TWI780844B - Driving circuit - Google Patents

Abstract

A driving circuit includes a driving transistor, a first driver, a second driver, and a light emitting diode. The driving transistor is configured to output a driving signal according to a voltage stored in a first node. The first driver is configured to store a data signal to the first node according to the first scan signal, and determine whether to output the driving signal according to the first scan signal, a second scan signal, and an emission signal. The second driver is configured to provide a first compensation voltage to the first node according to the driving signal and the emission signal output by the first driver. The light emitting diode includes an anode terminal and a cathode terminal, and the anode terminal is coupled to the first driver or the driving transistor. The light emitting diode is configured to receive the driving signal to emit light.

Description

Drive circuit

This case is related to a display device, and in particular to a driving circuit applied to a micro light emitting diode display.

Active Micro-LED (AMLED) display has the advantages of high contrast, high color saturation and high brightness, making it one of the next-generation popular display technologies. When the traditional AMLED display is in operation, due to the temperature rise of the panel, the thermal effect of the light-emitting diode, that is, the reduction of its luminous efficiency and cross-voltage (Vled), leads to the brightness attenuation of the AMLED display. In view of this, how to solve the thermal effect of light-emitting diodes to provide high-quality AMLED displays is a technical problem to be solved in the industry.

This Summary is intended to provide a simplified summary of the disclosure in order to provide the reader with a basic understanding of the disclosure. This summary is not an extensive overview of the disclosure and it is not intended to identify key/critical elements of the embodiments or to delineate the scope of the disclosure.

One of the technical aspects of this case relates to a driving circuit. The drive circuit includes a drive transistor, a first driver, a second driver and light emitting diodes. The driving transistor is used for outputting a driving signal according to the voltage stored at the first node. The first driver is used for storing the data signal to the first node according to the first scan signal, and determining whether to output the drive signal according to the first scan signal, the second scan signal and the emission signal. The second driver is used for providing the first compensation voltage to the first node according to the driving signal and the emission signal output by the first driver. The light-emitting diode includes an anode end and a cathode end, and the anode end is coupled to a first driver or a driving transistor for receiving a driving signal to emit light.

Therefore, according to the technical content of the present application, the driving circuit shown in the embodiment of the present application can prevent the luminance from decaying as the temperature increases when the AMLED is in operation. In addition, the driving circuit of this case can improve the brightness attenuation problem of the display screen by compensating the voltage, so that the AMLED can display high-quality screens.

After referring to the following embodiments, those with ordinary knowledge in the technical field of this case can easily understand the basic spirit and other invention objectives of this case, as well as the technical means and implementation aspects adopted in this case.

In order to make the description of the disclosure more detailed and complete, the following provides an illustrative description of the implementation and specific embodiments of the present case; but this is not the only form of implementing or using the specific embodiments of the present case. The description covers features of various embodiments as well as method steps and their sequences for constructing and operating those embodiments. However, other embodiments can also be used to achieve the same or equivalent functions and step sequences.

Unless otherwise defined in this specification, the meanings of scientific and technical terms used herein are the same as those understood and commonly used by those with ordinary knowledge in the technical field to which this case belongs. In addition, the singular nouns used in this specification include the plural forms of the nouns, and the plural nouns used also include the singular forms of the nouns, unless the context conflicts with the context.

In addition, regarding the "coupling" or "connection" used herein, it may refer to two or more elements being in direct physical or electrical contact with each other, or indirect physical or electrical contact with each other, or it may refer to two or more components. elements interact or act on each other.

In this article, the term "circuit" generally refers to an object that is connected in a certain way by one or more transistors and/or one or more active and passive components to process signals.

Certain terms are used in the specification and claims to refer to particular elements. However, those skilled in the art should understand that the same element may be referred to by different terms. The description and the scope of the patent application do not use the difference in the name as the way to distinguish the components, but the difference in the function of the components as the basis for the distinction. The term "comprising" mentioned in the specification and scope of patent application is an open term, so it should be interpreted as "including but not limited to".

FIG. 1 is a block diagram of a driving circuit according to an embodiment of the present invention. As shown in the figure, the driving circuit 100 includes a driving transistor T1, a first driver 110, a second driver 120, and a light emitting diode D1, and the light emitting diode D1 includes an anode end and a cathode end. In terms of connection, the driving transistor T1 is coupled to the first driver 110, the first driver 110 is coupled to the second driver 120, and the anode terminal of the light-emitting diode D1 is coupled to the first driver 110 or the driving transistor T1. .

In order to provide high display quality micro-light-emitting diode drive circuit technology, this project provides a drive circuit 100 as shown in Figure 2 and waveforms of various control signal levels as shown in Figure 3 to control the drive circuit 100, the drive circuit The detailed operation of 100 is as follows.

As shown in FIG. 2 and FIG. 3 , the driving transistor T1 is used to output a driving signal according to the voltage stored in the first node N. For example, the driving signal can be the required current Iled of the light emitting diode D1.

Subsequently, the first driver 110 is used to store the data signal Vdata to the first node N according to the first scan signal S1 , and determine whether to output a driving signal according to the first scan signal S1 , the second scan signal S2 and the emission signal EM.

Then, the second driver 120 is used to provide the first compensation voltage to the first node N according to the driving signal and the emission signal EM output by the first driver 110 . The light emitting diode D1 is used for receiving a driving signal to emit light. For example, the second driver 120 may be a transistor T4.

FIG. 3 is a schematic diagram illustrating waveforms of various control signal levels according to an embodiment of the present invention. FIG. 4 to FIG. 6 are schematic diagrams illustrating the operation of the driving circuit shown in FIG. 1 according to another embodiment of the present invention. Please refer to FIG. 3 and FIG. 4 together. In one embodiment, the first driver 110 includes a storage capacitor C1. In the first phase P1, the storage capacitor C1 stores the data signal Vdata and the first pull-down signal Vref respectively at the first end and the second end of the storage capacitor C1 according to the first scan signal S1 and the second scan signal S2.

Please refer to FIG. 3 and FIG. 5 together. In another embodiment, in the second phase P2, the storage capacitor C1 stores the first terminal and the second terminal of the storage capacitor C1 respectively according to the first scanning signal S1. The data signal Vdata and the second compensation voltage. For example, the threshold voltage of the transistor T1 is Vth_T1, so the second compensation voltage is VDD-Vth_T1.

Please refer to FIG. 3 and FIG. 6 together. In another embodiment, in the third phase P3, the storage capacitor stores the first compensation at the first terminal and the second terminal of the storage capacitor C1 according to the transmission signal EM. voltage and coupling voltage, and the light-emitting diode receives the driving signal to emit light. For example, the voltage value of the terminal Q is VSS+Vled, and is transmitted to the first terminal of the storage capacitor through the transistor T4, so the first compensation voltage is VSS+Vled. However, the first terminal of the storage capacitor C1 stores The voltage is adjusted to VSS+Vled by the data signal Vdata, therefore, the voltage adjustment value (VSS+Vled-Vdata) of the first terminal of the storage capacitor C1 will be coupled to the second terminal of the storage capacitor C1, plus the voltage of the storage capacitor C1 The second compensation voltage (VDD-Vth_T1) originally stored at the second terminal finally stores the coupled voltage stored at the second terminal of the storage capacitor C1 as (VDD-Vth_T1+Vled+VSS-Vdata).

…公式1 In another embodiment, the calculation method of the above driving signal is disclosed as follows. Please refer to Figure 6, the calculation formula of the driving signal is as follows:

…Formula 1

The above-mentioned Iled is a driving signal, k is a process parameter of the transistor T1, Vsg_T1 is a source gate voltage of the transistor T1, and Vth_T1 is a threshold voltage of the transistor T1. Also, Vsg_T1=Vs_T1-Vg_T1. For example, Vg_T1 is the gate voltage of transistor T1, at this time, Vg_T1=VDD-|Vth_T1|+Vled+VSS-Vdata. In addition, Vs_T1 is the source voltage of the transistor T1. At this time, the source voltage of the transistor T1 is the power supply voltage VDD. Therefore, the source voltage Vs_T1=VDD, so Vsg_T1=VDD-(VDD – |Vth_T1| + Vled + VSS - Vdata) = |Vth_T1| - Vled - VSS + Vdata.

…公式2 Then, the above-mentioned Vsg_T1 is brought into Formula 1 to obtain the calculation formula of the driving signal as follows:

...Formula 2

Since the luminance of the light-emitting diode is equal to the product of the luminous efficiency and the driving signal Iled, when the luminous efficiency and cross-voltage (Vled) of the light-emitting diode become smaller due to thermal effects, as shown in formula 2, the process parameters k, When the data signal Vdata and the second pull-down signal Vss are at constant values, when the diode cross voltage Vled becomes smaller, the driving signal Iled becomes larger, thereby compensating for the brightness attenuation phenomenon caused by the reduced luminous efficiency of the LED.

FIG. 7 is a detailed circuit diagram of a driving circuit according to another embodiment of the present application. Compared with the driving circuit 100 shown in FIG. 1 , the connection method of the driving transistor T4 of the driving circuit 100A in FIG. 7 is different. In one embodiment, one end of the transistor T4 of the driving circuit 100A is also coupled to the first node N, but the other end of the transistor T4 of the driving circuit 100A is coupled to the first node between the transistor T6 and the driving transistor T1 Two nodes Q1. It should be noted that, in the embodiment shown in FIG. 7, the component numbers are similar to those in FIG. 1, and have similar structural and electrical operation features. For the sake of brevity, details are not repeated here.

FIG. 8 is a block diagram of a driving circuit according to another embodiment of the present application. FIG. 9 is a detailed circuit diagram of a driving circuit according to another embodiment of the present application. Please refer to FIG. 8 and FIG. 9 together. In one embodiment, the driving circuit 800 includes a light emitting diode D1, a first driving circuit 810, a second driving circuit 820, and a driving transistor T1. The light emitting diode D1 includes an anode end and a cathode end. In terms of connection, the cathode terminal of the light emitting diode D1 is coupled to the first driver 810 or the driving transistor T1, the first driver 810 is coupled to the second driver 820, and the driving transistor T1 is coupled to the first driver 810 .

In operation, the light emitting diode D1 is used for receiving a driving signal to emit light. The first driver 810 is used to store the data signal Vdata to the first node N according to the first scan signal S1, and determine whether to provide a driving signal according to the first scan signal S1, the second scan signal S2 and the emission signal EM. For example, the driving signal can be the required current Iled of the LED.

Then, the second driver 820 is used to provide the first compensation voltage to the first node N according to the emission signal EM. The driving transistor T1 is used for providing a driving signal to the light emitting diode according to the data signal stored in the first node N and the first compensation voltage. For example, the second driver 820 can be a transistor T4.

FIG. 10 is a schematic diagram illustrating waveforms of various control signal levels according to another embodiment of the present invention. FIG. 11 to FIG. 13 are schematic diagrams illustrating the operation of the driving circuit shown in FIG. 9 according to yet another embodiment of the present application. Please refer to FIG. 10 and FIG. 11 together. In one embodiment, the first driver 810 includes a storage capacitor C1. In the first phase P1, the storage capacitor C1 stores the data signal Vdata and the first pull-down signal Vref respectively at the first end and the second end of the storage capacitor C1 according to the first scan signal S1 and the second scan signal S2.

Please refer to FIG. 10 and FIG. 12 together. In another embodiment, during the second phase P2, the storage capacitor C1 stores data at the first terminal and the second terminal of the storage capacitor C1 according to the first scanning signal S1. The signal Vdata and the second pull-down signal VSS. For example, the threshold voltage of the transistor T1 is Vth_T1, so the second compensation voltage is VSS+Vth_T1.

Please refer to FIG. 10 and FIG. 13 together. In yet another embodiment, during the third phase P3, the storage capacitor C1 stores the first compensation at the first terminal and the second terminal of the storage capacitor C1 according to the transmission signal EM. voltage and coupling voltage. Then, the light emitting diode D1 receives the driving signal and emits light. For example, the voltage value of the terminal Q is (VDD-Vled). However, the storage voltage at the first terminal of the storage capacitor C1 is adjusted to (VDD-Vled) by the data signal Vdata. Therefore, the first terminal of the storage capacitor C1 The voltage adjustment value (VDD-Vled-Vdata) at the terminal will be coupled to the second terminal of the storage capacitor C1, plus the second compensation voltage (VSS+ Vth_T1) originally stored at the second terminal of the storage capacitor C1, and finally stored in the storage capacitor C1 The coupling voltage stored at the second terminal of the VSS is (VSS+ Vth_T1-Vled+ VDD-Vdata).

…公式3 In another embodiment, the calculation method of the above driving signal is disclosed as follows. Please refer to Figure 10, the calculation formula of the driving signal is as follows:

…Formula 3

The above-mentioned Iled is a driving signal, k is a process parameter of the transistor T1, Vgs_T1 is a gate-source voltage of the transistor T1, and Vth_T1 is a threshold voltage of the transistor T1. In addition, Vgs_T1=Vg_T1-Vs_T1. For example, Vg_T1 is the gate voltage of the transistor T1, at this time, Vg_T1=VSS+Vth_T1−VLED+VDD−Vdata. In addition, Vs_T1 is the source voltage of the transistor T1. At this time, the source voltage of the transistor T1 is the second pull-down signal VSS. Therefore, the source voltage Vs_T1=VSS, so Vgs_T1=(VSS+Vth_T1-VLED+VDD –Vdata) - VSS= Vth_T1–VLED+VDD– Vdata.

…公式4 Then, put the above Vgs_T1 into formula 3 to get the calculation formula of the driving signal as follows:

…Formula 4

Since the luminance of the light-emitting diode is equal to the product of the luminous efficiency and the driving signal Iled, when the luminous efficiency and the cross-voltage (Vled) of the light-emitting diode become smaller due to the thermal effect, as shown in formula 4, the process parameters k, When the power supply voltage VDD and the data signal Vdata are at constant values, when the diode cross voltage Vled decreases, the driving signal Iled increases, thereby compensating for the brightness attenuation phenomenon caused by the decrease of the luminous efficiency of the light emitting diode.

FIG. 14 is a detailed circuit diagram of a driving circuit according to another embodiment of the present application. Compared with the driving circuit 800 shown in FIG. 8, the connection method of the driving transistor T4 of the driving circuit 800A in FIG. 14 is different. In one embodiment, one end of the transistor T4 of the driving circuit 800A is also coupled to the first node N, but the other end of the transistor T4 of the driving circuit 800A is coupled to the first node between the transistor T6 and the driving transistor T1 Two nodes Q1. It should be noted that, in the embodiment shown in FIG. 7, the component numbers are similar to those in FIG. 1, and have similar structural and electrical operation features. For the sake of brevity, details are not repeated here.

As can be seen from the implementation manner of the present case described above, the application of the present case has the following advantages. The drive circuits 100 , 100A, 800 , and 800A shown in the embodiment of the present case can prevent the brightness of the AMLED from decaying as the temperature rises during operation. In addition, the driving circuits 100, 100A, 800, and 800A of this application can improve the problem of brightness attenuation of the display screen by compensating the voltage, so that the AMLED can display high-quality screens.

Although the specific examples of the present case are disclosed in the above implementation manners, they are not intended to limit the present case. Please note that in the foregoing figures, the shapes, sizes and proportions of components are for illustration only, and are for the understanding of this case by those with ordinary knowledge in the technical field of this case, and are not intended to limit this case. Those with ordinary knowledge in the technical field of this case can make various changes and modifications without departing from the principle and spirit of this case. Therefore, the scope of protection of this case should be defined by the scope of the accompanying patent application. .

100, 100A, 800 and 800A: drive circuit

110, 110A, 810 and 810A: first driver

120, 820: second driver

T1: drive transistor

D1: light emitting diode

S1: the first scan signal

S2: Second scan signal

EM: transmit signal

Data: data signal

Vdata: data signal

VDD: power supply voltage

VSS: the second pull-down signal

T2～T6: Transistor

N: first node

Q: endpoint

Q1: Second node

In order to make the above and other purposes, features, advantages and embodiments of this case more obvious and understandable, the accompanying drawings are explained as follows: FIG. 1 is a block diagram of a driving circuit according to an embodiment of the present invention. FIG. 2 is a detailed circuit diagram of a driving circuit according to an embodiment of the present invention. FIG. 3 is a schematic diagram illustrating waveforms of various control signal levels according to an embodiment of the present invention. FIG. 4 to FIG. 6 are schematic diagrams illustrating the operation of the driving circuit shown in FIG. 1 according to another embodiment of the present invention. FIG. 7 is a detailed circuit diagram of a driving circuit according to another embodiment of the present application. FIG. 8 is a block diagram of a driving circuit according to another embodiment of the present application. FIG. 9 is a detailed circuit diagram of a driving circuit according to another embodiment of the present application. FIG. 10 is a schematic diagram illustrating waveforms of various control signal levels according to another embodiment of the present invention. FIG. 11 to FIG. 13 are schematic diagrams illustrating the operation of the driving circuit shown in FIG. 9 according to yet another embodiment of the present application. FIG. 14 is a detailed circuit diagram of a driving circuit according to another embodiment of the present application. In accordance with common practice, the various features and elements in the drawings are not drawn to scale, but are drawn in a manner to best present specific features and elements relevant to the case. In addition, the same or similar reference numerals refer to similar elements/components in different drawings.

Domestic deposit information (please note in order of depositor, date, and number) none Overseas storage information (please note in order of storage country, institution, date, and number) none

100: drive circuit

110: First drive

120:Second drive

T1: drive transistor

D1: light emitting diode

S1: the first scan signal

S2: Second scan signal

EM: transmit signal

Data: data signal

Vdata: data signal

VDD: power supply voltage

VSS: the second pull-down signal

Claims (10)

A drive circuit comprising: a driving transistor for outputting a driving signal according to a voltage stored at a first node; A first driver, used to store a data signal to the first node according to a first scan signal, and determine whether to output the drive signal according to the first scan signal, a second scan signal and a transmission signal; a second driver, used to provide a first compensation voltage to the first node according to the driving signal and the emission signal output by the first driver; and A light-emitting diode includes an anode end and a cathode end, wherein the anode end is coupled to the first driver or the driving transistor, and is used for receiving the driving signal to emit light. The driving circuit as described in claim 1, wherein the first driver includes a storage capacitor, wherein in a first stage, the storage capacitor is in a storage capacitor according to the first scan signal and the second scan signal The first terminal and a second terminal respectively store the data signal and a first pull-down signal. The drive circuit as described in claim 2, wherein in a second stage, the storage capacitor stores the data signal and a first terminal respectively at the first terminal and the second terminal of the storage capacitor according to the first scan signal Two compensation voltages. The drive circuit as described in claim 3, wherein in a third stage, the storage capacitor stores the first compensation voltage and a coupling at the first end and the second end of the storage capacitor according to the transmission signal, respectively voltage, wherein the LED receives the driving signal to emit light. The driving circuit as claimed in claim 1, wherein the second driver, the first driver and the driving transistor are coupled to a second node. A drive circuit comprising: A light-emitting diode, including an anode end and a cathode end, is used to receive a driving signal to emit light; A first driver, used to store a data signal to a first node according to a first scan signal, and determine whether to provide the drive signal according to the first scan signal, a second scan signal and an emission signal; a second driver, used to provide a first compensation voltage to the first node according to the transmit signal; and a driving transistor for providing the driving signal to the light emitting diode according to the data signal stored in the first node and the first compensation voltage, wherein the cathode terminal is coupled to the first driver or the driver Transistor. The driving circuit as described in claim 6, wherein the first driver includes a storage capacitor, wherein in a first stage, the storage capacitor is in a storage capacitor according to the first scan signal and the second scan signal The first terminal and a second terminal respectively store the data signal and a first pull-down signal. The drive circuit as described in claim 7, wherein in a second stage, the storage capacitor stores the data signal and a first terminal respectively at the first terminal and the second terminal of the storage capacitor according to the first scan signal Two pull-down signals. The drive circuit as described in claim 8, wherein in a third stage, the storage capacitor stores the first compensation voltage and a coupling at the first terminal and the second terminal of the storage capacitor according to the transmission signal, respectively voltage, wherein the LED receives the driving signal to emit light. The driving circuit as claimed in claim 6, wherein the first driver, the second driver and the driving transistor are coupled to a second node.

Images