TWI789846B - Driving circuit - Google Patents

Abstract

A driving circuit includes a driver, a driving transistor, a reset transistor and a light-emitting diode. The driver is configured to store a data voltage according to a scanning signal, and determining whether to provide a power supply voltage according to the data voltage, the previous-stage emission signal and the latter-stage emission signal. The driving transistor is coupled to the driver and configured to output the power supply voltage according to the latter-stage emission signal. The reset transistor is coupled to the driving transistor and configured to output a first pull-down signal according to the transmission signal. The light-emitting diode is coupled to the driving transistor and configured to emit light according to the power supply voltage. The previous-stage emission signal, the emission signal, and the latter-stage emission signal correspond to the first to n-th level signals, and n is a positive integer greater than 1.

Description

Drive circuit

This case is related to a display device, and in particular to a driving circuit applied to an active matrix organic light emitting diode display.

Active-matrix organic light-emitting diode (AMOLED) display has the advantages of high contrast, high color saturation and good luminous efficiency, making it one of the hot technologies in the next generation. When the traditional AMOLED display is operated at low frequency, the brightness gradually decreases due to TFT leakage, and the brightness difference between the active frame and the skip frame causes the AMOLED display to flicker. Therefore, how to provide AMOLED driving circuits and displays with high display quality 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 driving circuit includes a driver, a driving transistor, a reset transistor and a light emitting diode. The driver is used to store the data voltage according to the scan signal, and decides whether to provide the power supply voltage according to the data voltage, the previous transmission signal and the subsequent transmission signal. The driving transistor is coupled to the driver, and is used for outputting a power supply voltage according to a post-transmitting signal. The reset transistor is coupled to the driving transistor and used for outputting a first pull-down signal according to the transmitting signal. The light-emitting diode is coupled to the drive transistor, and is used to receive the power supply voltage to emit light, wherein the front-stage emission signal, emission signal and rear-stage emission signal correspond to the first to nth-level signals, and n is a positive value greater than 1 integer.

Therefore, according to the technical content of the present application, the driving circuit shown in the embodiment of the present application can make the brightness of the AMOLED be the same during the active phase (Active frame) and the skip phase (Skip frame) operation. In addition, the driving circuit of this case can resist TFT leakage. Therefore, using the driving circuit shown in the embodiment of this case can improve the flickering problem of the display screen, so that AMOLED 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 schematic diagram illustrating a driving circuit according to an embodiment of the present invention. As shown in the figure, the driving circuit 100 includes a driver 110 , a driving transistor T6 , a reset transistor T7_2 and a light emitting diode D1 . In connection, the driver 110 is coupled to the driving transistor T6, the driving transistor T6 is coupled to the reset transistor T7_2 and the light emitting diode D1, and the reset transistor T7_2 is coupled to the light emitting diode D1.

In order to provide high display quality active matrix organic light emitting diode drive circuit technology, this project provides a drive circuit 100 as shown in Figure 1 and waveforms of various control signal levels as shown in Figure 2 to control the drive circuit 100, The related operations of the driving circuit 100 are described in detail below.

As shown in FIG. 1 and FIG. 2, the driver 110 is used to store the data voltage Vdata according to the scan signal Scan, and to store the data voltage Vdata according to the data voltage Vdata, the previous emission signal EM(n-1) and the subsequent emission signal EM(n+ 1) to decide whether to provide the power supply voltage VDD. For example, the driver 110 provides the data voltage Vdata to the gate of the transistor T4, and the driver 110 controls whether to provide the power supply voltage by providing the previous emission signal EM(n-1) to the gate of the transistor T1. VDD. In addition, transistors T1 and T4 can be implemented by any suitable type of P-type transistors, such as: P-type thin-film transistors (Thin-film Transistor, TFT), P-type metal-oxide semiconductor field-effect transistors (Metal-Oxide -Semiconductor Field-Effect Transistor, PMOSFET), etc., but not limited thereto.

Subsequently, the driving transistor T6 is coupled to the driver 110 and used to output the power supply voltage VDD according to the post-stage emission signal EM(n+1). The reset transistor T7_2 is used to output the first pull-down signal Vrefn to the driving transistor T6 according to the emission signal EM(n). In addition, the driving transistor T6 can be implemented by any suitable type of P-type transistor, such as: P-type thin-film transistor (Thin-film Transistor, TFT), P-type metal-oxide-semiconductor field-effect transistor (Metal-Oxide- Semiconductor Field-Effect Transistor, PMOSFET), etc., and the reset transistor T7_2 can be implemented by any suitable type of N-type transistor, for example: N-type oxide semiconductor thin film transistor (Oxide Thin-film Transistor, Oxide TFT), N-type thin-film transistor (Thin-film Transistor, TFT) and N-type metal-oxide-semiconductor field-effect transistor (Metal-Oxide-Semiconductor Field-Effect Transistor, PMOSFET), etc., but not limited thereto.

Then, the light emitting diode D1 is used to receive the power supply voltage VDD to emit light. For example, when the power supply voltage VDD is transmitted to the light emitting diode D1 through the driver 110 and the driving transistor T6, the light emitting diode D1 receives the power supply voltage VDD to emit light. In addition, the preceding transmission signal EM(n-1), the transmission signal EM(n) and the subsequent transmission signal EM(n+1) correspond to the first to nth level signals, n is a positive integer greater than 1, and the previous The difference between the first pulse of the stage emission signal EM(n-1) and the second pulse of the emission signal EM(n) is one period.

Please refer to FIG. 2 and FIG. 3 together. In one embodiment, the driver 110 includes a storage capacitor C1. In the first active phase P1, the storage capacitor C1 stores the data voltage Vdata and the first Pull down signal Vrefn. Then, the LED D1 is reset according to the emission signal EM(n). For example, the reset transistor T7_2 outputs the first pull-down signal Vrefn according to the emission signal EM(n), and the light-emitting diode D1 receives the first pull-down signal Vrefn to reset. this In addition, the voltage range of the first pull-down signal Vrefn may be -5~5V.

Please refer to FIG. 2 and FIG. 4 together. In another embodiment, during the second active phase P2, the storage capacitor C1 is in the The first terminal and the second terminal respectively store the data voltage Vdata and the compensation voltage. For example, if the voltage provided by the power supply voltage VDD is VDD, and the threshold voltage of the transistor T4 is Vth_T4, then the compensation voltage is (VDD−Vth_T4).

Please refer to Fig. 2 and Fig. 5 together. In yet another embodiment, during the third active phase P3, the storage capacitor C1 is connected between the first terminal and the second terminal according to the post-transmission signal EM(n+1). The second pull-down signal Vrefp and the coupling voltage are respectively stored, wherein the driving transistor T6 outputs the power supply voltage VDD according to the subsequent emission signal EM(n+1). Then, the light emitting diode D1 receives the power supply voltage VDD to emit light. For example, the first end of the storage capacitor C1 stores the data voltage Vdata in the second active phase P2, and then the first end of the storage capacitor C1 is adjusted to the second pull-down signal Vrefp in the third active phase P3, therefore, the storage capacitor C1 The voltage modulation value (Vrefp-Vdata) of the first terminal of C1 will be coupled to the second terminal of storage capacitor C1, plus the compensation voltage originally stored at the second terminal of storage capacitor C1 is (VDD-Vth_T4), the final storage capacitor The coupled voltage stored at the second terminal of C1 is (VDD-Vth_T4+Vrefp-Vdata). In addition, the transistor T2 can be realized by any suitable type of P-type transistor, for example: P-type thin-film transistor (Thin-film Transistor, TFT), P-type metal-oxide-semiconductor field-effect transistor (Metal-Oxide-Semiconductor Field-Effect Transistor, PMOSFET), etc., but not limited thereto.

Please refer to FIG. 6 and FIG. 7 together. In yet another embodiment, the driver 110 includes a storage capacitor C1. During the first jumping phase S1, the storage capacitor C1 is switched on according to the post-stage emission signal EM(n+1). The first terminal and the second terminal respectively store the second pull-down signal Vrefp and the threshold voltage. Then, the LED D1 is reset according to the emission signal EM(n). For example, if the threshold voltage of the transistor T4 is Vgs_T4, the threshold voltage stored at the second terminal of the storage capacitor C1 is Vgs_T4. Then, the reset transistor T7-2 is turned on according to the emission signal EM(n), so that the light-emitting diode D1 receives the first pull-down signal Vrefn to reset.

In addition, the voltage range of the first pull-down signal Vrefn may be -5~5V. Furthermore, the reset transistor T7_2 can be implemented by any suitable type of N-type transistor, for example: N-type oxide semiconductor thin-film transistor (Oxide Thin-film Transistor, Oxide TFT), N-type thin-film transistor (Thin-film Transistor, film Transistor, TFT), and N-type metal-oxide-semiconductor field-effect transistor (Metal-Oxide-Semiconductor Field-Effect Transistor, PMOSFET), etc., but not limited thereto.

Please refer to FIG. 6 and FIG. 8 together. In another embodiment, during the second skipping phase S2, the storage capacitor C1 maintains the first terminal and the second terminal to respectively store the second pull-down signal Vrefp and the threshold voltage. In addition, The LED D1 maintains the reset voltage. For example, if the threshold voltage of the transistor T4 is Vgs_T4, the threshold voltage stored at the second terminal of the storage capacitor C1 is Vgs_T4. Then, the transistor T7-2 according to the emission signal EM(n) And turn on, so that the light-emitting diode D1 continues to receive the first pull-down signal Vrefn to maintain the reset voltage. In addition, the voltage range of the first pull-down signal Vrefn may be -5~5V.

Please refer to FIG. 6 and FIG. 9 together. In yet another embodiment, during the third skipping stage S3, the storage capacitor C1 is connected between the first terminal and the second terminal according to the post-transmission signal EM(n+1). The second pull-down signal Vrefp and the threshold voltage are respectively stored. Then, the driving transistor T6 outputs the power supply voltage VDD according to the subsequent emission signal EM(n+1). Subsequently, the light emitting diode D1 receives the power supply voltage VDD to emit light. For example, if the threshold voltage of the transistor T4 is Vgs_T4, the threshold voltage stored at the second terminal of the storage capacitor C1 is Vgs_T4, and the transistor T4 is turned on according to the threshold voltage. Then, the driver 110 provides the power supply voltage VDD by providing the previous emission signal EM(n−1) to the gate of the transistor T1.

FIG. 10 is a schematic diagram illustrating a driving circuit according to another embodiment of the present application. Compared with the driving circuit 100 in FIG. 1 , the difference of the driving circuit 100A in FIG. 10 is the electrical connection between the reset transistor T7_2 and the scanning signal Scan. In the embodiment of FIG. 10 , the reset transistor T7_2 can be used to output the first pull-down signal Vrefn according to the scan signal Scan. Under the electrical connection mode and corresponding electrical operation of the driving circuit 100A in FIG. 10, it can still achieve the same effect as the driving circuit 100 in FIG. It is the same as the output brightness of Skip frame.

FIG. 11 is a schematic diagram illustrating a driving circuit according to another embodiment of the present application. Compared with the driving circuit 100 in FIG. 1 , the difference of the driving circuit 100B in FIG. 11 is that one transistor T3 is reduced, so that this case can still achieve the original expected effect while reducing the number of driving components. Please refer to FIG. 1 and FIG. 11 together. In yet another embodiment, the driver 110 or 110B may further include a transistor T3. In addition, the transistor T3 can be realized by any suitable type of P-type transistor, for example: P-type thin-film transistor (Thin-film Transistor, TFT), P-type metal-oxide-semiconductor field-effect transistor (Metal-Oxide-Semiconductor Field-Effect Transistor, PMOSFET), etc., but not limited thereto.

Please refer to FIG. 1 , FIG. 10 and FIG. 11 together. In one embodiment, the driving transistor T6 and the reset transistor T7_2 are different types of transistors. For example, when the driving transistor T6 is an N-type transistor, the reset transistor T7_2 is a P-type transistor, and vice versa. When the driving transistor T6 is a P-type transistor, the reset transistor T7_2 It is an N-type transistor. Then, the driving transistor T6 and the reset transistor T7_2 can be made of different types of materials. In addition, the driving transistor T6 and the reset transistor T7_2 mentioned above can be oxide semiconductor thin-film transistor (Oxide Thin-film Transistor, Oxide TFT), thin-film transistor (Thin-film Transistor, TFT), and metal oxide Metal-Oxide-Semiconductor Field-Effect Transistor (PMOSFET), etc., but not limited thereto.

Please refer to FIG. 1 , FIG. 10 and FIG. 11 together. In yet another embodiment, the driver 110 includes the emitting transistor T7_1 , and the emitting transistor T7_1 and the reset transistor T7_2 are the same type of transistor. For example, the emitter transistor T7_1 and the reset transistor T7_2 can use an oxide semiconductor thin-film transistor (Oxide Thin-film Transistor, Oxide TFT), which is used to reduce the change of the threshold voltage of the transistor over time, so as to reduce the electric current. The effect of gradual decrease in brightness due to TFT leakage.

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 driving circuit 100 shown in the embodiment of the present case can make the brightness of the AMOLED be the same in the active phase (Active frame) and the skip phase (Skip frame) operation. In addition, the driving circuit of this case can resist TFT leakage. Therefore, using the driving circuit shown in the embodiment of this case can improve the flickering problem of the display screen, so that AMOLED 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 and 100B: drive circuit

110, 110A and 110B: Drivers

T6: drive transistor

T7_2: reset transistor

D1: light emitting diode

T7_1: Transmitter transistor

T1~T5: Transistor

C1: storage capacitor

EM(n-1): Front-stage emission signal

EM(n1): transmit signal

EM(n+1): post-transmission signal

Scan: scan signal

Vdata: data signal

Vrefn: the first pull-down signal

Vrefp: the second pull-down signal

VDD: power supply voltage

VSS: pull down signal

200: Various control signal levels in the active phase

P1~P3: Activity stage

300: Various control signal levels in the jump phase

S1~S3: jump stage

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 schematic diagram illustrating a driving circuit according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing waveforms of various control signal levels according to an embodiment of the present invention. FIG. 3 to FIG. 5 are schematic diagrams illustrating the operation of the driving circuit shown in FIG. 1 according to another embodiment of the present invention. FIG. 6 is a schematic diagram illustrating waveforms of various control signal levels according to another embodiment of the present invention. FIG. 7 to FIG. 9 are schematic diagrams illustrating the operation of the driving circuit shown in FIG. 1 according to another embodiment of the present application. FIG. 10 is a schematic diagram illustrating a driving circuit according to another embodiment of the present application. FIG. 11 is a schematic diagram illustrating 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.

100: drive circuit

110: drive

T6: drive transistor

T7_2: reset transistor

D1: light emitting diode

T7_1: Transmitter transistor

T1~T5: Transistor

C1: storage capacitor

EM(n-1): Front-stage emission signal

EM(n1): transmit signal

EM(n+1): post-transmission signal

Scan: scan signal

Vdata: data signal

Vrefn: the first pull-down signal

Vrefp: the second pull-down signal

VDD: power supply voltage

VSS: pull down signal

Claims (10)

A driving circuit, comprising: a driver, used to store a data voltage according to a scanning signal, and determine whether to provide a power supply voltage according to the data voltage, a previous-stage transmission signal and a subsequent-stage transmission signal; a driving circuit a crystal, coupled to the driver, and used to output the power supply voltage according to the post-transmission signal; a reset transistor, coupled to the driving transistor, and used to output a first pull-down according to a transmission signal signal; and a light-emitting diode, coupled to the drive transistor, and used to receive the power supply voltage to emit light, wherein the front-stage emission signal, the emission signal and the rear-stage emission signal correspond to the first stage to the first stage n-level signal, n is a positive integer greater than 1, wherein the difference between the first pulse of the previous transmission signal and the second pulse of the transmission signal is one cycle. The driving circuit as described in claim 1, wherein the driver includes a storage capacitor, wherein in a first active phase, the storage capacitor is connected to a first end according to the emission signal, the subsequent emission signal and the scanning signal and a second terminal store the data voltage and the first pull-down signal respectively, wherein the light emitting diode is reset according to the emission signal. The drive circuit as described in claim 2, wherein during a second active phase, the storage capacitor stores the material voltage and a compensation voltage, wherein the LED is reset according to the emission signal. The driving circuit as described in claim 3, wherein in a third active phase, the storage capacitor stores a second pull-down signal and a coupling voltage at the first terminal and the second terminal respectively according to the subsequent transmission signal , wherein the drive transistor outputs the power supply voltage according to the post-transmission signal, and wherein the light emitting diode receives the power supply voltage to emit light. The driving circuit as described in claim item 1, wherein the driver includes a storage capacitor, wherein during a first skipping phase, the storage capacitor stores the first end and the second end respectively according to the post-stage transmission signal The second pull-down signal and a threshold voltage, wherein the LED is reset according to the emission signal. The driving circuit as described in claim 5, wherein in a second jumping phase, the storage capacitor maintains the first terminal and the second terminal to respectively store the second pull-down signal and the threshold voltage, wherein the light emitting diode Resetting is performed according to the transmission signal. The driving circuit as described in claim 6, wherein in a third jumping stage, the storage capacitor stores the second pull-down signal and the threshold voltage at the first end and the second end respectively according to the subsequent transmission signal , wherein the driving transistor outputs the power supply voltage according to the post-stage emission signal voltage, wherein the LED receives the power supply voltage to emit light. The driving circuit according to claim 1, wherein the reset transistor is used to output the first pull-down signal according to the scan signal. The driving circuit according to claim 1, wherein the driving transistor and the reset transistor are different types of transistors. The driving circuit according to claim 1, wherein the driver comprises an emitting transistor, wherein the emitting transistor and the reset transistor are of the same type.

Images