CN115035855B - Voltage compensation circuit, voltage compensation driving method and display device - Google Patents

Voltage compensation circuit, voltage compensation driving method and display device Download PDF

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Publication number
CN115035855B
CN115035855B CN202210724210.XA CN202210724210A CN115035855B CN 115035855 B CN115035855 B CN 115035855B CN 202210724210 A CN202210724210 A CN 202210724210A CN 115035855 B CN115035855 B CN 115035855B
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control signal
control
control switch
turned
signal
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CN115035855A (en
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杜辉
李荣荣
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HKC Co Ltd
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HKC Co Ltd
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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
    • G09G2310/00—Command of the display device
    • G09G2310/02—Addressing, scanning or driving the display screen or processing steps related thereto
    • G09G2310/0264—Details of driving circuits
    • 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
    • G09G2320/02—Improving the quality of display appearance
    • G09G2320/0233—Improving the luminance or brightness uniformity across the screen
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
    • Y02B20/30—Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Control Of Indicators Other Than Cathode Ray Tubes (AREA)

Abstract

The application provides a voltage compensation circuit, a voltage compensation driving method and a display device. The voltage compensation circuit comprises a driving transistor, a light emitting unit, a storage capacitor and first to fifth control switches, wherein the first control switch responds to a first control signal to apply a power supply signal to a first end of the driving transistor; a second control switch is responsive to a second control signal to apply a data signal to a second terminal of the storage capacitor; the third control switch is used for responding to a third control signal to connect the first end of the driving transistor with the first end of the storage capacitor; the fourth control switch is used for responding to a fourth control signal to connect the second end of the driving transistor to the ground; the fifth control switch is used for responding to a fifth control signal to connect the second end of the driving transistor with the first pole of the light emitting unit, and the second pole of the light emitting unit is grounded. According to the technical scheme, the condition that the display brightness is uneven due to the driving transistor can be reduced, and the display effect of the whole image is improved.

Description

Voltage compensation circuit, voltage compensation driving method and display device
Technical Field
The present disclosure relates to the field of display technologies, and in particular, to a voltage compensation circuit, a voltage compensation driving method, and a display device.
Background
In the display panel, many light emitting devices are driven by a current. For example, in a display panel of an OLED (organic light-Emitting Diode), a driving transistor is provided to drive the OLED to light. However, the threshold voltages of the driving transistors themselves are different due to the process or the aging of the devices, and the threshold voltages of the driving transistors are not uniform. Thus, different driving currents are generated under the same driving voltage. The difference of the driving currents further causes the currents flowing to the OLEDs to be different, which causes uneven display brightness of the display panel and affects the display effect of the whole image.
The above information disclosed in the background section is only for enhancement of understanding of the background of the application and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art.
Disclosure of Invention
An object of the present invention is to provide a voltage compensation circuit, a voltage compensation driving method, and a display device, which can reduce the uneven display brightness caused by a driving transistor and improve the display effect of the whole image.
According to an aspect of the present application, there is provided a voltage compensation circuit including a driving transistor, a light emitting unit, a storage capacitor, and first to fifth control switches;
the first control switch is used for responding to a first control signal to apply a power supply signal to the first end of the driving transistor;
the second control switch is used for responding to a second control signal to apply a data signal to a second end of the storage capacitor;
the third control switch is used for responding to a third control signal to connect the first end of the driving transistor with the first end of the storage capacitor and transfer a power supply signal applied to the driving transistor to the first end of the storage capacitor;
the fourth control switch is used for responding to a fourth control signal so as to enable the second end of the driving transistor to be grounded;
the fifth control switch is used for responding to a fifth control signal to connect the second end of the driving transistor with the first pole of the light emitting unit, and the second pole of the light emitting unit is grounded.
In one aspect, the first to fifth control switches are each transistor switches;
the control end of the first control switch is connected with a first scanning line for providing the first control signal, the first end of the first control switch is connected with a power line for providing the power signal, and the second end of the first control switch is connected with the first end of the driving transistor;
the control end of the second control switch is connected with a second scanning line for providing the second control signal, the first end of the second control switch is connected with a data line for providing the data signal, and the second end of the second control switch is connected with the second end of the storage capacitor;
the control end of the third control switch is connected with a third scanning line for providing the third control signal, the first end of the third control switch is respectively connected with the second end of the first control switch and the first end of the driving transistor, and the second end of the third control switch is respectively connected with the first end of the storage capacitor and the control end of the driving transistor;
the control end of the fourth control switch is connected with a fourth scanning line for providing the fourth control signal, the first end of the fourth control switch is connected with the second end of the driving transistor, and the second end of the fourth control switch is grounded;
the control end of the fifth control switch is connected with a fifth scanning line for providing the fifth control signal, the first end of the fifth control switch is respectively connected with the first end of the fourth control switch and the second end of the driving transistor, and the second end of the fifth control switch is connected with the first pole of the light emitting unit.
In one aspect, the driving transistor and the first to fifth control switches are oxide thin film transistors.
In one aspect, the driving transistor and the first to fifth control switches are N-type thin film transistors.
In one aspect, the light emitting unit is an organic light emitting diode, an anode of the organic light emitting diode is connected with the second end of the fifth control switch, and a cathode of the organic light emitting diode is grounded.
In one aspect, the scanning direction of the voltage compensation circuit is from row 1 to the last row; wherein,,
the first control signal is provided by an nth row scan line, the second control signal is provided by an n+1th row scan line, the third control signal is provided by an n+2th row scan line, the fourth control signal is provided by an n+3rd row scan line, and the fifth control signal is provided by an n+4th row scan line, wherein N is a positive integer greater than or equal to 1.
In order to solve the above-described problems, according to an aspect of the present application, there is also provided a voltage compensation driving method for driving a voltage compensation circuit as described above, the voltage compensation driving method including:
a charging stage, wherein the first control switch is turned on by the first control signal, the third control switch is turned on by the third control signal, the second control switch is turned off by the second control signal, the fourth control switch is turned off by the fourth control signal, and the fifth control switch is turned off by the fifth control signal;
a threshold latching stage, wherein the third control switch is turned on by the third control signal, the fourth control switch is turned on by the fourth control signal, the first control switch is turned off by the first control signal, the second control switch is turned off by the second control signal, and the fifth control switch is turned off by the fifth control signal;
a data loading stage, wherein the first control switch is turned on by the first control signal, the second control switch is turned on by the second control signal, the third control switch is turned on by the third control signal, and meanwhile, the fourth control switch is turned off by the fourth control signal, and the fifth control switch is turned off by the fifth control signal;
and in a light emitting stage, the first control switch is turned on by using the first control signal, the fifth control switch is turned on by using the fifth control signal, the second control switch is turned off by using the second control signal, the third control switch is turned off by using the third control signal, and the fourth control switch is turned off by using the fourth control signal.
In one aspect, during the charging phase, the first control signal and the second control signal are high, and the third control signal, the fourth control signal, and the fifth control signal are low;
in the threshold latching stage, the third control signal and the fourth control signal are at high level, and the first control signal and the second control signal and the fifth control signal are at low level;
in the data loading stage, the first control signal, the second control signal and the third control signal are high level, and the fourth control signal and the fifth control signal are low level;
in the light emitting stage, the first control signal and the fifth control signal are at high level, and the second control signal, the third control signal and the fourth control signal are at low level.
In one aspect, during the charging phase, the voltage at the first end of the storage capacitor is VDD;
in the threshold latching stage, the voltage of the first end of the storage capacitor is released from VDD to V C Wherein V is C ＝V th ，V th VDD is greater than V, representing the threshold voltage of the drive transistor th ；
In the data loading stage, the voltage of the second end of the storage capacitor is V data The voltage of the storage capacitor is VDD+V C -V data ；
In the light emitting stage, the voltage of the driving transistor is V GS ，
V GS ＝VDD+V C -V data -V th ＝VDD-V data 。
In order to solve the above-mentioned problems, according to an aspect of the present application, there is also provided a display device including a power line for supplying the power signal and a voltage compensation circuit as described above, the display device further including a data line for supplying the data signal and a timing control unit respectively connected to the first to fifth control switches, the timing control unit for supplying the first to fifth control signals.
In the technical scheme of the application, the first control switch is conducted under the action of the first control signal, the third control switch is conducted under the action of the third control signal, and the rest control switches are turned off. At this time, a power signal is applied to the second terminal of the storage capacitor. The third control switch is controlled to be conducted through the third control signal, the fourth control switch is controlled to be conducted through the fourth control signal, and the rest control switches are closed. The voltage stored in the storage capacitor starts to be released through the driving transistor, and along with the release of the voltage, when the insufficient voltage supports the opening of the driving transistor, the storage voltage of the storage capacitor is equal to the threshold voltage of the driving transistor. When the light emitting unit is required to be lighted, the storage capacitor is stored with the storage voltage, and the voltage of the power supply signal and the voltage of the data signal are overlapped. And the storage voltage stored in the storage capacitor is released, and the storage voltage can compensate the driving transistor. Since the storage voltages are matched to the threshold voltages of the corresponding driving transistors. That is, the threshold voltage of the driving transistor is low, and the storage voltage is low. The threshold voltage of the driving transistor is high, and the storage voltage is high. And the storage voltage can be offset with the threshold voltage of the driving transistor, so that the current for finally lighting the light emitting unit is not influenced by the driving transistor, the condition that the driving transistor causes uneven display brightness is eliminated, and the display effect of the whole image is improved.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application.
Drawings
The above and other objects, features and advantages of the present application will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings.
FIG. 1 is a schematic diagram of a voltage compensation circuit according to a first embodiment of the present application;
FIG. 2 is a schematic diagram of the current flow in the voltage compensation circuit when the storage capacitor is charged;
FIG. 3 is a schematic diagram of the current flow in the voltage compensation circuit when the storage capacitor is discharged;
FIG. 4 is a schematic diagram of the current flow in the voltage compensation circuit during data loading;
FIG. 5 is a schematic diagram showing the current flow in the voltage compensation circuit when the light emitting unit is turned on;
FIG. 6 is a timing control diagram in a voltage compensation circuit;
FIG. 7 is a flow chart showing steps of a voltage compensation driving method according to a second embodiment of the present application;
fig. 8 is a schematic circuit diagram of a display device according to a third embodiment of the present application.
The reference numerals are explained as follows:
t0, driving transistor; 10. a timing control unit; q, a light-emitting unit; t1, a first control switch; t2, a second control switch; t3, a third control switch; t4, a fourth control switch; t5, a fifth control switch; C. a storage capacitor; c1, a first polar plate; c2, a second polar plate.
Detailed Description
While this application is susceptible of embodiment in different forms, there is shown in the drawings and will herein be described in detail, specific embodiments thereof with the understanding that the present disclosure is to be considered as an exemplification of the principles of the application and is not intended to limit the application to that as illustrated herein.
Thus, reference to one feature indicated in this specification will be used to describe one of the features of an embodiment of the application, and not to imply that each embodiment of the application must have the described feature. Furthermore, it should be noted that the present specification describes a number of features. Although certain features may be combined together to illustrate a possible system design, such features may be used in other combinations not explicitly described. Thus, unless otherwise indicated, the illustrated combinations are not intended to be limiting.
In the embodiments shown in the drawings, indications of orientation (such as up, down, left, right, front and rear) are used to explain the structure and movement of the various elements of the present application are not absolute but relative. These descriptions are appropriate when these elements are in the positions shown in the drawings. If the description of the position of these elements changes, the indication of these directions changes accordingly.
Example embodiments will now be described more fully with reference to the accompanying drawings. However, the exemplary embodiments may be embodied in many forms and should not be construed as limited to the examples set forth herein; rather, these example embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the example embodiments to those skilled in the art. The drawings are merely schematic illustrations of the present application and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and thus a repetitive description thereof will be omitted.
Preferred embodiments of the present application are further elaborated below in conjunction with the drawings of the present specification.
Example 1
Referring to fig. 1, the present embodiment provides a voltage compensation circuit, which includes a driving transistor T0, a light emitting unit Q, a storage capacitor C, and first to fifth control switches T5; the light emitting unit Q emits light under the driving of current. It should be noted that the voltage compensation circuit is generally integrated on a circuit board with a small area. A switch is provided to control the lighting unit Q to be turned on and off, and a driving transistor T0 is provided to control the lighting unit Q in order to reduce the occupied area of the switch, the driving transistor T0 being a micro structure capable of being integrated in a circuit board. The light emitting unit Q circuit is controlled to be turned on or off by the driving transistor T0.
A first control switch T1 for responding to the first control signal to apply a power signal to a first terminal of the driving transistor T0; after the first control switch T1 receives the first control signal, the first end and the second end of the first control switch T1 may be turned on or turned off, and after the first end and the second end of the first control switch T1 are turned on, the driving transistor T0 is turned on with the power supply voltage, so that the power supply signal released by the power supply voltage is applied to the first end of the driving transistor T0 after passing through the first control switch T1.
A second control switch T2 for responding to the second control signal to apply the data signal to the second terminal of the storage capacitor C; after the second control switch T2 receives the second control signal, the first end and the second end of the second control switch T2 may be turned on or turned off, after the first end and the second end of the second control switch T2 are turned on, the storage capacitor C is turned on with the data line, so that the data signal released by the data line is applied to the second end of the storage capacitor C after passing through the second control switch T2, the data signal is used to change the voltage of the storage capacitor C, and further change the voltage applied to the driving transistor T0, and the current of the further driving transistor T0 is changed accordingly, so that the brightness of the light emitting unit Q is also changed accordingly. In short, the brightness of the light emitting unit Q is changed by the data signal.
A third control switch T3 for transferring a power signal applied to the driving transistor T0 to the first terminal of the storage capacitor C in response to a third control signal to connect the first terminal of the driving transistor T0 and the first terminal of the storage capacitor C; after the third control switch T3 receives the third control signal, the first end and the second end of the third control switch T3 may be turned on or turned off, and after the first end and the second end of the third control switch T3 are turned on, the first end of the driving transistor T0 and the first end of the storage capacitor C are turned on, so that the power signal originally applied to the driving transistor T0 is transferred to the first end of the storage capacitor C through the third control switch T3.
A fourth control switch T4 for responding to the fourth control signal to ground the second terminal of the driving transistor T0; after the fourth control switch T4 receives the fourth control signal, the first end and the second end of the fourth control switch T4 may be turned on or turned off, and after the first end and the second end of the fourth control switch T4 are turned on, the second end of the driving transistor T0 is grounded, so that the driving transistor T0 releases the voltage to the ground, the electric quantity of the storage capacitor C may be reduced accordingly until the driving transistor T0 is turned off, and at this time, the voltage of the storage capacitor C is equal to the threshold voltage of the driving transistor T0.
And a fifth control switch T5 for connecting the second terminal of the driving transistor T0 to the first electrode of the light emitting unit Q and the second electrode of the light emitting unit Q to ground in response to the fifth control signal. The first pole of the light emitting unit Q may be understood as an anode and the second pole of the light emitting unit Q may be understood as a cathode. After the fifth control switch T5 receives the fifth control signal, the first end and the second end of the fifth control switch T5 may be turned on or off, and after the first end and the second end of the fifth control switch T5 are turned on, the second end of the driving transistor T0 is turned on with the light emitting unit Q, so as to drive the light emitting unit Q to light up.
In the technical solution of this embodiment, the first control switch T1 is turned on under the action of the first control signal, the third control switch T3 is turned on under the action of the third control signal, and the remaining control switches are turned off. At this time, a power signal is applied to the second terminal of the storage capacitor C. The third control switch T3 is controlled to be turned on by the third control signal, the fourth control switch T4 is controlled to be turned on by the fourth control signal, and the rest control switches are turned off. The voltage stored in the storage capacitor C starts to be released through the driving transistor T0, and as the voltage is released, the storage voltage of the storage capacitor C is equal to the threshold voltage of the driving transistor T0 when the insufficient voltage supports the driving transistor T0 to be turned on. In order to turn on the driving transistor T0, a sufficient voltage must be input to the driving transistor T0, that is, the driving transistor T0 has the lowest voltage that is turned on, which is the threshold voltage.
When the light emitting unit Q is required to be turned on, the storage capacitor C has stored the storage voltage, and the voltage of the power supply signal and the voltage of the data signal are superimposed. And releases the storage voltage stored in the storage capacitor C, which can compensate the driving transistor T0. Since the storage voltage is matched with the threshold voltage of the corresponding driving transistor T0. That is, the threshold voltage of the driving transistor T0 is low, and the storage voltage is low. The threshold voltage of the driving transistor T0 is high, and the storage voltage is high. And the storage voltage can be offset with the threshold voltage of the driving transistor T0, so that the current for finally lighting the light emitting unit Q is not affected by the driving transistor T0, thereby eliminating the situation that the driving transistor T0 causes uneven display brightness and improving the display effect of the whole image.
Further, the first to fifth control switches T5 are transistor switches; thus, it should be noted that the first end of the control switch may be understood as a source, the second end as a drain, and the control end as a gate. Alternatively, the source and drain are interchanged, the first end of the control switch may be understood as the drain, the second end as the source, and the control end as the gate. The connection mode of each device in the voltage compensation circuit at least comprises the following contents:
the control end of the first control switch T1 is connected with a first scanning line for providing a first control signal, the first end of the first control switch T1 is connected with a power line for providing a power signal, and the second end of the first control switch T1 is connected with the first end of the driving transistor T0; the first terminal and the second terminal of the first control switch T1 are turned on, and a power signal is applied to the first terminal of the driving transistor T0.
The control end of the second control switch T2 is connected with a second scanning line for providing a second control signal, the first end of the second control switch T2 is connected with a data line for providing a data signal, and the second end of the second control switch T2 is connected with the second end of the storage capacitor C; the first terminal and the second terminal of the second control switch T2 are turned on, and the data signal is applied to the second terminal of the storage capacitor C.
The control end of the third control switch T3 is connected with a third scanning line for providing a third control signal, the first end of the third control switch T3 is respectively connected with the second end of the first control switch T1 and the first end of the driving transistor T0, and the second end of the third control switch T3 is respectively connected with the first end of the storage capacitor C and the control end of the driving transistor T0; the first terminal and the second terminal of the third control switch T3 are turned on, and the power signal is transferred to the first terminal of the storage capacitor C.
The control end of the fourth control switch T4 is connected with a fourth scanning line for providing a fourth control signal, the first end of the fourth control switch T4 is connected with the second end of the driving transistor T0, and the second end of the fourth control switch T4 is grounded; the first and second terminals of the fourth control switch T4 are turned on, and the voltage of the storage capacitor C is discharged to the ground through the driving transistor T0 and the fourth control switch T4.
The control end of the fifth control switch T5 is connected to a fifth scan line for providing a fifth control signal, the first end of the fifth control switch T5 is connected to the first end of the fourth control switch T4 and the second end of the driving transistor T0, respectively, and the second end of the fifth control switch T5 is connected to the first pole of the light emitting unit Q. The first and second terminals of the fifth control switch T5 are turned on, and the driving transistor T0 drives the light emitting unit Q to be turned on. In this embodiment, there is only one capacitor, namely, the storage capacitor C, and there are only five control switches, so the number of electronic switches is small, and the structure is simple.
Further, the driving transistor T0, and the first to fifth control switches T1 to T5 can be understood as MOS (Metal Oxide Semiconductor Field Effect Transistor, MOSFET) transistors, which have a relatively convenient voltage control. The device has the advantages of small volume, light weight, long service life, high input resistance, low noise, good thermal stability, strong anti-interference capability, low power consumption and the like. The driving transistor T0 and the first to fifth control switches T1 to T5 may also be understood as TFT (Thin Film Transistors) switching Transistors. In this embodiment, the driving transistor T0 and the first to fifth control switches T5 are oxide thin film transistors, i.e., TFT switching transistors. The TFT switch tube has the advantages of high density, high resolution, energy conservation and portability.
The driving transistor T0 and the first to fifth control switches T1 to T5 may be P-type transistors or N-type transistors. In this embodiment, the driving transistor T0 and the first to fifth control switches T5 are all N-type thin film transistors. The first end and the second end are conducted when the N-type thin film transistor receives a high level, and are disconnected when the N-type thin film transistor receives a low level. The voltage value of the high level is generally 5V,12V or 15V, and the low level is generally 0V.
In one aspect, the light emitting unit Q is an OLED (Organic Light Emitting Diode ), an anode of the organic light emitting diode is connected to the second terminal of the fifth control switch T5, and a cathode of the organic light emitting diode is grounded. The cathodes of the leds may also be connected to other common electrodes. For example, the OLED lamps in the light emitting unit Q may be one or more. When a plurality of OLED lamps are used, the light emitting unit Q may be understood as a string of a plurality of OLED lamps connected in series.
Referring to fig. 6, in one aspect, the scan direction of the voltage compensation circuit is from row 1 to the last row; the first control signal is provided by an N+1th row scanning line, the second control signal is provided by an N+2nd row scanning line, the fourth control signal is provided by an N+3rd row scanning line, and the fifth control signal is provided by an N+4th row scanning line, wherein N is a positive integer greater than or equal to 1. It can be seen that the first control signal to the fifth control signal are provided with the scan signals by different scan lines. Separate control can ensure independence of each control switch.
Wherein Sn represents a first control signal provided by the N-th row scanning line, and Sn+1 represents a second control signal provided by the N+1-th row scanning line; sn+2 represents a third control signal supplied from the n+2th row scanning line; sn+3 represents a fourth control signal supplied from the n+3rd row scanning line; sn+4 represents a fifth control signal supplied from the n+4th row scanning line. In fig. 6, it can be seen that the four timing control phases are divided, and 1 represents a charging phase; 2 represents a threshold latch stage; 3 represents a data loading stage; 4 represents a light emitting phase.
Example two
Referring to fig. 7, the present application further provides a voltage compensation driving method for driving the voltage compensation circuit as above, the voltage compensation driving method includes:
referring to fig. 2, in step S10, in the charging stage, the first control switch T1 is turned on by the first control signal, the third control switch T3 is turned on by the third control signal, the second control switch T2 is turned off by the second control signal, the fourth control switch T4 is turned off by the fourth control signal, and the fifth control switch T5 is turned off by the fifth control signal; so that the first terminal of the storage capacitor C is connected to the power supply signal. The storage capacitor C comprises a first polar plate C1 and a second polar plate C2, the first polar plate C1 and the second polar plate C2 are oppositely arranged, a first end of the storage capacitor C is defined as a point A, a second end of the storage capacitor C is defined as a point B, the point A is adjacent to the point A, the point A is the first polar plate C1, and the point B is adjacent to the point B, the point B is the second polar plate C2. According to the preset time, the power supply voltage applies a power supply signal to the storage capacitor C, and the voltage V of the storage capacitor C at the point A A The voltage at the point B is equal to VDD and is V B Equal to 0.
Referring to fig. 3, in step S20, in the threshold latching stage, the third control switch T3 is turned on by using the third control signal, the fourth control switch T4 is turned on by using the fourth control signal, the first control switch T1 is turned off by using the first control signal, the second control switch T2 is turned off by using the second control signal, and the fifth control switch T5 is turned off by using the fifth control signal; storage capacitor C gives driving transistor T0The power is supplied, the gate voltage of the driving transistor T0 is VDD, the storage capacitor C is discharged, and the current of the storage capacitor C flows to the ground through the third control switch T3, the driving transistor T0, and the fourth control switch T4 in sequence. The electric quantity of the storage capacitor C gradually becomes lower, and when the voltage of the storage capacitor C after discharging is equal to the threshold voltage of the driving transistor T0, the driving transistor T0 is automatically turned off. At this time, the storage capacitor C stores the equivalent voltage V which matches the threshold voltage of the driving transistor T0 A ＝V th ，V th Representing the threshold voltage of the drive transistor T0. At this time, only the first end of the storage capacitor C has a voltage, the voltage V of the storage capacitor C C And voltage V at point A A Equal, V C ＝V A ＝V th 。
Referring to fig. 4, in step S30, in the data loading stage, the first control switch T1 is turned on by the first control signal, the second control switch T2 is turned on by the second control signal, the third control switch T3 is turned on by the third control signal, and the fourth control switch T4 is turned off by the fourth control signal, and the fifth control switch T5 is turned off by the fifth control signal; at this time, the second plate C2 of the storage capacitor C is connected to the data line through the second control switch T2, and the point B of the storage capacitor C has the voltage V provided by the data line data At this time, the voltage on the storage capacitor C is the voltage difference between the first electrode plate C1 and the second electrode plate C2, and the voltage at the point a is subtracted by the voltage at the point B. And with the first control switch T1 open, the power signal is again applied to point B. Thus, it was obtained:
V GS ＝VDD+V A -V data ＝VDD+V th -V data
V GS representing the driving voltage of the storage capacitor C driving transistor T0.
Referring to fig. 5, in step S40, in the lighting stage, the first control switch T1 is turned on by the first control signal, the fifth control switch T5 is turned on by the fifth control signal, the second control switch T2 is turned off by the second control signal, the third control switch T3 is turned off by the third control signal, and the fourth control switch T4 is turned off by the fourth control signal.
At this time, V GS ＝VDD+V th -V data -V th ＝VDD-V data The voltage of the storage voltage is applied to the gate of the driving transistor T0, and it can be seen from the equation that the threshold voltage of the driving transistor T0 does not exist. That is, the threshold voltage of the driving transistor T0 cannot influence the light emitting unit Q, thereby completing the influence of the variation of the driving transistor T0 itself on the light emitting unit Q.
Specifically, the driving transistor T0 and the first to fifth control switches T5 are all N-type thin film transistors, so as to successfully control each N-type thin film transistor. In the charging stage, the first control signal and the second control signal are high level, and the third control signal, the fourth control signal and the fifth control signal are low level; thus, the first control switch T1 and the second control switch T2 are turned on, and the third control switch T3, the fourth control switch T4, and the fifth control switch T5 are turned off.
In the threshold latching stage, the third control signal and the fourth control signal are high level, and the first control signal and the second control signal and the fifth control signal are low level; thus, the third control switch T3 and the fourth control switch T4 are turned on, and the first control switch T1, the second control switch T2, and the fifth control switch T5 are turned off.
In the data loading stage, the first control signal, the second control signal and the third control signal are high level, and the fourth control signal and the fifth control signal are low level; thus, the first control switch T1, the second control switch T2, and the third control switch T3 are turned on, and the fourth control switch T4 and the fifth control switch T5 are turned off.
In the light emitting stage, the first control signal and the fifth control signal are at high level, and the second control signal, the third control signal and the fourth control signal are at low level. Thus, the first control switch T1 and the fifth control switch T5 are turned on, and the second control switch T2, the third control switch T3, and the fourth control switch T4 are turned off.
Specifically, the voltage change process of the storage capacitor C includes that, in a charging phase, the voltage of the first end of the storage capacitor C is VDD;
during the threshold latching phase, the first end of the storage capacitor C is electrically connected toThe voltage is released from VDD to a threshold voltage equal to the driving transistor T0, where V C ＝V A ＝V th At this time, the voltage of the storage capacitor C is also the voltage of the point A, V C ＝V A ，V th VDD is greater than V, representing the threshold voltage of the drive transistor T0 th The method comprises the steps of carrying out a first treatment on the surface of the VDD is greater than V th Ensuring that the drive transistor T0 can be normally driven on.
In the data loading stage, the voltage of the second end of the storage capacitor C is V data The voltage of the storage capacitor C is VDD+V C -V data The method comprises the steps of carrying out a first treatment on the surface of the In the light emitting stage, the voltage of the driving transistor T0 is V GS ，
V GS ＝VDD+V C -V data -V th ＝VDD-V data . After the storage capacitor C passes through the charging stage and the threshold latching stage, the point A of the storage capacitor C stores the equivalent voltage V which is related to the corresponding driving transistor T0 th . The second polar plate C2 is connected with the data line through a second control switch T2, the second control signal provides high level, and the second control switch T2 is conducted. The second polar plate C2 stores the voltage V provided by the lower data line data The third control switch T3 is conducted, and the voltage stored in the first polar plate C1 is the voltage VDD and the equivalent voltage V of the power supply signal th And (3) summing. At this time, the voltage of the storage capacitor C is the voltage difference between the first and second plates C1 and C2, i.e. V GS ＝VDD+V th -V data . From this, the voltage V provided by the data line data The magnitude of the output voltage can be influenced, thereby influencing the brightness of the light emitting unit Q. Voltage V provided by data line data The smaller the total output voltage, the larger the current, and the higher the luminance of the light emitting unit Q. Voltage V provided by data line data The larger the total output voltage is, the smaller the current is, and the lower the luminance of the light emitting unit Q is.
Further, the threshold voltage of the driving transistor T0 is also V th . The current through the driving transistor T0 is i= [ WC μ (V GS -V th ) 2 ]2L, V GS Is carried into the formula of the formula,
I＝[WCμ(VDD+V th -V data -V th ) 2 ]/2L, then
I＝[WCμ(VDD-V data ) 2 ]From this, it can be seen that the threshold voltage of the driving transistor T0 is eliminated, and the threshold voltage of the driving transistor T0 does not exist in the current calculation formula for driving the light emitting unit Q to light up, and the brightness of the light emitting unit Q is not affected.
Where μ is electron mobility, C is the capacitance per unit area of the transistor, W represents the transistor channel width, L represents the transistor channel length, these parameters being relatively constant.
Example III
Referring to fig. 8, the present application further provides a display device, the display device includes a power line and a voltage compensation circuit, the power line is used for providing a power signal, the display device further includes a data line and a timing control unit 10, the data line is used for providing a data signal, the timing control unit 10 is respectively connected to the first to fifth control switches T5, and the timing control unit 10 is used for providing the first to fifth control signals.
The scan control signal is transmitted to the first to fifth control switches T5 through the same timing control unit 10. In fig. 7, the control sequences are divided into four, and 1 represents a charging phase; 2 represents a threshold latch stage; 3 represents a data loading stage; 4 represents a light emitting phase.
The embodiments of the display device of the present invention include all the technical solutions of all the embodiments of the voltage compensation circuit, and the achieved technical effects are also identical, and are not described herein again.
While the present application has been described with reference to several exemplary embodiments, it is understood that the terminology used is intended to be in the nature of words of description and illustration rather than of limitation. As the present application may be embodied in several forms without departing from the spirit or essential attributes thereof, it should be understood that the above-described embodiments are not limited by any of the details of the foregoing description, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the metes and bounds of the claims, or equivalences of such metes and bounds are therefore intended to be embraced by the appended claims.

Claims (8)

1. A voltage compensation circuit comprises a driving transistor, a light emitting unit, a storage capacitor and first to fifth control switches, and is characterized in that,
the first control switch is used for responding to a first control signal to apply a power supply signal to the first end of the driving transistor;
the second control switch is used for responding to a second control signal to apply a data signal to a second end of the storage capacitor;
the third control switch is used for responding to a third control signal to connect the first end of the driving transistor with the first end of the storage capacitor and transfer a power supply signal applied to the driving transistor to the first end of the storage capacitor;
the fourth control switch is used for responding to a fourth control signal so as to enable the second end of the driving transistor to be grounded;
the fifth control switch is used for responding to a fifth control signal to connect the second end of the driving transistor with the first pole of the light emitting unit, and the second pole of the light emitting unit is grounded;
the light-emitting unit is an organic light-emitting diode, the anode of the organic light-emitting diode is connected with the second end of the fifth control switch, and the cathode of the organic light-emitting diode is grounded;
the scanning direction of the voltage compensation circuit is from the 1 st row to the last row; wherein,,
the first control signal is provided by an nth row scan line, the second control signal is provided by an n+1th row scan line, the third control signal is provided by an n+2th row scan line, the fourth control signal is provided by an n+3rd row scan line, and the fifth control signal is provided by an n+4th row scan line, wherein N is a positive integer greater than or equal to 1.
2. The voltage compensation circuit of claim 1 wherein said first through fifth control switches are transistor switches;
the control end of the first control switch is connected with a first scanning line for providing the first control signal, the first end of the first control switch is connected with a power line for providing the power signal, and the second end of the first control switch is connected with the first end of the driving transistor;
the control end of the second control switch is connected with a second scanning line for providing the second control signal, the first end of the second control switch is connected with a data line for providing the data signal, and the second end of the second control switch is connected with the second end of the storage capacitor;
the control end of the third control switch is connected with a third scanning line for providing the third control signal, the first end of the third control switch is respectively connected with the second end of the first control switch and the first end of the driving transistor, and the second end of the third control switch is respectively connected with the first end of the storage capacitor and the control end of the driving transistor;
the control end of the fourth control switch is connected with a fourth scanning line for providing the fourth control signal, the first end of the fourth control switch is connected with the second end of the driving transistor, and the second end of the fourth control switch is grounded;
the control end of the fifth control switch is connected with a fifth scanning line for providing the fifth control signal, the first end of the fifth control switch is respectively connected with the first end of the fourth control switch and the second end of the driving transistor, and the second end of the fifth control switch is connected with the first pole of the light emitting unit.
3. The voltage compensation circuit of claim 1 wherein the drive transistor and the first through fifth control switches are oxide thin film transistors.
4. The voltage compensation circuit of claim 3 wherein said driving transistor and said first through fifth control switches are N-type thin film transistors.
5. A voltage compensation driving method for driving the voltage compensation circuit according to claim 1, the voltage compensation driving method comprising:
a charging stage, wherein the first control switch is turned on by the first control signal, the third control switch is turned on by the third control signal, the second control switch is turned off by the second control signal, the fourth control switch is turned off by the fourth control signal, and the fifth control switch is turned off by the fifth control signal;
a threshold latching stage, wherein the third control switch is turned on by the third control signal, the fourth control switch is turned on by the fourth control signal, the first control switch is turned off by the first control signal, the second control switch is turned off by the second control signal, and the fifth control switch is turned off by the fifth control signal;
a data loading stage, wherein the first control switch is turned on by the first control signal, the second control switch is turned on by the second control signal, the third control switch is turned on by the third control signal, and meanwhile, the fourth control switch is turned off by the fourth control signal, and the fifth control switch is turned off by the fifth control signal;
and in a light emitting stage, the first control switch is turned on by using the first control signal, the fifth control switch is turned on by using the fifth control signal, the second control switch is turned off by using the second control signal, the third control switch is turned off by using the third control signal, and the fourth control switch is turned off by using the fourth control signal.
6. The method of claim 5, wherein,
in the charging phase, the first control signal and the second control signal are at high level, and the third control signal, the fourth control signal and the fifth control signal are at low level;
in the threshold latching stage, the third control signal and the fourth control signal are at high level, and the first control signal and the second control signal and the fifth control signal are at low level;
in the data loading stage, the first control signal, the second control signal and the third control signal are high level, and the fourth control signal and the fifth control signal are low level;
in the light emitting stage, the first control signal and the fifth control signal are at high level, and the second control signal, the third control signal and the fourth control signal are at low level.
7. The method of voltage compensation driving according to claim 6, wherein,
in the charging stage, the voltage of the first end of the storage capacitor is VDD;
in the threshold latching stage, the voltage of the first end of the storage capacitor is released from VDD to V C Wherein V is C ＝V th ，V th VDD is greater than V, representing the threshold voltage of the drive transistor th ；
In the data loading stage, the voltage of the second end of the storage capacitor is V data The voltage of the storage capacitor is VDD+V C －V data ；
In the light emitting stage, the voltage of the driving transistor is V GS ，
V GS ＝VDD+V C －V data －V th ＝VDD－V data 。
8. A display device comprising a power supply line for supplying the power supply signal and the voltage compensation circuit according to claim 1, characterized in that the display device further comprises a data line for supplying the data signal and a timing control unit for supplying the first to fifth control signals, respectively, the timing control unit being connected to the first to fifth control switches.
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