CN109243367A - Threshold voltage circuit for detecting and method for detecting - Google Patents
Threshold voltage circuit for detecting and method for detecting Download PDFInfo
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- CN109243367A CN109243367A CN201811095426.4A CN201811095426A CN109243367A CN 109243367 A CN109243367 A CN 109243367A CN 201811095426 A CN201811095426 A CN 201811095426A CN 109243367 A CN109243367 A CN 109243367A
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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
-
- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G2320/00—Control of display operating conditions
- G09G2320/04—Maintaining the quality of display appearance
- G09G2320/043—Preventing or counteracting the effects of ageing
Abstract
The present invention provides a kind of threshold voltage circuit for detecting, wherein, the threshold voltage circuit for detecting includes: first switch (SW_R), and one end is connect with one end of device to be detected, and when precharge of the first switch (SW_R) in sense mode is connected；Detection lines (Sen), one end are connect with described one end of first switch (SW_R), for pre-charge pressure to be written to device to be detected in first switch (SW_R) conducting；Sampling capacitance (Cc) is connected to, for acquiring the threshold voltage of device to be detected with described one end of detection lines (Sen) when the parasitic capacitance (Cp) of detection lines (Sen) discharges completion.Above-mentioned threshold voltage circuit for detecting is made of first switch (SW_R), detection lines (Sen) and sampling capacitance (Cc), and the detecting of threshold voltage can be only realized by the control to detection lines, and circuit for detecting is simple.
Description
Technical field
The present invention relates to field of display technology, and in particular to a kind of threshold voltage circuit for detecting and threshold voltage detecting side
Method and further relate to luminance compensation circuit, luminance compensation method and display panel.
Background technique
AMOLED (Active Matrix Organic Light Emitting Diode, Organic Light Emitting Diode) plate
Display screen makes luminescent device using organic material, and device flows through larger current.Display screen, can not by using for a long time
OLED device is caused to deteriorate with avoiding, the threshold voltage of OLED device changes, and luminous efficiency reduces, so that display screen
Brightness decline and long-term image retention.It in view of the above deficiencies, can be using OLED device threshold voltage circuit for detecting to OLED device
Threshold voltage is detected, and is compensated according to the device threshold voltage after detecting to OLED device, and OLED device threshold is avoided
The problem of decline of brightness of display screen caused by threshold voltage changes and long-term image retention.
In the prior art, usual OLED display screen be applied to consumer field, the life requirements to OLED be not it is very high, due to
The reasons such as element leakage, compensation operation complexity, so that detecting OLED device threshold voltage can dramatically increase cost；Therefore the prior art
In the threshold voltage of OLED device is not detected usually；But in the field more demanding to OLED device service life and image retention
(such as vehicle-mounted or industrial control field) needs to detect the threshold voltage of OLED device, however, OLED device in the prior art
Threshold voltage circuit for detecting process that the threshold voltage of OLED device is detected it is more complex, control difficulty is big, it would be highly desirable to solve
Certainly.
Summary of the invention
Based on this, it is necessary in view of the above technical problems, provide a kind of simple OLED threshold voltage detecting of control mode
Circuit, method for detecting, luminance compensation circuit, luminance compensation method and display panel.
For this purpose, the invention provides the following technical scheme:
First aspect present invention provides a kind of threshold voltage circuit for detecting, comprising: first switch, one end with it is to be detected
One end of device connects, and when precharge of the first switch in sense mode is connected；Detection lines, one end and described first
Described one end connection of switch, for pre-charge pressure to be written to the device to be detected in first switch conducting；Sampling
Capacitor is connected to when the parasitic capacitance discharge of the detection lines is completed with described one end of the detection lines, described for acquiring
The threshold voltage of device to be detected.
Optionally, the detection lines and scan line or power supply line, which overlap, forms the parasitic capacitance.
Optionally, the parasitic capacitance of the detection lines is used within the detecting period provide electricity to the device to be detected
Lotus so that the charge flow through the device to be detected until voltage and the device to be detected of the parasitic capacitance it is another
The sum of the voltage at end and the device threshold voltage to be detected are equal.
Optionally, further includes: second switch, one end are connect with described one end of the detection lines, the other end and institute
Sampling capacitance connection is stated, for controlling the connection of the sampling capacitance Yu the detection lines.
Optionally, further includes: A/D converter is connected to the sampling capacitance, when the sampling capacitance samples completion,
For the threshold voltage of the collected device to be detected of the sampling capacitance to be carried out A/D conversion.
Optionally, further includes: third switch, one end are connect with the sampling capacitance, and the other end and the A/D are converted
Device connection, for controlling the connection of the A/D converter Yu the sampling capacitance.
Optionally, the device to be detected is OLED.
Second aspect of the present invention provides a kind of threshold voltage method for detecting, includes the following steps: pre- in sense mode
When charging, pre-charge pressure is written to device to be detected by detection lines, so that the voltage on the anode of the device to be detected
For the pre-charge pressure；In the detection lines and the device to be detected disconnects and the voltage etc. of the parasitic capacitance of the detection lines
When the sum of the cathode voltage of the device to be detected and threshold voltage, it is connected to sampling capacitance and one end of the detection lines；
When the sampled capacitor voltage is equal to the voltage on device to be detected, the voltage value on the sampling capacitance is acquired, it will be described
The cathode voltage of voltage value and the device to be detected on sampling capacitance makees difference to obtain the threshold value electricity of the device to be detected
Pressure.
Optionally, after the step of acquiring the voltage value on the sampling capacitance, further includes: completed in the sampling capacitance
When sampling, the threshold voltage is subjected to A/D conversion.
Third aspect present invention provides a kind of luminance compensation circuit, comprising: any threshold in first aspect present invention
Threshold voltage circuit for detecting；Controller, for treating detector according to the collected threshold voltage of threshold voltage circuit for detecting
Part carries out luminance compensation.
Fourth aspect present invention provides a kind of display panel, including the threshold value as described in any in first aspect present invention
Luminance compensation circuit described in voltage detection circuit or second aspect of the present invention.
Fifth aspect present invention provides a kind of luminance compensation method, comprising: any described according to a second aspect of the present invention
Threshold voltage method for detecting obtain the current threshold voltage of device to be detected；Detector is treated according to the current threshold voltage
Part carries out luminance compensation.
Optionally, detecting device is treated according to the current threshold voltage and carries out luminance compensation, comprising: according to described current
Threshold voltage determines the current threshold voltage variable quantity of the current threshold voltage and initial threshold voltage；According to the current threshold
Threshold voltage variable quantity is searched and the current threshold in the corresponding relationship of the threshold voltage variation amount and luminous efficiency that pre-establish
The corresponding current luminous efficiency of threshold voltage variable quantity；Detecting device, which is treated, according to the current luminous efficiency carries out luminance compensation.
Optionally, detecting device is treated according to the current luminous efficiency and carries out luminance compensation, comprising: according to described current
Luminous efficiency determines compensated pixel current；Detecting device, which is treated, according to the compensated pixel current carries out brightness benefit
It repays.
Optionally, compensated pixel current is obtained by following formula,
Wherein, I is compensated pixel current；η0For the initial light emission efficiency of device to be detected；η is device to be detected
Current luminous efficiency；I0For the initial pixel electric current of device to be detected.
Optionally, detecting device is treated according to the compensated pixel current and carries out luminance compensation, comprising: according to described
Compensated pixel current determines compensated voltage data signal value；It is determined according to the compensated voltage data signal value
Compensated grayscale；Detecting device, which is treated, according to the compensated grayscale carries out brightness control.
Optionally, when device to be detected is OLED and initial pixel electric current is I0=k (VELVDD-VDATA)2When, by as follows
Formula obtains compensated voltage data signal value,
Wherein, V 'DATAFor compensated voltage data signal value；VELVDDFor AMOLED display screen supply voltage；VDATAFor
Voltage data signal before compensation.
Technical solution of the present invention has the advantages that
1. threshold voltage circuit for detecting provided by the invention, comprising: first switch, one end of one end and device to be detected
Connection, when precharge of the first switch in sense mode, are connected；Detection lines, one end are described with the first switch
One end connection, for pre-charge pressure to be written to the device to be detected in first switch conducting；Sampling capacitance, in institute
It is connected to when stating the parasitic capacitance discharge completion of detection lines with described one end of the detection lines, for acquiring the device to be detected
Threshold voltage.Above-mentioned threshold voltage circuit for detecting is made of first switch, detection lines and sampling capacitance, only by detecting
The control of line can realize the detecting of threshold voltage, and circuit for detecting is simple.
2. threshold voltage circuit for detecting provided by the invention, the detection lines and scan line or power supply line it is overlapping formed it is described
Parasitic capacitance.It makes full use of parasitic capacitance to carry out threshold voltage detecting in above-mentioned threshold voltage circuit for detecting, saves component, section
About production cost.
3. threshold voltage method for detecting provided by the invention when including the following steps: the precharge in sense mode, leads to
It crosses detection lines and pre-charge pressure is written to device to be detected, so that the voltage on the anode of the device to be detected is the preliminary filling
Voltage；It is equal in the voltage of the detection lines and the device disconnection to be detected and the parasitic capacitance of the detection lines described wait detect
When surveying the sum of cathode voltage and the threshold voltage of device, it is connected to sampling capacitance and one end of the detection lines；In the sampling
When capacitance voltage is equal to the voltage on device to be detected, the voltage value on the sampling capacitance is acquired, it will be on the sampling capacitance
Voltage value and the cathode voltage of the device to be detected make difference to obtain the threshold voltage of the device to be detected.Above-mentioned detecting
Method, which only passes through detection lines, can detect threshold voltage, and without the cooperation of data line or scan line, detecting control is simple easy
Operation.
4. luminance compensation circuit provided by the invention, comprising: above-mentioned mentioned described in any item threshold voltages detecting
Circuit；Controller carries out brightness for treating detecting device according to the collected threshold voltage of threshold voltage circuit for detecting
Compensation.Above-mentioned luminance compensation circuit is due to using above-mentioned threshold voltage circuit for detecting, it may have the simple advantage of circuit structure.
5. luminance compensation method provided by the invention, comprising: obtain device to be detected according to above-mentioned threshold voltage method for detecting
The current threshold voltage of part；Detecting device, which is treated, according to the current threshold voltage carries out luminance compensation.Luminance compensation method by
In using above-mentioned threshold voltage method for detecting, threshold voltage, the simple easily behaviour of detecting control only can be detected by detection lines
Make；In addition, treating detecting device according to the threshold voltage detected carries out luminance compensation, avoid due to device degradation to be detected
Caused by luminous efficiency be substantially reduced, the defect of brightness of display screen decline and long-term image retention.
Detailed description of the invention
It, below will be to specific in order to illustrate more clearly of the specific embodiment of the invention or technical solution in the prior art
Embodiment or attached drawing needed to be used in the description of the prior art be briefly described, it should be apparent that, it is described below
Attached drawing is some embodiments of the present invention, for those of ordinary skill in the art, before not making the creative labor
It puts, is also possible to obtain other drawings based on these drawings.
Fig. 1 is the schematic diagram of an application scenarios of threshold voltage circuit for detecting in the embodiment of the present invention；
Fig. 2 is the schematic diagram of a specific example of threshold voltage circuit for detecting in the embodiment of the present invention；
Fig. 3 is the schematic diagram of another specific example of threshold voltage circuit for detecting in the embodiment of the present invention；
Fig. 4 is the schematic diagram of another specific example of threshold voltage circuit for detecting in the embodiment of the present invention；
Fig. 5 is the timing diagram of a specific example of threshold voltage circuit for detecting in the embodiment of the present invention；
Fig. 6 is the flow chart of a specific example of threshold voltage method for detecting in the embodiment of the present invention；
Fig. 7 is the flow chart of another specific example of threshold voltage method for detecting in the embodiment of the present invention；
Fig. 8 is the schematic diagram of a specific example of luminance compensation circuit in the embodiment of the present invention；
Fig. 9 is the flow chart of another specific example of luminance compensation method in the embodiment of the present invention；
Figure 10 is the flow chart of another specific example of luminance compensation method in the embodiment of the present invention；
Figure 11 is the flow chart of another specific example of luminance compensation method in the embodiment of the present invention；
Figure 12 is the flow chart of another specific example of luminance compensation method in the embodiment of the present invention.
Specific embodiment
In order to which the objects, technical solutions and advantages of invention are more clearly understood, with reference to the accompanying drawings and embodiments, to this
Invention is further elaborated.It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, not
For limiting the present invention.
In the description of the present invention, it is to be understood that, term " center ", " transverse direction ", "upper", "lower" "left", "right",
The orientation or positional relationship of the instructions such as "vertical", "horizontal", "top", "bottom", "inner" and "outside" is side based on the figure
Position or positional relationship, are merely for convenience of description of the present invention and simplification of the description, rather than the device or member of indication or suggestion meaning
Part must have a particular orientation, be constructed and operated in a specific orientation, therefore be not considered as limiting the invention.This
Outside, it should be noted that when element is referred to as " being formed on another element ", it can be directly connected on another element or
Person may be simultaneously present centering elements.When an element is considered as " connection " another element, it be can be directly connected to separately
One element exists simultaneously centering elements.On the contrary, there is no centres when element is referred to as " directly existing " another element "upper"
Element.
As described in background, there are the controls of the threshold voltage circuit for detecting of OLED device for display screen in the prior art
The problem of mode complexity, inventor are that OLED device threshold value is electric in the prior art the study found that there is the reason of this problem
It presses circuit for detecting during sampling the threshold voltage of OLED device, needs under detection signal and data-signal co- controlling
Realize the acquisition of device threshold voltage.
Fig. 1 be the embodiment of the present invention an application scenarios schematic diagram, as shown in Figure 1, threshold voltage circuit for detecting 1 with to
It detects device 2 to connect, the threshold voltage for treating detecting device 2 is detected.Specifically, device 2 to be detected can be OLED,
Threshold voltage circuit for detecting 1 is connected with the anode of OLED, and the cathode of OLED can be connect with a fixed current potential.When OLED is being shown
Under mode, threshold voltage circuit for detecting 1 is without work of detection and examination；When OLED is under sense mode, threshold voltage circuit for detecting 1 is right
The threshold voltage of OELD is detected, and entire detecting process includes three phases (pre-charging stage, reconnaissance phase and sampling rank
Section).
Based on this, the present invention provides a kind of threshold voltage circuit for detecting, the detecting processes of the threshold voltage circuit for detecting
Simply, control mode is simple, can well solve the above problem.
Threshold voltage circuit for detecting provided by the invention, as shown in Figure 2, comprising: first switch SW_R, detection lines Sen with
And sampling capacitance Cc, in which:
First switch SW_R, one end are connect with one end of device to be detected, the other end and pre-charge pressure VrefConnection,
It is connected when precharge of the first switch SW_R in sense mode；
Detection lines Sen, one end are connect with one end of first switch SW_R, are used in first switch SW_R conducting, to
Device to be detected provides pre-charge pressure Vref；
Sampling capacitance Cc is connected to one end of detection lines Sen when the parasitic capacitance Cp of detection lines Sen discharges completion, uses
In the threshold voltage for acquiring device to be detected.
Above-mentioned threshold voltage circuit for detecting is made of first switch SW_R, detection lines Sen and sampling capacitance Cc, is only passed through
The detecting of threshold voltage can be realized to the control of detection lines, circuit for detecting is simple and detecting mode is simple.
In an alternative embodiment, device to be detected can be Organic Light Emitting Diode OLED；Certainly, in other embodiments
In, device to be detected can also be other semiconductor devices, such as thin film transistor (TFT), as needed rationally setting.
In an alternative embodiment, one end of first switch SW_R is connected by the anode of detection switch SW1 and OLED, the
The other end and pre-charge pressure V of one switch SW_RrefConnection.
Detection switch SW1 includes detecting control terminal, first end and second end, is specifically connected as the first of detection switch SW1
End is connect by detection lines Sen with one end of first switch SW_R, anode (A point) connection of second end and OLED, detecting control
End is connect with detection control signal SCAN1, the cathode and first voltage V of OLEDEVLSSConnection.
The control terminal that detection control signal SCAN1 controls detection switch SW1 in display mode is closed, under sense mode
Control the control terminal conducting of detection switch SW1.Above-mentioned display module is sub-pixel drive circuit works, driving current IDIt flows through
OLED, picture are normally shown；Sense mode is that sub-pixel driving circuit does not work, driving current IDIt is 0.
Detection lines and scan line or power supply line, which overlap, forms parasitic capacitance.In an alternative embodiment, detection lines and transverse direction
Scan line or lateral power supply line overlap and form parasitic capacitance；Certainly, in other embodiments, parasitic capacitance can also by detection lines with
Longitudinal scanning line or longitudinal power supply line are overlapped and are formed, as needed rationally setting.
One end (B point) of parasitic capacitance Cp is connect with detection lines Sen, and the other end is connect with second voltage, second voltage
Size by it is actually used to display panel determine, be only a fixed current potential, with the practical work process of parasitic capacitance Cp without
It closes, therefore for convenience, in the present embodiment, the other end of parasitic capacitance Cp is grounded, as shown in Figure 2.In first switch SW_
When R is connected, pre-charge pressure VrefParasitic capacitance Cp is written, and the anode of OLED is written by detection switch SW1, at this point, VA=VB
=Vref.To pre-charge pressure VrefFirst switch SW_R is disconnected after write-in, after first switch SW_R is disconnected, parasitic capacitance Cp and OLED
Device forms discharge loop, and the charge stored on parasitic capacitance Cp flows through OLED by detection switch SW1, realizes parasitic capacitance Cp
Electric discharge, the voltage of parasitic capacitance Cp is gradually reduced during discharge, until the voltage of parasitic capacitance Cp and the cathode of OLED
Until the sum of voltage and threshold voltage are equal, discharge process terminates, at this point, the voltage V on parasitic capacitance CpB=VELVSS+Vth。
In order to make parasitic capacitance Cp electric discharge sufficiently, discharge time should be longer, in an alternative embodiment, such as 8 cun of display screens,
The preferred scope of discharge time is more than or equal to 30 μ s；Certainly, in other embodiments, discharge time can be according to parasitic capacitance
Size reasonable setting, the size of display screen is bigger, and parasitic capacitance Cp is bigger, and the quantity of electric charge stored on Cp is more, and electric discharge is taken
Between it is longer, specific discharge time can by test test obtain.
In an alternative embodiment, when the parasitic capacitance Cp of detection lines Sen discharges completion, sampling capacitance Cc passes through second
Switch SMP is connected to one end of detection lines Sen.Specially one end of second switch SMP is connect with sampling capacitance Cc, the other end with
Detection lines Sen connection.When parasitic capacitance Cp electric discharge is completed, first switch SW_R is in an off state, second switch SMP conducting,
Voltage (the V of B point on parasitic capacitance CpELVSS+Vth) sampled on sampling capacitance Cc, after the completion of sampling, second switch SMP is disconnected
It opens, at this point, the voltage on sampling capacitance is VELVSS+Vth。
The specific work process of above-mentioned threshold voltage circuit for detecting are as follows:
Pre-charging stage, detection switch SW1 conducting, first switch SW_R conducting, second switch SMP are disconnected, detection lines Sen
Parasitic capacitance is pre-charged, by pre-charge pressure VrefOLED device is written, so that VA=VB=Vref；
Reconnaissance phase, detection switch SW1 conducting, first switch SW_R disconnect, second switch SMP disconnect, parasitic capacitance to
Device to be detected provides charge, so that charge flows through device to be detected until the voltage of parasitic capacitance Cp and the anode of OLED device
Voltage is equal, VB=VELVSS+Vth；
Sample phase, detection switch SW1 are disconnected, and first switch SW_R is disconnected, and second switch SMP conducting, sampling capacitance is adopted
Collect the voltage in parasitic capacitance, so that the voltage on sampling capacitance is VELVSS+Vth。
On the basis of above-mentioned threshold voltage circuit for detecting, as shown in Figure 2, further includes: A/D converter ADC, with sampling electricity
Hold Cc connection, sampling capacitance Cc sample complete when, for by the threshold voltage of the collected device to be detected of sampling capacitance Cc
Carry out A/D conversion.By the threshold voltage V of collected OLED devicethAnalog-to-digital conversion is carried out, digital signal is converted into, convenient for place
Manage the subsequent processing to threshold voltage of device.
In an alternative embodiment, as shown in Fig. 2, A/D converter is connected to by third switch SW_S with sampling capacitance Cc,
Specially one end of third switch SW_S is connect with sampling capacitance Cc, and the other end is connect with A/D converter, for controlling A/D
The connection of converter and sampling capacitance Cc.
It include multiple sub-pixels on display panel, each sub-pixel is correspondingly connected with a threshold voltage circuit for detecting,
The threshold voltage of OLED, i.e., can acquire each OLED by threshold voltage circuit for detecting in the corresponding acquisition sub-pixel of sample circuit
Threshold voltage.
In an alternative embodiment, as shown in figure 4, including three sub-pixels (the first sub-pixel, the second sub-pixel and thirds
Sub-pixel), since ADC converts the voltage stored on sampling capacitance one by one, therefore third switch SW_S is connected one by one.In order to
Convenient for the description of timing control, three sub-pixels respectively correspond three third switches, are denoted as SW_S1, SW_S2 and SW_S3.ADC
When sampling, SW_S1 conducting acquires the threshold voltage V of OLED in the first sub-pixelth1；SW_S2 conducting, acquires in the second sub-pixel
The threshold voltage V of OLEDth2；SW_S3 conducting, acquires the threshold voltage V of OLED in third sub-pixelth3.Certainly, other optional
In embodiment, the number of sub-pixel is rationally arranged as needed.
In conjunction with the practical application scene of threshold voltage circuit for detecting, the worked of threshold voltage circuit for detecting is discussed in detail
Journey, Fig. 5 is the timing diagram of a specific example of threshold voltage circuit for detecting, as shown in figure 5, high potential controls first switch
The conducting of SW_R, second switch SMP and third switch SW, conversely, low potential controls its disconnection.
In t1 stage (pre-charging stage), first switch SW_R conducting, second switch SMP is disconnected, pre-charge pressure VrefWrite-in
The parasitic capacitance Cp of detection lines Sen, and pass through the anode A point of detection switch SW1 write-in OLED, VA=VB=Vref, that is, complete pre-
Charging process.
At t2 stage (discharge regime), first switch SW_R is disconnected, and second switch SMP is disconnected, B point on parasitic capacitance Cp
Charge flows through OLED by detection switch SW1, realizes and discharges parasitic capacitance Cp, the current potential of t2 stage endoparasitism capacitor Cp is always
Decline, until the voltage of parasitic capacitance Cp is equal with the sum of OLED cathode voltage and threshold voltage, at this point, VB=VELVSS+Vth.For
Make Cp electric discharge sufficiently, should ensure that t2 time long enough.
In t3 stage (sample phase), first switch SW_R is disconnected always, is first connected second switch SMP, parasitic electricity
Hold the B point voltage (V of CpELVSS+ Vth) it is collected on sampling capacitance Cc, then, second switch SMP is disconnected, third switch SW_
S1, SW_S2, SW_S3 are sequentially turned on, and ADC is converted one by one, finally by the voltage output after conversion to controller.
The present embodiment also provides a kind of threshold voltage method for detecting, is applied in above-mentioned threshold voltage circuit for detecting, such as Fig. 6
It is shown, including step S11-S13:
Step S11: when precharge in sense mode, being written pre-charge pressure to device to be detected by detection lines, with
So that the anode voltage of device to be detected is pre-charge pressure.
Step S12: it is disconnected in detection lines and device to be detected and the voltage of the parasitic capacitance of detection lines is equal to device to be detected
When the sum of cathode voltage and threshold voltage of part, it is connected to sampling capacitance with one end of detection lines.
Step S13: when sampling capacitance collects the voltage on device to be detected, acquiring the voltage value on sampling capacitance,
The cathode voltage of voltage value and device to be detected on sampling capacitance is made into difference to obtain the threshold voltage of device to be detected.
For the ease of the subsequent processing to threshold voltage of processor, above-mentioned threshold voltage method for detecting, as shown in fig. 7,
Further include step S14 after step S13:
Step S14: when sampling capacitance is completed to sample, threshold voltage is subjected to A/D conversion.
The detailed process of above-mentioned method for detecting is referring to the description in threshold voltage circuit for detecting, and details are not described herein.
The detecting process of above-mentioned threshold voltage method for detecting is simple, control mode is simple.
The present embodiment also provides a kind of luminance compensation circuit, as shown in Figure 8, comprising: appointing mentioned in above-described embodiment
Threshold voltage circuit for detecting 1 described in one；Controller 3, for according to the collected threshold voltage pair of threshold voltage circuit for detecting
Device to be detected carries out luminance compensation.
Above-mentioned luminance compensation circuit, due to using above-mentioned mentioned threshold voltage circuit for detecting, so that threshold voltage
Detecting it is simpler easy to operate；In addition, treating detecting device by luminance compensation circuit carries out luminance compensation, so that after compensation
Luminance constant, avoid device aging and the overall brightness of display screen caused to decline；According to the deterioration journey of each pixel
Degree carries out separate compensation, so that display screen overall brightness is consistent, extends the service life of display screen and reduces display image retention.
The present embodiment also provides a kind of display panel, comprising: any threshold voltage detects electricity in above-described embodiment
Luminance compensation circuit described in road or above-described embodiment.
The present embodiment also provides a kind of display screen, comprising: the display panel in above-described embodiment.
The present embodiment also provides a kind of display equipment, comprising: the display screen in above-described embodiment.In an alternative embodiment
In, display equipment can be shown in equipment for vehicle-carrying display screen, industry control display screen, computer display screen, TV, PAD etc..To the product longevity
It, can using the display screen with compensation circuit in the present embodiment for life and the more demanding vehicle-mounted and industrial control field of image retention
The problem of very good solution device degradation, extends life of product.
The present embodiment also provides a kind of luminance compensation method, as shown in Figure 9, comprising:
Step S1: the current threshold of device to be detected is obtained according to the threshold voltage method for detecting mentioned in above-described embodiment
Threshold voltage.
In an alternative embodiment, device to be detected is OLED device, acquires the current threshold voltage of OLED device, step
S1 is referring to threshold voltage method for detecting, and details are not described herein.
Step S2: detecting device is treated according to current threshold voltage and carries out luminance compensation.
In an alternative embodiment, as shown in Figure 10, step S2 specifically includes step S21-S23:
Step S21: the current threshold voltage of current threshold voltage and initial threshold voltage is determined according to current threshold voltage
Variable quantity.Current threshold voltage variable quantity is can be obtained into as difference in current threshold voltage and initial threshold voltage.
Step S22: according to current threshold voltage variable quantity in the threshold voltage variation amount and luminous efficiency pre-established
Current luminous efficiency corresponding with current threshold voltage variable quantity is searched in corresponding relationship.
In an alternative embodiment, threshold voltage variation amount pass corresponding with luminous efficiency can be obtained in the following way
System.Specifically: it is big by using testing piece (testing piece is same batch output with product, and technological parameter and device architecture are identical)
It measures test piece and does burn-in test, the mapping for recording threshold voltage and luminous efficiency of the OLED device under different degradations is closed
System, as shown in table 1；Luminous efficiency in table 1 is with the lengthening for using the time, and luminous efficiency gradually decreases, i.e. η0> η1> η2>
η3, η0For the initial light emission efficiency of OLED device, VTH0For the initial threshold voltage of OLED device.
The mapping relations of threshold voltage and luminous efficiency under the different degradations of table 1
Above-mentioned device threshold voltage is arranged more, then subsequent compensation is more accurate, as needed rationally setting.
After obtaining the mapping relations of threshold voltage and luminous efficiency, so available threshold voltage variation amount, △ VTHi
=VTHi-VTH0, wherein i >=1 obtains the mapping relations of threshold difference and luminous efficiency, as shown in table 2.
The mapping relations of threshold voltage variation amount and luminous efficiency under the different degradations of table 2
| Device threshold difference | Luminous efficiency |
| - | η0 |
| △VTH1 | η1 |
| △VTH2 | η2 |
| △VTH3 | η3 |
| … | … |
According to current threshold voltage variable quantity △ VthIn threshold voltage variable quantity and the corresponding relationship of luminous efficiency
Search corresponding current luminous efficiency η.
In an alternative embodiment, current threshold voltage variable quantity △ VthSpecific corresponding relationship with luminous efficiency can are as follows:
As △ VthEqual to threshold voltage variable quantity △ VTHiWhen, △ VthCorresponding luminous efficiency is ηi；As △ VthPositioned at adjacent two
A threshold voltage variable quantity threshold voltage variation amount △ VTHiWith △ VTHi+1When, △ VthCorresponding luminous efficiency be and △ Vth
Luminous efficiency corresponding to immediate threshold voltage variable quantity；As △ VthChange positioned at two neighboring threshold voltage
Measure △ VTHiWith △ VTHi+1When middle position, △ VthCorresponding luminous efficiency is ηi.Those skilled in the art can be according to the present embodiment
Description, rationally be arranged current threshold voltage variable quantity △ VthWith the specific corresponding relationship of luminous efficiency.
Step S23: detecting device is treated according to current luminous efficiency and carries out luminance compensation.
Above-mentioned luminance compensation method, by treat detecting device carry out luminance compensation, through the foregoing embodiment mentioned in
Threshold voltage method for detecting obtain current threshold voltage, characterize device degradation with the variable quantity of threshold voltage, calculate
Compensate grayscale out, reached compensation OLED device deterioration, improve the AMOLED display screen service life and it is long when image retention effect
In an alternative embodiment, as shown in figure 11, step S23 specifically includes step S231-S232:
Step S231: compensated pixel current is determined according to current luminous efficiency.
In an alternative embodiment, compensated pixel current is obtained by following formula,
Wherein, I is compensated pixel current；η0For the initial light emission efficiency of device to be detected；η is device to be detected
Current luminous efficiency；I0For the initial pixel electric current of device to be detected.
Compensated luminous efficiency is L=(I* η)/S=[(η0/η)*I0* η]/S=(η0*I0)/S, can by above-mentioned formula
Know, compensated luminous efficiency is unrelated with current luminous efficiency, luminance constant, avoids hair caused by OLED device deterioration
Light efficiency lower, improve the AMOLED display screen service life and it is long when image retention.
Step S232: detecting device is treated according to compensated pixel current and carries out luminance compensation.
In an alternative embodiment, as shown in figure 12, step S232 specifically includes step S2321-S2323:
Step S2321: compensated voltage data signal value is determined according to compensated pixel current.
In an alternative embodiment, when device to be detected is OLED and initial pixel electric current is I0=k (VELVDD-VDATA)2
When, constant k=1/2* μ * Cox, compensated voltage data signal value is obtained by following formula (compensation formula),
Wherein, V 'DATAFor compensated voltage data signal value；VELVDDFor AMOLED display screen supply voltage；VDATAFor
Voltage data signal before compensation.
Step S2322: compensated grayscale is determined according to compensated voltage data signal value.
In an alternative embodiment, any grayscale in the prior art can be used and determine that method obtains compensated grayscale.
Step S2323: detecting device is treated according to compensated grayscale and carries out brightness control.According to compensated grayscale control
The light emission luminance of OLED device processed, realizes luminance compensation.
In an alternative embodiment, specially compensated grayscale is inputted in the driving circuit of pixel, so that OLED
Light emission luminance is kept constant.
Above-mentioned luminance compensation method finds device light emitting efficiency according to the current threshold voltage of OLED device, obtains Gain
Value, and then compensated grayscale value is calculated.OLED device deterioration is compensated in a manner of electric compensation, with compensation formula
Make to deteriorate that slight device Gain value is smaller, and electric current increasing degree is smaller；It is larger to deteriorate serious device Gain value, electric current increases
Amplitude is larger.Therefore, it can be achieved that the effect that image retention is mitigated or eliminated；Luminance loss caused by efficiency declines also is compensated, and is increased
Add the service life of AMOLED display panel.
Although being described in conjunction with the accompanying the embodiment of the present invention, those skilled in the art can not depart from the present invention
Spirit and scope in the case where various modifications and variations can be made, such modifications and variations are each fallen within by appended claims institute
Within the scope of restriction.
Claims (10)
1. a kind of threshold voltage circuit for detecting characterized by comprising
First switch (SW_R), one end are connect with one end of device to be detected, and the first switch (SW_R) is in sense mode
In precharge when be connected；
Detection lines (Sen), one end are connect with described one end of the first switch (SW_R), in the first switch
(SW_R) when being connected, pre-charge pressure is written to the device to be detected；
Sampling capacitance (Cc), the parasitic capacitance (Cp) of the detection lines (Sen) discharge complete when with the detection lines (Sen)
One end connection, for acquiring the threshold voltage of the device to be detected.
2. threshold voltage circuit for detecting according to claim 1, which is characterized in that the detection lines and scan line or power supply
Line is overlapping to form the parasitic capacitance；The parasitic capacitance (Cp) of the detection lines (Sen) be used in reconnaissance phase to it is described to
It detects device and charge is provided, so that the charge flows through voltage and institute of the device to be detected up to the parasitic capacitance (Cp)
Voltage and the sum of the device threshold voltage to be detected for stating the other end of device to be detected are equal.
3. threshold voltage circuit for detecting according to claim 1, which is characterized in that further include:
Second switch (SMP), one end are connect with described one end of the detection lines (Sen), the other end and sampling electricity
Hold (Cc) connection, for controlling the connection of the sampling capacitance (Cc) Yu the detection lines (Sen).
4. threshold voltage circuit for detecting according to claim 1, which is characterized in that further include:
A/D converter is connected to the sampling capacitance (Cc), and when the sampling capacitance (Cc) samples completion, being used for will be described
The threshold voltage of the collected device to be detected of sampling capacitance (Cc) carries out A/D conversion.
5. threshold voltage circuit for detecting according to claim 4, which is characterized in that further include:
Third switchs (SW_S), and one end is connect with the sampling capacitance (Cc), and the other end is connect with the A/D converter,
For controlling the connection of the A/D converter Yu the sampling capacitance (Cc).
6. -5 any threshold voltage circuit for detecting according to claim 1, which is characterized in that the device to be detected is
OLED。
7. a kind of threshold voltage method for detecting, which comprises the steps of:
When precharge in sense mode, pre-charge pressure is written to device to be detected by detection lines, so that described wait detect
The voltage surveyed on the anode of device is the pre-charge pressure；
It is disconnected in the detection lines and the device to be detected and the voltage of the parasitic capacitance (Cp) of the detection lines is equal to described
When the sum of cathode voltage and threshold voltage of device to be detected, it is connected to sampling capacitance and one end of the detection lines；
When the sampling capacitance (Cc) voltage is equal to the voltage on device to be detected, the voltage on the sampling capacitance is acquired
The cathode voltage of voltage value and the device to be detected on the sampling capacitance is made difference to obtain the device to be detected by value
Threshold voltage.
8. a kind of luminance compensation circuit characterized by comprising
Threshold voltage circuit for detecting of any of claims 1-6；
Controller carries out brightness benefit for treating detecting device according to the collected threshold voltage of threshold voltage circuit for detecting
It repays.
9. a kind of display panel characterized by comprising such as threshold voltage of any of claims 1-6 detecting electricity
Road or luminance compensation circuit according to any one of claims 8.
10. a kind of luminance compensation method characterized by comprising
Threshold voltage method for detecting according to claim 7 obtains the current threshold voltage of device to be detected；
Detecting device, which is treated, according to the current threshold voltage carries out luminance compensation.
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