CN110610682A - Display panel, pixel circuit detection method and display device - Google Patents
Display panel, pixel circuit detection method and display device Download PDFInfo
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- CN110610682A CN110610682A CN201910769314.0A CN201910769314A CN110610682A CN 110610682 A CN110610682 A CN 110610682A CN 201910769314 A CN201910769314 A CN 201910769314A CN 110610682 A CN110610682 A CN 110610682A
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- 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
- G09G3/006—Electronic inspection or testing of displays and display drivers, e.g. of LED or LCD displays
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- 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
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Abstract
The embodiment of the invention relates to the technical field of display, and discloses a display panel, a pixel circuit detection method and a display device. In the present invention, a display panel includes: a plurality of pixel units arranged in an array, each pixel unit including a pixel circuit, the pixel circuit including: a light emitting element; a driving transistor for driving the light emitting element; the first switching tube is used for responding to a scanning signal of the first scanning line and accessing a data voltage signal provided by the data line; the detection module is used for acquiring a first detection current flowing through the light-emitting element after the first switch tube is connected into a first data voltage signal of the data line; the control unit is used for obtaining a voltage set value of a second data voltage signal of the data line according to the first detection current in the plurality of pixel circuits; and the writing module is used for controlling the driving transistor to drive the light-emitting element to emit light after the first switch tube is connected into the second voltage data signal of the data line, so that the problem of poor uniformity of a display picture can be solved.
Description
Technical Field
The embodiment of the invention relates to the technical field of display, in particular to a display panel, a pixel circuit detection method and a display device.
Background
With the continuous development of technology, Organic Light-Emitting diodes (OLEDs) have been rapidly developed by virtue of their advantages of high brightness, low driving voltage, energy saving, etc. In general, in an organic light emitting diode display device, it is necessary to drive and control a light emitting element by a pixel circuit. The conventional pixel circuit includes a switching transistor, a storage capacitor, and a driving transistor, wherein when the switching transistor responds to a scan signal of a scan line, a data signal of a data line is provided to a gate of the driving transistor to charge the storage capacitor, and then the driving transistor adjusts a driving current according to a voltage of the storage capacitor, thereby controlling the light emitting element to emit light.
The inventor finds that at least the following problems exist in the prior art: due to the differences in characteristics of TFTs, the aging of driving transistors, and the differences in the attenuation of organic light emitting materials in different regions, the display panel has a problem of poor uniformity of the display screen.
Disclosure of Invention
An object of embodiments of the present invention is to provide a display panel, a method for detecting a pixel circuit, and a display device, which can improve the problem of poor uniformity of a display screen.
To solve the above technical problem, an embodiment of the present invention provides a display panel including: a plurality of pixel units arranged in an array, each of the pixel units including a pixel circuit, the pixel circuit including: a light emitting element; a driving transistor for driving the light emitting element; the first switching tube is used for responding to a scanning signal of the first scanning line and accessing a data voltage signal provided by the data line; the detection module is used for acquiring a first detection current flowing through the light-emitting element after the first switch tube is connected into a first data voltage signal of a data line; a control unit, configured to obtain a voltage setting value of a second data voltage signal of the data line according to the first detection current in the plurality of pixel circuits; and the writing module is used for controlling the driving transistor to drive the light-emitting element to emit light after the first switch tube is connected into the second voltage data signal of the data line.
The embodiment of the present invention further provides a method for detecting a pixel circuit, which is applied to the display panel, and includes: acquiring a first detection current flowing through the light-emitting element after the first switch tube is connected to a first data voltage signal of a data line by using the detection module; obtaining a voltage set value of a second data voltage signal of the data line according to the first detection current in the plurality of pixel circuits by using the control unit; and controlling the driving transistor to drive the light-emitting element to emit light after the first switch tube is connected into the second voltage data signal of the data line by using the writing module.
Embodiments of the present invention also provide a display device including the display panel as described above.
Compared with the prior art, the embodiment of the invention can utilize the detection module to detect the first data voltage signal of the data line after the first switch tube is connected with the first data voltage signal of the data line, obtaining a first detection current flowing through the light emitting element, obtaining a reference current flowing through the light emitting element in a plurality of pixel circuits, obtaining a voltage set value of a second data voltage signal of the data line by using a control unit according to the first detection current in the plurality of pixel circuits, that is, the voltage value of the data voltage signal supplied from the adjusted data line is preset by using the reference current flowing through the light emitting element in the plurality of pixel circuits, so that the currents flowing through the light emitting elements in the plurality of pixel circuits are substantially equal under the action of the adjusted data voltage signal provided by the data line, the uniformity of the brightness of the light emitting elements in the plurality of pixel circuits is made higher, thereby improving the problem of poor uniformity of the display screen.
In addition, the detection module includes: the second switch tube is used for responding to the scanning signal of the second scanning line and providing the reference signal of the first reference line to the source electrode of the driving transistor; the first storage capacitor is used for storing the voltage between the grid electrode and the source electrode of the driving transistor and taking the charged voltage as the driving voltage of the driving transistor; the current on the first reference line is the first detection current.
In addition, the write module includes: a third switching tube for supplying a reference signal of a second reference line to the source of the driving transistor in response to a scan signal of a third scan line; and the second storage capacitor is used for storing the voltage between the grid electrode and the source electrode of the driving transistor and taking the charged voltage as the driving voltage of the driving transistor so as to drive the light-emitting element to emit light.
In addition, in the pixel row direction, two adjacent pixel units share a reference line, wherein the reference line is at least one of the first reference line and the second reference line; preferably, the first switching tubes of the two pixel units sharing the reference line are both connected to the first scan line, the second switching tubes of the two pixel units sharing the reference line are both connected to the second scan line, and the third switching tubes of the two pixel units sharing the reference line are both connected to the third scan line. By sharing the reference line by two adjacent pixel units, the number of reference lines to be provided can be reduced.
In addition, the pixel driving circuit further comprises a data driver, wherein the data driver is used for providing a data signal for one of the two pixel units sharing the reference line and providing black data or turn-off voltage for the other one of the two pixel units, so that the two pixel units sharing the reference line are not driven simultaneously.
In addition, the detection module includes: the second switch tube is used for responding to the scanning signal of the second scanning line and providing the reference signal of the first reference line to the source electrode of the driving transistor; the first storage capacitor is used for storing voltage between a grid electrode and a source electrode of the driving transistor, the charged voltage is used as driving voltage of the driving transistor, and the first detection current is node current of the second switching tube and the first reference line; after the detection module is used for acquiring a first data voltage signal of the first switch tube connected to the data line, a first detection current flowing through the light-emitting element specifically includes: in a first period, the first switch tube and the second switch tube are turned on, a first data voltage signal is input into the data line, and a first reference voltage signal is input into the first reference line; and in a second time interval, closing the first switch tube, opening the second switch tube, and acquiring the current on the first reference line as the first detection current.
In addition, the write module includes: a third switching tube for supplying a reference signal of a second reference line to the source of the driving transistor in response to a scan signal of a third scan line; a second storage capacitor for storing a voltage between a gate and a source of the driving transistor and driving the light emitting element to emit light by using the charged voltage as a driving voltage of the driving transistor; after the writing module is used for controlling the driving transistor to drive the light-emitting element to emit light after the first switch tube is connected to the second voltage data signal of the data line, the method specifically includes: in a third time interval, the first switching tube and the third switching tube are turned on, the data line inputs a second data voltage signal, the second reference line inputs a second reference voltage signal, and a voltage set value of the second data voltage signal is set according to the first detection current in the plurality of pixel circuits; in a fourth period, the first switch tube is closed, the third switch tube is opened, and the second storage capacitor provides charges for the driving transistor to drive the light-emitting element to emit light; preferably, in the fourth period, the method further includes: and acquiring a second detection current on the second reference line.
In addition, the obtaining, by the control unit, a voltage setting value of a second data voltage signal of the data line according to the first detection current in the plurality of pixel circuits specifically includes: calculating an average value of the first detection currents in a plurality of the pixel circuits; obtaining a voltage set value of the second data voltage signal according to the average value of the first detection current; preferably, the obtaining of the voltage setting value of the second data voltage signal according to the average value of the first detection current specifically includes: obtaining a voltage setting value of the second data voltage signal according to the following formula:wherein Vdata is a voltage setting value of the second data voltage signal, K ═ u × Cox (W/L), Cox is a gate oxide capacitance per unit area, u is a mobility, W is a gate width of the driving transistor, L is a channel length of the driving transistor,for a plurality of said pixel circuitsVth is a threshold voltage of the driving transistor, VrefIs the voltage value of the reference signal of the second reference line.
Drawings
One or more embodiments are illustrated by way of example in the accompanying drawings, which correspond to the figures in which like reference numerals refer to similar elements and which are not to scale unless otherwise specified.
Fig. 1 is a schematic structural diagram of a pixel circuit of a display panel according to a first embodiment of the present invention;
fig. 2 is a flowchart of a detection method of a pixel circuit according to a second embodiment of the present invention;
fig. 3 is a timing chart of switching control in the detection method of the pixel circuit according to the second embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, it will be appreciated by those of ordinary skill in the art that numerous technical details are set forth in order to provide a better understanding of the present application in various embodiments of the present invention. However, the technical solution claimed in the present application can be implemented without these technical details and various changes and modifications based on the following embodiments.
A first embodiment of the present invention relates to a display panel, as shown in fig. 1, including: a plurality of pixel units arranged in an array, each pixel unit including a pixel circuit, the pixel circuit including: the display device comprises a light emitting element, a driving transistor T0, a first switch tube T1, a detection module 11, a control unit (not shown), and a writing module 12, wherein the light emitting element may be an OLED light emitting element, the driving transistor T0 is configured to drive the light emitting element OLED, the first switch tube T1 is configured to access a data voltage signal provided by a data line in response to a Scan signal of a first Scan line Scan1, the detection module 11 is configured to obtain a first detection current flowing through the light emitting element OLED after the first switch tube T1 accesses the first data voltage signal of the data line, the control unit is configured to obtain a voltage setting value of a second data voltage signal of the data line according to the first detection current in the plurality of pixel circuits, and the writing module 12 is configured to control the driving transistor T0 to drive the light emitting element OLED to emit light after the first switch tube T1 accesses the second voltage data signal of the data line.
Specifically, the pixel circuit further includes a plurality of Data lines Data1-Datan, a plurality of Scan lines Scan1-Scann and a plurality of reference lines Ref1-Refn, wherein the plurality of Data lines are used for providing Data signals for the pixel units, the plurality of Scan lines are used for providing Scan signals for the pixel units, the plurality of reference lines are used for providing reference signals for the pixel units, the reference signals are used for erasing voltage values stored in the capacitor of a previous frame and preparing for a next timing phase, and the values of the reference signals are generally simulated according to device characteristics by a panel end array design as a default.
In this embodiment, the detection module 11 may include a second switch transistor T2 and a first storage capacitor C1, where the second switch transistor T2 is configured to respond to the Scan signal of the second Scan line Scan2 (if the second switch transistor T2 is a PMOS transistor, the Scan signal of the second Scan line Scan2 is at a low level, and conversely, if the second switch transistor T2 is an NMOS transistor, the Scan signal of the second Scan line Scan2 is at a high level), provide the reference signal of the first reference line Ref1 to the source of the driving transistor T0, and the first storage capacitor C1 is configured to store a voltage between the gate and the source of the driving transistor T0 and use the charged voltage as a driving voltage of the driving transistor T0, where a current on the first reference line Ref1 is a first detection current.
Specifically, the connection relationship of each device is as follows:
the drain of the first switch transistor T1 is connected to the corresponding data line, the gate is connected to the corresponding first Scan line Scan1, the source is connected to the first terminal of the first storage capacitor C1 and the control terminal of the driving transistor T0, and the common connection terminal is used as the first node N1.
The drain of the driving transistor T0 is connected to the first voltage signal ELVDD, the source is connected to the second terminal of the first storage capacitor C1, the anode of the light emitting device OLED, and the drain of the second switching transistor T2, the common connection terminal is used as the second node N2, and the cathode of the light emitting device OLED is connected to the second voltage signal ELVSS.
The gate of the second switch transistor T2 is connected to the second Scan line Scan2, and the source is connected to the first reference line Ref 1.
In combination with the connection relationship between the above devices, the working principle of the detection module 11 is as follows:
in a first period T1, the first switch transistor T1 and the second switch transistor T2 are turned on. The first switching transistor T1 supplies a first data voltage signal of a corresponding data line to the gate of the driving transistor T0, i.e., at the first node N1 in the figure, in response to a Scan signal of the first Scan line Scan1, to charge the first storage capacitor C1. The second switch transistor T2 provides the first reference voltage signal of the first reference line Ref1 to the source of the driving transistor T0, i.e., at the second node N2 in the figure, in response to the Scan signal of the second Scan line Scan2, and performs anode reset on the light emitting element OLED.
The first storage capacitor C1 is used to store the voltage between the gate and the source of the driving transistor T0, i.e., the difference between the voltages at the node N1 and the node N2, and to take the charged voltage as the driving voltage Vgs of the driving transistor T0, which is Vdata-Vref. When the charging voltage (Vdata-Vref) on the first storage capacitor C1 is higher than the threshold voltage Vth of the driving transistor T0, the driving transistor T0 supplies a current proportional to the driving voltage Vgs stored in the first storage capacitor C1 to the light emitting element OLED through the second node N2.
During the second time period T2, the first switch tube T1 is turned off, and the second switch tube T2 is kept open. The second switching transistor T2 is used as an output path between the driving transistor T0 and the first reference line Ref1, at this time, the driving transistor T0 supplies a current proportional to the driving voltage Vgs stored in the first storage capacitor C1 to the second node N2 and outputs the current to the first reference line Ref1 through the second switching transistor T2, and the current on the first reference line Ref1 is collected as the first detection current through the data driver connected to the first reference line Ref 1.
That is, as the first storage capacitor C1 is discharged, the voltage of the first reference line Ref1 increases, and when the driving voltage Vgs of the first storage capacitor C1 reaches the threshold voltage Vth of the driving transistor T0, the voltage on the first reference line Ref1 reaches a saturation value Vb (Vb-Vdata-Vth), that is, exceeds the transition point Vb, the driving voltage Vgs of the driving transistor T0 is greater than the threshold voltage Vth to drive the light emitting element OLED to emit light. When the first switch transistor T1 is turned off and only the second switch transistor T2 is turned on, the current flowing through the light emitting element OLED can be detected from the reference line, and the theoretical formula is 0.5cox × u w/L (Vgs-Vth) ^ 2.
It is noted that, in the first period t1 and the second period t2, the control unit controls the light emitting element OLED not to emit light, and specifically, the module end is set to have a value of 00 by dimming 51, i.e., the general register value of the dimming setting is set to 00, so that the light emitting element OLED does not emit light at this time even if there is current supplied to the light emitting element OLED.
It is understood that the first storage capacitor C1 may also be another voltage storage unit, the first switch transistor T1 and the driving transistor T0 together form a driving circuit of the light emitting device OLED, and the voltage storage unit may include a plurality of switch transistors and a plurality of capacitors, so as to achieve high quality display.
In this embodiment, the control unit (not shown) is configured to calculate an average value of the first detection currents in the plurality of pixel circuitsAccording to the average value of the first detected currentAnd obtaining a voltage set value of the second data voltage signal. Further, since the driving transistor T0 is saturated, the drain current formula is: i is 0.5cox w/L (Vgs-Vth) 2, Vgs is Vdata-Vref, and the voltage set value of the second data voltage signal is obtained by conversion according to the formulaWherein Vdata is a second data voltageThe voltage setting value of the signal, K ═ u × Cox (W/L), Cox is the gate oxide capacitance per unit area, u is the mobility, W is the gate width of the driving transistor T0, L is the channel length of the driving transistor T0,which is an average value of the first detection currents in the plurality of pixel circuits, Vth is a threshold voltage of the driving transistor T0, and Vref is a voltage value of a reference signal of the second reference line Ref 2.
In practical applications, the writing module 12 may include a third switching transistor T3 and a second storage capacitor C2, the third switching transistor T3 is configured to provide the reference signal of the second reference line Ref2 to the source of the driving transistor T0 in response to the Scan signal of the third Scan line Scan3, and the second storage capacitor C2 is configured to store the voltage between the gate and the source of the driving transistor T0 and use the charged voltage as the driving voltage of the driving transistor T0 to drive the light emitting element OLED to emit light.
Specifically, the connection relationship of each device is as follows:
a first terminal of the second storage capacitor C2 is connected to the control terminal of the driving transistor T0, and a second terminal of the second storage capacitor C2 is connected to the source of the driving transistor T0.
The gate of the third switching transistor T3 is connected to the third Scan line Scan3, the drain is connected to the source of the driving transistor T0 and the second terminal of the second storage capacitor C2, the common connection terminal is the third node N3, and the source is connected to the second reference line Ref 2.
In combination with the connection relationship of the above devices, the working principle of the write module 12 is as follows:
in the third time period T3, the first switching tube T1 and the third switching tube T3 are turned on. The first switching transistor T1 supplies a second data voltage signal of a corresponding data line to the gate of the driving transistor T0, i.e., at the first node N1 in the figure, in response to a Scan signal of the first Scan line Scan1, to charge the second storage capacitor C2. The third switching transistor T3 supplies the second reference voltage signal of the second reference line Ref2 to the source of the driving transistor T0, i.e., the third node N3 in the drawing, in response to the Scan signal of the third Scan line Scan3, and anodically resets the light emitting element OLED.
The second storage capacitor C2 is used to store the voltage between the gate and the source of the driving transistor T0, i.e., the difference between the voltages at the node N1 and the node N3, and to take the charged voltage as the driving voltage Vgs of the driving transistor T0, which is Vdata-Vref. When the charging voltage (Vdata-Vref) on the second storage capacitor C2 is higher than the threshold voltage Vth of the driving transistor T0, the driving transistor T0 supplies a current proportional to the driving voltage Vgs stored in the second storage capacitor C2 to the light emitting element OLED through the third node N3, thereby driving the light emitting element OLED to emit light.
During the fourth period T4, the first switch transistor T1 is turned off, and the third switch transistor T3 is kept open. The third switching transistor T3 is used as an output path between the driving transistor T0 and the second reference line Ref2, at this time, the driving transistor T0 supplies a current proportional to the driving voltage Vgs stored in the second storage capacitor C2 to the third node N3 and outputs the current to the second reference line Ref2 through the third switching transistor T3, and the current on the second reference line Ref2 is collected as a second detection current through the data driver connected to the second reference line Ref2, wherein the obtained second detection current can be used as a reference current to prepare for next adjustment of the voltage value of the data voltage signal of the data line.
Specifically, if after the first switch tube T1 is connected to the second voltage data signal of the data line, the write-in module 12 controls the driving transistor T0 to drive the light-emitting element OLED to emit light, and the light-emitting luminance of each region is still not uniform enough, the control unit may further calculate an average value of the second detection currents in the plurality of pixel circuits, and obtain a voltage setting value of the third data voltage signal of the data line according to the average value of the second detection currents (specifically, the same formula as "obtaining the voltage setting value of the second data voltage signal according to the average value of the first detection current", which is not described here again), and after the first switch tube T1 is connected to the third voltage data signal of the data line, the write-in module 12 controls the driving transistor T0 to drive the light-emitting element OLED to emit light, so as to further improve the uniformity of the display screen.
That is, as the second storage capacitor C2 is discharged, the voltage of the second reference line Ref2 increases, and when the driving voltage Vgs of the second storage capacitor C2 reaches the threshold voltage Vth of the driving transistor T0, the voltage on the second reference line Ref2 reaches a saturation value Vb (Vb-Vdata-Vth), that is, exceeds the transition point Vb, the driving voltage Vgs of the driving transistor T0 is greater than the threshold voltage Vth to drive the light emitting element OLED to emit light. When the first switch tube T1 is turned off and only the third switch tube T3 is turned on, the current flowing through the light emitting element OLED can be detected from the reference line, and the theoretical formula is 0.5cox × u w/L (Vgs-Vth) ^ 2.
It is understood that the second storage capacitor C2 may also be another voltage storage unit, the first switch transistor T1 and the driving transistor T0 together form a driving circuit of the light emitting device OLED, and the voltage storage unit may include a plurality of switch transistors and a plurality of capacitors, so as to achieve high quality display.
Optionally, in the pixel row direction, two adjacent pixel units share a reference line, which is at least one of the first reference line Ref1 and the second reference line Ref2, so that the number of reference lines can be reduced.
In addition, the display panel may further include a data driver 13, where the data driver 13 is configured to provide a data signal to one of the two pixel units sharing the reference line and provide black data or an off voltage to the other of the two pixel units, so that the two pixel units sharing the reference line are not driven simultaneously, and in practical applications, the data driver 13 is configured to generate two data signals, data1 and data2, where, when the data1 is a valid data signal, the data2 is black data or off data, and it is ensured that one of the two pixel units sharing the reference line is working and the other one is not working.
Preferably, the first switching tubes T1 of the two pixel cells sharing the reference line are connected to the first Scan line Scan1, the second switching tubes T2 of the two pixel cells sharing the reference line are connected to the second Scan line Scan2, and the third switching tubes T3 of the two pixel cells sharing the reference line are connected to the third Scan line Scan 3. By sharing the reference line by two adjacent pixel units, the number of reference lines to be provided can be reduced. Of course, whether the scan lines are shared may not be limited, and will not be described herein.
Compared with the prior art, the embodiment of the invention can obtain the reference current flowing through the light emitting element OLED in the plurality of pixel circuits by obtaining the first detection current flowing through the light emitting element OLED after the first data voltage signal of the first switch tube T1 connected to the data line is obtained by the detection module 11, obtain the voltage set value of the second data voltage signal of the data line by the control unit according to the first detection current in the plurality of pixel circuits, that is, the voltage value of the adjusted data voltage signal supplied from the data line is preset by using the reference current flowing through the light emitting element OLED in the plurality of pixel circuits, so that the currents flowing through the light emitting elements OLED in the plurality of pixel circuits are substantially equal under the action of the data voltage signal supplied from the adjusted data line, the uniformity of the luminance of the light emitting elements OLED in the plurality of pixel circuits is made higher, thereby improving the problem of poor uniformity of the display screen.
A second embodiment of the present invention relates to a method for detecting a pixel circuit, which is applied to the display panel as shown in fig. 2 and 3, and includes the following steps:
s11: and acquiring a first detection current flowing through the light-emitting element after the first switch tube is connected into the first data voltage signal of the data line by using the detection module.
Specifically, the detection module 11 may include a second switch transistor T2 and a first storage capacitor C1, where the second switch transistor T2 is configured to respond to the Scan signal of the second Scan line Scan2 and provide the reference signal of the first reference line Ref1 to the source of the driving transistor T0, and the first storage capacitor C1 is configured to store the voltage between the gate and the source of the driving transistor T0 and use the charged voltage as the driving voltage of the driving transistor T0, and the connection relationship of the specific devices is similar to that of the first embodiment, and is not described herein again.
In this step, specifically, the first time period T1 and the second time period T2 are included, in the first time period T1, the first switch tube T1 and the second switch tube T2 are turned on, the data line inputs the first data voltage signal, and the first reference line Ref1 inputs the first reference voltage signal; in the second time period T2, the first switch tube T1 is turned off, the second switch tube T2 is turned on, and the current on the first reference line Ref1 is obtained as the first detection current.
In the first period T1, the first switching transistor T1 supplies the first data voltage signal of the corresponding data line to the gate of the driving transistor T0, i.e., at the first node N1 in the figure, in response to the Scan signal of the first Scan line Scan1, and charges the first storage capacitor C1. The second switch transistor T2 provides the first reference voltage signal of the first reference line Ref1 to the source of the driving transistor T0, i.e., at the second node N2 in the figure, in response to the Scan signal of the second Scan line Scan2, and performs anode reset on the light emitting element OLED.
The first storage capacitor C1 is used to store the voltage between the gate and the source of the driving transistor T0, i.e., the difference between the voltages at the node N1 and the node N2, and to take the charged voltage as the driving voltage Vgs of the driving transistor T0, which is Vdata-Vref. When the charging voltage (Vdata-Vref) on the first storage capacitor C1 is higher than the threshold voltage Vth of the driving transistor T0, the driving transistor T0 supplies a current proportional to the driving voltage Vgs stored in the first storage capacitor C1 to the light emitting element OLED through the second node N2.
During the second period T2, the second switch tube T2 serves as an output path between the driving transistor T0 and the first reference line Ref1, at this time, the driving transistor T0 supplies a current proportional to the driving voltage Vgs stored in the first storage capacitor C1 to the second node N2 and outputs the current to the first reference line Ref1 through the second switch tube T2, and the current on the first reference line Ref1 is collected as the first detection current through the data driver 13 connected to the first reference line Ref 1.
S12: and obtaining a voltage set value of a second data voltage signal of the data line by using the control unit according to the first detection current in the plurality of pixel circuits.
Specifically, in this step, the average value of the first detection currents in the plurality of pixel circuits is calculatedAccording to the average value of the first detected currentAnd obtaining a voltage set value of the second data voltage signal.
Further, since the driving transistor T0 is saturated, the drain current formula is: i is 0.5cox w/L (Vgs-Vth) 2, Vgs is Vdata-Vref, and the voltage set value of the second data voltage signal is obtained by conversion according to the formula Wherein Vdata is a voltage setting value of the second data voltage signal, K ═ u × Cox (W/L), Cox is a gate oxide capacitance per unit area, u is a mobility, W is a gate width of the driving transistor T0, L is a channel length of the driving transistor T0,which is an average value of the first detection currents in the plurality of pixel circuits, Vth is a threshold voltage of the driving transistor T0, and Vref is a voltage value of a reference signal of the second reference line Ref 2.
S13: and controlling the driving transistor to drive the light-emitting element to emit light after the first switch tube is connected to the second voltage data signal of the data line by using the writing module.
Specifically, the writing module 12 may include a third switching tube T3 and a second storage capacitor C2, where the third switching tube T3 is configured to provide the reference signal of the second reference line Ref2 to the source of the driving transistor T0 in response to the Scan signal of the third Scan line Scan3, and the second storage capacitor C2 is configured to store the voltage between the gate and the source of the driving transistor T0, and use the charged voltage as the driving voltage of the driving transistor T0 to drive the light emitting element OLED to emit light.
In this step, specifically, a third time period T3 and a fourth time period T4 are included, in the third time period T3, the first switching tube T1 and the third switching tube T3 are turned on, the data line inputs a second data voltage signal, and the second reference line Ref2 inputs a second reference voltage signal, wherein a voltage setting value of the second data voltage signal is set according to the first detection current in the plurality of pixel circuits; during the fourth period T4, the first switch transistor T1 is turned off, the third switch transistor T3 is turned on, and the second storage capacitor C2 provides the charge for the driving transistor T0 to drive the light emitting element OLED to emit light, and preferably, during the fourth period T4, the method further includes: a second detection current on a second reference line Ref2 is obtained.
In the third time period T3, the first switching tube T1 and the third switching tube T3 are turned on. The first switching transistor T1 supplies a second data voltage signal of a corresponding data line to the gate of the driving transistor T0, i.e., at the first node N1 in the figure, in response to a Scan signal of the first Scan line Scan1, to charge the second storage capacitor C2. The third switching transistor T3 supplies the second reference voltage signal of the second reference line Ref2 to the source of the driving transistor T0, i.e., the third node N3 in the drawing, in response to the Scan signal of the third Scan line Scan3, and anodically resets the light emitting element OLED.
The second storage capacitor C2 is used to store the voltage between the gate and the source of the driving transistor T0, i.e., the difference between the voltages at the node N1 and the node N3, and to take the charged voltage as the driving voltage Vgs of the driving transistor T0, which is Vdata-Vref. When the charging voltage (Vdata-Vref) on the second storage capacitor C2 is higher than the threshold voltage Vth of the driving transistor T0, the driving transistor T0 supplies a current proportional to the driving voltage Vgs stored in the second storage capacitor C2 to the light emitting element OLED through the third node N3, thereby driving the light emitting element OLED to emit light.
During the fourth period T4, the first switch transistor T1 is turned off, and the third switch transistor T3 is kept open. The third switching transistor T3 is used as an output path between the driving transistor T0 and the second reference line Ref2, at this time, the driving transistor T0 supplies a current proportional to the driving voltage Vgs stored in the second storage capacitor C2 to the third node N3 and outputs the current to the second reference line Ref2 through the third switching transistor T3, and the current on the second reference line Ref2 is collected as a second detection current through the data driver 13 connected to the second reference line Ref2, wherein the second detection current can be obtained as a reference current in preparation for next adjusting the voltage value of the data voltage signal of the data line.
Compared with the prior art, the embodiment of the invention can obtain the reference current flowing through the light emitting element OLED in the plurality of pixel circuits by obtaining the first detection current flowing through the light emitting element OLED after the first data voltage signal of the first switch tube T1 connected to the data line is obtained by the detection module 11, obtain the voltage set value of the second data voltage signal of the data line by the control unit according to the first detection current in the plurality of pixel circuits, that is, the voltage value of the adjusted data voltage signal supplied from the data line is preset by using the reference current flowing through the light emitting element OLED in the plurality of pixel circuits, so that the currents flowing through the light emitting elements OLED in the plurality of pixel circuits are substantially equal under the action of the data voltage signal supplied from the adjusted data line, the uniformity of the luminance of the light emitting elements OLED in the plurality of pixel circuits is made higher, thereby improving the problem of poor uniformity of the display screen.
A third embodiment of the present invention provides a display device including the display panel described above. The display device can be a product or a component with a television function, such as a display panel, a mobile phone, a tablet computer, a television, a display, a digital photo frame or a navigator.
It can be understood by those skilled in the art that the technical details in the first embodiment are still applicable to this embodiment, and the technical effects of this embodiment are similar to those of the first embodiment, and are not described herein again.
The steps of the above methods are divided for clarity, and the implementation may be combined into one step or split some steps, and the steps are divided into multiple steps, so long as the same logical relationship is included, which are all within the protection scope of the present patent; it is within the scope of the patent to add insignificant modifications to the algorithms or processes or to introduce insignificant design changes to the core design without changing the algorithms or processes.
It will be understood by those of ordinary skill in the art that the foregoing embodiments are specific examples for carrying out the invention, and that various changes in form and details may be made therein without departing from the spirit and scope of the invention in practice.
Claims (10)
1. A display panel, comprising: a plurality of pixel units arranged in an array, each of the pixel units including a pixel circuit, the pixel circuit including:
a light emitting element;
a driving transistor for driving the light emitting element;
the first switching tube is used for responding to a scanning signal of the first scanning line and accessing a data voltage signal provided by the data line;
the detection module is used for acquiring a first detection current flowing through the light-emitting element after the first switch tube is connected into a first data voltage signal of a data line;
a control unit, configured to obtain a voltage setting value of a second data voltage signal of the data line according to the first detection current in the plurality of pixel circuits;
and the writing module is used for controlling the driving transistor to drive the light-emitting element to emit light after the first switch tube is connected into the second voltage data signal of the data line.
2. The display panel of claim 1, wherein the detection module comprises:
the second switch tube is used for responding to the scanning signal of the second scanning line and providing the reference signal of the first reference line to the source electrode of the driving transistor;
the first storage capacitor is used for storing the voltage between the grid electrode and the source electrode of the driving transistor and taking the charged voltage as the driving voltage of the driving transistor;
the current on the first reference line is the first detection current.
3. The display panel of claim 2, wherein the write module comprises:
a third switching tube for supplying a reference signal of a second reference line to the source of the driving transistor in response to a scan signal of a third scan line;
and the second storage capacitor is used for storing the voltage between the grid electrode and the source electrode of the driving transistor and taking the charged voltage as the driving voltage of the driving transistor so as to drive the light-emitting element to emit light.
4. The display panel according to claim 3, wherein in a pixel row direction, two adjacent pixel units share a reference line, the reference line being at least one of the first reference line and the second reference line;
preferably, the first switching tubes of the two pixel units sharing the reference line are both connected to the first scan line, the second switching tubes of the two pixel units sharing the reference line are both connected to the second scan line, and the third switching tubes of the two pixel units sharing the reference line are both connected to the third scan line.
5. The display panel according to claim 4, further comprising a data driver for supplying a data signal to one of the two pixel units sharing the reference line and supplying black data or an off voltage to the other of the two pixel units so that the two pixel units sharing the reference line are not driven at the same time.
6. A detection method of a pixel circuit, applied to the display panel according to claim 1, comprising:
acquiring a first detection current flowing through the light-emitting element after the first switch tube is connected to a first data voltage signal of a data line by using the detection module;
obtaining a voltage set value of a second data voltage signal of the data line according to the first detection current in the plurality of pixel circuits by using the control unit;
and controlling the driving transistor to drive the light-emitting element to emit light after the first switch tube is connected into the second voltage data signal of the data line by using the writing module.
7. The detection method of the pixel circuit according to claim 6, wherein the detection module comprises:
the second switch tube is used for responding to the scanning signal of the second scanning line and providing the reference signal of the first reference line to the source electrode of the driving transistor;
the first storage capacitor is used for storing voltage between a grid electrode and a source electrode of the driving transistor, the charged voltage is used as driving voltage of the driving transistor, and the first detection current is node current of the second switching tube and the first reference line;
the obtaining of the first detection current flowing through the light emitting element after the first switch tube is connected to the first data voltage signal of the data line by using the detection module specifically includes:
in a first period, the first switch tube and the second switch tube are turned on, a first data voltage signal is input into the data line, and a first reference voltage signal is input into the first reference line;
and in a second time interval, closing the first switch tube, opening the second switch tube, and acquiring the current on the first reference line as the first detection current.
8. The pixel circuit detection method according to claim 6, wherein the writing module comprises:
a third switching tube for supplying a reference signal of a second reference line to the source of the driving transistor in response to a scan signal of a third scan line;
a second storage capacitor for storing a voltage between a gate and a source of the driving transistor and driving the light emitting element to emit light by using the charged voltage as a driving voltage of the driving transistor;
after the writing module is used for controlling the driving transistor to drive the light-emitting element to emit light after the first switch tube is connected to the second voltage data signal of the data line, the method specifically includes:
in a third time interval, the first switching tube and the third switching tube are turned on, the data line inputs a second data voltage signal, the second reference line inputs a second reference voltage signal, and a voltage set value of the second data voltage signal is set according to the first detection current in the plurality of pixel circuits;
in a fourth period, the first switch tube is closed, the third switch tube is opened, and the second storage capacitor provides charges for the driving transistor to drive the light-emitting element to emit light;
preferably, in the fourth period, the method further includes: and acquiring a second detection current on the second reference line.
9. The method according to claim 6, wherein obtaining the voltage setting value of the second data voltage signal of the data line according to the first detection current in the plurality of pixel circuits by the control unit comprises:
calculating an average value of the first detection currents in a plurality of the pixel circuits;
obtaining a voltage set value of the second data voltage signal according to the average value of the first detection current;
preferably, the obtaining of the voltage setting value of the second data voltage signal according to the average value of the first detection current specifically includes: obtaining a voltage setting value of the second data voltage signal according to the following formula:
wherein Vdata is a voltage setting value of the second data voltage signal, K ═ u × Cox (W/L), Cox is a gate oxide capacitance per unit area, u is a mobility, W is a gate width of the driving transistor, L is a channel length of the driving transistor,is an average value of the first detection currents in a plurality of the pixel circuits, Vth is a threshold voltage of a driving transistor, VrefIs the voltage value of the reference signal of the second reference line.
10. A display device characterized by comprising the display panel according to any one of claims 1 to 5.
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