This application is related to and claims priority from Chinese Patent Application No. 201611126639.X, filed on Dec. 9, 2016, entitled “Organic Light Emitting Pixel Compensation Circuit, Organic Light Emitting Display Panel, and Method for Driving the Panel,” the entire disclosure of which is hereby incorporated by reference for all purposes.
The present application relates to the field of display technology, and particularly to an organic light emitting pixel compensation circuit, an organic light emitting display panel, and a driving method.
With the development of display technologies, liquid crystal displays (LCDs) and organic light emitting diode (OLED) displays, as two types of popular display devices, are more widely used in various portable electronic devices.
LCD is a non-self-luminous device, and OLED is an organic self-luminous device. Compared with the LCD, the OLED display has faster response speed, higher contrast and wider viewing angle, so the OLED display receives more attention.
However, in a conventional OLED display, generally only the threshold voltage of a driving transistor of the light emitting diode is compensated, without considering the impact from the deterioration of the light emitting element. For example, as time passes, the forward voltage drops across the light-emitting element (the lowest forward voltage at which the light-emitting element can be turned on at a prescribed forward current) is increased when the current flows through the light-emitting element. The light-emitting element is usually connected to a source and a drain of the driving transistor. As a result, the potential difference between the source and drain of the driving transistor decreases. Therefore, the light-emitting current flowing through the light-emitting element also decreases, resulting in display anomalies.
In view of the defects or disadvantages existing in the conventional OLED drivers, it is desirable to provide an organic light emitting pixel compensation circuit, an organic light emitting display panel, and a driving method, to solve the existing technical problems.
According to an aspect of the present application, an organic light emitting pixel compensation circuit is provided, which includes an external compensation module comprising a data line, a reference voltage line, a reset control line, a first detection control line, a second detection control line, a first input/output terminal, a second input/output terminal, a reset unit, a threshold voltage detection unit, a deterioration voltage detection unit, a data processing unit, and an adder unit. The reset unit is connected to the reference voltage line, the second input/output terminal, and configured to transmit a signal provided from the reference voltage line to the second input/output terminal, based on a signal from the reset control line. The threshold voltage detection unit is connected to the data line, the first input/output terminal, and the data processing unit, and configured to transmit a voltage on the first input/output terminal to the data processing unit, based on a signal from the first detection control line. The deterioration voltage detection unit is connected to the second input/output terminal and the data processing unit, and configured to transmit a voltage on the second input/output terminal to the data processing unit, based on a signal from the second detection control line. The data processing unit is connected to the threshold voltage detection unit, the deterioration voltage detection unit, and the adder unit, and configured to process the voltages provided from the threshold voltage detection unit and the deterioration voltage detection unit, and transmit the processed voltages to the adder unit. The adder unit is connected to the data processing unit and the data line, and configured to provide a compensated voltage, based on the voltage provided from the data processing unit and the voltage on the data line.
According to another aspect of the present application, an organic light emitting display panel is also provided, which includes a display region and a non-display region surrounding the display region. A plurality of external compensation modules is arranged in the non-display region. Each of the external compensation modules includes a data line, a reference voltage line, a reset control line, a first detection control line, a second detection control line, a first input/output terminal, a second input/output terminal, a reset unit, a threshold voltage detection unit, a deterioration voltage detection unit, a data processing unit, and an adder unit. The reset unit is connected to the reference voltage line and the second input/output terminal, and configured to transmit a signal provided from the reference voltage line to the second input/output terminal, based on a signal from the reset control line. The threshold voltage detection unit is connected to the data line, the first input/output terminal, and the data processing unit, and configured to transmit a voltage on the first input/output terminal to the data processing unit, based on a signal from the first detection control line. The deterioration voltage detection unit is connected to the second input/output terminal and the data processing unit, and configured to transmit a voltage on the second input/output terminal to the data processing unit, based on a signal from the second detection control line. The data processing unit is connected to the threshold voltage detection unit, the deterioration voltage detection unit, and the adder unit, and configured to process the voltages provided from the threshold voltage detection unit and the deterioration voltage detection unit, and transmit the processed voltages to the adder unit. The adder unit is connected to the data processing unit and the data line, and configured to provide a compensated voltage, based on the voltage provided from the data processing unit and the voltage on the data line.
According to another aspect of the present application, a method for driving an organic light emitting display panel is further provided. The method includes the following. During initialization, a data line provides a data voltage, a reference voltage line provides a reference voltage, a first source voltage terminal provides a first voltage, a data voltage write unit transmits the data voltage to a gate of a driving transistor based on a signal from a first scan line, a reset detection control unit is turned on based on a signal from a second scan line, a reset unit transmits the reference voltage to an anode of a light emitting element based on a signal from a reset control line, and a light emission control unit transmits the first voltage to a first electrode of the driving transistor based on a signal from a light emission control line. During detection of a threshold voltage, the light emission control unit is turned off based on a signal from the light emission control line, the voltage on the first electrode of the driving transistor is transmitted via a first input/output terminal to a threshold voltage detection unit, and the threshold voltage detection unit implements the detection on the driving transistor based on a signal from the first detection control line. During writing of the first voltage, the threshold voltage detection unit is turned off based on a signal from the first detection control line, the reset unit is turned off based on a signal from the reset control line, a data processing unit processes the detected voltage to obtain a threshold voltage, an adder unit performs compensation on the data voltage based on the threshold voltage, and the data voltage write unit transmits the compensated data voltage to the gate of the driving transistor based on a signal from the first scan line. During detection of a deterioration voltage, the light emission control unit is turned on based on a signal from the light emission control line, an anode voltage of the light emitting element is transmitted to a second input/output terminal, and a deterioration voltage detection unit implements the detection on the light emitting element based on a signal from a second detection control line. During writing of a second voltage, the light emission control unit is turned off based on a signal from the light emission control line, the deterioration voltage detection unit is turned off based on a signal from the second detection control line, the data processing unit processes the detected anode voltage to obtain a deterioration voltage, the adder unit performs compensation on the data voltage based on the deterioration voltage, and the data voltage write unit transmits the compensated data voltage to the gate of the driving transistor based on a signal from the first scan line. During light emission, the data voltage write unit is turned off based on a signal from the first scan line, the reset detection control unit is turned off based on a signal from the second scan line, the light emission control unit is turned on based on a signal from the light emission control line, and the light emitting element emits light.
According to the solutions provided in the present application, the anode voltage of the second input/output terminal is detected and processed to produce a compensated voltage, and the compensated voltage is fed via the data line back to the gate of the driving transistor, thereby achieving the deterioration compensation for the light emitting element.
Other features, objects, and advantages of the present application will become more apparent upon reading of the following detailed description of the non-limiting embodiments with reference to the accompanying drawings.
The present application will be further described below in detail in combination with the accompanying drawings and the embodiments. It should be appreciated that the specific embodiments described herein are merely used for explaining the relevant invention, rather than limiting the invention. In addition, it should be noted that, for the ease of description, only the parts related to the relevant invention are shown in the accompanying drawings.
It should also be noted that the embodiments in the present application and the features in the embodiments may be combined with each other on a non-conflict basis. The present application will be described below in detail with reference to the accompanying drawings and in combination with the embodiments.
As shown in
The reset unit 113 is connected to the reference voltage line Ref and the second input/output terminal 102, and configured to transmit a signal provided from the reference voltage line Ref to the second input/output terminal 102, based on a signal from the reset control line SW3. The threshold voltage detection unit 111 is connected to the data line Data, the first input/output terminal 101 and the data processing unit 114, and configured to transmit a voltage signal on the first input/output terminal 101 to the data processing unit 114 based on a signal from the first detection control line SW1. The deterioration voltage detection unit 112 is connected to the second input/output terminal 102 and the data processing unit 114, and configured to transmit a voltage signal on the second input/output terminal 102 to the data processing unit 114 based on a signal from the second detection control line SW2. The data processing unit 114 is connected to the threshold voltage detection unit 111, the deterioration voltage detection unit 112, and the adder unit 115, and configured to process the voltage signals provided from the threshold voltage detection unit 111 and the deterioration voltage detection unit 112, and transmit the processed voltage signals to the adder unit 115. The adder unit 115 is connected to the data processing unit 114, and the data line Data, and configured to provide a compensated voltage signal based on the voltage signal provided from the data processing unit 114 and the voltage signal on the data line Data.
In this embodiment, the threshold voltage detection unit 111 detects a threshold voltage of a driving transistor in an organic light emitting pixel from the first input/output terminal 101, and a compensated data voltage is fed back to the data line Data after the processing by the data processing unit 114 and the addition by the adder unit 115. In this way, the threshold voltage of the organic light emitting pixel is compensated. Meanwhile, the deterioration voltage detection unit 112 detects an anode voltage signal of a light emitting element in an organic light emitting pixel from the second input/output terminal 102, and a compensated data voltage is fed back to the data line Data after the processing by the data processing unit 114 and the addition by the adder unit 115. In this way, deterioration compensation is performed on the light emitting element of the organic light emitting pixel.
The organic light emitting pixel compensation circuit 100a may further include a plurality of internal compensation modules 12a, and each of the internal compensation modules 12a may include a data voltage storage unit 121, a data voltage write unit 122, a reset detection control unit 123, a light emission control unit 124, a light emitting element D1, a driving transistor DT, a light emission control line SW4, a first scan line S1, and a second scan line S2.
The data voltage storage unit 121 is connected to a gate of the driving transistor DT, and configured to store a gate voltage signal of the driving transistor DT. The data voltage write unit 122 is connected to the data line Data and the gate of the driving transistor DT, and configured to transmit a signal from the data line Data to the gate of the driving transistor DT based on a signal from the first scan line S1. The reset detection control unit 123 is connected to an anode of the light emitting element D1 and the second input/output terminal 102, and configured to transmit an anode voltage signal of the light emitting element D1 to the second input/output terminal 102 or transmit a voltage signal of the second input/output terminal 102 to the anode of the light emitting element D1, based on a signal from the second scan line S2. The light emission control unit 124 is connected to a first source voltage terminal VDD and a first electrode of the driving transistor DT, and configured to control the light emission of the light emitting element D1, based on a signal from the light emission control line SW4. A cathode of the light emitting element D1 is connected to a second source voltage terminal VEE. A second electrode of the driving transistor DT is connected to the anode of the light emitting element D1, and the first electrode of the driving transistor DT is connected to the first input/output terminal 101.
The internal compensation module 12a may transmit a voltage signal including the threshold voltage of the driving transistor DT to the first input/output terminal 101, and then a compensated data voltage is transmitted to the gate of the driving transistor DT via the data line Data, to accomplish the compensation on the threshold voltage. In addition, the internal compensation module 12a may further transmit a voltage signal including the anode voltage of the light emitting element D1 to the second input/output terminal 102, and then a compensated data voltage is transmitted to the gate of the driving transistor DT via the data line Data, to accomplish the deterioration compensation.
The structure of the embodiment shown in
Unlike the embodiment shown in
The light emission control unit 116 is connected to the first source voltage terminal VDD and the first input/output terminal 101, and configured to transmit a voltage signal of the first source voltage terminal VDD to the first input/output terminal 101, based on a signal from the light emission control line SW4.
In this embodiment, because the light emission control line SW4 and the light emission control unit 116 are arranged in the external compensation module 11b, the circuit structure of the internal compensation module 12b is simplified, and the area occupied by the internal compensation module 12b is reduced, which facilitates the increase in the aperture ratio of the organic light emitting pixel, and the fabrication of an organic light emitting display panel with a high PPI.
An organic light emitting pixel compensation circuit 200a shown in
The implementation shown in
The threshold voltage detection unit 211 may include a first switch transistor T1 and a first capacitor C1. A gate of the first switch transistor T1 is connected to the first detection control line SW1, a first electrode of the first switch transistor T1 is connected to the first input/output terminal 201, a second terminal of the first capacitor C1 is grounded, and a second electrode of the first switch transistor T1 and a first terminal of the first capacitor C1 are connected to the data processing unit 214.
The deterioration voltage detection unit 212 may include a second switch transistor T2 and a second capacitor C2. A gate of the second switch transistor T2 is connected to the second detection control line SW2, a first electrode of the second switch transistor T2 and a first terminal of the second capacitor C2 are connected to the second input/output terminal 202, a second terminal of the second capacitor C2 is grounded, and a second electrode of the second switch transistor T2 is connected to the data processing unit 214.
The reset detection control unit 223 may include a third switch transistor T3. A gate of the third switch transistor T3 is connected to the second scan line S2, a first electrode of the third switch transistor T3 is connected to the second input/output terminal 202, and a second electrode of the third switch transistor T3 is connected to an anode of the light emitting element D1.
The reset unit 213 may include a fourth switch transistor T4. A gate of the fourth switch transistor T4 is connected to the reset control line SW3, a first electrode of the fourth switch transistor T4 is connected to the reference voltage line Ref, and a second electrode of the fourth switch transistor T4 is connected to the second input/output terminal 202.
The organic light emitting pixel compensation circuit 200a may further include a common voltage line Vcom. The data voltage storage unit 221 includes a third capacitor C3, and the data voltage write unit 222 includes a fifth switch transistor T5. A first terminal of the third capacitor C3 is connected to a gate of the driving transistor DT, a second terminal of the third capacitor C3 is connected to the common voltage line Vcom, a gate of the fifth switch transistor T5 is connected to the first scan line S1, a first electrode of the fifth switch transistor T5 is connected to the data line Data, and a second electrode of the fifth switch transistor T5 is connected to the gate of the driving transistor DT.
The light emission control unit 224 may include a sixth switch transistor T6. A gate of the sixth switch transistor T6 is connected to the light emission control line SW4, a first electrode of the sixth switch transistor T6 is connected to the first source voltage terminal VDD, a second electrode of the sixth switch transistor T6 is connected to a first electrode of the driving transistor DT.
The organic light emitting pixel compensation circuit 200b shown in
Unlike the organic light emitting pixel compensation circuit 200a shown in
The light emission control unit 216 may include a sixth switch transistor T6. A gate of the sixth switch transistor T6 is connected to the light emission control line SW4, a first electrode of the sixth switch transistor T6 is connected to the first source voltage terminal VDD, a second electrode of the sixth switch transistor T6 is connected to the first input/output terminal 201.
Although the first switch transistor T1, the second switch transistor T2, the third switch transistor T3, the fourth switch transistor T4, the fifth switch transistor T5, the sixth switch transistor T6, and the driving transistor DT shown in
Optionally, the organic light emitting pixel compensation circuit may further include a threshold voltage storage unit and a deterioration voltage storage unit connected to the data processing unit.
As shown in
For example, after the threshold compensation is performed on the driving transistor DT in the organic light emitting pixel compensation circuit 100a, the threshold voltage may be stored in the threshold voltage storage unit; and after the deterioration compensation is performed on the light emitting element D1 in the organic light emitting pixel compensation circuit 100a, the deterioration voltage may be stored in the deterioration voltage storage unit.
As such, before the data processing unit transmits the threshold voltage to the adder unit, the threshold voltage is compared with that stored in the threshold voltage storage unit. If the threshold voltage is different from that stored in the threshold voltage storage unit, the threshold voltage is transmitted to the adder unit, for compensating the threshold voltage of the driving transistor.
Similarly, before the data processing unit transmits the deterioration voltage to the adder unit, the deterioration voltage is compared with that stored in the deterioration voltage storage unit. If the deterioration voltage is different from that stored in the deterioration voltage storage unit, the deterioration voltage is transmitted to the adder unit, for performing deterioration compensation on the light emitting element.
Optionally, the organic light emitting pixel compensation circuit may further include a driving circuitry, in which a lookup table memory is arranged, and configured to store current-voltage characteristic parameters of the light emitting element.
As shown in
As such, during deterioration compensation at a later time, the data processing unit may transmit the anode voltage signal obtained by the deterioration voltage detection unit to the lookup table memory in the driving circuitry, and may look up the deterioration voltage of the light emitting element D1, and transmit the deterioration voltage to the adder unit for performing deterioration compensation on the light emitting element D1, thereby simplifying the process for processing the anode voltage signal by the data processing unit.
As shown in
In this embodiment, the threshold voltage detection unit detects a threshold voltage of a driving transistor in an organic light emitting pixel from the first input/output terminal, and a compensated data voltage is fed back to the data line after the processing by the data processing unit and the addition by the adder unit. In this way, the threshold voltage of the organic light emitting pixel is always compensated. Meanwhile, the deterioration voltage detection unit detects an anode voltage signal of alight emitting element in an organic light emitting pixel from the second input/output terminal, and a compensated data voltage is fed back to the data line after the processing by the data processing unit and the addition by the adder unit. In this way, the deteriorated voltage of the organic light emitting pixel is compensated to remain constant.
The display region 32 may include a plurality of rows of pixel units 323 and a plurality of columns of pixel units 324. Each row of the pixel units 323 may include a plurality of sub-pixels 322, and each column of the pixel units 324 may include a plurality of sub-pixels 322. An internal compensation module 321 may be arranged in each of the sub-pixels 322, and the internal compensation module 321 may have the same circuit structure as that of the internal compensation module 22a shown in
The internal compensation module 321 may transmit a voltage signal including the threshold voltage of the driving transistor to the first input/output terminal, and then a compensated data voltage from the external compensation module 311 is transmitted to the gate of the driving transistor via the data line, to accomplish the compensation on the threshold voltage. In addition, the internal compensation module 321 may further transmit a voltage signal including the anode voltage of the light emitting element to the second input/output terminal, and then a compensated data voltage from the external compensation module 311 is transmitted to the gate of the driving transistor via the data line, to accomplish the deterioration compensation.
The working principle of the organic light emitting display panel 300 shown in
The timing diagram in
An equivalent circuit diagram of the organic light emitting pixel compensation circuit 200a is as shown in
In this stage, the potential Vg at the gate (that is, the node N2) of the driving transistor DT is Vdata, the potential Vs at a source (that is, the first electrode or the node N1 of the driving transistor DT) of the driving transistor DT is Vdd, and the anode potential Voled+ of the light emitting element D1 is Vref.
Stage P2: The light emission control line SW4 provides a high level signal, the first detection control line SW1 provides a low level signal, the sixth switch transistor T6 connected to SW4 is turned off, and the first switch transistor T1 connected to SW1 is turned on. An equivalent circuit diagram of the organic light emitting pixel compensation circuit 200a is as shown in
In this stage, the source of the driving transistor DT discharges to the first capacitor C1, the source potential Vs is gradually decreased from Vdd to Vdata+|Vth|, the discharge is stopped, and the source potential Vs is maintained by the first capacitor C1. Here, Vth is the threshold voltage of the driving transistor DT.
Stage P3: The first detection control line SW1 and the reset control line SW3 provide a high level signal, and the first switch transistor T1 connected to SW1 and the fourth switch transistor T4 connected to SW3 are turned off. An equivalent circuit diagram of the organic light emitting pixel compensation circuit 200a is as shown in
In this stage, the data processing unit 214 acquires the source potential Vs from the first capacitor C1, acquires the voltage signal Vdata from the data line Data and processes them (for example, performs subtraction of the two voltage signals, Vs−Vdata), to obtain the threshold voltage |Vth|, and transmit the threshold voltage |Vth| to the adder unit 215. After addition by the adder unit 215, a compensated data voltage signal Vdata′ (Vdata′=Vdata−|Vth|) is fed back to the gate (that is, the node N2) of the driving transistor DT via the data line Data. The compensated data voltage signal Vdata′ is maintained by the third capacitor C3.
Stage P4: The second detection control line SW2 and the light emission control line SW4 provide a low level signal, and the second switch transistor T2 connected to SW2, the sixth switch transistor T6 connected to SW4, and the driving transistor DT, connected to N1 at its source, are turned on. An equivalent circuit diagram of the organic light emitting pixel compensation circuit 200a is as shown in
In this stage, the potential Vs at the source (that is, the node N1) of the driving transistor DT is Vdd, the potential Vg at the gate (that is, the node N2) of the driving transistor DT is Vdata′, and the anode potential Voled+ of the light emitting element D1 is transmitted through the third switch transistor T3 and the second switch transistor T2 to the data processing unit 214.
A transistor's current in a saturated region is calculated by the formula:
I=k(|Vgs|−|Vth|)2(1+λ·Vds) (1)
Therefore the light-emitting current flowing through the light-emitting element D1 in Stage P4 is calculated to be:
I
oled
=k(Vdd−Vdata′−|Vth|)2(1+λ(Vdd−Voled+)) (2)
where Vgs is the potential difference between the gate and the source of the driving transistor DT, Vds is the potential difference between the source and the drain (the second electrode of the driving transistor DT) of the driving transistor DT, and λ is a channel length modulation parameter; k is calculated from:
where μ is the channel mobility of the driving transistor DT, cox is the gate oxide capacitance per unit area of the driving transistor DT, and
is width-to-length ratio of the channel of the driving transistor DT.
By simplifying Formula (2), the light-emitting current flowing through the light-emitting element D1 in Stage P4 is
I
oled
=k(Vdd−Vdata)2(1+λ(Vdd−Voled+)) (3)
It can be seen from Formula (3) that the light-emitting current Ioled is independent of the threshold voltage Vth of the driving transistor DT. Therefore, in case that the anode voltage Vdada of the light emitting element D1 is kept unchanged, the constant light-emitting current Ioled can be obtained as long as the first voltage signal Vdd and data voltage signal Vdata are applied to the organic light emitting display panel 300 in this embodiment, thereby avoiding the influence of the threshold voltage Vth of the driving transistor DT on the light emitting current Ioled. As a result, the display unevenness due to the threshold difference of the driving transistor DT is avoided.
In Stage P5, the second detection control line SW2 and the light emission control line SW4 provide a high level signal, and the second switch transistor T2 connected to SW2 and the sixth switch transistor T6 connected to SW4 are turned off. An equivalent circuit diagram of the organic light emitting pixel compensation circuit 200a is as shown in
The external data processing unit 214 processes the anode voltage signal Voled+, to obtain a deterioration voltage ΔVoled of the light emitting element D1, and transmits the obtained deterioration voltage ΔVoled to the external adder unit 215. After addition by the adder unit 215, a compensated data voltage signal Vdata″ (Vdata″=Vdata−|Vth|−ΔVoled) is fed back to the gate (that is, the node N2) of the driving transistor DT via the data line Data, and the compensated data voltage Vdata″ is therefore maintained by the third capacitor C3.
A process for processing the anode voltage signal Voled+ by the data processing unit 214 to obtain the deterioration voltage ΔVoled is as described below. A forward voltage Voled (Voled=Voled−Vee, where Vee is a voltage signal provided by the second source voltage terminal VEE) of the light emitting element D1 is calculated; a current value corresponding to the forward voltage Voled of the light emitting element D1 is obtained based on the previously stored current-voltage characteristic parameters of the light emitting element; the brightness of the light emitting element D1 is calculated from the current value; and if the decay of the brightness of the light emitting element D1 (relative to the original brightness of the light emitting element D1) exceeds a preset value (for example, 3%), deterioration compensation of the light emitting element is needed, and a deterioration voltage ΔVoled is obtained based on the previously stored current-voltage characteristic parameters of the light emitting element.
In stage P6, the first scan line S1 and the second scan line S2 provide a high level signal, the light emission control line SW4 provides a low level signal, the fifth switch transistor T5 and the third switch transistor T3 are turned off, the sixth switch transistor T6 and the driving transistor DT are turned on, and the light emitting element D1 emits light. An equivalent circuit diagram of the organic light emitting pixel compensation circuit 200a is as shown in
The potential Vs at the source (that is, the node N1) of the driving transistor DT is Vdd, the potential Vg at the gate (that is, the node N2) of driving transistor DT is Vdata″, and the light emitting current flowing through the light emitting element D1 is
I
oled
=k(Vdd−Vdata+ΔVoled)2(1+λ(Vdd−Voled+)) (4)
As can be known from comparison of Formulas (3) and (2), after deterioration compensation of the light emitting element D1, the light emitting current Ioled is increased. In case of brightness decay of the organic light emitting display panel 300 according to this embodiment after long time of use, the light emitting current is increased by means of deterioration compensation, thereby avoiding the brightness decay caused by deterioration of the light emitting element D1, and effectively extending the service life of the organic light emitting display panel 300.
The sixth switch transistor T6 and the light emission control line SW4 may be arranged in the internal compensation module 321 of the sub-pixel 322, and the light emission control lines SW4 of the sub-pixels 322 in the same row of pixel units 323 are connected together. That is to say, the sixth switch transistors T6 in the same row of pixel units 323 may share a common light emission control line SW4, and the first voltage signal Vdd controls the simultaneous light emission of the sub-pixels 322 in the same row of pixel units 323, based on a signal from the light emission control line SW4.
As such, the threshold voltage of the driving transistor DT and the deterioration voltage of the light emitting element D1 can be compensated with one row of pixel units 323 as a unit, thereby increasing the signal processing speed.
The internal compensation modules 321 in the sub-pixels 322 of the same column of pixel units 324 may be connected to the same external compensation module 311.
At least two adjacent columns of the pixel units 324 may be connected to a same reference voltage line. The sub-pixels 322 in at least two adjacent columns of the pixel units 324 may share a common reference voltage line Ref, whereby wiring of the reference voltage line Ref in the sub-pixel 322 is reduced. Correspondingly, at least two adjacent external compensation modules 311 may share a common reset unit (not shown), which simplifies the circuit structure of the external compensation module, and reduces the area occupied by the external compensation module 311.
Optionally, the external compensation modules 311 may share a common data processing unit. Correspondingly, the external compensation modules 311 may share a common adder unit. In this manner, the circuit structure of the external compensation module 311 is further simplified, and the area occupied by the external compensation module 311 is further reduced.
Optionally, a threshold voltage storage unit (not shown) and a deterioration voltage storage unit (not shown) may also be arranged in the non-display region 31 of the organic light emitting display panel 300. The threshold voltage storage unit is connected to the data processing unit, and configured to store the threshold voltage provided by the data processing unit; and the deterioration voltage storage unit is connected to the data processing unit, and configured to store the deterioration voltage provided by the data processing unit.
For example, in
As such, before the data processing unit transmits the threshold voltage to the adder unit, the threshold voltage is compared with that stored in the threshold voltage storage unit. If the threshold voltage is different from that stored in the threshold voltage storage unit, the threshold voltage is transmitted to the adder unit, for compensating the threshold voltage of the driving transistor in the sub-pixel 322.
Similarly, before the data processing unit transmits the deterioration voltage to the adder unit, the deterioration voltage is compared with that stored in the deterioration voltage storage unit. If the deterioration voltage is different from that stored in the deterioration voltage storage unit, the deterioration voltage is transmitted to the adder unit, for performing deterioration compensation on the light emitting element in the sub-pixel 322.
Optionally, a driving circuitry (not shown) is further arranged in the non-display region 31 of the organic light emitting display panel 300, in which a lookup table memory is arranged, and configured to store current-voltage characteristic parameters of the light emitting element.
All the pixel units on the organic light emitting display panel may be pre-compensated (including threshold compensation and deterioration compensation), and the current-voltage characteristic parameters of the light emitting element before and after compensation are stored in the lookup table memory.
As such, during deterioration compensation at a later time, the data processing unit may transmit the anode voltage signal obtained by the deterioration voltage detection unit to the lookup table memory, to look up the deterioration voltage of the light emitting element, and transmit the deterioration voltage to the adder unit for performing deterioration compensation on the light emitting element in the sub-pixel 322, thereby simplifying the process for processing the anode voltage signal by the data processing unit
In this embodiment, each row of the pixel units may be connected with one first scan line and one second scan line.
For example, in some application scenarios, the signals from the first scan lines S1-Sm and the signals from the second scan line S1′-Sm′ are generated respectively by a shift register 33 and a shift register 34, shown in
In addition, the internal compensation module 321 in each sub-pixel 322 on the organic light emitting display panel 300 includes, in addition to the driving transistor and the light emitting element, only three switch transistors (for example, the fifth switch transistor, the sixth switch transistor, and the third switch transistor) and one storage capacitor, the circuit structure is simple, and the threshold compensation and the deterioration compensation can be accomplished only by transmitting a voltage signal including the threshold voltage of the driving transistor and the anode voltage signal of the light emitting element to the external compensation module 311. Therefore, the present invention is applicable to the organic light emitting display devices of various sizes.
The structure compensation circuitry of the embodiment shown in
This embodiment in
It can be known from the waveforms of S1 and S2 in
Specifically, as shown in
Correspondingly, the scan lines S1-Sm may be provided by a shift register 63, whereby the area occupied by the internal compensation module 621 is further reduced.
The structure of the circuitry of the embodiment shown in
Unlike the embodiment shown in
This embodiment has the following benefits.
On one hand, the sixth switch transistor T6 and the light emission control line SW4 are migrated from the internal compensation module 721 in each sub-pixel 722 of the display region 72 into the external compensation module 711 in the non-display region 71, which not only simplifies the circuit structure of the internal compensation module 721, but also reduces the area occupied by the internal compensation module 721 in the sub-pixel 722, thus facilitating the increase in the aperture ratio of the sub-pixel 722, and also the fabrication of an display panel with a high PPI.
On the other hand, the sixth switch transistor T6 and the light emission control line SW4 are arranged in the external compensation module 711, and the sixth switch transistor T6 and the light emission control line SW4 are effectively multiplexed, which simplifies the circuit structure of the organic light emitting display panel 700.
Moreover, because the first voltage signal Vdd can control the simultaneous light emission of all the sub-pixels 722 on the organic light emitting display panel 700 based on a signal from the light emission control line SW4, all the sub-pixels 722 on the organic light emitting display panel 700 can be collectively compensated. After all the sub-pixels 722 are compensated, all the sub-pixels 722 on the organic light emitting display panel 700 emit light based on a signal from the light emission control line SW4. In this way, visual discomforts caused by line-by-line scan, such as tailing and the like, are avoided. Particularly, when the display panel 700 is applied in a VR (Virtual Reality) device, the visual discomforts during scanning are avoided, thus eliminating the discomfort of a user such as dizziness and the like.
Moreover, the present application further discloses a method for driving an organic light emitting display panel, including the organic light emitting display panels according to various embodiments above.
Step 801: during initialization, a data line provides a data voltage signal, a reference voltage line provides a reference voltage signal, a first source voltage terminal provides a first voltage signal, a data voltage write unit transmits the data voltage signal to a gate of a driving transistor based on a signal from a first scan line, a reset detection control unit is turned on based on a signal from a second scan line, a reset unit transmits the reference voltage signal to an anode of a light emitting element based on a signal from a reset control line, and a light emission control unit transmits the first voltage signal to a first electrode of the driving transistor based on a signal from a light emission control line.
Step 802: during detection of a threshold voltage, the light emission control unit is turned off based on a signal from the light emission control line, the voltage signal on the first electrode of the driving transistor is transmitted via a first input/output terminal to a threshold voltage detection unit, and the threshold voltage detection unit implements the detection on the driving transistor based on a signal from the first detection control line.
Step 803: during writing the first voltage, the threshold voltage detection unit is turned off based on a signal from the first detection control line, the reset unit is turned off based on a signal from the reset control line, a data processing unit processes the detected voltage signal to obtain a threshold voltage, an adder unit performs compensation on the data voltage signal based on the threshold voltage, and the data voltage write unit transmits the compensated data voltage signal to the gate of the driving transistor based on a signal from the first scan line.
Step 804: during detection of a deterioration voltage, the light emission control unit is turned on based on a signal from the light emission control line, an anode voltage signal of the light emitting element is transmitted to a second terminal, and a deterioration voltage detection unit implements the detection on the light emitting element based on a signal from a second detection control line.
Step 805: during writing a second voltage, the light emission control unit is turned off based on a signal from the light emission control line, the deterioration voltage detection unit is turned off based on a signal from the second detection control line, the data processing unit processes the detected anode voltage signal to obtain a deterioration voltage, the adder unit performs compensation on the data voltage signal based on the deteriorated voltage, and the data voltage write unit transmits the compensated data voltage signal to the gate of the driving transistor based on a signal from the first scan line.
Step 806: during light emission, the data voltage write unit is turned off based on a signal from the first scan line, the reset detection control unit is turned off based on a signal from the second scan line, the light emission control unit is turned on based on a signal from the light emission control line, and the light emitting element emits light
Here, when the method for driving an organic light emitting display panel according to this embodiment is used with an organic light emitting display panel (for example, the organic light emitting display panel 300 shown in
Optionally, in the driving method according to this embodiment, the reference voltage signal is not higher than the second voltage signal provided from the second source voltage terminal. As a result, light emission of the light emitting element resulting from a leakage current formed due to the fact that the voltage signal applied to the anode of the light emitting element is larger than the voltage signal applied to the cathode of the light emitting element during initialization (see Stage P1 shown in
Optionally, in the driving method according to this embodiment, after each row of pixel units are compensated, the light emission control unit is turned on based on a signal from the light emission control line, and the light emitting element emits light. That is, by controlling an output signal from the light emission control line, the pixels in each row of pixel units enter a light emission stage simultaneously.
As such, the threshold voltage of the driving transistor and the deterioration voltage of the light emitting element can be compensated with one row of pixel units as a unit, thereby increasing the signal processing speed.
Optionally, in the driving method according to this embodiment, after all the sub-pixels on the organic light emitting display panel are compensated, the light emission control unit is turned on based on a signal from the light emission control line, and the light emitting element emits light. That is, by controlling an output signal from the light emission control line, all the sub-pixels on the organic light emitting display panel enter a light emission stage simultaneously.
Therefore, all the sub-pixels on the organic light emitting display panel can be compensated collectively, and after all the sub-pixels are compensated, all the sub-pixels on organic light emitting display panel emit light simultaneously. In this way, visual discomforts caused by line-by-line scan, such as tailing and the like, are avoided. Particularly, when the organic light emitting display panel of the present application is applied in a VR device, the visual discomforts caused during scanning are avoided, thus avoiding the discomfort of a user such as dizziness and the like.
It should be appreciated by those skilled in the art that the scope of the present application is not limited to the technical solutions formed by specific combinations of the above-mentioned technical features, but also cover other technical solutions formed by any combinations of the above-mentioned technical features or equivalent features thereof without departing from the concept of the present invention, such as, technical solutions formed by replacing the above-mentioned features with technical features with similar functions as (but not limited to) those disclosed in the present application.
Number | Date | Country | Kind |
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201611126639.X | Dec 2016 | CN | national |