 7, wherein said first to said sixth transistors are metal oxide semiconductor field effect transistors (MOSFET);

wherein said gates of said first transistor and said second transistor are shorted to receive corresponding voltage level control signals, said sources of said first transistor and said second transistor are shorted and electrically connected to said drain of said first thin film transistor, said source of said first transistor is input by said data current, said source of said second transistor is input by said power voltage;

wherein said gates of said third transistor and said fourth transistor are shorted to receive corresponding voltage level control signals, said sources of said third transistor and said fourth transistor are shorted and electrically connected to said drain of said third thin film transistor, said drain of said third transistor is input by said reference voltage, said drain of said fourth transistor is connected to said second ADC;

wherein said gates of said fifth transistor and said sixth transistor are shorted to receive corresponding voltage level control signals, said sources of said fifth transistor and said sixth transistor are shorted and electrically connected to said drain of said second thin film transistor, said drain of said fifth transistor is input by said data voltage during said displaying mode and is input by said initializing voltage during said detecting mode, said drain of said sixth transistor is connected to said first ADC.

13. The driving circuit according to claim 12, wherein during said data writing phase of said displaying mode:

said scan signal is in said high voltage level, said gates of said first transistor and said second transistor receive said low voltage level, said gates of said third, said fourth, said fifth and said sixth transistors receive said high voltage level;

wherein during said illuminating phase of said displaying mode;

said scan signal is in said low voltage level, said gates of said first transistor and said second transistor receive said low voltage level, said gates of said third, said fourth, said fifth and said sixth transistors receive said high voltage level;

wherein during said voltage level initializing phase of said detecting mode;

said scan signal is in said high voltage level, said gates of said first transistor and said second transistor receive said low voltage level, said gates of said third, said fourth, said fifth and said sixth transistors receive said high voltage level;

wherein during said detecting phase of said detecting mode;

said scan signal is in said high voltage level, said gates of said first transistor and said second transistor receive said high voltage level, said gates of said third, said fourth, said fifth and said sixth transistors receive said low voltage level.

14. The driving circuit according to claim 7, wherein said first to said sixth transistors, said first and second ADCs are disposed in a driver chip.

15. An organic light emitting diode (OLED) display apparatus comprising an OLED pixel driving circuit, wherein an operating status of said driving circuit comprises a displaying mode and a detecting mode, said driving circuit comprising:

a first thin film transistor, a gate of said first thin film transistor electrically connected to a first node, a source of said first thin film transistor electrically connected to a second node, a drain of said first thin film transistor electrically connected to a data current through a first transistor and electrically connected to a power voltage through a second transistor;

a second thin film transistor, a gate of said second thin film transistor electrically connected to a scan signal, a source of said second thin film transistor electrically connected to said first node, a drain of said second thin film transistor electrically connected to a data signal, electrically connected to a data voltage through a fifth transistor during said displaying mode, electrically connected to a initializing voltage through said fifth transistor during said detecting mode and electrically connected to a first analog to digital converter (ADC) through a sixth transistor;

a third thin film transistor, a gate of said third thin film transistor electrically connected to said scan signal, a source of said third thin film transistor electrically connected to said second node, a drain of said third thin film transistor simultaneously electrically connected to a reference voltage through a third transistor and a second ADC through a fourth transistor;

a capacitor, one end of said capacitor electrically connected to said first node, the other end of said capacitor electrically connected to said second node; and

an OLED, an anode of said OLED electrically connected to said second node, a cathode of said OLED electrically connected to a common ground;

wherein said first to said sixth transistors, said first and second ADCs are disposed in a driver chip;

wherein said displaying mode comprises a data writing phase and an illuminating phase;

wherein during said data writing phase of said displaying mode, said scan signal is in a high voltage level so as to enable the conductions of said second thin film transistor and said third thin film transistor, said second transistor, said fifth transistor and said third transistor are conducted under control by the corresponding voltage level control signals, said first node is written with said data voltage through said second thin film transistor and said fifth transistor, said second node is written with said reference voltage through said third thin film transistor and said third transistor;

wherein during said illuminating phase of said displaying mode, said scan signal is in a low voltage level so as to disable the conductions of said second thin film transistor and said third thin film transistor, charges stored in said capacitor are attributed to a difference between said data voltage and said reference voltage, and said OLED illuminates;

wherein said detecting mode comprises a voltage level initializing phase and a detecting phase;

wherein during said voltage level initializing phase of said detecting mode;

said scan signal is in said high voltage level so as to enable the conductions of said second thin film transistor and said third thin film transistor, said fifth transistor and said third transistor are conducted under control by the corresponding voltage level control signals, said first node is written with said initializing voltage through said second thin film transistor and said fifth transistor, said second node is written with said reference voltage through said third thin film transistor and said third transistor;

wherein during said detecting phase of said detecting mode;

said scan signal is in said high voltage level, said fifth transistor and said third transistor are cut off under control by the corresponding voltage level control signals, said first transistor, said sixth transistor and said fourth transistor are conducted under control by the corresponding voltage level control signals, said second node is charged and discharged by inputting different values of said data current through said first thin film transistor, said first ADC detects a voltage level of said first node through said second thin film transistor and said sixth transistor after said data current is stabilized, said second ADC detects a voltage level of said second node through said third thin film transistor and said fourth transistor, whereby a voltage threshold of said first thin film transistor and an intrinsic conductivity factor value are detected.

16. The display apparatus according to claim 15, wherein during said detecting phase of said detecting mode:

said second node is charged and discharged by inputting a first data current through said first thin film transistor, said first ADC detects said voltage level of said first node through said second thin film transistor and said sixth transistor after said first data current is stabilized, said second ADC detects said voltage level of said second node through said third thin film transistor and said fourth transistor, whereby a first voltage difference between said gate and said source of said first thin film transistor is obtained; and

said second node is charged and discharged by inputting a second data current through said first thin film transistor, said first ADC detects said voltage level of said first node through said second thin film transistor and said sixth transistor after said second data current is stabilized, said second ADC detects said voltage level of said second node through said third thin film transistor and said fourth transistor, whereby a second voltage difference between said gate and said source of said first thin film transistor is obtained;

wherein said voltage threshold of said first thin film transistor and said intrinsic conductivity factor value is obtained according to the simultaneous equations of Idata1=k(Vgs1−

Vth) and Idata2=k(Vgs2−

Vth), in which Idata1 is said first data current, Vgs1 is said first voltage difference, Idata2 is said second data current, Vgs2 is said second voltage difference, Vth is said voltage threshold of said first thin film transistor, and k is said intrinsic conductivity factor value.

17. The display apparatus according to claim 15, wherein said first to said sixth transistors are switching components;

wherein the control ends of said first transistor and said second transistor are configured to receive corresponding voltage level control signals, the first connecting points of said first transistor and said second transistor are shorted then electrically connected to said drain of said first thin film transistor, a second connecting point of said first transistor is input by said data current, a second connecting point of said second transistor is input by said power voltage, the control ends of said third transistor and said fourth transistor are configured to receive corresponding voltage level control signals, the first connecting points of said third transistor and said fourth transistor are shorted then electrically connected to said drain of said third thin film transistor, a second connecting point of said third transistor is input by said reference voltage, a second connecting point of said fourth transistor is connected to said second ADC;

wherein the control ends of said fifth transistor and said sixth transistor are configured to receive corresponding voltage level control signals, the first connecting points of said fifth transistor and said sixth transistor are shorted then electrically connected to said drain of said second thin film transistor, a second connecting point of said fifth transistor is input by said data voltage during said displaying mode and is input by said initializing voltage during said detecting mode, a second connecting point of said sixth transistor is connected to said first ADC.

18. The display apparatus according to claim 17, wherein during said data writing phase of said displaying mode:

said scan signal is in said high voltage level, said control ends of said first, said fourth and said sixth transistors receive said low voltage level, said control ends of said second, said third and said fifth transistors receive said high voltage level;

wherein during said illuminating phase of said displaying mode;

said scan signal is in said low voltage level, said control ends of said first, said fourth and said sixth transistors receive said low voltage level, said control ends of said second, said third and said fifth transistors receive said high voltage level;

wherein during said voltage level initializing phase of said detecting mode;

said scan signal is in said high voltage level, said control ends of said first, said second, said fourth and said sixth transistors receive said low voltage level, said control ends of said third and said fifth transistors receive said high voltage level;

wherein during said detecting phase of said detecting mode;

said scan signal is in said high voltage level, said control ends of said first, said fourth and said sixth transistors receive said high voltage level, said control ends of said second, said third and said fifth transistors receive said low voltage level.

19. The display apparatus according to claim 15, wherein said first to said sixth transistors are metal oxide semiconductor field effect transistors (MOSFET);

wherein said gates of said first transistor and said second transistor are shorted to receive corresponding voltage level control signals, said sources of said first transistor and said second transistor are shorted and electrically connected to said drain of said first thin film transistor, said source of said first transistor is input by said data current, said source of said second transistor is input by said power voltage;

wherein said gates of said third transistor and said fourth transistor are shorted to receive corresponding voltage level control signals, said sources of said third transistor and said fourth transistor are shorted and electrically connected to said drain of said third thin film transistor, said drain of said third transistor is input by said reference voltage, said drain of said fourth transistor is connected to said second ADC;

wherein said gates of said fifth transistor and said sixth transistor are shorted to receive corresponding voltage level control signals, said sources of said fifth transistor and said sixth transistor are shorted and electrically connected to said drain of said second thin film transistor, said drain of said fifth transistor is input by said data voltage during said displaying mode and is input by said initializing voltage during said detecting mode, said drain of said sixth transistor is connected to said first ADC.

20. The display apparatus according to claim 19, wherein during said data writing phase of said displaying mode:

said scan signal is in said high voltage level, said gates of said first transistor and said second transistor receive said low voltage level, said gates of said third, said fourth, said fifth and said sixth transistors receive said high voltage level;

wherein during said illuminating phase of said displaying mode;

said scan signal is in said low voltage level, said gates of said first transistor and said second transistor receive said low voltage level, said gates of said third, said fourth, said fifth and said sixth transistors receive said high voltage level;

wherein during said voltage level initializing phase of said detecting mode;

said scan signal is in said high voltage level, said gates of said first transistor and said second transistor receive said low voltage level, said gates of said third, said fourth, said fifth and said sixth transistors receive said high voltage level;

wherein during said detecting phase of said detecting mode;

said scan signal is in said high voltage level, said gates of said first transistor and said second transistor receive said high voltage level, said gates of said third, said fourth, said fifth and said sixth transistors receive said low voltage level.