CN114627805A

CN114627805A - Drive circuit, drive method of LED unit and display panel

Info

Publication number: CN114627805A
Application number: CN202210514805.2A
Authority: CN
Inventors: 黄尊恺; 庄永漳
Original assignee: Laiyu Optoelectronic Technology Suzhou Co ltd
Current assignee: Laiyu Optoelectronic Technology Suzhou Co ltd
Priority date: 2022-05-12
Filing date: 2022-05-12
Publication date: 2022-06-14
Anticipated expiration: 2042-05-12
Also published as: CN114627805B

Abstract

The embodiment of the specification provides a driving circuit, a driving method of an LED unit and a display panel, wherein the driving circuit comprises: the voltage-pulse width converter is provided with a voltage input end and a signal output end and converts the input voltage of the voltage input end into a control signal with corresponding duration; a row selection switch module, which switches on the input voltage for the voltage input end of the voltage-pulse width converter under the condition of receiving a row selection signal; and the current switch module is controlled by the control signal and is in a conducting state in the maintaining process of the control signal. By converting the analog signal into a corresponding digital pulse width signal and keeping the current flowing through the light emitting unit constant, a simpler driving circuit of the LED unit is provided.

Description

Drive circuit, drive method of LED unit and display panel

Technical Field

The present disclosure relates to the field of electronic circuits, and in particular, to a driving circuit, a driving method of an LED unit, and a display panel.

Background

The LED unit has the advantages of high brightness, high contrast, low power consumption, long service life, quick response and the like, and can be applied to the fields of AR/VR glasses, projectors and the like.

In the related art, the light emitting unit may be driven by a digital signal. In the digital driving method, the light emitting unit is only in a lighting state and a non-lighting state, and the current flowing through the light emitting unit when the pixel emits light tends to be constant. The display of different gray scales is realized by controlling the lighted time length of the light-emitting unit in a fixed period and taking the light-emitting time length as a fixed proportion.

However, the digital driving method has a complex timing sequence, and requires a complex and redundant peripheral memory circuit and a control circuit to cooperate to realize the basic display function, so that the digital driving chip is also difficult to satisfy the requirement of LED unit display for miniaturization.

Disclosure of Invention

In view of the above, embodiments of the present disclosure are directed to providing a driving circuit, a method of an LED unit, and a display panel, which simplify the driving circuit to some extent.

This specification embodiment provides a drive circuit, includes: the voltage-pulse width converter is provided with a voltage input end and a signal output end and converts the input voltage of the voltage input end into a control signal with corresponding duration; a row selection switch module, which switches on the input voltage for the voltage input end of the voltage-pulse width converter under the condition of receiving a row selection signal; and the current switch module is controlled by the control signal and is in a conducting state in the maintaining process of the control signal.

The embodiment of the present specification provides a driving method of an LED unit, including: in response to the row selection switch module receiving that the row selection signal is in a first state, switching on an input voltage for a voltage input end of the voltage-pulse width converter; the voltage-pulse width converter outputs a control signal with corresponding duration to the current switch module corresponding to the input voltage; the current switch module is controlled by the control signal and is in a conducting state in the maintaining process of the control signal, so that the LED unit is lightened.

Embodiments of the present specification provide a display panel including: an LED unit array, comprising a plurality of said driving circuits as in any of the above embodiments arranged in an array; the row driving circuit line is used for providing a row selection signal for controlling the state of a row selection switch module in the driving circuit; a serial-to-parallel conversion circuit for converting a serial input image signal into a parallel digital signal; and the digital-to-analog conversion circuit is used for converting the parallel digital signals output by the serial-to-parallel conversion circuit into analog signals to be used as the input voltage of the driving circuit.

The embodiment of the specification provides a driving circuit. The analog signal is converted into the digital pulse width signal corresponding to the analog signal according to the charging and discharging characteristics of the energy storage module, so that the lighting time of the light-emitting unit is controlled to display different gray scales, and a simpler driving circuit is provided to a certain extent.

Drawings

Fig. 1 is a schematic diagram of an LED unit driving architecture according to an embodiment.

Fig. 2 is a schematic diagram of a driving circuit according to an embodiment.

Fig. 3 is a diagram illustrating an exemplary driving circuit according to an embodiment.

Fig. 4 is a diagram illustrating an exemplary driving circuit according to an embodiment.

Fig. 5 is a timing diagram of a driving circuit according to an embodiment.

FIG. 6 is a diagram illustrating an embodiment of a driving circuit in a data writing phase.

Fig. 7a is a diagram illustrating an embodiment of a driving circuit in a light emitting stage.

Fig. 7b is an exemplary diagram of the driving circuit in the extinguishing phase according to one embodiment.

Fig. 8 is a schematic diagram of a driving circuit according to an embodiment.

Fig. 9 is a flowchart illustrating a driving method of an LED unit according to an embodiment.

Detailed Description

In order to make the technical solution of the present invention better understood, the technical solution of 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, not all of the embodiments of the present invention. All other embodiments obtained by a person of ordinary skill in the art without any inventive work based on the embodiments in the present specification belong to the protection scope of the present specification.

The embodiment of the specification provides a digital-analog hybrid driving circuit for an LED unit, and the circuit can comprise an analog driving chip. The analog driving chip can be integrated with complete functional modules such as a high-speed interface, serial-parallel conversion, a digital-to-analog converter, an output buffer and the like, does not need a complex peripheral circuit, and is easy to realize the miniaturization of the display panel. An externally input serial digital image signal can be directly converted into a parallel analog signal corresponding to the externally input serial digital image signal on a chip. In addition, the LED unit array in the circuit consists of digital-analog mixed type pixel units. The pixel unit does not directly control the current of the light-emitting unit by the received analog signal, but converts the analog signal into a digital pulse width signal corresponding to the analog signal, keeps the current flowing through the light-emitting unit unchanged, and controls the lighting time of the light-emitting unit by the digital pulse width signal to realize the display of different gray scales.

Referring to fig. 1, an embodiment of the present disclosure provides an LED unit driving architecture, which includes an LED unit array, a row driving circuit, a high-speed interface, a serial-to-parallel conversion circuit, a multi-channel digital-to-analog converter, a multi-channel analog output buffer, a clock, a reference circuit, and a control circuit. The row driving circuit provides a row scanning signal for the LED unit array, and can be used for controlling the state of a row selection switch module in the driving circuit. The high-speed interface and the serial-parallel conversion circuit can convert the image signal input in series into a parallel digital signal. The digital-to-analog converter may convert the image information from a digital signal to an analog signal. The output buffer may amplify the analog signal and provide the amplified analog signal to the array of LED units. After receiving the analog signal, the LED unit array can convert the analog signal into a digital pulse width signal, the current flowing through the light-emitting unit is kept unchanged, and the time length of the light-emitting unit which is lightened is controlled through the digital pulse width signal, so that the display of different gray scales can be realized.

Referring to fig. 2, the LED unit array may include a plurality of driving circuits and corresponding light emitting units. Specifically, referring to fig. 3, the driving circuit may include a voltage-to-pulse width converter 110, a row selection switch module 120, and a current switch module 130. Referring to fig. 4, the voltage-to-pulse width converter 110 may include a comparison module 114, an energy storage module 112, and a constant current discharge module 116.

Specifically, the energy storage module can be composed of a capacitor C₁And (4) forming. The capacitor C₁There may be a first connection end and a second connection end. The capacitor C₁The second connection terminal of the first terminal may be electrically connected to the ground line VSS.

The comparison module can be composed of a P-type MOS transistor M₄And an N-type MOS transistor M₅And (4) forming. The transistor M₄Is electrically connected with a power line VDD, and a transistor M₄And transistor M₅Is electrically connected with the drain electrode of the transistor M₄And the capacitor C₁The first connecting end is electrically connected. The transistor M₅Is provided with a reference voltage V_refThe transistor M is electrically connected with the reference voltage line₅The source electrode of the first transistor is electrically connected with the grounding line VSS. By designing the transistor M appropriately₄And a transistor M₅Can be made such that the transistor M₄The pull-up capability of the drain voltage is configured to be stronger than that of the transistor M₅Pull-down capability on drain voltage.

The row selection switch module can be composed of an N-type MOS transistor M₁And a P-type MOS transistor M₂And (4) forming. The transistor M₁And providing an input voltage V_dataThe data signal line is electrically connected with the source electrode and the capacitor C₁The first connecting end is electrically connected. The transistor M₂And the capacitor C₁The first connecting end is electrically connected. The transistor M₁Gate of (D) and transistor M₂The grid electrodes are respectively and electrically connected to the row scanning signal lines. A voltage signal V provided by the line scanning signal line_scanThe control circuit can be used as a row selection signal of the row selection switch module and used for controlling the state of the row selection switch module.

The constant current discharge module can be composed of an N-type MOS transistor M₃And (4) forming. The transistor M₃And the transistor M₂The drain electrode of the transistor is electrically connected. Transistor M₃The source electrode of the first transistor is electrically connected with the grounding wire VSS. Transistor M₃The grid is electrically connected with the reference voltage line. The transistor M₃Can be configured to operate in the saturation region.

The light emitting module may be constituted by an LED unit. The anode of the LED unit may be electrically connected to a common voltage line VCOM of the diode. The common voltage line may be supplied with a driving voltage for driving the light emitting module to emit light. Wherein the anodes of the LED units in the LED unit array may each be connected to the common voltage line.

The current switch module can be composed of a P-type MOS transistor M₆And (4) forming. The transistor M₆And the transistor M₄Is electrically connected to the drain of the transistor M6. The transistor M₆The source electrode of the LED unit is electrically connected with the cathode of the LED unit.

The driving circuit of the LED unit may further include an N-type MOS transistor M₇. The transistor M₇And the transistor M₆The source electrode is electrically connected, the source electrode is electrically connected with a grounding wire VSS, and the grid electrode is electrically connected with a reference voltage wire. The transistor M₇Can be configured to operate in a saturation region to control the current through the current switching module and the light emitting module to tend to be constant.

The reference voltage line can output a reference voltage V_refSo that the transistor M₃Transistor M₅And a transistor M₇Is in a conducting state. Wherein the transistor M₅And a transistor M₇Can work in the saturation region.

Referring to fig. 5, the driving pixel unit can operate in a data writing phase or a display phase.

In some embodiments, a data writing process of a driving circuit is provided. The driving circuit of the LED unit may operate in a data writing phase. A line scanning signal V supplied on the line scanning signal line_scanAnd under the condition of outputting high level, the row selection switch module is in a first state. At this time, the transistor M₁In the on state, the transistor M₂In the off state. Capacitor with a capacitor elementC₁The first connection terminal is conducted with the data signal line. According to the target gray-scale value to be displayed of the LED unit, the data signal line provides the corresponding input voltage V_dataAs said capacitor C₁And (6) charging. In particular, the capacitance C can be used₁Providing input voltages V of different values_dataSo that the capacitor has different amounts of electric energy after the charging is completed. Correspondingly, capacitance C₁It is also possible to have different values of the initial voltage.

Referring to fig. 5 and 6, the line scanning signal V provided by the line scanning signal line_scanAfter outputting the high level of the first specified duration, the capacitor C₁The initial voltage U can be obtained_cap. In some embodiments, the initial voltage U is obtained after the charging is completed, as shown in equation 1_capAnd an input voltage V provided by the data signal line_dataMay be substantially uniform. The first designated duration is the duration of the driving circuit of the LED unit in the data writing stage.

Line scanning signal V_scanTransistor M will output a low level for a second specified duration₁In the on state, the transistor M₂In the off state. Capacitor C₁The first connection terminal is conducted with the data signal line. When the driving circuit of the LED unit operates in the display stage, the driving circuit of the LED unit can control the LED unit to emit light and turn off.

The display stage can be divided into a lighting process of the LED unit and a turning-off process of the LED unit. Wherein the light emitting duration can be provided by the input voltage V provided by the data signal line_dataAnd (6) determining. In some embodiments, the duration of the display phase may be set to be fixed according to the input voltage V_dataAfter the light-emitting time period is determined, the extinguishing time period can also be determined. According to the ratio of the light-emitting time length to the extinguishing time length, the gray scale of the LED unit can be determined.

In some embodimentsIn (1), a light emitting process of the LED unit is provided. Please refer to fig. 5 and fig. 7 a. When the driving circuit is operated in the light-emitting stage, the transistor M₄When turned off, the LED unit is lit.

At this time, the transistor M₁In the off state, the transistor M₂Is in a conducting state. Capacitor C₁And is conducted with the grounding wire VSS. Capacitor C₁Forms a discharge current I between the first connection end and the grounding wire_a. Wherein the discharge current I_aCurrent flowing through transistor M₂And a transistor M₃To the ground line. Since the transistor M₃Is configured to operate in a saturation region, thereby discharging a current I_aTends to be constant. Current I_aCan be calculated from equation 2. In formula 2, β₃Is a transistor M₃The gain factor of (c). V_th3Is a transistor M₃The threshold voltage of (2).

With the capacitance C₁Sustained discharge, capacitor C₁Voltage V of the first connection terminal_capIt will also gradually decrease. Specifically, the capacitor C₁Voltage V_capCan be calculated by equation 3. In formula 3, T represents the capacitance C₁The discharge time period of (c). V_capThe voltage of the capacitor may be represented. C_capCan represent a capacitance C₁The capacitance value of (c).

In the capacitor C₁During the discharge process of (1), the transistor M₄And M₅A simple comparator is formed. Therefore, in the transistor M₄Is less than the gate voltage of the transistor M₅In the case of a gate voltage of (3), i.e. voltage V_capGreater than a reference voltage V_refIn the case of (2), the transistor M₄And (6) cutting off. At this time, the transistor M₆And the grounding wire VSS is turned on. Transistor M₆Is in a conducting state. At this time, the common voltage line VCOM is turned on with the ground line VSS to form the driving current I flowing through the LED unit_bAnd enabling the LED unit to emit light. Due to the drive current I_bFlows through the transistor M₇And a transistor M₇Is configured to operate in a saturation region, so that the driving current I_bThe current value of (a) tends to be constant so that the luminance of the LED unit tends to be constant during the light emission of the LED unit.

In some embodiments, a quenching process of an LED unit is provided. Please refer to fig. 5 and 7 b. The drive circuit may be in a blanking phase. The gate voltage of the transistor M4 is less than that of the transistor M₅In the case of a gate voltage of (3), i.e. voltage V_capIs less than the reference voltage V_refIn the case of (2), the transistor M₄And conducting. Due to the transistor M₅Is also in the on state, and the transistor M₄The pull-up capability of the drain voltage is configured to be larger than that of the transistor M₅Pull-down capability to drain voltage, therefore transistor M₆Is pulled up to a supply voltage close to the supply line VDD. At this time, the transistor M₆And when the LED unit is cut off, the LED unit is extinguished.

In some embodiments, the input voltage V provided according to the data signal line is provided when the driving circuit of the LED unit is in the display phase_dataDifferent values of (c), the initial voltage U obtained by the capacitor_capMay be different. Correspondingly, under the condition of a certain discharge rate, the voltage U of the capacitor_capDown to a reference voltage V supplied by a reference voltage line_refSo that the time points of the LED units from turning on to turning off are different. In other words, the proportions of the light emission time period and the light-off time period of the LED unit are different in the time period corresponding to the second designated time period. By adjusting the input voltage V supplied by the data signal line_dataThe ratio of the light-emitting time length and the extinguishing time length of the LED unit can be adjusted to control the gray scale of the LED unit.

Specifically, the light emitting time T of the LED unit_eCan pass throughAnd 4, determining.

Visible LED unit luminous time and input voltage V input by data signal line_dataIn a linear relationship. Wherein the input voltage is an analog signal. And, the current flowing through the LED unit during light emission tends to be constant, thereby realizing a gray scale corresponding to the input voltage.

Referring to fig. 8, the present description provides a driving circuit, which may include the following modules.

The voltage-to-pulse width converter 110 has a voltage input terminal and a signal output terminal, and the voltage-to-pulse width converter 110 converts an input voltage inputted from the voltage input terminal into a control signal of a corresponding duration.

The voltage-to-pulse width converter 110 may output a control signal for a corresponding duration according to the input voltage provided by the voltage input terminal. The output duration of the control signal may have a corresponding relationship with the value of the input voltage. In some embodiments, the voltage-to-pulse width converter 110 may be composed of an energy storage module and a comparison model. The energy storage module can be charged by switching on the input voltage for the energy storage module, and in the discharging process of the energy storage module, the comparison module compares the voltage of the energy storage module with the reference voltage and inputs a high level signal with corresponding duration. Wherein the voltage input may be an analog voltage signal provided by a data signal line. The high level signal may serve as a control signal for the voltage-to-pulse width converter 110. The reference voltage may be a reference voltage. Of course, the voltage-to-pulse width converter 110 may also be composed of an integrated chip and an external circuit, and the integrated chip collects and calculates the input voltage value and controls the corresponding output port to output a control signal with a corresponding duration.

The row selection switch module 120, upon receiving a row selection signal, switches on the input voltage for the voltage input terminal of the voltage-to-pulse width converter 110.

The voltage-to-pulse width converter 110 can control the voltage input terminal thereof to be conducted with the voltage input terminal supplied with the input voltage through the row selection switch module 120. Thereby providing the input voltage to the voltage-to-pulse width converter 110 to enable the voltage-to-pulse width converter 110 to output a control signal for a corresponding duration. Specifically, the row selection switch module 120 may be a transistor that may have a control terminal, and the control terminal may control the conduction of the transistor according to a row selection signal, so that the voltage input terminal of the voltage-to-pulse width converter 110 can be connected to an input voltage. Of course, in some embodiments, the row selection switch module 120 may include a plurality of transistors. The plurality of transistors may each be controlled by the row select signal. In some embodiments, the voltage input may be a signal data line.

The row selection signal may be a signal provided from a row scanning signal terminal. The line scanning signal terminal may provide a pulse width signal. In some embodiments, when the pulse width signal is at a high level, it may be understood that a row selection signal is provided to the row selection switch module. When the pulse width signal is at a low level, it may be understood that the row selection switch module stops providing the row selection signal.

The current switch module 130 is controlled by the control signal, and is in a conducting state in the maintaining process of the control signal.

The current switch module 130 may be configured to control conduction of a branch in which the LED units are connected in series, so that a driving current is generated in the branch in which the LED unit is located, so as to drive the LED unit to emit light. Specifically, for example, the branches may be electrically connected to a common voltage line and a ground line, respectively, when the branches include the current switching module 130 and the LED unit connected in series. When the current switching module 130 receives the control signal, the current switching module 130 may be turned on, so that a potential difference is generated between the common voltage line and the ground line to form a driving current.

In some embodiments, the LED unit may be controlled to be lit during a time period when the control signal is received by the current switching module 130 according to a time period when the control signal is received. The display gray scale value of the LED unit can be adjusted by controlling the proportion of the on time to the off time of the LED unit.

In some embodiments, the voltage-to-pulse width converter 110 may include a comparison module 114 and an energy storage module 112.

The energy storage module 112 has a first connection end electrically connected to the voltage input end. The energy storage module 112 may be an electronic device capable of storing electrical energy. Specifically, for example, the energy storage module 112 may be a capacitor. In case a voltage is applied across the capacitor, the capacitor may be charged. After the charging is completed, the capacitor can obtain an initial voltage. Accordingly, the capacitor can be discharged after charging. During the discharge process, the voltage of the capacitor may gradually decrease. In the charging process, one end of the capacitor electrically connected with the positive voltage can be used as a first connection end of the energy storage module. In some embodiments, the energy storage module 112 may also be an electronic device such as an inductor that can store electric energy.

The comparison module 114 has the signal output terminal, a first input terminal electrically connected to the first connection terminal of the energy storage module, and a second input terminal for receiving a reference voltage. The comparing module 114 can provide corresponding output electrical signals to the signal output terminal according to the received input electrical signals at the first input terminal and the second input terminal. Specifically, the comparing module 114 may be a voltage comparator. The first input terminal and the second input terminal of the comparing module 114 can be used as two input terminals of the voltage comparator, respectively. The output of the voltage comparator may be used as the signal output of the comparison module 114. According to the voltage value of the input end of the voltage comparator, a corresponding output signal can be provided for the output end of the voltage comparator. For example, in the case where the voltage of the first input terminal of the voltage comparator is greater than the voltage of the second output terminal, the output terminal of the voltage comparator may output a high level. Conversely, in the case where the voltage at the second input terminal of the voltage comparator is greater than the voltage at the first output terminal, the output terminal of the voltage comparator may output a low level. The comparison module 114 may be formed by an electronic device, for example, by a plurality of transistors. Of course, the comparing module 114 can also directly use a packaged chip.

Accordingly, in one driving cycle, the row selection switch module 120 has a first state after receiving the row selection signal and a second state opposite to the first state; the row selection switch module 120 is in the first state, and the first connection terminal of the energy storage module 112 is connected with the input voltage to charge the energy storage module; the row selection switch module 120 is in the second state, and closes the input voltage for the first connection end of the energy storage module 112 to discharge the energy storage module, so that the signal output end of the comparison module 114 outputs the control signal.

The row selection switch module 120 may be in a first state and a second state. When the row selection switch module 120 is in the first state and the second state, the driving circuit may be controlled to be in a data writing phase and a display phase, respectively. In the data writing phase, i.e. when the row selection switch module 120 is in the first state, the driving circuit operates to charge the energy storage module 112. Correspondingly, the row selection switch module 120 controls a voltage input terminal to be connected to the first connection terminal of the energy storage module, so as to charge the energy storage module 112.

In the display phase, i.e. when the row selection switch module 120 is in the second state, the driving circuit operates in a discharging state for the energy storage module 112. Accordingly, the row selection switch module 120 controls the voltage input terminal and the energy storage module 112 to be disconnected, and can connect the first connection terminal of the energy storage module 112 with the ground line to discharge the energy storage module 112. Of course, in some embodiments, the first connection end of the energy storage module 112 only needs to form a discharge branch, and is not necessarily electrically connected to the ground line. The row selection switch module 120 may be composed of a plurality of transistors. Alternatively, the row selection switch module 120 may be a packaged chip capable of implementing the function.

During the discharging process of the energy storage module 112, the voltage value of the first connection terminal of the energy storage module gradually decreases. The comparison module may compare the voltage value of the first connection terminal with a reference voltage, so as to control the signal output terminal to output the control signal.

The row selection switch module 120 controls the driving circuit to be in a data writing stage or a display stage to control the energy storage module 112 to charge and discharge, so that a control signal with corresponding duration is output to control the LED unit to emit light according to the duration that the voltage of the first connection end of the energy storage module 112 drops to the reference voltage in the discharging process, and the current passing through the LED unit tends to be constant to a certain extent. In addition, the voltage for charging the energy storage module 112 is different in magnitude, and the time duration of the generated control signal is also different, that is, the time duration of the LED units being lit is different. The gray scale of the LED unit can be adjusted by controlling the conduction time of the branch where the LED unit is located so as to control the proportion of the time of the LED unit between the on time and the off time. In addition, the analog signal is converted into the pulse width signal to control the gray scale of the LED unit, that is, the gray scale of the LED unit is controlled by the input voltage for charging the energy storage module 112.

In some embodiments, when the row selection switch module 120 is in the second state, the comparison module 114 compares the output voltage of the energy storage module 112 with the reference voltage during the discharging process of the energy storage module 112, and when the output voltage of the energy storage module 112 is greater than the reference voltage, the comparison module 114 outputs a control signal; in the case that the output voltage of the energy storage module 112 is less than the reference voltage, the comparison module 114 stops outputting the control signal to the current switching module 130.

With the row selection switch module 120 in the second state, the energy storage module 112 may be in a discharge state. At this time, the first input terminal and the second input terminal of the comparing module 114 may receive the voltage of the first connection terminal of the energy storage module 112 and the reference voltage provided by the reference voltage line, respectively. The initial voltage is obtained as a result of the energy storage module 112 being charged when the row selection switch module 120 is in the first state. Therefore, in the discharge state, the voltage at the first connection of the energy storage module 112 continuously decreases along with the discharge process. The comparison module 114 may compare the relationship between the voltage value of the first connection end of the energy storage module 112 and the reference voltage value at the same time in real time, and output a control signal when the voltage of the first connection end is greater than the reference voltage, so that the current switch module 130 is controlled by the control signal, and is in a conducting state in the maintaining process of the control signal, so that the LED unit is turned on. When the voltage of the first connection terminal is less than the reference voltage, the comparison module 114 may stop outputting the control signal to turn off the current switch module 130, so that the LED unit is turned off. And controlling the display gray-scale value of the LED unit according to the proportion of the lighting time and the extinguishing time of the LED unit.

Specifically, in a case that the output voltage of the energy storage module 112 is greater than the reference voltage, that is, the voltage of the first input terminal of the comparison module 114 is greater than the voltage of the second input terminal, the signal output terminal of the comparison module 114 may be provided with a high level. Since the signal output terminal of the comparison module 114 is electrically connected to the control terminal of the current switch module 130, the high level of the comparison module 114 can control the current switch module 130 to be turned on, so that the LED unit is turned on. In a case where the output voltage of the energy storage module 112 is less than the reference voltage, that is, the voltage of the first input terminal of the comparison module 114 is less than the voltage of the second input terminal, the signal output terminal of the comparison module 114 may be provided with a low level to control the current switch module 130 to be turned off, so that the LED unit is turned off.

In some embodiments, the row selection switch module 120 may include a first switch submodule and a second switch submodule; when the first switch submodule is in a conducting state and the second switch submodule is in a blocking state, the row selection switch module 120 is in the first state; when the first switch submodule is in the off state and the second switch submodule is in the on state, the row selection switch module 120 is in the second state.

The first switch submodule and the second switch submodule may be respectively used to control the conduction between the first connection terminal of the energy storage module 112 and the input voltage terminal provided with the input voltage, and to control the conduction between the first connection terminal of the energy storage module 112 and the ground line. The input voltage end provided with the input voltage can provide analog voltage signals with different voltage values along with time change. In the example provided in fig. 4, the input voltage terminal may be provided with an input voltage V_dataThe data signal line of (2). Under the condition that the row selection switch module 120 is in the first state, the first switch submodule may control the energy storage module 112 to be connected to the input voltage terminal, and the current switch module 130 may control the energy storage module 112 to be disconnected from the ground line, so that the energy storage module 112 may be charged by the input voltage. Under the condition that the row selection switch module 120 is in the second state, the first switch submodule may control the energy storage module 112 to be disconnected from the input voltage terminal, and the second switch submodule may control the energy storage module 112 to be connected to the ground line. At this time, a potential difference may be formed between the first end of the energy storage module 112 and the ground line to generate a current, so that discharging of the energy storage module 112 may be achieved. In some embodiments, the first and second sub-modules may be configured to not be turned on simultaneously. Specifically, the first switch submodule and the second switch submodule may be two same transistors, and are controlled by different electrical signals so that the two transistors cannot be turned on at the same time. Of course, the first switch submodule and the second switch submodule may also be two transistors with different types of structures and the same type, and are controlled by the same electric signal.

In some embodiments, the first switch submodule is a first transistor and the second switch submodule is a second transistor; the first transistor and the second transistor are respectively provided with a control end for receiving the same row selection signal; the first transistor is in a conducting state and the second transistor is in a blocking state when the row selection signal is received; the first transistor is in an off state and the second transistor is in an on state without receiving the row selection signal.

The conduction times of the first and second transistors may not have an intersection. Therefore, the conduction of the first transistor and the second transistor is controlled by the same row selection signal, so that the first transistor and the second transistor can not be conducted at the same time; on the other hand, the circuit can be simplified to some extent.

The row selection signal may be provided at a scan signal terminal. Wherein the scan signal terminal may be supplied with a row selection signal indicating a high level.

In some embodiments, when the row selection switch module 120 receives the row selection signal, it may indicate that the control terminal of the first transistor and the control terminal of the second transistor both receive a high level, so that the first transistor is turned on and the second transistor is turned off, so that the row selection switch module 120 is in the first state. In a case that the row selection switch module 120 does not receive the row selection signal, it may indicate that the control terminal of the first transistor and the control terminal of the second transistor both receive a low level, so that the first transistor is turned off and the second transistor is turned on, so that the row selection switch module 120 is in the second state. In the example shown in fig. 4, the transistor M₁And a transistor M₂May function as the first transistor and the second transistor, respectively.

In addition, the row selection switch module 120 may be in the first state and the second state for different durations. Accordingly, according to the specified time duration that the row selection switch module 120 is in the first state and the second state, the scan signal terminal may provide the pulse width signal with the corresponding duty ratio, that is, after the row selection signal with the first specified time duration is provided, the provision of the row selection signal is stopped within the second specified time duration. In other words, the row selection switch module 120 may continuously adjust the state of the row selection switch module 120 according to the pulse width signal provided by the scan signal terminal and according to a preset time duration, so that the energy storage module 112 is continuously charged and discharged. Specifically, the pulse width signal at the scanning signal terminal may provide a high level signal lasting for a first specified duration and a low level signal lasting for a second specified duration. In a period in which the high-level signal is supplied, the first transistor may be in an on state and the second transistor may be in an off state. In a period in which the low-level signal is supplied, the first transistor may be in an off state and the second transistor may be in an on state.

In the example provided in fig. 4, the transistor M₁And a transistor M₂There may be a first transistor and a second transistor, respectively. The transistor is selected as a component for controlling the conduction of the circuit, so that the circuit volume can be reduced, and the response speed can be higher when the transistor is controlled to be switched on and switched off. In some embodiments, the first transistor may be a transistor such as a MOS transistor or a transistor capable of controlling the circuit to be turned on or off.

In some embodiments, the first transistor is an N-type MOS transistor; correspondingly, the input end, the output end and the control end of the first transistor are respectively a drain end, a source end and a grid end of the N-type MOS tube; the second transistor is a P-type MOS transistor; correspondingly, the input end, the output end and the control end of the second transistor are respectively a source end, a drain end and a gate end of the P-type MOS transistor.

The first transistor and the second transistor can be of the same type and have different structures, wherein the conduction conditions of the N-type MOS transistor and the P-type MOS transistor are opposite. Therefore, by providing transistors of the same type and different structures, the state of the row selection switch module 120 can be controlled by the same row selection signal. In addition, the first transistor and the second transistor can be ensured not to be turned on simultaneously. In addition, the row selection switch module 120 is formed by MOS transistors, so that relatively low power consumption is achieved, and accuracy of controlling the light emitting duration of the LED units is improved to a certain extent.

Referring to fig. 4, in some embodiments, the voltage-to-pulse width converter 110 further includes a constant current discharge module 116 having an input terminal and an output terminal; when the row selection switch module 120 is in the second state, the constant current discharge module 116 is turned on between the input end of the constant current discharge module 116 and the first connection end of the energy storage module 112; the output end of the constant current discharge module 116 is connected to the ground line.

The constant current discharge module 116 may be configured to discharge the energy storage module 112. When the row selection switch module 120 is in the second state, the first connection terminal may have an initial potential after the energy storage module 112 is charged. The input terminal of the constant current discharge module 116 may provide a potential lower than the initial potential, so that a potential difference is formed between the first connection terminal of the energy storage module 112 and the input terminal of the constant current discharge module 116 to generate a current, so as to discharge the energy storage module 112. Specifically, the constant current discharge module 116 may have an output end electrically connected to the ground line and an input end electrically connected to the first connection end of the energy storage module 112. In some embodiments, when the row selection switch module 120 is in the second state, the input terminal and the output terminal of the constant current discharge module 116 may be conducted.

In some embodiments, the constant current discharge module 116 includes a third transistor having an input terminal, an output terminal, and a control terminal receiving the reference voltage; an input end and an output end of the third transistor can be respectively used as an input end and an output end of the constant current discharging module; the third transistor is configured to operate in a saturation region.

During the discharging process, the current passing through the constant current discharging module 116 may be attenuated as the voltage value of the first connection terminal of the energy storage module 112 decreases. The current decay may cause the rate of electrical energy released by the energy storage module per unit time to change. This may cause a non-linear relationship between the voltage value of the first connection terminal of the energy storage module 112 and the discharge time. The discharging time period is determined by the input voltage value for charging the energy storage module 112, so that the gray scale of the LED unit can be controlled. The introduction of the non-linear relationship is not beneficial to calculating the input voltage value required for enabling the LED unit to emit light at the specified gray scale.

Therefore, the constant current discharge module 116 may include a third transistor configured to operate in a saturation region, so that the current flowing through the constant current discharge module 116 tends to be constant during the discharge process. Referring to FIG. 4, a transistor M₃May be the third transistor. Through the transistor M₃Current of (I)_aTends to be constant, so that the discharge time of the energy storage module and the voltage of the first connection end of the energy storage module 112 tend to have a linear relation for calculation.

In some embodiments, the third transistor is an N-type MOS transistor; correspondingly, the input end, the output end and the control end of the third transistor are respectively a drain end, a source end and a gate end of the N-type MOS transistor. The N-type MOS tube has lower price compared with the P-type MOS tube, is convenient to control, has lower power consumption, and the current value flowing through the saturation region has smaller change caused by the voltage change at the two ends of the drain electrode and the source electrode. Therefore, the N-type MOS transistor is suitable for serving as a component for ensuring that the current of the constant current discharge module 116 tends to be constant to some extent.

In some embodiments, the comparison module 114 includes a fourth transistor and a fifth transistor; the fourth transistor has a drain terminal and a gate terminal electrically connected to the first connection terminal of the energy storage module 112; the fifth transistor is provided with a drain end which is electrically connected with the drain end of the fourth transistor and a grid which receives the reference voltage; the gate terminals of the fourth transistor and the fifth transistor are respectively used as a first input terminal and a second input terminal of the comparison module 114; the drain terminal of the fifth transistor serves as the signal output terminal of the comparison module 114.

The comparison module 114 can be used to compare values of a plurality of electrical signals. Specifically, the comparing module 114 may be a simple voltage comparator composed of a fourth transistor and a fifth transistor. Referring to FIG. 4, a transistor M₄And a transistor M₅May be the fourth transistor and the fifth transistor, respectively. The simple structure can be formed by two transistors with different structures sharing the drainA voltage comparator. And, since the voltage pull-up capability of the drain terminal of the fourth transistor is configured to be stronger than the voltage pull-down capability of the drain terminal of the fifth transistor, the signal output terminal of the comparison module 114 outputs a high level when the fourth transistor is turned on. Accordingly, in the case where the fourth transistor is turned off, the signal output terminal of the comparison module 114 outputs a low level. In some embodiments, the turn-on and turn-off of the fourth transistor may be determined according to a gate voltage of the fifth transistor. Specifically, when the gate voltage of the fourth transistor is greater than the gate voltage of the fifth transistor, the signal output terminal outputs a high level. And when the grid voltage of the fourth transistor is less than that of the fifth transistor, the signal output end outputs low level. Of course, the voltage signal at the output terminal may also be adjusted according to the selection type of the fourth transistor and the fifth transistor. In some embodiments, the voltage applied to the gate of the fifth transistor for comparison with the gate voltage of the fourth transistor may be selected according to the actual requirements of the circuit.

In some embodiments, the comparison module 114 may also compare the magnitude of the current. Specifically, the comparing module 114 may include a plurality of resistors, and the resistors are used for converting the current signal into the voltage signal to be input to the comparing module for comparison.

In some embodiments, the fourth transistor is a P-type MOS transistor, and the fifth transistor is an N-type MOS transistor; the grid end, the drain end and the source end of the fourth transistor are the grid end, the drain end and the source end of the P-type MOS tube; and the grid terminal, the drain terminal and the source terminal of the fifth transistor are the grid terminal, the drain terminal and the source terminal of the N-type MOS transistor.

In some embodiments, a voltage pull-up capability of a drain terminal of the fourth transistor is configured to be stronger than a voltage pull-down capability of a drain terminal of the fifth transistor.

By properly designing the width-to-length ratio of the fourth transistor and the fifth transistor, the pull-up capability of the fourth transistor can be stronger than the pull-down capability of the fifth transistor. In the case that the voltage of the first connection terminal of the energy storage module 112 is less than the reference voltage, the fourth transistor is turned on. At this time, the drain of the fourth transistor and the drain of the fifth transistor are respectively conducted on the power line and the ground line, and the drain of the fourth transistor is electrically connected with the drain of the fifth transistor. Since the pull-up capability of the fourth transistor is stronger than the pull-down capability of the fifth transistor, the drain voltage of the fourth transistor can be pulled up to be close to the voltage of the power supply line. Accordingly, this voltage may be used to control the conduction of the current switching module 130.

In some embodiments, the pull-up capability of the fourth transistor may also be configured to be weaker than the pull-down capability of the fifth transistor. Accordingly, the functions can be realized by adjusting other components.

In some embodiments, the current switching module 130 includes a sixth transistor; the sixth transistor has an input terminal serving as the input terminal of the current switch module 130, an output terminal serving as the output terminal of the current switch module 130, and a control terminal electrically connected to the signal output terminal of the comparison module 114.

The current switch module 130 may be configured to control conduction of the branch where the LED unit is located, so that the LED unit emits light. Specifically, the current switching module 130 may be a sixth transistor. The sixth transistor can more rapidly control the conduction of the branch where the unit is located, and the volume is small. Referring to FIG. 4, a transistor M₆May be the sixth transistor. The branch where the LED unit is located can be electrically connected with the power line. The current switch module 130 controls the conduction of the branch where the LED unit is located, so that the voltage applied to the LED unit tends to be stable to a certain extent, and thus the stability of the current is ensured to a certain extent, and the problem of wavelength drift of the LED unit is reduced. In addition, the conduction of the current switch module 130 is controlled by converting the analog signal into the pulse width signal, the time sequence is simple, the driving circuit of the LED unit does not need too many complex peripheral circuits, and the circuit volume and the power consumption are reduced.

In some embodiments, the sixth transistor is a P-type MOS transistor; and the input end, the output end and the control end of the sixth transistor are respectively a source end, a drain end and a gate end of the P-type MOS tube.

The gate terminal of the sixth transistor may receive the signal output of the comparison module 114. Accordingly, in a case where the fourth transistor is turned on, since a voltage pull-up capability of a drain terminal of the fourth transistor is configured to be stronger than a voltage pull-down capability of a drain terminal of the fifth transistor, a gate terminal of the sixth transistor receives a high level, and the sixth transistor is turned off. Conversely, when the fourth transistor is turned off, the gate of the sixth transistor is turned on with the ground line, and the sixth transistor is turned on. At this time, the branch where the LED unit is located is turned on. A current is generated between the common voltage line and the ground line, and the current may flow through the LED unit to cause the LED unit to emit light. By controlling the conduction time of the branch where the LED unit is located, the ratio of the lighting time to the extinguishing time of the LED unit can be controlled, and therefore the gray scale of the LED unit is adjusted.

In some embodiments, the circuit further comprises a seventh transistor in series with the current switching module 130; the seventh transistor has a control terminal receiving the reference voltage; the seventh transistor is configured to operate in a saturation region.

In some embodiments, the branch where the LED unit is located may further include a current stabilizing unit, configured to control a current flowing through the LED unit to tend to be constant, so as to ensure that the brightness of the LED unit tends to be stable in a light emitting time period, and to solve the problem of wavelength drift of the LED unit to a certain extent. Therefore, the gray scale of the LED unit can be adjusted by controlling the proportion of the time length of the LED unit for emitting light to the time length of the LED unit for extinguishing, and the problem that the gray scale of the LED unit is inaccurate due to unstable brightness of the LED unit in the light emitting stage can be avoided to a certain extent. The current stabilizing unit may be a seventh transistor. The seventh transistor may be configured to operate in a saturation region. Referring to FIG. 4, the transistor M₇May be a seventh transistor. In some embodiments, the seventh transistor may also be a current stabilizing diode, and may also be an electronic device such as a MOS transistor that can implement the current stabilizing function.

In some embodiments, the seventh transistor is an N-type MOS transistor; and the input end, the output end and the control end of the seventh transistor are respectively a source end, a drain end and a gate end of the N-type MOS tube. By utilizing the working characteristics of the MOS tube, the MOS tube can work in a saturation region by controlling the voltage between the source terminal and the grid terminal of the MOS tube. At this time, even if the voltage between the drain and the source is largely changed, the current flowing through the MOS transistor may tend to be constant.

In some embodiments, the row selection switch module 120 is in the first state, the energy storage module 112 receives a voltage input with an initial voltage, so that after the row selection switch module 120 changes to the second state, the comparison module 114 provides the current switch module 130 with a turn-on signal during a period of time that the energy storage module 112 drops from the initial voltage to the reference voltage during a discharge process of the energy storage module 112 through the constant current discharge module 116, so that the LED unit is turned on for a duration of the turn-on signal.

When the row selection switch module 120 is in the first state, the energy storage module 112 may be charged, so that the energy storage module 112 obtains initial power. Accordingly, the first connection of the energy storage module 112 may have an initial voltage. Specifically, the initial voltage value of the energy storage module 112 may be different after the charging is completed according to the difference of the voltage value applied by the energy storage module 112 in the charging process.

According to the difference of the initial voltage value of the energy storage module 112, the duration of the energy storage module 112 decreasing from the initial voltage value to the reference voltage value in the discharging process is also different, and the duration of the high level signal provided by the corresponding comparison module 114 to the current switching module 130 is also different, so that the duration of the LED unit being turned on can be controlled. According to the set time length of the row selection switch module 120 in the second state and the time length of the LED unit being turned on, the time length of turning off the LED unit can be determined. Therefore, the gray scale of the LED unit is controlled according to the proportion of the lighting time to the extinguishing time of the LED unit. In addition, referring to formula 3, the constant current discharging module 116 discharges the energy storage module 112, so that the discharging rate of the energy storage module 112 tends to be unchanged, and thus a linear relationship between the voltage drop value of the energy storage module 112 and the discharging time duration is formed, and the accuracy of determining the lighting time duration of the LED unit according to the initial voltage value can be better ensured.

In some embodiments, the LED unit and the current switch module 130 are electrically connected in series; when the current switching module 130 is turned on, the input terminal of the LED unit is turned on with the common voltage line, and the output terminal of the LED unit is turned on with the ground line.

The LED unit may be connected in series with the current switch module 130, so that the current switch module 130 may control the conduction of the series branch of the LED unit and the current switch module 130, and thus may control the LED unit to be lighted. When the current switching module 130 is turned on, the input terminal of the LED unit may be connected to a common voltage line, and the output terminal of the LED unit may be connected to a ground line, so that a driving current may be generated in a series branch of the LED unit and the current switching module 130 to turn on the LED unit.

Referring to fig. 9, the present specification provides a method for driving an LED unit, which may include the following steps.

Step S110: in response to the row select switch module receiving the row select signal being in the first state, the input voltage is turned on for the voltage input of the voltage-to-pulse width converter 110.

In case the row selection switch module 120 receives a row selection signal, a corresponding input voltage may be provided for the voltage-to-pulse width converter 110. Specifically, when the row selection switch module 120 receives a row selection signal, the voltage input terminal of the voltage-to-pulse width converter 110 and the input voltage line supplied with the input voltage may be turned on, so that the voltage input terminal of the voltage-to-pulse width converter 110 is turned on by the input voltage.

Step S120: and the voltage-pulse width converter outputs a control signal with corresponding duration to the current switch module corresponding to the input voltage.

After the voltage-to-pulse width converter 110 receives the input voltage, a control signal with a corresponding duration may be output to the current switching module 130 according to a value of the input voltage. In some embodiments, the voltage values with different values may correspond to control information with different durations.

Step S130: the current switch module is controlled by the control signal and is in a conducting state in the maintaining process of the control signal, so that the LED unit is lightened.

The current switching module 130 may be in a conductive state during a period of time when the control signal is received. At this time, the branch where the LED unit is located is turned on to form a driving current so that the LED unit is lit. And, the time length of the LED unit being lighted is different corresponding to the control signals with different time lengths. The gray scale of the LED unit may be adjusted by adjusting a ratio between the time periods in which the LED unit is turned on and off.

In some embodiments, the step of turning on the input voltage for the voltage input terminal of the voltage-to-pulse width converter 110 in response to the row selection switch module 120 receiving the row selection signal may include: the row selection switch module 120 connects a voltage input to the first connection terminal of the energy storage module 112 to charge the energy storage module 112; the first connection end is electrically connected with the voltage input end.

The voltage-to-pulse width converter may include an energy storage module 112 and a comparison module 114. With the row selection switch module 120 in the first state, a data value may be written for the driving circuit of the LED unit. Specifically, the energy storage module 112 may be charged such that the energy storage module 112 receives different amounts of electrical energy. The voltage value of the energy storage module 112 after charging is complete may represent the written data value. Specifically, the energy storage module 112 can be charged by controlling the first connection end of the energy storage module 112 to be connected to the voltage input end. Since the second connection terminal of the energy storage module 112 can be connected to the ground line, the input voltage provided by the voltage output terminal can charge the energy storage module 112 at this time. After the charging is completed, the voltage of the energy storage module 112 may approach the value of the input voltage.

Accordingly, the step of outputting the control signal with the corresponding duration to the current switching module 130 by the voltage-to-pulse width converter 110 corresponding to the input voltage may include: the row selection switch module 120 discharges the energy storage module in response to the row selection switch module 120 being in the second state.

After the energy storage module 112 is charged. The voltage at the first connection of the energy storage module 112 may be approximately the same as the input voltage. At this time, the row selection switch module 120 may change from the first state to the second state. When the row selection switch module 120 is in the second state, the first connection end of the energy storage module 112 may be connected to the ground line, and a potential difference may be generated between the first connection end of the energy storage module 112 and the ground line to form a current. The power in the energy storage module 112 decreases as the current is discharged. Accordingly, the voltage at the first connection of the energy storage module 112 is also gradually decreased.

During the discharging process of the energy storage module 112, comparing the reference voltage with the output voltage of the energy storage module 112 by the comparison module 114; and, when the output voltage of the energy storage module 112 is greater than the reference voltage, the comparing module outputs the control signal.

During the discharge process, the driving circuit is in the display phase. The voltage at the first connection terminal of the energy storage module 112 is gradually decreased. By comparing the voltage of the first connection terminal of the energy storage module 112 with the reference voltage, the conduction of the current switch module 130 can be controlled, so as to control the LED unit to be turned on. When the voltage of the first connection terminal of the energy storage module 112 is greater than the reference voltage, the current switch module 130 may be controlled to be turned on, so that the LED unit is turned on. Specifically, as time goes by, the voltage at the first connection of the energy storage module 112 decreases as the discharging process continues. At this time, the comparison module 114 in the driving circuit may compare the relationship between the voltage value of the first connection terminal of the energy storage module 112 and the reference voltage value in real time. During the time period when the row selection switch module 120 is in the second state and the voltage of the first connection terminal of the energy storage module 112 is greater than the reference voltage, the output terminal of the comparison module 114 may provide a low level for the current switch module 130. Thereby, the current switching module 130 may be controlled to be turned on, so that the LED unit is lit.

In the process of discharging the energy storage module, when the voltage of the first connection terminal of the energy storage module 112 is smaller than the reference voltage, the current switch module 130 may be controlled to be turned off, so that the LED unit is turned off. Specifically, in the time period when the row selection switch module 120 is in the second state and the voltage of the first connection end of the energy storage module 112 is smaller than the reference voltage, the output end of the comparison module 114 may provide a high level signal for the current switch module 130 to control the current switch module 130 to be turned off, so that the LED unit is turned off.

In some embodiments, the energy storage module 112 has an input voltage after charging; in response to the row selection switch module 120 being in the second state, the step of discharging the energy storage module 112 may include: in response to the row selection switch module 120 being in the second state, the constant current discharge module 116 is used to discharge the energy storage module 112, so as to control a duration of the output voltage of the energy storage module 112 decreasing to the reference voltage by controlling the value of the input voltage, so as to control a duration of the comparison module 114 outputting the control signal.

The energy storage module may be charged by the input voltage, and the voltage value of the energy storage module 112 may be the same as the input voltage value after the charging is completed. By discharging the energy storage module 112 through the constant current discharge module 116, the discharge current of the energy storage module 112 may be controlled, so that the discharge rate of the energy storage module 112 tends to be stable. Referring to equations 3 and 4, when the discharge current tends to be constant, the voltage drop rate of the first connection end of the energy storage module 112 may tend to be constant, and the time period for the voltage of the first connection end of the energy storage module 112 to drop to the reference voltage may have a positive correlation with the initial voltage value of the energy storage module 112 after the charging is completed. Therefore, by controlling the initial voltage value after the energy storage module 112 is charged, the time period for which the output voltage of the energy storage module 112 is decreased to the reference voltage can be controlled, so as to control the time period for which the comparison module 114 outputs the control signal, so as to control the time period for which the LED units are turned on when the row selection switch module 120 is in the second state.

In some embodiments, the driving method of the driving circuit may further include: the row selection switch module 120 is controlled to be in a first state and a second state opposite to the first state in one driving period to control the time length for which the LED unit is lighted, so as to control the display gray scale value of the LED unit through the time length for which the LED unit is lighted.

The row selection switch module 120 is controlled to be in the first state and the second state, so that the energy storage module 112 is charged and then discharged, and in the discharging process of the energy storage module 112, a control signal with a corresponding duration is output according to an initial voltage obtained after the energy storage module 112 is charged, so as to control the lighting duration of the LED. And the display gray scale of the LED unit can be adjusted according to the proportion of the LED lighting time to the LED extinguishing time. The second state opposite to the first state may indicate that the row selection switch modules in the first state and the second state have opposite conduction relationships. For example, the row selection switch module 120 may include a first transistor and a second transistor. In the case of a first state, the first transistor is turned on and the second transistor is turned off. Conversely, in the case of the second state, the first transistor is turned off and the second transistor is turned on. Wherein a voltage value of the initial voltage may be the same as a voltage value of the input voltage.

In some embodiments, the step of controlling the row selection switch module 120 to be in a first state and a second state opposite to the first state in one driving cycle may include: in a driving cycle, the input voltage value provided by the input voltage terminal is controlled when the row selection switch module 120 is in the first state, and the duration when the row selection switch module 120 is in the second state is controlled, so as to control the ratio between the duration when the LED unit is turned on and the duration when the LED unit is turned off, so as to control the display gray scale value of the LED unit.

The display gray scale value of the LED unit can be controlled by controlling the proportion of the time length of the LED unit which is lighted and the time length of the LED unit which is extinguished. Specifically, by applying different input voltages to the energy storage module 112, the energy storage module 112 has an initial voltage after the charging is completed, so that the lit time of the LED unit can be controlled. In addition, by controlling the duration that the row selection switch module 120 is in the second state, the duration that the energy storage module 112 is discharged can be controlled. The discharge time period of the energy storage module 112 may include a time period during which the LED unit is turned on and a time period during which the LED unit is turned off. In the case where the length of time that the LED unit is lit is determined, the length of time that the LED is extinguished can also be determined. The gray scale value of the LED unit can be controlled by the ratio between the time period for which the LED is turned on and the time period for which the LED is turned off. In some embodiments, the ratio between the lit time period and the extinguished time period may also be the ratio between the lit time period and the extinguished time period of the LED unit in a plurality of driving periods.

In some embodiments, when the row selection switch module 120 is in the first state, the energy storage module 112 receives a voltage input having an initial voltage; when the output voltage of the energy storage module 112 is greater than the reference voltage, the step of controlling the current switching module 130 to be turned on to turn on the LED includes: in response to the row selection switch module 120 changing from the first state to the second state, during the period when the energy storage module drops from the initial voltage to the reference voltage during the discharging process of the energy storage module through the constant current discharging module 116, the current switch module 130 is provided with a turn-on signal, so that the LED unit is turned on for the duration of the turn-on signal.

With the row selection switch module 120 in the first state, the energy storage module 112 may be charged. Accordingly, the energy storage module 112 may have an initial voltage after charging is complete. Referring to equation 1, the initial voltage may correspond to a voltage value of the input voltage applied to the energy storage module 112 during the charging process.

When the row selection switch module 120 changes from the first state to the second state, the energy storage module 112 may discharge through the constant current discharge module 116. As the discharge process continues, the voltage of the energy storage module 112 may gradually decrease until it is the same as the reference voltage. During this period of time, a turn-on signal may be provided to the current switching module 130, so that the LED unit is lit during this period of time. Specifically, the voltage of the first connection terminal of the energy storage module 112 may be compared with the reference voltage by the comparison module 114, and when the voltage value of the first connection terminal is greater than the reference voltage value, the current switching module 130 is continuously provided with a start signal enabling the current switching module to start.

Since the energy storage module 112 is discharged by the constant current discharge module 116, the discharge rate of the energy storage module 112 may tend to be constant. Referring to equation 3, the discharge time of the energy storage module 112 and the voltage drop of the energy storage module 112 may be in a linear relationship. Accordingly, the time duration for the initial voltage of different values to be reduced to the reference voltage is different. For example, the time period during which the larger value of the initial voltage is decreased to the reference voltage is longer than the time period during which the smaller value of the initial voltage is decreased to the reference voltage. This also causes the duration of the turn-on signal supplied to the current switching module 130 to be different, i.e., the duration of the LED units being lit. Please refer to fig. 4, V₁、V₂、V₃Respectively, voltages of different values. Wherein V₃Greater than V₂，V₂Greater than V₁. Correspondingly in the display phase, V₃The corresponding LED unit has the longest lighting time and V₂The shortest is V₁. Therefore, by applying different values of input voltage to the energy storage module 112 during the charging process, the time period for the Micro-LED to be turned on can be controlled. Correspondingly, please refer to formula 4, the time duration of the LED unit being turned on can also be calculated by taking the value of the initial voltage.

In some embodiments, the step of controlling the current switching module 130 to be turned off to turn off the LED unit when the output voltage of the energy storage module 112 is less than the reference voltage includes: in response to the row selection switch module 120 changing from the first state to the second state, after the voltage of the energy storage module 112 drops to the reference voltage in the process that the energy storage module 112 discharges through the constant current discharge module 116, a cutoff signal is provided for the current switch module 130 according to a set duration of the row selection switch module 120 being in the second state and a voltage drop duration of the voltage of the energy storage module 112 dropping to the reference voltage, so that the LED is turned off within a duration of the cutoff signal.

In the case that the voltage of the first connection terminal of the energy storage module 112 is less than the reference voltage, a cut-off signal may be provided to the current switching module 130. Specifically, the current switch module 130 may be provided with a turn-off signal by the comparison module 114. And, according to the duration of the row selection switch module 120 in the second state and the duration of the LED unit being turned on, the turn-off duration of the LED unit may be determined. The LED unit may be a Micro-LED.

The discharge current tends to be constant as the energy storage module 112 discharges. Referring to equation 3, the discharge duration is linear with the voltage drop of the first connection terminal of the energy storage module 112. In addition, in the process of comparing the voltage of the first connection end, by comparing the difference between the voltage of the first connection end of the energy storage module 112 and the reference voltage, the time length for the voltage of the first connection end of the energy storage module 112 to be reduced to the reference voltage can be calculated, so that a pulse width signal corresponding to the time length is formed to control the LED to emit light. Under the condition that the magnitude of the reference voltage is not changed, in the charging process, voltages with different values are applied to the energy storage module 112, so that different difference values are generated between the voltage of the energy storage module 112 and the reference voltage, and pulse width signals with different duty ratios are generated to control the LED to emit light. In some embodiments, the pulse width signals with different duty ratios can also be generated by adjusting the magnitude of the reference voltage.

The present specification embodiment provides a display panel, which may include: the LED unit array comprises a plurality of driving circuits which are arranged in an array. The row driving circuit is used for providing a row selection signal for controlling the state of a row selection switch module in the driving circuit; a serial-to-parallel conversion circuit for converting a serial input image signal into a parallel digital signal; and the digital-to-analog conversion circuit is used for converting the parallel digital signals output by the serial-to-parallel conversion circuit into analog signals so as to determine the voltage input of the driving circuit.

In some embodiments, the display panel may include a row driving circuit; the row driving circuit can provide a row scanning signal for the LED unit array so as to control the row selection switch module to be in a first state or a second state.

In some embodiments, the display panel may include a high-speed interface and a serial-to-parallel conversion circuit for converting a serial input image signal into a parallel digital signal.

In some embodiments, the display panel may include a digital-to-analog converter. The digital-to-analog converter can convert image information from a digital signal to an analog signal as a voltage input to the driving circuit.

In some embodiments, the display panel may include an output buffer. The output buffer is used for amplifying the analog signal and then supplying the amplified analog signal to the LED unit array.

In some embodiments, the display panel may include a plurality of LED unit arrays. The LED unit array may include a number of the driving circuits. The LED unit array can receive an analog voltage signal, convert the analog voltage signal into a digital pulse width signal, keep the current flowing through the light-emitting unit unchanged, and control the lighting of the light-emitting unit through the digital pulse width signal to realize different gray scales at all times.

In some embodiments, the LED unit array comprises a plurality of LED units, each of which has one end electrically connected to a common voltage line; the other end of the LED unit is electrically connected to the current switch module.

The plurality of LED units may correspond to a driving circuit of the LED unit, and the driving circuit may be configured to control a conduction condition of a branch in which the LED unit is located. The input end of the LED unit can be electrically connected to the same common voltage line, so that the branch circuit where the LED unit is located can generate driving current to enable the LED unit to be lightened by controlling the conduction condition of the branch circuit where the LED unit is located, and the LED unit is conveniently controlled to be lightened.

The description is made in a progressive manner among the embodiments of the present specification. The different embodiments focus on the different parts described compared to the other embodiments. After reading this specification, one skilled in the art can appreciate that many embodiments and many features disclosed in the embodiments can be combined in many different ways, and for the sake of brevity, all possible combinations of features in the embodiments are not described. However, as long as there is no contradiction between combinations of these technical features, the scope of the present specification should be considered as being described.

It should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

The above description is only an embodiment of the present disclosure, and is not intended to limit the scope of the claims of the present disclosure. Various modifications and changes may occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present application shall be included in the scope of the claims of the present application.

Claims

1. A driver circuit, comprising:

the voltage-pulse width converter is provided with a voltage input end and a signal output end and converts the input voltage of the voltage input end into a control signal with corresponding duration;

a row selection switch module, which switches on the input voltage for the voltage input end of the voltage-pulse width converter under the condition of receiving a row selection signal;

and the current switch module is controlled by the control signal and is in a conducting state in the maintaining process of the control signal.

2. The driving circuit according to claim 1, wherein the voltage-to-pulse width converter comprises a comparison module and an energy storage module;

the energy storage module is provided with a first connecting end electrically connected with the voltage input end;

the comparison module is provided with the signal output end, a first input end electrically connected with the first connecting end of the energy storage module and a second input end for receiving reference voltage;

correspondingly, in a driving period, the row selection switch module has a first state after receiving the row selection signal and a second state opposite to the first state; the row selection switch module is in the first state, and is used for connecting the first connection end of the energy storage module with the input voltage and charging the energy storage module; the row selection switch module is in the second state, the input voltage is closed by the first connection end of the energy storage module, and the energy storage module discharges, so that the signal output end of the comparison module outputs the control signal.

3. The driving circuit according to claim 2, wherein the comparing module compares the output voltage of the energy storage module with the reference voltage during discharging of the energy storage module when the row selection switch module is in the second state, and outputs the control signal when the output voltage of the energy storage module is greater than the reference voltage; and under the condition that the output voltage of the energy storage module is smaller than the reference voltage, the comparison module stops outputting the control signal.

4. The driving circuit of claim 2, wherein the row selection switch module comprises a first switch submodule and a second switch submodule; the row selection switch module is in the first state under the condition that the first switch submodule is in a conducting state and the second switch submodule is in a blocking state; and under the condition that the first switch submodule is in a cut-off state and the second switch submodule is in a conducting state, the row selection switch module is in the second state.

5. The driving circuit of claim 4, wherein the first switching sub-module is a first transistor and the second switching sub-module is a second transistor; the first transistor and the second transistor are respectively provided with a control end for receiving the same row selection signal; the first transistor is in a conducting state and the second transistor is in a blocking state when the row selection signal is received; the first transistor is in an off state and the second transistor is in an on state without receiving the row select signal.

6. The driving circuit of claim 2, wherein the voltage-to-pulse width converter further comprises a constant current discharge module having an input terminal and an output terminal; under the condition that the row selection switch module is in the second state, the input end of the constant current discharge module is conducted with the first connection end of the energy storage module; and the output end of the constant current discharge module is conducted with the grounding wire.

7. The driving circuit of claim 6, wherein the constant current discharging module comprises a third transistor having an input terminal, an output terminal, and a control terminal receiving the reference voltage; the input end and the output end of the third transistor are respectively used as the input end and the output end of the constant current discharging module; the third transistor is configured to operate in a saturation region.

8. The driving circuit according to claim 2, wherein the comparison module comprises a fourth transistor and a fifth transistor; the fourth transistor is provided with a drain end and a grid end which is electrically connected with the first connecting end of the energy storage module; the fifth transistor has a drain terminal electrically connected to the drain terminal of the fourth transistor and a gate terminal receiving the reference voltage; gate terminals of the fourth transistor and the fifth transistor are respectively used as a first input terminal and a second input terminal of the comparison module; and the drain end of the fifth transistor is used as a signal output end of the comparison module.

9. The driver circuit according to claim 8, wherein a voltage pull-up capability of a drain terminal of the fourth transistor is configured to be stronger than a voltage pull-down capability of a drain terminal of the fifth transistor.

10. The driving circuit of claim 2, wherein the current switching module comprises a sixth transistor; the sixth transistor is provided with an input end serving as an input end of the current switch module, an output end serving as an output end of the current switch module and a control end electrically connected with the signal output end of the comparison module.

11. The driving circuit of claim 1, further comprising a seventh transistor in series with the current switching module; the seventh transistor has a control terminal receiving a reference voltage; the seventh transistor is configured to operate in a saturation region.

12. The driving circuit according to claim 1, further comprising an LED unit, wherein the LED unit is illuminated when the current switching module is in the on state.

13. The driving circuit according to claim 12, wherein the LED unit and the current switching module are electrically connected in series; when the current switch module is turned on, the input end of the LED unit is turned on with a common voltage line, and the output end of the LED unit is turned on with a ground line.

14. A method of driving an LED unit, comprising:

in response to the row selection switch module receiving that the row selection signal is in a first state, switching on an input voltage for a voltage input end of the voltage-pulse width converter;

the voltage-pulse width converter outputs a control signal with corresponding duration to the current switch module corresponding to the input voltage;

the current switch module is controlled by the control signal and is in a conducting state in the maintaining process of the control signal, so that the LED unit is lightened.

15. The method of claim 14, wherein switching on the input voltage for the voltage input of the voltage-to-pulse width converter in response to the row select switch module receiving the row select signal comprises:

responding to a row selection signal received by a row selection switch module, connecting a first connection end of an energy storage module with an input voltage, and charging the energy storage module; the first connection end is electrically connected with the voltage input end;

correspondingly, the voltage-to-pulse width converter outputs a control signal with a corresponding duration to the current switch module corresponding to the input voltage, and includes:

in response to the row selection switch module being in a second state, discharging the energy storage module;

in the discharging process of the energy storage module, comparing the output voltage of the energy storage module with a reference voltage through a comparison module; under the condition that the output voltage of the energy storage module is greater than the reference voltage, the comparison module outputs the control signal;

and in the discharging process of the energy storage module, under the condition that the output voltage of the energy storage module is smaller than the reference voltage, the comparison module stops outputting the control signal.

16. The method of claim 15, wherein the energy storage module has an input voltage after charging; in response to the row selection switch module being in the second state, discharging the energy storage module, comprising:

and in response to the row selection switch module being in the second state, discharging the energy storage module by using the constant current discharge module, so as to control the time length of the output voltage of the energy storage module reduced to the reference voltage by controlling the input voltage value, and to control the time length of the comparison module outputting the control signal.

17. The method for driving an LED unit according to claim 15, further comprising:

and controlling the row selection switch module to be in a first state and a second state opposite to the first state in a driving period so as to control the lighting time of the LED unit, and controlling the display gray-scale value of the LED unit through the lighting time of the LED unit.

18. The method for driving the LED unit according to claim 17, wherein the step of controlling the row selection switch module to be in a first state and a second state opposite to the first state in one driving cycle comprises:

in a driving period, controlling the value of the input voltage provided by the input voltage end under the condition that the row selection switch module is in the first state, and controlling the duration of the row selection switch module in the second state so as to control the proportion between the duration of the LED unit being lightened and the duration of the LED unit being extinguished, so as to control the display gray scale value of the LED unit.

19. A display panel, comprising:

an LED unit array comprising a plurality of the driving circuits of any one of claims 1 to 13 arranged in an array;

the row driving circuit line is used for providing a row selection signal for controlling the state of a row selection switch module in the driving circuit;

a serial-to-parallel conversion circuit for converting a serial input image signal into a parallel digital signal;

and the digital-to-analog conversion circuit is used for converting the parallel digital signals output by the serial-to-parallel conversion circuit into analog signals to be used as the input voltage of the driving circuit.

20. The display panel of claim 19, wherein the array of LED units comprises a plurality of LED units having one end electrically connected to a common voltage line and another end electrically connected to the current switch module.