CN105139803B - AMOLED column drive circuits and its driving method - Google Patents

Abstract

The present invention provides an AMOLED column drive circuit, comprising: a linear digital-to-analog conversion circuit; a Gamma correction output stage circuit for gamma-correcting an analog signal output by the linear digital-to-analog conversion circuit, which is used to drive an OLED pixel array to emit light; providing a clock signal and A clock control signal generation circuit for the control signal; a bias circuit for providing a reference voltage. The AMOLED column driving method of the present invention includes: converting digital signals into analog signals, performing Gamma correction on the analog signals, and then inputting the Gamma-corrected analog signals into OLED pixel arrays to drive the OLED pixel arrays to emit light. The linear DAC of the present invention does not produce precision loss in the AMOLED column drive circuit, and when the resistance string DAC is used, it is not necessary to perform complicated matching work on the resistance string, which reduces the difficulty of design; at the same time, a DAC with a smaller area can be used, thereby further reducing the circuit. The overall area has the advantages of simple design, small area, high precision, and good image display effect.

Description

AMOLED column driving circuit and driving method thereof

technical field

The invention relates to the field of plane display technology, in particular to an AMOLED column drive circuit and a drive method thereof.

Background technique

In recent years, AMOLED (Active-matrix organic light-emitting diode, active-matrix organic light-emitting diode) is more and more used in mobile phones, tablet computers and other devices, because it is ultra-thin and light compared with other display technologies. , wide viewing angle, low power consumption, fast response, vivid colors and so on. AMOLED driving methods mainly include current driving, voltage driving and digital driving, etc. Among them, voltage driving has a fast response speed, and this method is similar to the current mainstream AMLCD display driving technology, so it is widely used in AMOLED display driving. In the field of AMOLED display, there is a problem that the luminance of OLED pixels has a nonlinear relationship with the input voltage, so the output voltage of the AMOLED column drive circuit must be corrected by Gamma, so that the color of the dark field gray scale of the AMOLED display system is significantly improved, and each gray The color error of the first level is significantly reduced, the dark field color details are clear, the image brightness and color are consistent, the transparency is good, the contrast is obvious, and the color performance of TVs with different screens of the same size is obviously consistent.

Gamma correction in AMOLED display systems is usually done in the column driver circuit. There are two types of existing technologies, one is Gamma correction in the analog domain, and the other is Gamma correction in the digital domain.

Gamma correction in the analog domain is mainly realized by designing a nonlinear digital-to-analog converter (Digital-to-AnalogConverter, DAC). The realization of the nonlinear DAC is to obtain a nonlinear reference voltage by adjusting the size of the resistor in the global resistor string. There are a large number of resistors with different resistance values in the string, so it takes a lot of effort to match the resistor strings, and consumes a lot of area. At the same time, the global resistor string of a nonlinear DAC usually requires many different reference voltages, which further increases the circuit. Complexity.

Gamma correction in the digital domain is mainly performed for linear DACs. The specific method is to map the input digital signal to a nonlinear Gamma curve through a lookup table. The digital signal obtained after mapping is used as the input of the linear DAC. In this way, the original input can be easily realized. The non-linear conversion between and output, the digital domain Gamma correction method simplifies the design of the DAC, and this method can apply some linear DACs with a small area to the AMOLED column drive circuit, reducing the area of the driver chip, but Linear Gamma correction also has some disadvantages. For example, this method loses the accuracy of the linear DAC during the mapping process, and the look-up table circuit containing the mapping relationship is usually integrated in the column drive circuit, which will further increase the chip area.

In summary, the design of the analog domain gamma correction circuit in the prior art is relatively complicated; while the design of the digital domain gamma correction is simple, and a linear DAC with a smaller area can be used in the AMOLED column drive circuit, but it will reduce the performance of the linear DAC. Therefore, how to balance the area and precision of the AMOLED column drive circuit has become one of the problems to be solved urgently by those skilled in the art.

Contents of the invention

In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide an AMOLED column drive circuit and its drive method, which is used to solve the problem that the design of the analog domain Gamma correction circuit in the prior art is relatively complicated, and the digital domain Gamma correction circuit uses Problems such as the reduction of the accuracy of the linear DAC.

In order to achieve the above purpose and other related purposes, the present invention provides an AMOLED column drive circuit, the AMOLED column drive circuit at least includes:

A linear digital-to-analog conversion circuit receives a digital signal and converts the digital signal into an analog signal;

The Gamma correction output stage circuit is connected to the output end of the linear digital-to-analog conversion circuit, performs Gamma correction on the analog signal output by the linear digital-to-analog conversion circuit, and outputs the corrected signal to the OLED pixel array to drive the linear digital-to-analog conversion circuit. The OLED pixel array emits light;

A clock control signal generation circuit, which provides a clock signal and a control signal for the AMOLED column drive circuit;

The bias circuit provides a reference voltage or reference current for the AMOLED column drive circuit.

Preferably, it also includes an input stage circuit connected to the input end of the linear digital-to-analog conversion circuit, the input stage circuit includes one or a combination of registers, latch circuits, and level conversion circuits, and the input stage circuit receives the The digital signal is buffered, level-converted and then output to the linear digital-to-analog conversion circuit.

Preferably, the linear digital-to-analog conversion circuit is a loop digital-to-analog conversion circuit or a resistor string digital-to-analog conversion circuit.

Preferably, the Gamma correction output stage circuit includes a current domain Gamma correction module and a current voltage conversion module; the current domain Gamma correction module receives the output signal of the linear digital-to-analog conversion circuit, and the linear digital-to-analog conversion circuit The output signal of the current domain Gamma correction module outputs a current signal after Gamma correction; the current voltage conversion module is connected to the output terminal of the current domain Gamma correction module, and converts the current signal output by the current domain Gamma correction module into a voltage signal.

More preferably, the current domain gamma correction module includes first to second NMOS transistors, first to sixth PMOS transistors, first to second operational amplifiers, first to second current sources, and variable resistors;

Wherein, the first to second PMOS transistors, the first NMOS transistor and the first current source are sequentially connected in series between the power supply and the ground, and the gate terminal of the first PMOS transistor is connected to the first NMOS transistor The drain terminal of the third to fourth PMOS transistors, the second NMOS transistor and the second current source are sequentially connected in series between the power supply and the ground, and the gate terminal of the third PMOS transistor is connected to the second The drain terminal of the NMOS transistor; the source terminal of the fifth PMOS transistor is connected to the power supply, the gate terminal is connected to the gate terminal of the third PMOS transistor, and the drain terminal is connected to the source terminal of the sixth PMOS transistor, and the sixth PMOS transistor is connected to the source terminal of the sixth PMOS transistor. The drain terminal of the current domain Gamma correction module is used as the output terminal of the current domain Gamma correction module; the gate terminals of the second PMOS transistor, the fourth PMOS transistor and the sixth PMOS transistor are connected to a bias voltage; the first NMOS transistor The gate terminal of the first operational amplifier is connected to the output terminal of the first operational amplifier, the non-inverting input terminal of the first operational amplifier is connected to the first reference voltage, and the inverting input terminal is connected to the source terminal of the first NMOS transistor; the second NMOS The gate end of the tube is connected to the output end of the second operational amplifier, the non-inverting input end of the second operational amplifier is connected to the output signal of the linear digital-to-analog conversion circuit, and the inverting input end is connected to the source of the second NMOS transistor. terminal; the variable resistor is connected between the source terminal of the first NMOS transistor and the second NMOS transistor, and the variable resistor is controlled by the output signal of the linear digital-to-analog conversion circuit.

More preferably, the variable resistor includes a resistor string, a plurality of switches, and a voltage comparator; wherein the resistor string is connected between the source terminals of the first NMOS transistor and the second MOS transistor, and each switch is connected in parallel At both ends of each resistor in the resistor string, the voltage comparator receives the output signal of the linear digital-to-analog converter and outputs the control signal of each switch tube.

More preferably, the current-voltage conversion module includes third to sixth NMOS transistors, a third operational amplifier, and a feedback resistor;

Wherein, the third to fourth NMOS transistors are sequentially connected in series between the output terminal of the current domain Gamma correction module and the ground, the gate terminal of the third NMOS transistor is connected to the drain terminal, and the gate terminal of the fourth NMOS transistor is connected in series. The gate terminal is connected to the drain terminal; the source terminal of the sixth NMOS transistor is grounded, the drain terminal is connected to the source terminal of the fifth NMOS transistor, and the gate terminal of the sixth NMOS transistor is connected to the gate terminal of the fourth NMOS transistor , the gate end of the fifth NMOS transistor is connected to the gate end of the third NMOS transistor; the drain end of the fifth NMOS transistor is connected to the inverting input end of the third operational amplifier, and the third operational amplifier The non-inverting input terminal is connected to the second reference voltage, and the output terminal of the third operational amplifier is connected to the inverting input terminal of the third operational amplifier through the feedback resistor.

In order to achieve the above purpose and other related purposes, the present invention provides an AMOLED column driving method, the AMOLED column driving method at least includes:

converting the digital signal into an analog signal, performing Gamma correction on the analog signal, and then inputting the Gamma corrected analog signal into the OLED pixel array to drive the OLED pixel array to emit light.

Preferably, the step of performing Gamma correction on the analog signal includes: realizing Gamma correction in the current domain by adjusting the resistance value of the variable resistor, and converting the Gamma-corrected current into a voltage to obtain a voltage that can be directly used in the OLED. Gamma corrected signal of the pixel array.

More preferably, the expression of the analog signal after Gamma correction is:

Wherein, V _CONSTANT , k is a constant, V _REF is a first reference voltage, R _VAR is a resistance value of the variable resistor, and V _DAC is an output analog signal after digital-to-analog conversion.

As mentioned above, the AMOLED column drive circuit and its drive method of the present invention have the following beneficial effects:

The AMOLED column drive circuit and the drive method thereof of the present invention design an output stage with a Gamma correction function, so that the linear DAC is used in the AMOLED column drive circuit without loss of precision, and when the resistor string DAC is used, it is not necessary to perform complicated matching work on the resistor string , which reduces the difficulty of designing the DAC. At the same time, a DAC with a smaller area such as a cyclic DAC can be used to further reduce the overall area of the circuit. It has the advantages of simple design, small area, high precision, and good image display effect.

Description of drawings

FIG. 1 is a schematic structural diagram of an AMOLED column drive circuit and an OLED pixel array of the present invention.

FIG. 2 is a schematic structural diagram of the Gamma correction output stage circuit of the present invention.

FIG. 3 is a schematic diagram showing the structure of the variable resistor of the present invention.

FIG. 4 shows a schematic diagram of input and output curves of a Gamma correction output stage circuit for realizing three-segment piecewise linearity.

Component designation description

1 AMOLED column drive circuit

11 Input stage circuit

12 Linear digital-to-analog conversion circuit

13 Gamma corrected output stage circuit

131 Current Domain Gamma Correction Module

132 current voltage conversion module

14 Clock control signal generation circuit

15 Bias circuit

2 OLED pixel array

detailed description

Embodiments of the present invention are described below through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation modes, and various modifications or changes can be made to the details in this specification based on different viewpoints and applications without departing from the spirit of the present invention.

Please refer to Figure 1 to Figure 4. It should be noted that the diagrams provided in this embodiment are only schematically illustrating the basic idea of the present invention, and only the components related to the present invention are shown in the diagrams rather than the number, shape and shape of the components in actual implementation. Dimensional drawing, the type, quantity and proportion of each component can be changed arbitrarily during actual implementation, and the component layout type may also be more complicated.

As shown in FIG. 1 , the present invention provides an AMOLED column drive circuit 1, and the AMOLED column drive circuit 1 at least includes:

An input stage circuit 11 , a linear digital-to-analog conversion circuit 12 , a Gamma correction output stage circuit 13 , a clock control signal generation circuit 14 and a bias circuit 15 .

Specifically, as shown in FIG. 1 , the input stage circuit 11 receives an input digital signal, processes the digital signal and sends it to the linear digital-to-analog conversion circuit 12 . In this embodiment, the input stage circuit 11 includes a register, a latch circuit, and a level conversion circuit, and buffers the digital signal, converts the level and outputs it to the linear digital-to-analog conversion circuit 12 .

Specifically, as shown in FIG. 1, the linear digital-to-analog conversion circuit 12 is connected to the output end of the input stage circuit 11, receives the digital signal output by the input stage circuit 11, and converts the digital signal into an analog signal. output. In this embodiment, the output terminal of the input stage circuit 11 is connected to a plurality of linear digital-to-analog conversion circuits 12 to output multi-channel signals to drive the OLED pixel array 2 . The linear digital-to-analog conversion circuit 12 can be a loop digital-to-analog conversion circuit, a resistor string digital-to-analog conversion circuit or a digital-to-analog conversion circuit of any other structure. In this embodiment, in order to reduce the overall area of the circuit, the linear digital-to-analog conversion circuit The analog-to-analog conversion circuit 12 adopts a cyclic digital-to-analog conversion circuit. If the linear digital-to-analog conversion circuit 12 adopts a resistor string digital-to-analog conversion circuit, then there is no need to perform complex matching work on the resistor strings, which reduces the difficulty of design.

Specifically, as shown in FIG. 1, the Gamma correction output stage circuit 13 is connected to the output end of the linear digital-to-analog conversion circuit 12, performs Gamma correction on the analog signal output by the linear digital-to-analog conversion circuit 12, and The corrected signal is output to the OLED pixel array 2 to drive the OLED pixel array 2 to emit light.

As shown in FIG. 2 , the Gamma correction output stage circuit 13 includes a current domain Gamma correction module 131 and a current-voltage conversion module 132 .

The current domain Gamma correction module 131 receives the output signal of the linear digital-to-analog conversion circuit 12 , and performs Gamma correction on the output signal of the linear digital-to-analog conversion circuit 12 to output a corresponding current signal. Specifically, as shown in FIG. 2, in this embodiment, the current domain Gamma correction module 131 includes a first NMOS transistor MN1, a second NMOS transistor MN2, a first PMOS transistor MP1, a second PMOS transistor MP2, a third PMOS transistor MP3, fourth PMOS transistor MP4, fifth PMOS transistor MP5, sixth PMOS transistor MP6, first operational amplifier B1, second operational amplifier B2, first current source Is1, second current source Is2 and variable resistor R _VAR . The first PMOS transistor MP1, the second PMOS transistor MP2, the first NMOS transistor MN1, and the first current source Is1 are sequentially connected in series between the power supply and the ground, and the gate terminal of the first PMOS transistor MP1 connected to the drain end of the first NMOS transistor MN1. The third PMOS transistor MP3, the fourth PMOS transistor MP4, the second NMOS transistor MN2, and the second current source Is2 are sequentially connected in series between the power supply and the ground, and the gate terminal of the third PMOS transistor MP3 connected to the drain end of the second NMOS transistor MN2. The currents flowing through the first current source Is1 and the second current source Is2 are both I _REF . The source end of the fifth PMOS transistor MP5 is connected to the power supply, the gate end is connected to the gate end of the third PMOS transistor MP3, and the drain end is connected to the source end of the sixth PMOS transistor MP6, and the drain end of the sixth PMOS transistor MP6 terminal as the output terminal of the current domain Gamma correction module 131. Gate terminals of the second PMOS transistor MP2 , the fourth PMOS transistor MP4 and the sixth PMOS transistor MP6 are connected to a bias voltage Vb. The first NMOS transistor MN1 and the second NMOS transistor MN2 form a differential pair, the gate terminal of the first NMOS transistor MN1 is connected to the output terminal of the first operational amplifier B1, and the non-inverting terminal of the first operational amplifier B1 The input terminal is connected to the first reference voltage V _REF , and the inverting input terminal is connected to the source terminal of the first NMOS transistor MN1. The gate terminal of the second NMOS transistor MN2 is connected to the output terminal of the second operational amplifier B2, and the non-inverting input terminal of the second operational amplifier B2 is connected to the output signal V _DAC , the inverting phase of the linear digital-to-analog conversion circuit 12 The input end is connected to the source end of the second NMOS transistor MN2. The variable resistor R _VAR is connected between the source terminals of the first NMOS transistor MN1 and the second NMOS transistor MN2 , and the variable resistor R _VAR is affected by the output signal V of the linear digital-to-analog conversion circuit 12 . _DAC control.

The variable resistor R _VAR may be a MOS voltage-controlled resistor or any form of variable resistor, which is not limited to this embodiment. As shown in FIG. 3 , in this embodiment, the variable resistor R _VAR includes a resistor string, a plurality of switches, and a voltage comparator. The resistor string includes a first resistor R1, a second resistor R2, and a third resistor R3 connected in series, and the resistor string is connected between the source ends of the first NMOS transistor MN1 and the second MOS transistor MN2. A switch SW1, a second switch SW2, and a third switch SW3 are respectively connected in parallel to both ends of the first resistor R1, the second resistor R2, and the third resistor R3, and the voltage comparator receives the linear data The output signal V _DAC of the analog converter 12 also outputs the control signals of each switch tube, and the voltage comparator outputs three control signals according to the value of the output signal V _DAC of the linear digital-to-analog conversion circuit 12 to control the first The switch SW1, the second switch SW2 and the third switch SW3 are on and off, the voltage comparator receives the output signal V _DAC of the linear digital-to-analog converter 12 in different voltage ranges, the first There is only one of the first resistor R1, the second resistor R2, and the third resistor R3 in the branch between the source end of the first NMOS transistor MN1 and the second NMOS transistor MN2, and the other two resistors When short-circuited, the resistance values of the first resistor R1, the second resistor R2 and the third resistor R3 are different, and the slopes of the transformation curves in the corresponding intervals are different, thereby realizing the piecewise nonlinearity of the transfer curve.

The current-voltage conversion module 132 is connected to the output terminal of the current-domain Gamma correction module 131, and converts the current signal output by the current-domain Gamma correction module 131 into a voltage signal. Specifically, as shown in FIG. 2, in this embodiment, the current-voltage conversion module 132 includes a third NMOS transistor MN3, a fourth NMOS transistor MN4, a fifth NMOS transistor MN5, a sixth NMOS transistor MN6, a third computing Amplifier B3 and feedback resistor R _BASE . The third NMOS transistor MN3 and the fourth NMOS transistor MN4 are sequentially connected in series between the output end of the current domain Gamma correction module 131 and the ground. In this embodiment, the drain end of the third NMOS transistor MN3 is connected to The drain terminal of the sixth PMOS transistor MP6, the gate terminal of the third NMOS transistor MN3 are connected to the drain terminal, and the gate terminal of the fourth NMOS transistor MN4 is connected to the drain terminal. The source terminal of the sixth NMOS transistor MN6 is grounded, the drain terminal is connected to the source terminal of the fifth NMOS transistor MN5, the gate terminal of the sixth NMOS transistor MN6 is connected to the gate terminal of the fourth NMOS transistor MN4, the The gate terminal of the fifth NMOS transistor MN5 is connected to the gate terminal of the third NMOS transistor MN3. The drain end of the fifth NMOS transistor MN5 is connected to the inverting input end of the third operational amplifier B3, the non-inverting input end of the third operational amplifier B3 is connected to the second reference voltage V _BASE , and the third operational amplifier B3 The output terminal of is connected to the inverting input terminal of the third operational amplifier B3 through the feedback resistor R _BASE .

Specifically, as shown in FIG. 1 , the clock control signal generating circuit 14 provides a clock signal and a control signal for the AMOLED column driving circuit 1 . In this embodiment, the clock control signal generation circuit 14 is connected to the input stage circuit 11, the linear digital-to-analog conversion circuit 12, and the input end of the Gamma correction output stage circuit 13 for providing the input The clock signal and control signal of the stage circuit 11, the linear digital-to-analog conversion circuit 12, and the Gamma correction output stage circuit 13.

Specifically, as shown in FIG. 1 , the bias circuit 15 provides a reference voltage or reference current for the AMOLED column drive circuit 1 . In this embodiment, the bias circuit 15 is connected to the linear digital-to-analog conversion circuit 12 and the Gamma correction output stage circuit 13 for providing a bias voltage and a reference voltage.

As shown in Figures 1 to 3, the working principle of the above-mentioned AMOLED column drive circuit is as follows:

The digital signal is output to each linear digital-to-analog conversion circuit 12 through a shift register, a latch and a level conversion circuit, and the linear digital-to-analog conversion circuit 12 outputs a corresponding analog voltage value, and the output of the linear digital-to-analog conversion circuit 12 As the input of Gamma correction output stage circuit 13. Gamma correction in the current domain is realized by adjusting the resistance of the variable resistor R _VAR , and the Gamma-corrected current is converted into a voltage to obtain a Gamma-corrected signal that can be directly used in the OLED pixel array. The voltage corrected by the Gamma correction output stage circuit 13 is input to the OLED pixel array 2 to drive the OLED pixel array 2 to emit light. The bias circuit 15 provides the required reference voltage for each module in the drive circuit, and the clock control signal generating circuit 14 provides timing signals and control signals for each module.

Specifically, as shown in FIG. ₂ , the expressions of the source terminal voltages V1 and V2 of the _first NMOS transistor MN1 and the second NMOS transistor MN2 in FIG. 2 can be calculated as follows:

Wherein, Ad is the differential mode gain of the first operational amplifier B1 and the second operational amplifier B2, Acm is the common mode gain of the first operational amplifier B1 and the second operational amplifier B2, V _GS1 and V _GS2 represent gate-source voltages of the first NMOS transistor MN1 and the second NMOS transistor MN2 respectively.

The difference between the above formula (1) and the above formula (2) can be obtained:

Since Ad>>Acm, the difference between V1 and V2 can be simplified as:

V ₁ -V ₂ ≈V _DAC -V _REF (4)

Therefore the current I _R flowing through the variable resistor R _VAR can be expressed as:

It can be seen from the above formula that if the size of the variable resistor R _VAR is different, the slope of the relationship curve between the output signal V _DAC of the linear digital-to-analog conversion circuit 12 and the current I _R of the variable resistor R _VAR is different. We can realize the piecewise linearity from the input voltage to the current by changing the size of the variable resistor R _VAR in different input voltage ranges.

As shown in FIG. 2, it is assumed that the current ratio between the branches of the current mirror composed of the third PMOS transistor MP3, the fourth PMOS transistor MP4, the fifth PMOS transistor MP5 and the sixth PMOS transistor MP6 is 1 : m, the current ratio between the branches of the current mirror composed of the third NMOS transistor MN3, the fourth NMOS transistor MN4, the fifth NMOS transistor MN5 and the sixth NMOS transistor NP6 is 1:n, then The following relationship will hold:

I _out ＝nI ₂ ＝mnI ₁ ＝mn(I _REF +I _R ) (6)

V _out ＝V _BASE +I _OUT R _BASE ＝V _BASE +mn(I _REF +I _R )R _BASE (7)

Wherein, I ₁ is the drain current of the second NMOS transistor MN2 , I ₂ is the drain current of the sixth PMOS transistor MP6 , and I _OUT is the drain current of the fifth NMOS transistor MN5 .

Further calculations can be obtained:

Where V _CONSTANT =V _BASE +mnI _REF R _BASE , k=mnR _BASE , both V _CONSTANT and k are constants.

As shown in Figure 2, through the current mirror circuit and the I/V conversion circuit, we have established the relationship between the input voltage V _DAC and the output voltage V _OUT , from the relationship we can see that by changing the variable resistor R _VAR Under different input voltages, the non-linear conversion between V _DAC and V _OUT can be realized, thereby realizing the function of Gamma correction.

As shown in Figure 4, the input and output curves of the Gamma correction output stage circuit that realizes three-section piecewise linearity are shown. The dotted line is the input and output curve before Gamma correction, and the solid line is the input and output curve after Gamma correction. When the value of V _DAC is in the interval V _X0 ~ V _X1 , V _X1 ~ V _X2 , V _X2 ~ V _X3 , the corresponding variable resistance values are R1, R2, and R3 respectively. Due to the resistance of R1, R2, and R3 Values are different, corresponding to the slope of the conversion curve between V _DAC and V _OUT is also different, thus realizing the function of piecewise linear Gamma correction.

As mentioned above, the AMOLED column drive circuit and its drive method of the present invention have the following beneficial effects:

The AMOLED column drive circuit and the drive method thereof of the present invention design an output stage with a Gamma correction function, so that the linear DAC is used in the AMOLED column drive circuit without loss of precision, and when the resistor string DAC is used, it is not necessary to perform complicated matching work on the resistor string , which reduces the difficulty of designing the DAC. At the same time, a DAC with a smaller area such as a cyclic DAC can be used to further reduce the overall area of the circuit. It has the advantages of simple design, small area, high precision, and good image display effect.

In summary, an AMOLED column driver circuit of the present invention includes: a linear digital-to-analog conversion circuit that receives a digital signal and converts the digital signal into an analog signal; a Gamma correction output stage circuit that is connected to the linear digital-to-analog conversion circuit The output end of the circuit performs Gamma correction on the analog signal output by the linear digital-to-analog conversion circuit, and outputs the corrected signal to the OLED pixel array to drive the OLED pixel array to emit light; the clock control signal generation circuit is the The AMOLED column drive circuit provides a clock signal and a control signal; a bias circuit provides a reference voltage or a reference current for the AMOLED column drive circuit. The invention converts digital signals into analog signals, performs Gamma correction on the analog signals, and then inputs the Gamma-corrected analog signals into OLED pixel arrays to drive the OLED pixel arrays to emit light. The AMOLED column drive circuit and the drive method thereof of the present invention design an output stage with a Gamma correction function, so that the linear DAC is used in the AMOLED column drive circuit without loss of precision, and when the resistor string DAC is used, it is not necessary to perform complicated matching work on the resistor string , which reduces the difficulty of designing the DAC. At the same time, a DAC with a smaller area such as a cyclic DAC can be used to further reduce the overall area of the circuit. It has the advantages of simple design, small area, high precision, and good image display effect. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has high industrial application value.

The above-mentioned embodiments only illustrate the principles and effects of the present invention, but are not intended to limit the present invention. Anyone skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical ideas disclosed in the present invention should still be covered by the claims of the present invention.

Claims (9)

1. a kind of AMOLED column drive circuits, it is characterised in that the AMOLED column drive circuits at least include：

Linear D/A converting circuit, receives data signal and the data signal is converted into analog signal；

Gamma corrects output-stage circuit, the output end of the linear D/A converting circuit is connected to, to the linear digital-to-analogue conversion The analog signal of circuit output carries out Gamma corrections, and by the signal output after correction to OLED pixel array, described in driving OLED pixel array light-emitting；Wherein, the Gamma corrections output-stage circuit includes current field Gamma correction modules and electric current electricity Press modular converter；The current field Gamma correction modules receive the output signal of the linear D/A converting circuit, and to described The output signal of linear D/A converting circuit carries out output current signal after Gamma corrections；The Current Voltage modular converter connects The output end of the current field Gamma correction modules is connected to, the current signal that the current field Gamma correction modules are exported turns It is changed to voltage signal；

Clock control signal generation circuit, clock signal and control signal are provided for the AMOLED column drive circuits；

Biasing circuit, reference voltage or reference current are provided for the AMOLED column drive circuits.

2. AMOLED column drive circuits according to claim 1, it is characterised in that：Also include being connected to the linear digital-to-analogue The input stage circuit of change-over circuit input, the input stage circuit is included in register, latch cicuit, level shifting circuit A kind of or combination, the input stage circuit receives the data signal, and to being exported after data signal caching, level conversion To the linear D/A converting circuit.

3. AMOLED column drive circuits according to claim 1, it is characterised in that：The linear D/A converting circuit is to follow Number of rings analog conversion circuit or resistance string D/A converting circuit.

4. AMOLED column drive circuits according to claim 1, it is characterised in that：The current field Gamma correction modules Including the first~the second NMOS tube, the first~the 6th PMOS, the first~the second operational amplifier, the first~the second current source with And variable resistor；

Wherein, the first~the second PMOS, first NMOS tube and first current source are sequentially connected in series in power supply Between ground, the grid end of first PMOS connects the drain terminal of first NMOS tube；3rd~the 4th PMOS, institute State the second NMOS tube and second current source is sequentially connected in series between power supply and ground, the grid end connection of the 3rd PMOS The drain terminal of second NMOS tube；The source termination power of 5th PMOS, grid end connect the 3rd PMOS grid end, Drain terminal connects the source of the 6th PMOS, and the drain terminal of the 6th PMOS is used as the current field Gamma correction modules Output end；The grid end of second PMOS, the 4th PMOS and the 6th PMOS connects a bias voltage； The grid end of first NMOS tube connects the output end of first operational amplifier, first operational amplifier it is same mutually defeated Enter the source that the first reference voltage of end connection, inverting input connect first NMOS tube；The grid end of second NMOS tube The output end of second operational amplifier is connected, the in-phase input end of second operational amplifier connects the linear digital-to-analogue The output signal of change-over circuit, inverting input connect the source of second NMOS tube；First NMOS tube and described the The variable resistor is connected between the source of two NMOS tubes, the variable resistor is exported by the linear D/A converting circuit Signal is controlled.

5. AMOLED column drive circuits according to claim 4, it is characterised in that：The variable resistor include resistance string, Multiple switch, voltage comparator；Wherein described resistance string is connected to the source of first NMOS tube and second NMOS tube Between, the two ends of each switch in parallel each resistance in the resistance string, the voltage comparator receives the linear digital-to-analogue conversion The output signal and output control signal of device.

6. AMOLED column drive circuits according to claim 1, it is characterised in that：The Current Voltage modular converter includes 3rd~the 6th NMOS tube, the 3rd operational amplifier and feedback resistance；

Wherein, the 3rd~the 4th NMOS tube is sequentially connected in series output end and ground in the current field Gamma correction modules Between, the grid end of the 3rd NMOS tube is connected with drain terminal, and the grid end of the 4th NMOS tube is connected with drain terminal；6th NMOS The source ground connection of pipe, drain terminal connect the source of the 5th NMOS tube, the grid end connection the described 4th of the 6th NMOS tube The grid end of NMOS tube, the grid end of the 5th NMOS tube connects the grid end of the 3rd NMOS tube；The leakage of 5th NMOS tube The inverting input of end connection the 3rd operational amplifier, the in-phase input end connection second of the 3rd operational amplifier is joined Voltage is examined, the output end of the 3rd operational amplifier is connected to the anti-of the 3rd operational amplifier by the feedback resistance Phase input.

7. a kind of driving method of AMOLED column drive circuits as described in claim 1~6 any one, it is characterised in that The driving method of the AMOLED column drive circuits includes：

Analog signal is converted digital signals into, Gamma corrections are carried out to the analog signal, after then Gamma is corrected Analog signal is input in OLED pixel array, to drive the OLED pixel array light-emitting.

8. the driving method of AMOLED column drive circuits according to claim 7, it is characterised in that：To the analog signal The step of carrying out Gamma corrections includes：Realize that the Gamma in current field is corrected by adjusting the resistance of variable resistor, will Electric current after Gamma corrections is converted into voltage, with after obtaining and can be directly used for being corrected through Gamma of the OLED pixel array Signal.

9. the driving method of AMOLED column drive circuits according to claim 8, it is characterised in that：After Gamma corrections The expression formula of analog signal is：

Wherein, V_CONSTANT, k be constant, V_REFFor the first reference voltage, R_VARFor the resistance of the variable resistor, V_DACTurn for digital-to-analogue The analog signal exported after changing.