CN108877668B - Pixel circuit, driving method thereof and display panel - Google Patents
Pixel circuit, driving method thereof and display panel Download PDFInfo
- Publication number
- CN108877668B CN108877668B CN201810842614.2A CN201810842614A CN108877668B CN 108877668 B CN108877668 B CN 108877668B CN 201810842614 A CN201810842614 A CN 201810842614A CN 108877668 B CN108877668 B CN 108877668B
- Authority
- CN
- China
- Prior art keywords
- node
- light emitting
- module
- signal end
- emitting device
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
- G09G3/30—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels
- G09G3/32—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED]
- G09G3/3208—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED]
- G09G3/3225—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED] using an active matrix
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Computer Hardware Design (AREA)
- General Physics & Mathematics (AREA)
- Theoretical Computer Science (AREA)
- Electroluminescent Light Sources (AREA)
- Control Of El Displays (AREA)
Abstract
The invention discloses a pixel circuit, a driving method thereof and a display panel. Because the driving module drives the monochromatic light emitting devices to emit light with the brightness increased or reduced along with the temperature rise through the brightness adjusting module and the conducted light emitting control module, the brightness proportion of the red, green and blue monochromatic light emitting devices is changed little or even unchanged under the high temperature condition, and therefore, the stability of the white-light white balance of the mixed white light of the red, green and blue monochromatic light emitting devices under the high temperature condition is ensured.
Description
Technical Field
The invention relates to the technical field of display, in particular to a pixel circuit, a driving method thereof and a display panel.
Background
With the popularization of the internet and the continuous development of display technology, high-quality display panels have become an important feature of many electronic consumer products. Compared with a liquid crystal display panel, the organic electroluminescent display panel has the advantages of self luminescence, low energy consumption, low production cost, wide viewing angle, high contrast, high response speed, more vivid color display, easier realization of lightness, thinness, flexibility and the like. At present, in the display fields of mobile phones, digital cameras, computers, personal digital assistants and the like, organic electroluminescent display panels have begun to replace traditional liquid crystal display panels, and are expected to become the mainstream choice of next generation display panels.
With the increase of the temperature, the brightness of the monochromatic light emitted by the red, green and blue sub-pixels in the organic electroluminescent display panel is enhanced, so that the brightness of the mixed white light of the red, green and blue sub-pixels is enhanced with the increase of the temperature. However, the brightness of the monochromatic light emitted by the blue sub-pixel is minimally increased, so that the mixed white light of the red, green and blue sub-pixels is yellow. For example, after the temperature is changed from room temperature to 70 ℃, the luminance of the mixed white light increases and the color coordinate is shifted toward yellow.
Disclosure of Invention
Embodiments of the present invention provide a pixel circuit, a driving method thereof and a display panel, which are used to achieve white balance of mixed white light of red, green and blue sub-pixels under high temperature conditions.
Therefore, an embodiment of the present invention provides a pixel circuit, including: the device comprises a reset module, a data writing module, a compensation module, a driving module, a light emitting control module, a brightness adjusting module and a monochromatic light emitting device;
the reset module is respectively connected with a reset signal end, a reference signal end, an initialization signal end, a first node and a second node, and is used for writing a signal of the reference signal end into the first node and writing a signal of the initialization signal end into the second node under the control of the reset signal end;
the data writing module is respectively connected with a scanning signal end, a data signal end and the first node and is used for writing the signal of the data signal end into the first node under the control of the scanning signal end;
the compensation module is respectively connected with the second node, the scanning signal end and the third node and is used for writing the threshold voltage of the driving module into the second node under the control of the scanning signal end;
the driving module is connected with a first power end, the second node and the third node respectively, the light-emitting control module is connected with a light-emitting control signal end, the reference signal end, the first node, the second node, one end of the brightness adjusting module and a first pole of the monochromatic light-emitting device respectively, a second pole of the monochromatic light-emitting device is connected with a second power end, and the other end of the brightness adjusting module is connected with the third node; the driving module is used for driving the monochromatic light emitting device to emit light with the brightness increasing or decreasing along with the temperature increase through the brightness adjusting module and the conducted light emitting control module under the control of the second node.
In a possible implementation manner, in the pixel circuit provided in the embodiment of the present invention, the reset module includes a first switching transistor and a second switching transistor;
the grid electrode of the first switch transistor is connected with the reset signal end, the first pole of the first switch transistor is connected with the reference signal end, and the second pole of the first switch transistor is connected with the first node;
and the grid electrode of the second switching transistor is connected with the reset signal end, the first pole of the second switching transistor is connected with the initialization signal end, and the second pole of the second switching transistor is connected with the second node.
In a possible implementation manner, in the pixel circuit provided in the embodiment of the present invention, the data writing module includes a third switching transistor;
the grid electrode of the third switching transistor is connected with the scanning signal end, the first electrode of the third switching transistor is connected with the data signal end, and the second electrode of the third switching transistor is connected with the first node.
In a possible implementation manner, in the pixel circuit provided in the embodiment of the present invention, the compensation module includes a fourth switching transistor;
and the grid electrode of the fourth switching transistor is connected with the scanning signal end, the first electrode of the fourth switching transistor is connected with the third node, and the second electrode of the fourth switching transistor is connected with the second node.
In a possible implementation manner, in the pixel circuit provided in the embodiment of the present invention, the driving module includes a driving transistor;
the gate of the driving transistor is connected to the second node, the first electrode is connected to the first power supply terminal, and the second electrode is connected to the third node.
In a possible implementation manner, in the pixel circuit provided in the embodiment of the present invention, the light-emitting control module includes a fifth switching transistor, a sixth switching transistor, and a capacitor;
a grid electrode of the fifth switching transistor is connected with the light-emitting control signal end, a first pole of the fifth switching transistor is connected with the reference signal end, and a second pole of the fifth switching transistor is connected with the first node;
the grid electrode of the sixth switching transistor is connected with the light-emitting control signal end, the first pole of the sixth switching transistor is connected with the fourth node, and the second pole of the sixth switching transistor is connected with the first pole of the monochromatic light-emitting device;
the capacitor is connected between the first node and the second node.
In a possible implementation manner, in the pixel circuit provided in the embodiment of the present invention, the brightness adjusting module includes a thermistor;
one end of the thermistor is connected with the fourth node, and the other end of the thermistor is connected with the third node.
In a possible implementation manner, in the pixel circuit provided in the embodiment of the present invention, the thermistor is a negative temperature coefficient thermistor, and the monochromatic light emitting device is a blue light emitting device; or the thermistor is a positive temperature coefficient thermistor, and the monochromatic light emitting device is a green light emitting device or a red light emitting device.
Based on the same inventive concept, the embodiment of the invention also provides a display panel, which comprises the pixel circuit;
when the pixel circuit is used for driving the blue light emitting device, the driving module is specifically used for driving the blue light emitting device to emit light with the brightness increased along with the temperature rise through the brightness adjusting module and the conducted light emitting control module under the control of the second node;
or, when the pixel circuit is used to drive a red light emitting device or a green light emitting device, the driving module is specifically used to drive the red light emitting device or the green light emitting device to emit light whose luminance decreases with an increase in temperature through the luminance adjusting module and the turned-on light emitting control module under the control of the second node.
Based on the same inventive concept, an embodiment of the present invention further provides a driving method of the pixel circuit, including:
in the first stage, a reset module writes a signal of a reference signal end into a first node and writes a signal of an initialization signal end into a second node under the control of a reset signal end;
in the second stage, the data writing module writes the signal of the data signal end into the first node under the control of the scanning signal end; the compensation module writes the threshold voltage of the driving module into the second node under the control of the scanning signal end;
and in the third stage, the driving module drives the monochromatic light emitting device to emit light with the brightness increasing or decreasing along with the temperature increase through the brightness adjusting module and the conducted light emitting control module under the control of the second node.
The invention has the following beneficial effects:
the pixel circuit, the driving method thereof and the display panel provided by the embodiment of the invention comprise the following steps: the device comprises a reset module, a data writing module, a compensation module, a driving module, a light emitting control module, a brightness adjusting module and a monochromatic light emitting device; the reset module is respectively connected with the reset signal end, the reference signal end, the initialization signal end, the first node and the second node, and is used for writing a signal of the reference signal end into the first node and writing a signal of the initialization signal end into the second node under the control of the reset signal end; the data writing module is respectively connected with the scanning signal end, the data signal end and the first node and is used for writing the signal of the data signal end into the first node under the control of the scanning signal end; the compensation module is respectively connected with the second node, the scanning signal end and the third node and is used for writing the threshold voltage of the driving module into the second node under the control of the scanning signal end; the driving module is respectively connected with the first power supply end, the second node and the third node, the light-emitting control module is respectively connected with the light-emitting control signal end, the reference signal end, the first node, the second node, one end of the brightness adjusting module and the first pole of the monochromatic light-emitting device, the second pole of the monochromatic light-emitting device is connected with the second power supply end, and the other end of the brightness adjusting module is connected with the third node; the driving module is used for driving the monochromatic light emitting device to emit light with the brightness increasing or decreasing along with the temperature increase through the brightness adjusting module and the conducted light emitting control module under the control of the second node. Because the driving module drives the monochromatic light emitting devices to emit light with the brightness increased or reduced along with the temperature rise through the brightness adjusting module and the conducted light emitting control module, the brightness proportion of the red, green and blue monochromatic light emitting devices under the high-temperature condition is changed little or even unchanged, and therefore, the stability of the white-light white balance of the mixed white light of the red, green and blue monochromatic light emitting devices under the high-temperature condition is ensured.
Drawings
Fig. 1 is a schematic structural diagram of a pixel circuit according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a specific structure of the pixel circuit shown in FIG. 1;
fig. 3 is a flowchart of a driving method of a pixel circuit according to an embodiment of the invention;
FIG. 4 is a diagram illustrating a pixel circuit according to the prior art;
FIG. 5 is a graph of saturation current of the drive transistor;
FIG. 6 is a timing diagram illustrating the operation of the pixel circuit shown in FIG. 2;
fig. 7 and 8 are schematic diagrams of resistances of respective portions of the pixel circuit shown in fig. 2.
Detailed Description
The following describes in detail specific embodiments of a pixel circuit, a driving method thereof, and a display panel according to embodiments of the present invention with reference to the accompanying drawings. It should be noted that the embodiments described in this specification are only a part of the embodiments of the present invention, and not all embodiments; and in case of conflict, the embodiments and features of the embodiments in the present application may be combined with each other; moreover, all other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without any creative effort belong to the protection scope of the present invention.
A pixel circuit provided in an embodiment of the present invention, as shown in fig. 1, includes: the device comprises a reset module 101, a data writing module 102, a compensation module 103, a driving module 104, a light-emitting control module 105, a brightness adjusting module 106 and a monochromatic light-emitting device OLED;
the Reset module 101 is connected to the Reset signal terminal Reset, the reference signal terminal Ref, the initialization signal terminal Vinit, the first node a, and the second node B, respectively, and configured to write a signal of the reference signal terminal Ref into the first node a and write a signal of the initialization signal terminal Vinit into the second node B under the control of the Reset signal terminal Reset;
the Data writing module 102 is connected to the scanning signal terminal Gate, the Data signal terminal Data, and the first node a, respectively, and configured to write a signal of the Data signal terminal Data into the first node a under the control of the scanning signal terminal Gate;
the compensation module 103 is connected to the second node B, the scan signal terminal Gate, and the third node C, respectively, and is configured to control the scan signal terminal Gate to apply the threshold voltage V of the driving module 104thWriting to the second node B;
the driving module 104 is connected to a first power terminal VDD, a second node B, and a third node C, the light-emitting control module 105 is connected to a light-emitting control signal terminal EM, a reference signal terminal Ref, a first node a, a second node B, one end of the brightness adjustment module 106, and a first electrode of the monochromatic light-emitting device OLED, a second electrode of the monochromatic light-emitting device OLED is connected to a second power terminal VSS, and the other end of the brightness adjustment module 106 is connected to the third node C; the driving module 104 is used for driving the single color light emitting device OLED to emit light with brightness increasing or decreasing with temperature increase through the brightness adjusting module 106 and the turned-on light emitting control module 105 under the control of the second node B.
In the pixel circuit provided in the embodiment of the present invention, the driving module 104 drives the monochromatic light emitting device OLED to emit light whose luminance increases or decreases with the increase of temperature through the luminance adjusting module 106 and the conducted light emitting control module 105, so that the luminance ratio of the red, green, and blue monochromatic light emitting devices OLED is maintained unchanged or changes very little under a high temperature condition, and thus, the stability of the white-light white balance of the mixed white light of the red, green, and blue monochromatic light emitting devices OLED under a high temperature condition is ensured.
In the pixel circuit provided by the embodiment of the invention, the signal voltage of the first power source terminal VDD is generally a high voltage, and the signal voltage of the second power source terminal VSS is generally a low voltage or ground. In practical applications, the voltages of the signals of the first power source terminal VDD and the second power source terminal VSS need to be designed and determined according to practical application environments, which is not limited herein.
The present invention will be described in detail with reference to specific examples. It should be noted that the specific examples are provided for better explaining the present invention, but not limiting the present invention.
Specifically, in the above pixel circuit provided by the embodiment of the present invention, as shown in fig. 2, the reset module 101 includes a first switch transistor T1 and a second switch transistor T2; wherein the gate of the first switching transistor T1 is connected to the Reset signal terminal Reset, the first pole is connected to the reference signal terminal Ref, and the second pole is connected to the first node a; the gate of the second switching transistor T2 is connected to the Reset signal terminal Reset, the first pole is connected to the initialization signal terminal Vinit, and the second pole is connected to the second node B.
The Data writing module 102 includes a third switching transistor T3, and the Gate of the third switching transistor T3 is connected to the scan signal terminal Gate, the first pole is connected to the Data signal terminal Data, and the second pole is connected to the first node a.
The compensation module 103 includes a fourth switching transistor T4, and a Gate of the fourth switching transistor T4 is connected to the scan signal terminal Gate, a first pole is connected to the third node C, and a second pole is connected to the second node B.
The driving module 104 includes a driving transistor Td having a gate connected to the second node B, a first electrode connected to the first power source terminal VDD, and a second electrode connected to the third node C.
The light emission control module 105 includes a fifth switching transistor T5, a sixth switching transistor T6, and a capacitor Cst; a gate of the fifth switching transistor T5 is connected to the emission control signal terminal EM, a first pole thereof is connected to the reference signal terminal Ref, and a second pole thereof is connected to the first node a; the grid electrode of the sixth switching transistor T6 is connected with the light-emitting control signal end EM, the first pole is connected with the fourth node D, and the second pole is connected with the first pole of the monochromatic light-emitting device OLED; the capacitor Cst is connected between the first node a and the second node B.
The brightness adjustment module 106 includes a thermistor TC, and one end of the thermistor TC is connected to the fourth node D, and the other end is connected to the third node C.
Further, the thermistor TC is a negative temperature coefficient thermistor NTC, and the monochromatic light emitting device OLED is a Blue light emitting device Blue OLED; or the thermistor TC is a positive temperature coefficient thermistor PTC, and the monochromatic light emitting device OLED is a Green light emitting device Green OLED or a Red light emitting device Red OLED.
It should be understood that the above is only an example of the specific structure of each block in the pixel circuit, and in the implementation, the specific structure of each block is not limited to the above structure provided by the embodiment of the present invention, and may be other structures known by those skilled in the art, and is not limited herein.
In addition, each Transistor mentioned in the above embodiments of the present invention may be a Thin Film Transistor (TFT), or may also be a Metal Oxide Semiconductor field effect Transistor (MOS), which is not limited herein; also, these transistors are all P-type transistors or N-type transistors. The first pole and the second pole of the transistors are respectively a source and a drain, and in practical application, the functions of the first pole and the second pole can be interchanged without specific distinction according to the types of the transistors and different input signals.
Correspondingly, for the pixel circuit provided in the embodiment of the present invention, an embodiment of the present invention further provides a driving method, as shown in fig. 3, which specifically includes the following steps:
s301, in the first stage, a reset module writes a signal of a reference signal end into a first node and writes a signal of an initialization signal end into a second node under the control of a reset signal end;
s302, in the second stage, the data writing module writes the signal of the data signal end into the first node under the control of the scanning signal end; the compensation module writes the threshold voltage of the driving module into the second node under the control of the scanning signal end;
and S303, in the third stage, the driving module drives the monochromatic light emitting device to emit light with the brightness increased or decreased along with the temperature change through the brightness adjusting module and the conducted light emitting control module under the control of the second node.
FIG. 4 shows a prior art pixel circuit, which is used to drive the RGB monochromatic light-emitting devices in the display panel, and the saturation of the RGB monochromatic light-emitting devices is shownThe current curve is shown in fig. 5, and it can be seen that the current in the saturation region is dependent on the voltage difference V between the drain and the source of the driving transistor TdDSIs increased. In addition, actually, under the high temperature condition, the brightness of the red, green and blue single-color light emitting devices is increased along with the increase of the temperature, however, the brightness of the red, green and blue single-color light emitting devices is increased at different proportions, wherein the increase of the brightness of the blue light emitting device is minimum, so that the mixed white light of the red, green and blue single-color light emitting devices is yellow.
Therefore, to realize white balance of mixed white light at high temperature, an embodiment of the present invention further provides a display panel, including the pixel circuit shown in fig. 2 provided in an embodiment of the present invention; the pixel circuit shown in fig. 2 is used for driving the blue light emitting device, so that the driving module is specifically used for driving the blue light emitting device to emit light with the brightness increased along with the temperature rise through the brightness adjusting module and the conducted light emitting control module under the control of the second node; meanwhile, the pixel circuit shown in fig. 4 is adopted to drive the red light emitting device and the green light emitting device, so that the brightness of the blue light emitting device is not increased too much relative to the red light emitting device and the green light emitting device along with the rise of the temperature, the brightness proportion of the red light emitting device and the green light emitting device is kept unchanged or changed very little, and the white balance of the mixed white light at high temperature is realized. Or, the pixel circuit shown in fig. 2 is adopted to drive the red light emitting device and the green light emitting device, and the driving module is specifically configured to drive the red light emitting device and the green light emitting device to emit light whose luminance decreases with an increase in temperature through the luminance adjusting module and the turned-on light emitting control module under the control of the second node; meanwhile, the blue light emitting device is driven by the pixel circuit shown in fig. 4, so that the brightness of the red light emitting device and the green light emitting device is not increased too much relative to the blue light emitting device along with the rise of the temperature, the brightness ratio of the red light emitting device and the green light emitting device is kept unchanged or changed very little, and the white balance of the mixed white light at high temperature is realized.
It is understood that the display panel may be: any product or component with a display function, such as a mobile phone, a vehicle-mounted display, a tablet computer, a television, a notebook computer, a digital camera, a navigator, an intelligent watch, a fitness wrist strap, a personal digital assistant, a self-service deposit/withdrawal machine, and the like. Other essential components of the display panel are understood by those skilled in the art, and are not described herein or should not be construed as limiting the present invention.
In order to better understand the technical solution of the present invention, two specific examples are described in detail below.
Example one
In the first embodiment, the pixel circuit shown in fig. 2 is used to drive the blue light-emitting device to emit light, and the pixel circuit shown in fig. 4 is used to drive the red light-emitting device and the green light-emitting device to emit light.
It should be noted that the pixel circuit shown in fig. 2 is similar to the pixel circuit shown in fig. 4, except that a thermistor TC is added to the pixel circuit shown in fig. 2 compared with the pixel circuit shown in fig. 4, so that the pixel circuit shown in fig. 2 can adjust the current flowing through the monochromatic light emitting device according to the temperature change, thereby adjusting the brightness of the monochromatic light emitting device, and therefore, the following only describes the operation of the pixel circuit shown in fig. 2 in detail. The working process of the pixel circuit shown in fig. 4 can refer to the working process of the pixel circuit shown in fig. 2, and repeated descriptions are omitted.
In the pixel circuit shown in fig. 2, each transistor is a P-type transistor, which is turned on under the action of a low level and turned off under the action of a high level; the thermistor TC is a negative temperature coefficient thermistor NTC, and the monochromatic light emitting device OLED is a Blue light emitting device OLED. The corresponding operation timing chart is shown in fig. 6, and specifically, the first stage t1, the second stage t2, and the third stage t3 in the operation timing chart shown in fig. 6 are taken as examples for detailed description.
First stage t 1: the emission control signal end EM outputs high level, the Reset signal end Reset outputs low level, and the scanning signal end Gate outputs high level.
The first switching transistor T1 and the second switching transistor T2 are in a conductive state by a low level of the Reset signal terminal Reset, referring to the signal V of the signal terminal RefrefWriting into the first node A via the turned-on first switching transistor T1, initializing the signal terminalThe signal of Vinit is written to the second node B through the turned-on second switching transistor T2, and the driving transistor Td is in a turned-on state under the control of the second node B. The third switching transistor T3 and the fourth switching transistor T4 are in an off state by a high level of the scan signal terminal Gate. The fifth switching transistor T5 and the sixth switching transistor T6 are in an off state by a high level of the emission control signal terminal EM.
Second stage t 2: the emission control signal end EM outputs high level, the Reset signal end Reset outputs high level, and the scanning signal end Gate outputs low level.
The third switching transistor T3 is turned on at a low level of the scan signal terminal Gate, and the signal V of the Data signal terminal DatadataThe first node a is written through the turned-on third switching transistor T3. The fourth switching transistor T4 is also in a turn-on state under the low level action of the scan signal terminal Gate, the driving transistor Td maintains the turn-on state, so that the driving transistor Td is equivalent to a diode, and the potential of the third node C becomes Vdd+VthAt this time, the potential of the second node B becomes Vdd+VthIn which V isddFor a high level signal, V, output from the first supply terminal VDDthIs the threshold voltage of the driving transistor Td. The first and second switching transistors T1 and T2 are in an off state by a high level of the Reset signal terminal Reset. The fifth switching transistor T5 and the sixth switching transistor T6 are in an off state by a high level of the emission control signal terminal EM.
Third stage t 3: the emission control signal end EM outputs a low level, the Reset signal end Reset outputs a high level, and the scanning signal end Gate outputs a high level.
The fifth switching transistor T5 and the sixth switching transistor T6 are turned on by a low level of the emission control signal terminal EM, refer to the signal V of the signal terminal RefrefThe turned-on fifth switching transistor T5 is written into the first node A, so that the potential variation of the first node A is Vref-Vdata. Since the amount of charge stored by the capacitor Cst is not changed, the potential of the second node B is changed from Vdd+VthChange to Vdd+Vth+Vref-VdataAt this time, the saturation current of the driving transistor Td is:
where μ is the mobility of the semiconductor layer carriers of the drive transistor Td, CoxIs the capacitance of the dielectric layer of the driving transistor Td, W/L is the channel width-to-length ratio of the driving transistor Td, VGSIs the voltage difference between the gate and the source of the driving transistor Td.
The saturation current curve of the driving transistor Td is shown in fig. 5, and it can be seen that the current in the saturation region is dependent on the voltage difference V between the drain and the source of the driving transistor TdDSIs increased. In addition, under high temperature conditions, the mobility μ of the semiconductor layer of the driving transistor Td increases with the increase in temperature, and if the thermistor TC is not included in the pixel circuit as shown in fig. 4, the saturation current I of the driving transistor Td increasesdI.e. the current for driving the monochromatic light emitting device OLED to emit light, the current for driving the monochromatic light emitting device OLED must be increased due to the increase of the mobility μ of the carrier with the temperature, resulting in the increase of the luminance of the monochromatic light emitting device OLED. However, the ratio of the brightness of the red, green and Blue monochromatic light emitting devices OLED is different, and the brightness of the Blue light emitting device OLED is increased at least, so that the mixed white light of the red, green and Blue monochromatic light emitting devices is yellow.
Based on this, in the embodiment of the invention, the pixel circuit containing the negative temperature coefficient thermistor NTC shown in fig. 2 is adopted to drive the Blue light emitting device Blue OLED to emit light, and the pixel circuit shown in fig. 4 is also adopted to drive the Red light emitting device Red OLED and the Green light emitting device Green OLED to emit light, so that under a high temperature condition, the brightness ratios of the Red light emitting device Red OLED, the Green light emitting device Green OLED and the Blue light emitting device Blue OLED are kept unchanged or slightly changed, and the white balance of mixed white light is realized.
Specifically, fig. 7 is a schematic diagram of the resistances of the portions of the pixel circuit shown in fig. 2. Specifically, in fig. 7, the negative temperature coefficient thermistor NTC is the thermistor of fig. 2The TC-blocking, Blue light emitting device Blue OLED is the monochromatic light emitting device OLED in fig. 2. And as shown in fig. 7, the difference between the first power source terminal VDD and the second power source terminal VSS is a constant value, R1 represents the resistance of the driving transistor Td, R2 represents the resistance of the switching transistor T6, R3 represents the resistance of the Blue light emitting device Blue OLED, and R4 represents the resistance of the negative temperature coefficient thermistor NTC. Since the NTC has a negative temperature coefficient and its resistance R4 decreases with increasing temperature, and accordingly, the resistance R1 of the driving transistor Td becomes large, the voltage difference V between the drain and the source of the driving transistor TdDSBecomes larger. As can be seen from the saturation current curve shown in fig. 5, the saturation current flowing through the Blue light emitting device Blue OLED increases, so that the increase in luminance of the Blue light emitting device Blue OLED with temperature increases is not too small relative to the Red light emitting device Red OLED and the Green light emitting device Green OLED, and further the luminance ratios of the three remain unchanged or change very little, thereby realizing white balance of mixed white light at high temperature.
As can be seen from the above description, although the resistance value and the temperature coefficient of the NTC are not constant, a proper resistance value and a proper temperature coefficient can be obtained after adjustment is performed according to the saturation current curve of the driving transistor Td and the voltage difference between the first power terminal VDD and the second power terminal VSS, so that the luminance ratios of the Blue light emitting device Blue OLED, the Red light emitting device Red OLED, and the Green light emitting device Green OLED are maintained unchanged or changed little, thereby implementing white balance of the mixed white light under a high temperature condition.
In the subsequent time period, the pixel circuit will repeat the operation process from t1 to t 3.
Example two
In the second embodiment, the pixel circuit shown in fig. 2 is used to drive the Red light emitting device Red OLED and the Green light emitting device Green OLED to emit light, and the pixel circuit shown in fig. 2 is provided with a positive temperature coefficient thermistor, and the pixel circuit shown in fig. 4 is also used to drive the Blue light emitting device Blue OLED to emit light.
It should be noted that, since the process of the pixel circuit shown in fig. 2 driving the Red light emitting device Red OLED and the Green light emitting device Green OLED to emit light is similar to the process of driving the Blue light emitting device Blue OLED to emit light, only the differences will be described below, and the repeated points will not be described again.
Specifically, under the condition that the thermistor TC is a positive temperature coefficient thermistor PTC and the monochrome light emitting device OLED is a Red light emitting device Red OLED or a Green light emitting device Green OLED, the schematic resistance diagram of each part of the pixel circuit shown in fig. 2 is shown in fig. 8. Specifically, in fig. 8, the positive temperature coefficient thermistor PTC is the thermistor TC in fig. 2, and the Red light emitting device Red OLED or the Green light emitting device Green OLED is the single color light emitting device OLED in fig. 2. And as shown in fig. 8, the difference between the first power terminal VDD and the second power terminal VSS is a constant value, R1 represents the resistance of the driving transistor Td, R2 represents the resistance of the switching transistor T6, R3 'represents the resistance of the Red light emitting device Red OLED or the Green light emitting device Green OLED, and R4' represents the resistance of the PTC thermistor PTC.
Since the PTC thermistor PTC has a positive temperature coefficient and its resistance R4 increases with increasing temperature, and accordingly, the resistance R1 of the driving transistor Td becomes smaller, and the voltage difference V between the drain and the source of the driving transistor Td becomes smallerDSAnd becomes smaller. As can be seen from the saturation current curve shown in fig. 5, the saturation current flowing through the Red OLED or the Green OLED is reduced, so that the increase in luminance of the Red OLED and the Green OLED is not too large relative to the increase in luminance of the Blue OLED, and the luminance ratio of the Red OLED and the Green OLED is maintained or changed little with the increase in temperature, thereby achieving white balance of the white light mixed at high temperature.
As can be seen from the above description, although the resistance value and the temperature coefficient of the PTC thermistor are not constant, a proper resistance value and a proper temperature coefficient can be obtained after adjustment is performed according to the saturation current curve of the driving transistor Td and the voltage difference between the first power terminal VDD and the second power terminal VSS, so that the luminance ratios of the Blue light emitting device Blue OLED, the Red light emitting device Red OLED, and the Green light emitting device Green OLED are maintained unchanged or changed little, thereby implementing white balance of the mixed white light under a high temperature condition.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (8)
1. A pixel circuit, comprising: the device comprises a reset module, a data writing module, a compensation module, a driving module, a light emitting control module, a brightness adjusting module and a monochromatic light emitting device;
the reset module is respectively connected with a reset signal end, a reference signal end, an initialization signal end, a first node and a second node, and is used for writing a signal of the reference signal end into the first node and writing a signal of the initialization signal end into the second node under the control of the reset signal end;
the data writing module is respectively connected with a scanning signal end, a data signal end and the first node and is used for writing the signal of the data signal end into the first node under the control of the scanning signal end;
the compensation module is respectively connected with the second node, the scanning signal end and the third node and is used for writing the threshold voltage of the driving module into the second node under the control of the scanning signal end;
the driving module is connected with a first power end, the second node and the third node respectively, the light-emitting control module is connected with a light-emitting control signal end, the reference signal end, the first node, the second node, one end of the brightness adjusting module and a first pole of the monochromatic light-emitting device respectively, a second pole of the monochromatic light-emitting device is connected with a second power end, and the other end of the brightness adjusting module is connected with the third node; the driving module is used for driving the monochromatic light emitting device to emit light with the brightness increasing or decreasing along with the temperature increase through the brightness adjusting module and the conducted light emitting control module under the control of the second node;
the brightness adjusting module comprises a thermistor, one end of the thermistor is connected with the fourth node, and the other end of the thermistor is connected with the third node;
the driving module comprises a driving transistor; the grid electrode of the driving transistor is connected with the second node, the first electrode of the driving transistor is connected with the first power supply end, and the second electrode of the driving transistor is connected with the third node;
and determining the resistance value and the temperature coefficient of the thermistor according to the saturation current curve of the driving transistor and the voltage difference between the first power supply end and the second power supply end.
2. The pixel circuit according to claim 1, wherein the reset module comprises a first switching transistor and a second switching transistor;
the grid electrode of the first switch transistor is connected with the reset signal end, the first pole of the first switch transistor is connected with the reference signal end, and the second pole of the first switch transistor is connected with the first node;
and the grid electrode of the second switching transistor is connected with the reset signal end, the first pole of the second switching transistor is connected with the initialization signal end, and the second pole of the second switching transistor is connected with the second node.
3. The pixel circuit according to claim 1, wherein the data writing module includes a third switching transistor;
the grid electrode of the third switching transistor is connected with the scanning signal end, the first electrode of the third switching transistor is connected with the data signal end, and the second electrode of the third switching transistor is connected with the first node.
4. The pixel circuit of claim 1, wherein the compensation module comprises a fourth switching transistor;
and the grid electrode of the fourth switching transistor is connected with the scanning signal end, the first electrode of the fourth switching transistor is connected with the third node, and the second electrode of the fourth switching transistor is connected with the second node.
5. The pixel circuit according to claim 1, wherein the light emission control module includes a fifth switching transistor, a sixth switching transistor, and a capacitor;
a grid electrode of the fifth switching transistor is connected with the light-emitting control signal end, a first pole of the fifth switching transistor is connected with the reference signal end, and a second pole of the fifth switching transistor is connected with the first node;
the grid electrode of the sixth switching transistor is connected with the light-emitting control signal end, the first pole of the sixth switching transistor is connected with the fourth node, and the second pole of the sixth switching transistor is connected with the first pole of the monochromatic light-emitting device;
the capacitor is connected between the first node and the second node.
6. The pixel circuit according to claim 1, wherein the thermistor is a negative temperature coefficient thermistor, and the single color light emitting device is a blue light emitting device; or the thermistor is a positive temperature coefficient thermistor, and the monochromatic light emitting device is a green light emitting device or a red light emitting device.
7. A display panel comprising the pixel circuit according to any one of claims 1 to 6;
when the pixel circuit is used for driving the blue light emitting device, the driving module is specifically used for driving the blue light emitting device to emit light with the brightness increased along with the temperature rise through the brightness adjusting module and the conducted light emitting control module under the control of the second node;
or, when the pixel circuit is used to drive a red light emitting device or a green light emitting device, the driving module is specifically used to drive the red light emitting device or the green light emitting device to emit light whose luminance decreases with an increase in temperature through the luminance adjusting module and the turned-on light emitting control module under the control of the second node.
8. A method of driving a pixel circuit according to any one of claims 1 to 6, comprising:
in the first stage, a reset module writes a signal of a reference signal end into a first node and writes a signal of an initialization signal end into a second node under the control of a reset signal end;
in the second stage, the data writing module writes the signal of the data signal end into the first node under the control of the scanning signal end; the compensation module writes the threshold voltage of the driving module into the second node under the control of the scanning signal end;
and in the third stage, the driving module drives the monochromatic light emitting device to emit light with the brightness increasing or decreasing along with the temperature increase through the brightness adjusting module and the conducted light emitting control module under the control of the second node.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810842614.2A CN108877668B (en) | 2018-07-27 | 2018-07-27 | Pixel circuit, driving method thereof and display panel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810842614.2A CN108877668B (en) | 2018-07-27 | 2018-07-27 | Pixel circuit, driving method thereof and display panel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN108877668A CN108877668A (en) | 2018-11-23 |
| CN108877668B true CN108877668B (en) | 2021-01-22 |
Family
ID=64305689
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810842614.2A Active CN108877668B (en) | 2018-07-27 | 2018-07-27 | Pixel circuit, driving method thereof and display panel |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN108877668B (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2020107420A1 (en) * | 2018-11-30 | 2020-06-04 | Boe Technology Group Co., Ltd. | Pixel circuit, driving method, and display apparatus |
| CN109754756B (en) * | 2019-03-27 | 2020-06-30 | 京东方科技集团股份有限公司 | Pixel circuit, driving method thereof, display substrate and display device |
| CN110111723A (en) * | 2019-06-18 | 2019-08-09 | 京东方科技集团股份有限公司 | Pixel circuit and its driving method, display panel |
| CN113870791B (en) * | 2021-10-11 | 2023-07-25 | 京东方科技集团股份有限公司 | Pixel driving circuit and driving method thereof |
| CN114241982B (en) * | 2021-12-29 | 2023-08-15 | 湖北长江新型显示产业创新中心有限公司 | Display panel and display device |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20010020672A1 (en) * | 2000-03-08 | 2001-09-13 | Minolta Co., Ltd. | Image-sensing device |
| CN1499470A (en) * | 2002-10-29 | 2004-05-26 | 东北先锋电子股份有限公司 | Driver of active luminous display panel |
| US20040212703A1 (en) * | 2003-04-25 | 2004-10-28 | Minolta Co., Ltd. | Image sensing apparatus |
| CN102262868A (en) * | 2011-08-05 | 2011-11-30 | 福建华映显示科技有限公司 | Circuit and method for compensating color deviation of color sequential method |
Family Cites Families (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100686335B1 (en) * | 2003-11-14 | 2007-02-22 | 삼성에스디아이 주식회사 | Pixel circuit in display device and Driving method thereof |
| KR100688799B1 (en) * | 2004-11-17 | 2007-03-02 | 삼성에스디아이 주식회사 | Light emitting display, and method for driving light emitting display and pixel circuit |
| US20070052632A1 (en) * | 2005-09-06 | 2007-03-08 | Chih-Liang Wu | Driving method which drives display units of different frequency spectra with respective sweep signals and apparatus based on the same |
| KR20070077719A (en) * | 2006-01-24 | 2007-07-27 | 삼성전기주식회사 | Driver of color led |
| KR100833760B1 (en) * | 2007-01-16 | 2008-05-29 | 삼성에스디아이 주식회사 | Organic light emitting display |
| CN101707052B (en) * | 2009-12-09 | 2012-03-28 | 中航华东光电有限公司 | RGB-based method for adjusting white balance of LED backlight |
| CN103177692A (en) * | 2013-03-27 | 2013-06-26 | 深圳市光祥科技有限公司 | Temperature compensation control circuit for automatically adjusting color temperature of LED (Light Emitting Diode) display screen and control method |
| CN106094319B (en) * | 2016-06-17 | 2019-08-16 | 京东方科技集团股份有限公司 | A kind of display base plate and display device |
| CN106910461B (en) * | 2017-05-11 | 2020-12-22 | 京东方科技集团股份有限公司 | Display panel, display device and display driving method |
| CN107180612B (en) * | 2017-07-24 | 2019-02-05 | 京东方科技集团股份有限公司 | A kind of pixel circuit and display panel |
-
2018
- 2018-07-27 CN CN201810842614.2A patent/CN108877668B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20010020672A1 (en) * | 2000-03-08 | 2001-09-13 | Minolta Co., Ltd. | Image-sensing device |
| CN1499470A (en) * | 2002-10-29 | 2004-05-26 | 东北先锋电子股份有限公司 | Driver of active luminous display panel |
| US20040212703A1 (en) * | 2003-04-25 | 2004-10-28 | Minolta Co., Ltd. | Image sensing apparatus |
| CN102262868A (en) * | 2011-08-05 | 2011-11-30 | 福建华映显示科技有限公司 | Circuit and method for compensating color deviation of color sequential method |
Also Published As
| Publication number | Publication date |
|---|---|
| CN108877668A (en) | 2018-11-23 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN108492770B (en) | Pixel compensation circuit, driving method thereof, display panel and display device | |
| CN108877668B (en) | Pixel circuit, driving method thereof and display panel | |
| CN107358917B (en) | Pixel circuit, driving method thereof, display panel and display device | |
| CN107464526B (en) | Pixel compensation circuit, driving method thereof and display device | |
| CN108470539B (en) | Pixel circuit, driving method thereof, display panel and display device | |
| US11227544B2 (en) | Pixel circuit, electroluminescent display panel, driving methods thereof, and display device | |
| CN107808630B (en) | Pixel compensation circuit, driving method thereof, display panel and display device | |
| WO2017031909A1 (en) | Pixel circuit and drive method thereof, array substrate, display panel, and display apparatus | |
| WO2018210051A1 (en) | Pixel driving circuit, pixel driving method and display device | |
| JP7025213B2 (en) | Electronic circuits and drive methods, display panels, and display devices | |
| WO2018149167A1 (en) | Pixel driving circuit and driving method thereof, and display panel | |
| WO2016074359A1 (en) | Pixel circuit, organic electroluminescence display panel, and display device and driving method therefor | |
| CN107369413B (en) | Pixel compensation circuit, driving method thereof, display panel and display device | |
| WO2016074418A1 (en) | Pixel circuit, driving method, and display device | |
| WO2021223743A1 (en) | Pixel driving circuit, display panel, driving method, and display device | |
| US9972245B2 (en) | Pixel circuit, driving method for the pixel circuit, display panel, and display device | |
| WO2023011333A1 (en) | Pixel driving circuit and driving method therefor, and display panel | |
| CN112634833A (en) | Pixel circuit, driving method thereof and display panel | |
| US11532267B2 (en) | Pixel driving circuit with light-emitting control sub-circuit and display control sub-circuit and driving method therefor, display panel and display apparatus | |
| CN112992071A (en) | Pixel circuit, driving method thereof and display device | |
| WO2016004693A1 (en) | Pixel circuit, driving method therefor, and display device | |
| CN204130142U (en) | A kind of image element circuit, organic EL display panel and display device | |
| US20210210013A1 (en) | Pixel circuit and driving method, display panel, display device | |
| WO2019001067A1 (en) | Pixel circuit and driving method therefor, and display panel | |
| CN113870791B (en) | Pixel driving circuit and driving method thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |