CN109671397B - Light emitting current control circuit, pixel circuit, display device, and display driving method - Google Patents
Light emitting current control circuit, pixel circuit, display device, and display driving method Download PDFInfo
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- CN109671397B CN109671397B CN201910118129.5A CN201910118129A CN109671397B CN 109671397 B CN109671397 B CN 109671397B CN 201910118129 A CN201910118129 A CN 201910118129A CN 109671397 B CN109671397 B CN 109671397B
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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
- G09G3/3233—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 with pixel circuitry controlling the current through the light-emitting element
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- Control Of El Displays (AREA)
- Electroluminescent Light Sources (AREA)
Abstract
The invention provides a light-emitting current control circuit, a pixel circuit, a display device and a display driving method. The light-emitting current control circuit comprises a proportional control circuit and a conversion circuit, wherein the proportional control circuit comprises a first branch circuit and a second branch circuit, the first branch circuit is connected with the conversion circuit, and the second branch circuit is connected with the light-emitting element; the proportional control circuit is used for controlling the current value of a first current flowing through the first branch circuit and the current value of a second current flowing through the second branch circuit to be in a proportional relation; the conversion circuit is further connected with a data line and used for converting the data voltage on the data line into the first current. The invention simplifies the mask design, and accurately controls the current value of the second current for driving the light-emitting element to emit light through data voltage regulation, and the regulation mode is simple.
Description
Technical Field
The present invention relates to the field of display technologies, and in particular, to a light emitting current control circuit, a pixel circuit, a display device, and a display driving method.
Background
With the development of the display industry, the OLED (Organic Light-Emitting Diode) display technology has the advantages of self-luminescence, wide viewing angle, almost infinite contrast, low power consumption, and very high response speed, and thus, the highly portable and foldable display technology becomes possible, and is gradually favored and paid attention to by the public.
The conventional AMOLED display module cannot accurately control the current value of the current for driving the light-emitting element to emit light by data voltage regulation while simplifying the mask design, and cannot realize constant current control on the premise of simplifying the structure, so that the current flowing through the light-emitting element is not influenced by the line impedance of a display panel.
Disclosure of Invention
The invention mainly aims to provide a light-emitting current control circuit, a pixel circuit, a display device and a display driving method, and solves the problems that in the prior art, the mask design cannot be simplified, the current value of a second current for driving a light-emitting element to emit light can be accurately controlled through data voltage adjustment, and constant current control cannot be realized on the premise of simplifying the structure, so that the current flowing through the light-emitting element is not influenced by the line impedance of a display panel.
In order to achieve the above object, the present invention provides a light emitting current control circuit including a proportional control circuit and a conversion circuit, wherein,
the proportion control circuit comprises a first branch circuit and a second branch circuit, the first branch circuit is connected with the conversion circuit, and the second branch circuit is connected with the light-emitting element;
the proportional control circuit is used for controlling the current value of a first current flowing through the first branch circuit and the current value of a second current flowing through the second branch circuit to be in a proportional relation;
the conversion circuit is further connected with a data line and used for converting the data voltage on the data line into the first current.
In implementation, the first branch comprises a first resistor and a first transistor, and the second branch comprises a second resistor and a second transistor;
the first end of the first resistor and the first end of the second resistor are both connected with a power supply voltage end;
a control electrode of the first transistor is connected with a control electrode of the second transistor;
a first pole of the first transistor is connected with the second end of the first resistor, and a first pole of the second transistor is connected with the second end of the second resistor;
a second pole of the first transistor is connected to the conversion circuit, and a second pole of the second transistor is connected to the light emitting element.
In practice, the resistance value of the first resistor is equal to the resistance value of the second resistor, the type of the first transistor is the same as the type of the second transistor, and the electrical parameter of the first transistor is the same as the electrical parameter of the second transistor.
In implementation, the conversion circuit comprises an operational amplifier, a first conversion resistor, a second conversion resistor and a third conversion resistor;
the first input end of the operational amplifier is connected with the data line;
the second input end of the operational amplifier is connected with the first voltage end through the first conversion resistor, and the second input end of the operational amplifier is also connected with the output end of the operational amplifier through the second conversion resistor; the output end of the operational amplifier is also connected with the second voltage end through the third conversion resistor.
The invention also provides a pixel circuit, which comprises a light-emitting element, a conduction control circuit and the light-emitting current control circuit;
the second branch in the proportional control circuit included in the light-emitting current control circuit is connected with the first pole of the light-emitting element;
the second pole of the light-emitting element is connected with the first end of the conduction control circuit, and the second end of the conduction control circuit is connected with the third voltage end;
the control end of the conduction control circuit is connected with the grid line, and the conduction control circuit is used for controlling the second pole of the light-emitting element to be communicated with the third voltage end under the control of the grid driving signal on the grid line.
The invention also provides a display device, which comprises N luminous current control circuits, a display substrate, M rows of N columns of pixel units, M rows of grid lines and N columns of data lines; the M rows and N columns of pixel units, the M rows of grid lines and the N columns of data lines are arranged on the display substrate;
the first poles of the light-emitting elements included in the pixel units positioned in the nth column are connected with the second branch in the proportional control circuit included in the nth light-emitting current control circuit;
the pixel units in the mth row are connected with the gate line in the mth row;
a conversion circuit in the nth light-emitting current control circuit is connected with an nth column data line;
m and N are both positive integers, M is a positive integer less than or equal to M, and N is a positive integer less than or equal to N.
In practice, the pixel unit in the mth row and the nth column comprises a light-emitting element in the mth row and the nth column and a conduction control circuit in the mth row and the nth column;
the second branch in the proportional control circuit included in the nth light-emitting current control circuit is connected with the first pole of the nth light-emitting element in the mth row;
the second pole of the mth row and nth column light-emitting element is connected with the first end of the mth row and nth column conduction control circuit, and the second end of the mth row and nth column conduction control circuit is connected with the third voltage end;
and the control end of the m-th row and n-th column conduction control circuit is connected with the m-th row grid line, and the m-th row and n-th column conduction control circuit is used for controlling the communication between the second pole of the m-th row and n-th column light-emitting element and the third voltage end under the control of the gate drive signal on the m-th row grid line.
In practice, the light-emitting current control circuit is disposed in a peripheral region of the display substrate.
In practice, the display device of the invention further comprises a driving integrated circuit; the light-emitting current control circuit is integrated in the driving integrated circuit.
The invention also provides a display driving method applied to the display device, and the display driving method comprises the following steps: in the display period of the time period of the display,
a conversion circuit in the nth light-emitting current control circuit converts the data voltage on the nth data line into corresponding first current, a proportional control circuit in the nth light-emitting current control circuit controls the current value of the first current to be in a proportional relation with the current value of second current flowing through a second branch in the proportional control circuit, and the second current is supplied to the nth pixel unit;
n is a positive integer less than or equal to N, which is a positive integer.
In practice, the pixel unit in the mth row and the nth column comprises a light-emitting element in the mth row and the nth column and a conduction control circuit in the mth row and the nth column; in an mth scan period included in the display period,
the grid line of the mth row is opened, the conduction control circuit of the mth row and the nth column controls the communication between the second pole of the light-emitting element of the mth row and the nth column and the third voltage end, and the nth light-emitting current control circuit provides the second current to the light-emitting element of the mth row and the nth column;
m is a positive integer less than or equal to M, M is a positive integer.
Compared with the prior art, the luminous current control circuit, the pixel circuit, the display device and the display driving method can simplify the mask design, and can accurately control the current value of the second current for driving the luminous element to emit light through data voltage adjustment, thereby adjusting gray scale display.
Drawings
Fig. 1 is a structural diagram of a light emission current control circuit according to an embodiment of the present invention;
fig. 2 is a block diagram of a light emitting current control circuit according to another embodiment of the present invention;
fig. 3 is a circuit diagram of a light emitting current control circuit according to another embodiment of the present invention;
FIG. 4 is a circuit diagram of a pixel circuit according to an embodiment of the present invention;
FIG. 5 is a block diagram of an embodiment of a display device according to the present invention;
FIG. 6 is a timing diagram illustrating the operation of the display device shown in FIG. 5 according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The transistors used in all embodiments of the present invention may be transistors, thin film transistors, or field effect transistors or other devices with the same characteristics. In the embodiment of the present invention, in order to distinguish two poles of the transistor except the control pole, one pole is called a first pole, and the other pole is called a second pole.
In practical operation, when the transistor is a triode, the control electrode may be a base electrode, the first electrode may be a collector electrode, and the second electrode may be an emitter electrode; alternatively, the control electrode may be a base electrode, the first electrode may be an emitter electrode, and the second electrode may be a collector electrode.
In practical operation, when the transistor is a thin film transistor or a field effect transistor, the control electrode may be a gate electrode, the first electrode may be a drain electrode, and the second electrode may be a source electrode; alternatively, the control electrode may be a gate electrode, the first electrode may be a source electrode, and the second electrode may be a drain electrode.
As shown in fig. 1, the light emitting current control circuit according to the embodiment of the present invention includes a proportional control circuit 11 and a conversion circuit 12, wherein,
the proportional control circuit 11 comprises a first branch L1 and a second branch L2, the first branch L1 is connected with the conversion circuit 12, and the second branch L2 is connected with the light emitting element EL;
the proportional control circuit 11 is used for controlling the current value of the first current I1 flowing through the first branch L1 to be in a proportional relation with the current value of the second current I2 flowing through the second branch L2;
the conversion circuit 12 is also connected to a Data line Data for converting a Data voltage on the Data line Data into the first current I1.
The light emitting current control circuit according to the embodiment of the present invention converts the Data voltage on the Data line Data into the first current I1 through the conversion circuit 12, and the proportional control circuit 11 can control the current value of the first current I1 flowing through the first branch L1 and the current value of the second current I2 flowing through the second branch L2 to be in a proportional relationship, and transmit the second current I2 to the light emitting element EL, and through Data voltage adjustment, the current value of the second current driving the light emitting element EL to emit light can be accurately controlled, so that gray scale display can be adjusted, the adjustment method is simple, and on the premise of simplifying the structure, constant current control can be implemented, so that the current flowing through the light emitting element is not affected by line impedance of a panel.
Specifically, the light emitting element EL may be an organic light emitting diode, but is not limited thereto.
In a specific implementation, the first branch may include a first resistor and a first transistor, and the second branch may include a second resistor and a second transistor;
the first end of the first resistor and the first end of the second resistor are both connected with a power supply voltage end;
a control electrode of the first transistor is connected with a control electrode of the second transistor;
a first pole of the first transistor is connected with the second end of the first resistor, and a first pole of the second transistor is connected with the second end of the second resistor;
a second pole of the first transistor is connected to the conversion circuit, and a second pole of the second transistor is connected to the light emitting element.
Specifically, the resistance value of the first resistor is equal to the resistance value of the second resistor, the type of the first transistor is the same as the type of the second transistor, and the electrical parameter of the first transistor is the same as the electrical parameter of the second transistor, so that the proportional control circuit is in a current mirror structure.
In a specific implementation, the first transistor and the second transistor may be of the same type, for example, the first transistor and the second transistor may be PNP transistors or NPN transistors at the same time, or the first transistor and the second transistor may be NMOS (N-Metal-Oxide-Semiconductor) transistors at the same time, or the first transistor and the second transistor may be pmos (P-Metal-Oxide-Semiconductor) transistors at the same time, or the first transistor and the second transistor may be N TFTs (Thin film transistors) at the same time, or the first transistor and the second transistor may be P-type TFTs at the same time, but not limited thereto.
In a specific implementation, the electrical parameter of the first transistor is the same as the electrical parameter of the second transistor. For example, the electrical parameters may include parameters such as width-to-length ratio, power consumption, volt-ampere parameters, and the like, and the types of the electrical parameters are well known to those skilled in the art and are not described herein.
As shown in fig. 2, based on the embodiment of the light emitting current control circuit shown in fig. 1, the first branch L1 includes a first transistor VT1 and a first resistor R1, and the second branch L2 includes a second transistor VT2 and a second resistor R2, wherein,
the base of VT1 is connected with the base of VT 2;
the first end of R1 and the first end of R2 are both connected to a supply voltage terminal for providing a supply voltage VCC;
the emitter of the VT1 is connected with the second end of the R1, and the emitter of the VT2 is connected with the second end of the R2;
the collector of VT1 is connected to conversion circuit 12, and the collector of VT2 is connected to light emitting element EL.
In the embodiment shown in fig. 2, the resistance value of R1 is equal to the resistance value of R2, and the electrical parameters of VT1 are the same as those of VT2, but not limited thereto.
In a specific implementation, the proportional control circuit 11 may include a first branch L1 and a second branch L2, the first branch L1 includes a first resistor R1 and a first transistor VT1, and the second branch L2 includes a second resistor R2 and a second transistor VT2, that is, the proportional control circuit 11 is in a current mirror structure, so that a current value of a first current flowing through the first branch L1 is equal to a current value flowing through the second branch L2, and a current direction of the first current is the same as a current direction of the second current.
In a specific implementation, the conversion circuit may include an operational amplifier, a first conversion resistor, a second conversion resistor, and a third conversion resistor;
the first input end of the operational amplifier is connected with the data line;
the second input end of the operational amplifier is connected with the first voltage end through the first conversion resistor, and the second input end of the operational amplifier is also connected with the output end of the operational amplifier through the second conversion resistor; the output end of the operational amplifier is also connected with the second voltage end through the third conversion resistor.
Specifically, the first voltage end may be a ground end or a low voltage end, and the first voltage end may be a ground end or a low voltage end, but not limited thereto.
Specifically, on the basis of the embodiment of the light emission current control circuit shown in fig. 2, as shown in fig. 3, the conversion circuit 12 includes an operational amplifier Cmp, a first conversion resistor R3, a second conversion resistor R4, and a third conversion resistor R5;
the positive phase input end of the operational amplifier Cmp is connected with the Data line Data;
the negative phase input end of the operational amplifier Cmp is connected with the ground end GND through the first switching resistor R3, and the negative phase input end of the operational amplifier Cmp is also connected with the output end of the operational amplifier Cmp through the second switching resistor R4; the output end of the operational amplifier Cmp is further connected to the ground GND through the third transfer resistor R5.
In the embodiment shown in fig. 3, VT1 and VT2 are PNP transistors, but not limited thereto.
In the embodiment shown in fig. 3, the first voltage terminal and the second voltage terminal are ground terminals, but not limited thereto.
In the embodiment shown in fig. 3, the resistance value of R3 is equal to the resistance value of R4, but not limited thereto, and in actual operation, the resistance value of R3 may not be equal to the resistance value of R4.
In the embodiment shown in fig. 3, the first input terminal of the operational amplifier Cmp is a positive phase input terminal thereof, and the second input terminal of the operational amplifier Cmp is a negative phase input terminal thereof, but not limited thereto.
When the embodiment shown in fig. 3 works, Data outputs a Data voltage Vdata, wherein Vdata is a positive value, I1 is I2, and the current direction of I1 and the current direction of I2 are both from top to bottom;
I1＝IR5+IR4；
the voltage Vdata at the positive phase input end of Cmp is equal to the voltage at the negative phase input end of Cmp, so the current value of the current IR3 flowing through R3 is equal to Vdata/Rz3, the direction of IR3 is from the right end of R3 to the left end of R3, and the voltage at the output end of Cmp is equal to 2 Vdata; wherein Rz3 is the resistance value of R3;
the current IR5 flowing through R5 has a current value equal to 2Vdata/Rz5, with the current flow of IR5 being from top to bottom; wherein Rz5 is the resistance value of R5;
the current value of the current IR4 flowing through R4 is equal to Vdata/Rz4, and the direction of IR4 is from the right end of R4 to the left end of R4; wherein Rz4 is the resistance value of R4;
i1 is equal to Vdata/Rz4+2Vdata/Rz5 and since I1 is equal to I2, I2 is equal to Vdata/Rz4+2Vdata/Rz 5;
the second branch L2 provides I2 to the light emitting element EL.
The pixel circuit comprises a light-emitting element, a conduction control circuit and the light-emitting current control circuit;
the second branch in the proportional control circuit included in the light-emitting current control circuit is connected with the first pole of the light-emitting element;
the second pole of the light-emitting element is connected with the first end of the conduction control circuit, and the second end of the conduction control circuit is connected with the third voltage end;
the control end of the conduction control circuit is connected with the grid line, and the conduction control circuit is used for controlling the second pole of the light-emitting element to be communicated with the third voltage end under the control of the grid driving signal on the grid line.
In a specific implementation, the third voltage terminal may be a ground terminal, or may be a low voltage terminal, but is not limited thereto.
When the pixel circuit works, when the grid line is opened, the conduction control circuit controls the second pole of the light-emitting element to be communicated with the third voltage end under the control of the grid line, and the second branch provides the light-emitting element with the second current value so that the light-emitting element emits light.
In a specific implementation, the light emitting element may be an organic light emitting diode, the first electrode of the light emitting element is an anode of the organic light emitting diode, and the second electrode of the light emitting element is a cathode of the organic light emitting diode.
Specifically, the conduction control circuit may include a control transistor;
and the control electrode of the control transistor is connected with the grid line, the first electrode of the control transistor is connected with the second electrode of the light-emitting element, and the second electrode of the control transistor is connected with the third voltage end.
As shown in fig. 4, the pixel circuit according to the embodiment of the present invention includes the embodiment of the light emitting current control circuit shown in fig. 3, and the pixel circuit according to the embodiment of the present invention further includes a light emitting element and a control transistor VT 3;
the light-emitting element is an organic light-emitting diode (OLED);
the collector of the VT2 is connected to the anode of the OLED;
the Gate of the VT3 is connected to the Gate line Gate, the drain of the VT3 is connected to the cathode of the OLED, and the source of the VT3 is connected to the ground GND.
In the embodiment shown in fig. 4, the third voltage terminal is a ground terminal, the VT3 is an N-type field effect transistor, and the light emitting device is an organic light emitting diode, but not limited thereto.
When the embodiment of the pixel circuit shown in fig. 4 of the present invention is in operation, when the Gate line Gate is scanned, the Gate outputs a high level, VT3 is turned on, the current passes through R2 and VT2 from the power voltage end to the OLED, and forms a loop through VT3, so that the current IOLED flowing through the OLED is IR5+ IR 4; IR5 is the current through R5, IR4 is the current through R4; the current flowing through the OLED can be adjusted by adjusting the Data voltage output by the Data according to the required gray scale or brightness;
at this time, when the Data voltage outputted from the Data is a positive voltage, the direction of the current flowing through the OLED is from top to bottom.
When the embodiment of the pixel circuit shown in fig. 4 of the present invention is in operation, when the Gate line Gate is not scanned, the Gate outputs a low level, VT3 is turned off, and the OLED does not emit light.
The display device provided by the embodiment of the invention comprises N luminous current control circuits, a display substrate, M rows of N columns of pixel units, M rows of grid lines and N columns of data lines; the M rows and N columns of pixel units, the M rows of gate lines and the N columns of data lines may be disposed on the display substrate;
the first poles of the light-emitting elements included in the pixel units positioned in the nth column are connected with the second branch in the proportional control circuit included in the nth light-emitting current control circuit;
the pixel units in the mth row are connected with the gate line in the mth row;
a conversion circuit in the nth light-emitting current control circuit is connected with an nth column data line;
m and N are both positive integers, M is a positive integer less than or equal to M, and N is a positive integer less than or equal to N.
In practical operation, M rows and N columns of pixel units, M rows and N columns of gate lines, and the display device according to the embodiment of the present invention may include N light-emitting current control circuits, one light-emitting current control circuit corresponds to one column of pixel units, a conversion circuit in an nth light-emitting current control circuit is connected to an nth column of pixel units, first poles of light-emitting elements included in the nth column of pixel units are all connected to a second branch in a proportional control circuit included in the nth light-emitting current control circuit, and pixel units in an mth row are all connected to an mth row of gate lines.
The display device provided by the embodiment of the invention has a simple structure, can accurately control the driving current of the light-emitting element while simplifying the mask design, realizes accurate gray scale adjustment, is easier to realize high brightness and high resolution, and ensures that the current flowing through the light-emitting element under the same gray scale is not influenced by the line impedance of the display panel.
The display device provided by the embodiment of the invention can be any product or component with a display function, such as a mobile phone, a tablet personal computer, a television, a display, a notebook computer, a digital photo frame, a navigator and the like.
When the display device of the embodiment of the invention works, in the display period,
a conversion circuit in the nth light-emitting current control circuit converts the data voltage on the nth data line into corresponding first current, a proportional control circuit in the nth light-emitting current control circuit controls the current value of the first current to be in a proportional relation with the current value of second current flowing through a second branch in the proportional control circuit, and the second current is supplied to the nth pixel unit;
n is a positive integer less than or equal to N, which is a positive integer.
Specifically, the light emitting element may be an organic light emitting diode, and the first electrode of the light emitting element is an anode of the organic light emitting diode, but not limited thereto.
In a specific implementation, the pixel unit in the mth row and the nth column may include a light emitting element in the mth row and the nth column, and an on-state control circuit in the mth row and the nth column;
the second branch in the proportional control circuit included in the nth light-emitting current control circuit is connected with the first pole of the nth light-emitting element in the mth row;
the second pole of the mth row and nth column light-emitting element is connected with the first end of the mth row and nth column conduction control circuit, and the second end of the mth row and nth column conduction control circuit is connected with the third voltage end;
and the control end of the m-th row and n-th column conduction control circuit is connected with the m-th row grid line, and the m-th row and n-th column conduction control circuit is used for controlling the communication between the second pole of the m-th row and n-th column light-emitting element and the third voltage end under the control of the gate drive signal on the m-th row grid line.
Specifically, the mth row and nth column light emitting element may be an mth row and nth column organic light emitting diode, a first electrode of the mth row and nth column light emitting element is an anode of the mth row and nth column organic light emitting diode, and a second electrode of the mth row and nth column light emitting element is a cathode of the mth row and nth column organic light emitting diode;
the mth row and nth column conduction control circuit may include the mth row and nth column control transistor; and the control electrode of the nth control transistor in the mth row is connected with the gate line in the mth row, the first electrode of the nth control transistor in the mth row is connected with the cathode of the nth organic light-emitting diode in the mth row, and the second electrode of the nth control transistor in the mth row is connected with the third voltage end.
In a specific implementation, the third voltage terminal may be a low voltage terminal, and may also be a ground terminal, but not limited thereto.
According to one embodiment, the light emitting current control circuit may be disposed in a peripheral area of the display substrate by a mask drawing.
According to another specific implementation, the display device according to the embodiment of the invention may further include a driving integrated circuit; the light-emitting current control circuit is integrated in the driving integrated circuit.
The display device according to the present invention is described below with reference to an embodiment.
As shown in fig. 5, a display device according to an embodiment of the present invention includes N embodiments of the light-emitting current control circuit shown in fig. 3, a display substrate (not shown in fig. 5), M rows and N columns of pixel units, M rows of gate lines, and N columns of data lines;
the M rows and N columns of pixel units are arranged in an AA area (an effective display area) of the display substrate (not shown in FIG. 5);
the N light-emitting current control circuits are drawn outside the AA area through a mask (i.e., the N light-emitting current control circuits are disposed in a peripheral area of the display substrate (not shown in fig. 5);
the nth light emitting current control circuit comprises an nth first triode VT1n, an nth first resistor R1n, an nth second triode VT2n, an nth second resistor R2n, an nth operational amplifier Cmpn, an nth first conversion resistor R3n, an nth second conversion resistor R4n and an nth third conversion resistor R5 n; the positive phase input end of Cmpn is connected with an nth row data line Datan;
the pixel unit in the mth row and the nth column comprises an organic light emitting diode OLEDMn in the mth row and the nth column and a control transistor VT3mn in the mth row and the nth column, wherein the anode of the OLEDMn is connected with the collector of VT2 n;
the grid of VT3mn is connected with the grid line Gatem of the mth row, the drain of VT3mn is connected with the cathode of OLEDMn, and the source of VT3mn is connected with the ground end GND;
m and N are both positive integers, M is a positive integer less than or equal to M, and N is a positive integer less than or equal to N;
in fig. 5, a first row and a first column of pixel units, an mth row and a first column of pixel units, an M +1 th row and a first column of pixel units, a first light-emitting current control circuit, an mth row and a first column of pixel units, a first row and an nth column of pixel units, an mth row and an nth column of pixel units, an nth light-emitting current control circuit, a first row and an nth column of pixel units, an mth row and an nth column of pixel units, an M +1 th row and an nth column of pixel units, and an nth light-emitting current control circuit are drawn, wherein,
OLED11 is a first row and first column of pixel cells, and VT311 is a first row and first column of control transistors;
OLEDm1 is the m-th row and first column pixel unit, and VT3m1 is the m-th row and first column control transistor;
OLEDm +11 is the pixel unit in the first column of the m +1 th row, and VT3m +11 is the control transistor in the first column of the m +1 th row;
the OLEM 1 is the pixel unit in the first column of the M-th row, and the VT3M1 is the control transistor in the first column of the M-th row;
OLED1n is the first row nth column pixel unit, VT31n is the first row nth column control transistor;
OLEDmn is the nth pixel unit in the mth row, and VT3mn is the nth control transistor in the mth row;
OLEDm +1n is the nth pixel unit in the (m + 1) th row, and VT3m +1n is the nth control transistor in the (m + 1) th row;
OLEDMN is the pixel unit of the nth column of the Mth row, VT3Mn is the control transistor of the nth column of the Mth row;
OLED1N is the first row Nth column pixel unit, VT31N is the first row Nth column control transistor;
OLEDMN is the pixel unit of the Nth column of the mth row, VT3mN is the control transistor of the Nth column of the mth row;
OLEDm +1N is the nth column pixel unit in the (m + 1) th row, and VT3m +1N is the nth column control transistor in the (m + 1) th row;
the OLEMN is the pixel unit in the Nth row and the Nth column, and the VT3MN is the control transistor in the Nth row and the Nth column;
as shown in fig. 5, the first light-emitting current control circuit includes a first transistor VT11, a first resistor R11, a first second transistor VT21, a first second resistor R21, a first operational amplifier Cmp1, a first switching resistor R31, a first second switching resistor R41, and a first third switching resistor R51; the non-inverting input terminal of Cmpn is connected to the first column Data voltage Data 1;
the nth light emitting current control circuit comprises an nth first triode VT1N, an nth first resistor R1N, an nth second triode VT2N, an nth second resistor R2N, an nth operational amplifier CmpN, an nth first converting resistor R3N, an nth second converting resistor R4N and an nth third converting resistor R5N; the non-inverting input terminal of CmpN is connected to the nth column data voltage DataN.
In the embodiment shown in fig. 5, Data1 is a first column Data line, Datan is an nth column Data line, Gate1 is a first row Gate line, Gate is an mth row Gate line, Gate +1 is an M +1 th row Gate line, and Gate is an mth row Gate line.
In fig. 5, reference numeral VCC is a power supply voltage, and VCC is provided by a power supply voltage terminal.
In the embodiment shown in fig. 5, each control transistor is an N-type field effect transistor, and each transistor is a PNP-type transistor, but not limited thereto.
As shown in fig. 6, in operation of the embodiment of the display device of the present invention shown in fig. 5,
when the gate line Gatem of the mth row is scanned, Gatem outputs a high level, other gate lines output a low level, Datan outputs a data voltage of the nth column of the mth row, VT3mn is turned on, so that the cathode of OLEDmn is connected to the ground terminal GND, current flows from the power supply voltage terminal to OLEDmn through R2mn and the turned-on VT2mn to drive OLEDmn to emit light, and the current IOLED (m, n) flowing through the OLEDmn at this time is related to the data voltage of the nth column of the mth row of the Datan output;
when the gate line Gatem + 1 of the m +1 th row is scanned, Gatem +1 outputs a high level, the gate lines of the other rows output a low level, Datan outputs an nth column data voltage of the m +1 th row, VT3m +1n is turned on, so that the cathode of OLEDm +1n is connected to the ground terminal GND, and current flows from the power supply voltage terminal to OLEDm +1n through R2m +1n and the turned-on VT2m +1n to drive OLEDm +1n to emit light, where IOLED (m +1, n) flowing through OLEDm +1n is related to the nth column data voltage of the m +1 th row output by Datan.
In fig. 6, only the nth column data voltage of the mth row output by the nth column data line Datan when the mth row of gate lines is scanned and the nth column data voltage of the m +1 row output by Datan when the m +1 row of gate lines is scanned are exemplarily shown, and in actual operation, Datan outputs a corresponding data voltage when each row of gate lines is scanned.
The embodiment of the display device shown in fig. 5 of the present invention can perform 100% load driving by a special panel design and matching with corresponding timing control, the driving is not limited by the number of scanning electrodes, each pixel can be independently and selectively adjusted, the magnitude of the current for driving the light emitting element to emit light can be accurately controlled by adjusting the data voltage, so as to adjust gray scale display, and the adjustment mode is simple. In addition, the pixel structure in the specific embodiment of the display device shown in fig. 5 of the present invention is simple, which facilitates mask design and can realize constant current control, so that the current flowing through each light emitting element to emit light is not affected by the line impedance of the panel.
The display driving method according to the embodiment of the present invention is applied to the display device, and includes: in the display period of the time period of the display,
a conversion circuit in the nth light-emitting current control circuit converts the data voltage on the nth data line into corresponding first current, a proportional control circuit in the nth light-emitting current control circuit controls the current value of the first current to be in a proportional relation with the current value of second current flowing through a second branch in the proportional control circuit, and the second current is supplied to the nth pixel unit;
n is a positive integer less than or equal to N, which is a positive integer.
Specifically, the pixel unit in the mth row and the nth column may include a light emitting element in the mth row and the nth column and an on-state control circuit in the mth row and the nth column; in an mth scan period included in the display period,
the grid line of the mth row is opened, the conduction control circuit of the mth row and the nth column controls the communication between the second pole of the light-emitting element of the mth row and the nth column and the third voltage end, and the nth light-emitting current control circuit provides the second current to the light-emitting element of the mth row and the nth column;
m is a positive integer less than or equal to M, M is a positive integer.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (10)
1. A light emitting current control circuit is characterized by comprising a proportional control circuit and a conversion circuit, wherein,
the proportion control circuit comprises a first branch circuit and a second branch circuit, the first branch circuit is connected with the conversion circuit, and the second branch circuit is connected with the light-emitting element;
the proportional control circuit is used for controlling the current value of a first current flowing through the first branch circuit and the current value of a second current flowing through the second branch circuit to be in a proportional relation;
the conversion circuit is also connected with a data line and is used for converting a data voltage on the data line into the first current;
the first branch circuit comprises a first resistor and a first transistor, and the second branch circuit comprises a second resistor and a second transistor;
the first end of the first resistor and the first end of the second resistor are both connected with a power supply voltage end;
a control electrode of the first transistor is connected with a control electrode of the second transistor;
a first pole of the first transistor is connected with the second end of the first resistor, and a first pole of the second transistor is connected with the second end of the second resistor;
a second pole of the first transistor is connected to the conversion circuit, and a second pole of the second transistor is connected to the light emitting element.
2. The light emission current control circuit according to claim 1, wherein a resistance value of the first resistor is equal to a resistance value of the second resistor, a type of the first transistor is the same as a type of the second transistor, and an electrical parameter of the first transistor is the same as an electrical parameter of the second transistor.
3. The light emission current control circuit according to claim 1 or 2, wherein the conversion circuit includes an operational amplifier, a first conversion resistor, a second conversion resistor, and a third conversion resistor;
the first input end of the operational amplifier is connected with the data line;
the second input end of the operational amplifier is connected with the first voltage end through the first conversion resistor, and the second input end of the operational amplifier is also connected with the output end of the operational amplifier through the second conversion resistor; the output end of the operational amplifier is also connected with the second voltage end through the third conversion resistor.
4. A pixel circuit comprising a light emitting element, a turn-on control circuit, and the light emission current control circuit according to any one of claims 1 to 3;
the second branch in the proportional control circuit included in the light-emitting current control circuit is connected with the first pole of the light-emitting element;
the second pole of the light-emitting element is connected with the first end of the conduction control circuit, and the second end of the conduction control circuit is connected with the third voltage end;
the control end of the conduction control circuit is connected with the grid line, and the conduction control circuit is used for controlling the second pole of the light-emitting element to be communicated with the third voltage end under the control of the grid driving signal on the grid line.
5. A display device, comprising N light-emitting current control circuits according to any one of claims 1 to 3, a display substrate, M rows and N columns of pixel units, M rows of gate lines, and N columns of data lines; the M rows and N columns of pixel units, the M rows of grid lines and the N columns of data lines are arranged on the display substrate;
the first poles of the light-emitting elements included in the pixel units positioned in the nth column are connected with the second branch in the proportional control circuit included in the nth light-emitting current control circuit;
the pixel units in the mth row are connected with the gate line in the mth row;
a conversion circuit in the nth light-emitting current control circuit is connected with an nth column data line;
m and N are both positive integers, M is a positive integer less than or equal to M, and N is a positive integer less than or equal to N.
6. The display device according to claim 5, wherein the pixel unit of the mth row and the nth column comprises a light emitting element of the mth row and the nth column and a conduction control circuit of the mth row and the nth column;
the second branch in the proportional control circuit included in the nth light-emitting current control circuit is connected with the first pole of the nth light-emitting element in the mth row;
the second pole of the mth row and nth column light-emitting element is connected with the first end of the mth row and nth column conduction control circuit, and the second end of the mth row and nth column conduction control circuit is connected with the third voltage end;
and the control end of the m-th row and n-th column conduction control circuit is connected with the m-th row grid line, and the m-th row and n-th column conduction control circuit is used for controlling the communication between the second pole of the m-th row and n-th column light-emitting element and the third voltage end under the control of the gate drive signal on the m-th row grid line.
7. The display device according to claim 5 or 6, wherein the light emission current control circuit is provided in a peripheral region of the display substrate.
8. The display device according to claim 5 or 6, further comprising a driver integrated circuit; the light-emitting current control circuit is integrated in the driving integrated circuit.
9. A display driving method applied to the display device according to any one of claims 5 to 8, the display driving method comprising: in the display period of the time period of the display,
a conversion circuit in the nth light-emitting current control circuit converts the data voltage on the nth data line into corresponding first current, a proportional control circuit in the nth light-emitting current control circuit controls the current value of the first current to be in a proportional relation with the current value of second current flowing through a second branch in the proportional control circuit, and the second current is supplied to the nth pixel unit;
n is a positive integer less than or equal to N, which is a positive integer.
10. The display driving method according to claim 9, wherein the m row and n column pixel units comprise an m row and n column light emitting element and an m row and n column conduction control circuit; in an mth scan period included in the display period,
the grid line of the mth row is opened, the conduction control circuit of the mth row and the nth column controls the communication between the second pole of the light-emitting element of the mth row and the nth column and the third voltage end, and the nth light-emitting current control circuit provides the second current to the light-emitting element of the mth row and the nth column;
m is a positive integer less than or equal to M, M is a positive integer.
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