This application claims priority of China Patent Application No. 201910294345.5, filed on Apr. 12, 2019, the entirety of which is incorporated by reference herein.
The disclosure relates to an electronic device, and more particularly to an electronic device that comprises a light-emitting component.
Electronic devices are widely used as they possess the favorable advantages of having a thin profile, being light in weight, and emitting low levels of radiation. Generally, the display devices of these electronic devices comprise self-luminous display devices and non-self-luminous display devices. A non-self-luminous display device may use a backlight source to achieve the display function. Therefore, the size of a non-self-luminous display device is larger than the size of a self-luminous display device.
In accordance with an embodiment, an electronic device comprises a pixel. The pixel receives a data signal and comprises a driving transistor, an emitting circuit, and a reset circuit. The driving transistor comprises a first gate, a first source/drain and a second source/drain. The first source/drain receives a first operation voltage. The emitting circuit is coupled to the driving transistor. The reset circuit is coupled to the first gate to set the voltage of the first gate. In a reset period, the voltage of the first gate is equal to a first predetermined voltage. In a write period, the voltage of the first gate is equal to a first difference between the first operation voltage and the threshold voltage of the driving transistor. In a display period, the voltage of the first gate is equal to the sum of the first difference and a second difference, wherein the second difference is the difference between a reference voltage and the data signal.
In accordance with another embodiment, a pixel comprises a driving transistor, a lighting transistor, a light-emitting diode, a compensation transistor, a first reset transistor, a first capacitor and a second capacitor. The driving transistor comprises a first gate, a first source/drain and a second source/drain. The first source/drain receives a first operation voltage. The lighting transistor is coupled to the driving transistor and receives a lighting signal. The light-emitting diode comprises an anode coupled to the lighting transistor and a cathode receiving a second operation voltage. The compensation transistor is coupled between the first gate and the second source/drain and receives a scan signal. The first reset transistor comprises a second gate, a third source/drain and a fourth source/drain. The second gate receives a reset signal. The third source/drain receives a first predetermined voltage. The fourth source/drain is coupled to the first gate. The first capacitor is coupled between the first gate and the first source/drain. The second capacitor is coupled between the first gate and a node. In a reset period, the first reset transistor is turned on to transmit the first predetermined voltage to the first gate. In a write period, the compensation transistor and the driving transistor are turned on, and the voltage of the first gate is equal to a first difference between the first operation voltage and the threshold voltage of the driving transistor. In a display period, the driving transistor and the lighting transistor are turned on to light the light-emitting diode.
The disclosure can be more fully understood by referring to the following detailed description and examples with references made to the accompanying drawings, wherein:
The present disclosure will be described with respect to particular embodiments and with reference to certain drawings, but the disclosure is not limited thereto and is limited by the claims. The drawings described are schematic and are non-limiting. In the drawings, the size of some of the elements may be exaggerated for illustrative purposes and not drawn to scale. The dimensions and the relative dimensions do not correspond to actual dimensions in the practice of the disclosure.
As shown in
The driving transistor 210 comprises a first gate 211, a first source/drain 212 and a second source/drain 213. The first gate 211 is coupled to the reset circuit 240, the compensation circuit 250 and the storage circuit 260. The first source/drain 212 receives a first operation voltage ARVDD. The second source/drain 213 is coupled to the lighting circuit 220 and the compensation circuit 250. In this embodiment, the driving transistor 210 may comprise a first P-type transistor. As shown in
The lighting circuit 220 may be coupled to the driving transistor 210 to transmit a driving current to the emitting circuit 230. The circuit structure of the lighting circuit 220 is not limited in the present disclosure. Any circuit can serve as the lighting circuit 220, as long as the circuit is capable of transmitting a driving current.
The emitting circuit 230 is coupled to the lighting circuit 220 and receives a second operation voltage ARVSS. In this embodiment, the emitting circuit 230 is connected to the lighting circuit 220 and the driving transistor 210 in series between the first operation voltage ARVDD and the second operation voltage ARVSS. In one embodiment, the emitting circuit 230 may comprise a light-emitting component 231. The type of the light-emitting component 231 is not limited in the present disclosure. In one embodiment, the light-emitting component 231 may comprise a light-emitting diode (LED), an organic light-emitting diode (OLED), a mini LED, a micro LED, a Quantum Dot (QD), a QD LED referred to as a Q LED, any of a variety of appropriate light-emitting components, or combinations thereof, but the disclosure is not limited. In other embodiments, the light-emitting component in the emitting circuit 230 may have phosphors material or fluorescence material.
The reset circuit 240 may be coupled to the first gate 211 to set the voltage of the first gate 211. In the present disclosure does not limit the circuit structure of the reset circuit 240. Any circuit can serve as the reset circuit 240, as long as the circuit is capable of setting the voltage of the first gate 211.
The compensation circuit 250 may be coupled between the first gate 211 and the second source/drain 213. In this embodiment, the compensation circuit 250 is also configured to set the voltage of the first gate 211. In one embodiment, when the compensation circuit 250 turns on the path between the first gate 211 and the second source/drain 213, the driving transistor 210 is referred to as a diode-connected transistor.
The storage circuit 260 may be coupled to the first gate 211. In this embodiment, the driving transistor 210 operates according to the voltage stored in the storage circuit 260. In a reset period, the reset circuit 240 may set the voltage of the first gate to be equal to a first predetermined voltage. In a write period, the compensation circuit 250 turns on the path between the first gate 211 and the second source/drain 213. Therefore, the voltage of the first gate 211 may be equal to a first difference between the first operation voltage ARVDD and the threshold voltage of the driving transistor 210. In a display period, the driving transistor 210 generates a driving current according to the voltage stored in the storage circuit 260. At this time, the voltage of the first gate 211 may be equal to the sum of the first difference and a second difference, wherein the second difference is the difference between a reference voltage and a data signal. The second difference between the reference voltage and the data signal is described in greater detail below. In the display period, the lighting circuit 220 transmits the driving current generated by the driving transistor 210 to the emitting circuit 230.
In other embodiments, the pixel 200B further comprises a data input circuit 280. The data input circuit 280 is coupled to the storage circuit 260. In the write period, the data input circuit 280 transmits a data signal to the storage circuit 260 according to a scan signal. The present disclosure does not limit the circuit structure of the data input circuit 280. Any circuit can serve as the data input circuit 280, as long as the circuit is capable of transmitting a data signal to the storage circuit 260 according to a scan signal.
In another embodiment, the pixel 200B further comprises a second set circuit 290. The second set circuit 290 may be coupled to the anode or the cathode of the light-emitting component 231. For example, the second set circuit 290 may be coupled to the anode of the light-emitting component 231. The cathode of the light-emitting component 231 may receive other voltage or connect to a ground. In the reset period, the second set circuit 290 may set the voltage of the anode of the cathode of the light-emitting component 231 to be equal to a second predetermined voltage. The circuit structure of the second set circuit 290 is not limited in the present disclosure. Any circuit can serve as the second set circuit 290, as long as the circuit is capable of setting the voltage of the anode of the cathode of the light-emitting component 231.
In other embodiments, the pixel 200B further comprises an impedance circuit 295. The impedance circuit 295 may be coupled to the second set circuit 290. Before the light-emitting component 231 is formed, the tester may enable other circuits of the pixel 200B to generate a driving current, which is used to drive the light-emitting component 231. When the driving current passes through the impedance circuit 295, the voltage difference across the impedance circuit 295 is changed with change of the driving current. Therefore, the tester determines whether the driving current reaches a target value according to the voltage difference across the impedance circuit 295. If the driving current does not reach the target value, it means that the pixel 200B fails to operate correctly. At this time, the tester may replace the pixel 200B with a redundancy pixel or does not dispose the light-emitting component 231 in the pixel 200B.
The lighting circuit 320 may comprise a lighting transistor 321. The lighting transistor 321 may be coupled between the driving transistor 310 and the emitting circuit 330 and receive a lighting signal EM. In a display period, the lighting transistor 321 is turned on to transmit a driving current ID to the emitting circuit 330. The type of lighting transistor 321 is not limited in the present disclosure. In this embodiment, the lighting transistor 321 comprises a P-type transistor. As shown in
The emitting circuit 330 may comprise a light-emitting component 331. The light-emitting component 331 is lighted according to the driving current ID. In this embodiment, the anode of the light-emitting component 331 may be coupled to the lighting transistor 321. The cathode of the light-emitting component 331 may receive the second operation voltage ARVSS. The second operation voltage ARVSS is lower than the first operation voltage ARVDD. In one embodiment, the second operation voltage ARVSS is a ground voltage or a negative voltage.
The reset circuit 340 comprises a first reset transistor 341 and a second reset transistor 342, but the disclosure is not limited thereto. As shown in
The second reset transistor 342 comprises a third gate, a fifth source/drain and a sixth source/drain. The third gate of the second reset transistor 342 may receive the reset signal RST. The fifth source/drain of the second reset transistor 342 receives a reference voltage VREF. The sixth source/drain of the second reset transistor 342 is coupled to the node N. In the reset period, the second reset transistor 342 is also turned on to transmit the reference voltage VREF to the node N.
The types of first reset transistor 341 and the second reset transistor 342 are not limited in the present disclosure. In one embodiment, the first reset transistor 341 and the second reset transistor 342 comprise N-type transistors or P-type transistor. In other embodiments, the type of first reset transistor 341 may be different from the type of second reset transistor 342. For example, one of the first reset transistor 341 and the second reset transistor 342 comprises an N-type transistor and the other comprises P-type transistor. In this case, the gates of the first reset transistor 341 and the second reset transistor 342 may receive different reset signals, such as a first reset signal and a second reset signal, the phase of the first reset signal is opposite to the phase of the second reset signal. In this embodiment, the first reset transistor 341 may comprise a second P-type transistor. Furthermore, the second reset transistor 342 comprises a third P-type transistor.
The pixel 300 further comprises a compensation circuit 350. The compensation circuit 350 comprises a compensation transistor 351. The compensation transistor 351 may be coupled between the first gate 311 and the second source/drain 313 and receive a scan signal Sn. In a write period, the compensation transistor 351 is turned on such that the driving transistor 310 serves as a diode. The type of compensation transistor 351 is not limited in the present disclosure. In this embodiment, the compensation transistor 351 may comprise a P-type transistor. The gate of the P-type transistor receives the scan signal Sn. The source of the P-type transistor is coupled to the first gate 311. The drain of the P-type transistor is coupled to the second source/drain 313. In other embodiments, the compensation transistor 351 may comprise an N-type transistor.
The storage circuit comprises a first capacitor C1 and a second capacitor Cst. The first capacitor C1 is configured to stabilize the voltage of the first gate 311. As shown in
The first set circuit 370 comprises a first set transistor 371. The first set transistor 371 comprises a fourth gate, a seventh source/drain and an eighth source/drain. The fourth gate of the first set transistor 371 may receive the lighting signal EM. The seventh source/drain of the first set transistor 371 may receive a reference voltage VREF. The eighth source/drain of the first set transistor 371 may be coupled to the node N. In a display period, the first set transistor 371 is turned on to transmit the reference voltage VREF to the node N. In this case, since the voltage of the node N is equal to the reference voltage VREF, the voltage stored in the first capacitor C1 can be maintained. The type of first set transistor 371 is not limited in the present disclosure. In this embodiment, the first set transistor 371 may comprise a P-type transistor. In some embodiments, the first set transistor 371 may comprise an N-type transistor.
The data input circuit 380 comprises a data input transistor 381. The data input transistor 381 is coupled to the node N and transmits the data signal DT to the node N according to the scan signal Sn. In a write period, the data input transistor 381 is turned on to transmit the data signal DT to the node N. The type of data input transistor 381 is not limited in the present disclosure. In one embodiment, the data input transistor 381 comprises a P-type transistor. In other embodiment, the data input transistor 381 comprises an N-type transistor.
In a write period T330, the scan signal Sn is at the low level to turn on the driving transistor 310, the data input transistor 381 and the compensation transistor 351. Since the data input transistor 381 is turned on, the voltage of the node N is equal to the data signal DT. Furthermore, since the driving transistor 310 and the compensation transistor 351 are turned on, the voltage of the first gate 311 is equal to a first difference (ARVDD−VTH) between the first operation voltage ARVDD and the threshold voltage of the driving transistor 310.
In a display period T350, the lighting signal EM is at the low level. Therefore, the first set transistor 371 and the lighting transistor 321 are turned on. Since the first set transistor 371 is turned on, the voltage of the node N is equal to the reference voltage VREF. At this time, the voltage of the first gate 311 is equal to the first difference and a second difference due to the capacitance coupling effect. The second difference is a difference (VREF−DT) between the reference voltage VREF and the data signal DT. In other words, the voltage of the first gate 311 expressed by the following equation (1):
VG=ARVDD−VTH+(VREF−DT) (1)
wherein VTH is the threshold voltage of the driving transistor 310, (ARVDD−VTH) is the first difference, and (VREF−DT) is the second difference.
In the display period T350, the driving current ID generated by the driving transistor 310 is expressed by the following equation (2):
ID=K(VSG−VTH)2 (2)
wherein K is a conduction parameter.
If the gate voltage of the driving transistor 310 and the source voltage of the driving transistor 310 are substituted into equation (2), the substituted result is expressed by the following equation (3):
ID=K(DT−VREF)2 (3)
According to equation (3), the driving current ID generated by the driving transistor 310 is not interfered by the threshold voltage of the driving transistor 310. Therefore, when the threshold voltage of the driving transistor 310 is shifted, the driving current ID does not be interfered. Additionally, in the display period T350, since the lighting transistor 321 is turned on, the lighting transistor 321 turns the driving current ID to the emitting circuit 330 to light the light-emitting component 331.
In this embodiment, a turning-off period T320 is between the reset period T310 and the write period T330. In the turning-off period T320, the reset signal RST and the scan signal Sn are at the high level to avoid that the data input transistor 381 and the second reset transistor 342 are turned on simultaneously, and the voltage of the node N is interfered. The duration of the turning-off period T320 is not limited in the present disclosure. In some embodiment, the turning-off period T320 can be omitted.
Furthermore, a turning-off period T340 is between the write period T330 and the display period T350. In the turning-off period T340, the lighting signal EM is at the high level to measure the voltage of the first gate 311 at a predetermined value. The duration of the write period T330 is not limited in the present disclosure. In one embodiment, the turning-off period T340 is longer than the turning-off period T320.
In other embodiments, the control signal CN is the previous scan signal (e.g., Sn−1) or the next scan signal (e.g., Sn+1). Taking
The type of second set transistor 391 is not limited in the present disclosure. In this embodiment, the second set transistor 391 may comprise a P-type transistor. In other embodiments, the second set transistor 391 may comprise an N-type transistor.
In this embodiment, when the light-emitting component 331 does not dispose in the pixel 500 yet, if all circuits in the pixel 500 are activated, the driving transistor 310 generates a driving current ID passing through the impedance circuit 395. The tester measures the voltage of the node TN to determine whether the driving current ID reaches a target value. If the driving current ID does not reach the target value, it means that the pixel 500 is not operating correctly. At this time, the tester may try to repair the pixel 500 or replace the pixel 500 with a redundancy pixel. In one embodiment, when the pixel 500 is operating abnormal, the tester does not dispose the light-emitting component 331 in the pixel 500.
The materials of the semiconductor layers of the above transistors are not limited in the present disclosure. In one embodiment, the materials of the semiconductor layers of the above transistors may comprise amorphous silicon, polysilicon, low-temperature polysilicon (LTPS), oxide semiconductor, a variety of other material or combinations thereof. The oxide semiconductor may comprise indium gallium zinc oxide (IGZO).
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. All features of the embodiments can be mixed and used as long as they do not violate the spirit of the disclosed or they do not conflict with each other.
While the disclosure has been described by way of example and in terms of the embodiments, it should be understood that the disclosure is not limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). For example, it should be understood that the system, device and method may be realized in software, hardware, firmware, or any combination thereof. Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.
Number | Date | Country | Kind |
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201910294345.5 | Apr 2019 | CN | national |
This application claims the benefit of U.S. Provisional Application No. 62/731,146, filed on Sep. 14, 2018, which is hereby incorporated by reference in its entirety.
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