CN107367854B

CN107367854B - Drive circuit and drive method of liquid crystal panel and electronic curtain

Info

Publication number: CN107367854B
Application number: CN201710712429.7A
Authority: CN
Inventors: 张银龙; 张春兵; 郭瑞; 孟智明; 郝卫; 刘松; 程金辉
Original assignee: BOE Technology Group Co Ltd; Beijing BOE Display Technology Co Ltd
Current assignee: BOE Technology Group Co Ltd; Beijing BOE Display Technology Co Ltd
Priority date: 2017-01-06
Filing date: 2017-08-10
Publication date: 2020-05-05
Anticipated expiration: 2037-08-10
Also published as: CN106646960A; CN107367854A

Abstract

The invention discloses a driving circuit, a driving method and an electronic curtain of a liquid crystal panel, wherein the circuit comprises the following components: the step-down converting circuit for providing the driving voltage for the liquid crystal panel further comprises: a first feedback circuit based on a negative feedback amplifying circuit; and the output control circuit is used for switching on the first feedback circuit as the feedback circuit of the buck conversion circuit. The invention can provide the driving voltage in a lower voltage range; meanwhile, the voltage-reducing conversion circuit can provide enough power for one IC to drive the whole liquid crystal panel, and can meet the driving power requirement of the electronic curtain liquid crystal panel at lower cost.

Description

Drive circuit and drive method of liquid crystal panel and electronic curtain

Technical Field

The present invention relates to the field of liquid crystal technologies, and in particular, to a driving circuit and a driving method for a liquid crystal panel, and an electronic curtain.

Background

The liquid crystal light-adjusting film (or called liquid crystal light-adjusting panel) is a smart film, and the film is directly attached to glass to form the electronic curtain. The electronic curtain realizes the photoelectric function of the film by utilizing the optical characteristics of the liquid crystal. In fact, after the electronic curtain is powered on, the loaded voltage can make the liquid crystal film (or called liquid crystal panel) present a penetrating state and an opaque state, so that the double requirements of people on glass penetration and privacy protection are met, which cannot be met by other types of curtains at present. Moreover, the electronic curtain has an insulating and reflecting effect on the heat energy of light, so that the indoor environment is warm in winter and cool in summer, and the electronic curtain has the effects of environmental protection and energy conservation and is wide in product application.

At present, a method for driving a liquid crystal panel of an electronic window covering is shown in fig. 1. One liquid crystal Panel (Panel) is driven by a plurality of ICs. One IC driving circuit is provided for each IC in a PCB connected to the liquid crystal panel. The PCB also provides Gamma voltage for each path of IC drive circuit, and the IC drive circuit converts the Gamma voltage into gray scale voltage required by the IC, thereby adjusting the optical characteristics of the liquid crystal and achieving the effect of driving the liquid crystal panel. However, this method requires a plurality of ICs for driving each panel, which leads to high cost.

Therefore, the industry considers a cost reduction: the PCB is directly connected to the liquid crystal panel through an FPC (Flexible printed circuit) and drives one IC, whereby the IC drives the entire liquid crystal panel, as shown in fig. 2. Because one IC drives the whole liquid crystal panel to have a large load, if the circuit in the PCB board adopts the traditional Gamma voltage driving circuit, the power requirement of the whole liquid crystal panel driving can not be met. Thus, a liquid crystal panel has been proposed in which an electronic curtain is driven by a Buck circuit (step-down converter circuit) having feedback.

The Buck circuit with feedback comprises a chip integrated with the Buck circuit and a feedback circuit externally connected with the Buck circuit of the chip. The feedback circuit of the Buck circuit generally employs a voltage divider circuit composed of series resistors, as shown in fig. 3. For example, in fig. 3, a resistor R301 is connected in series with a resistor R302, one end of the resistor R301 is connected to the voltage output end of the Buck circuit, the other end of the resistor R301 is connected to one end of the resistor R302, the other end of the resistor R302 is grounded, and a connection point between the resistor R301 and the resistor R302 is connected to the feedback end of the Buck circuit. The voltage output by the Buck circuit is used for driving an IC on the liquid crystal panel, and then the IC drives the whole liquid crystal panel.

However, in practical applications, the inventor of the present invention found that although the Buck circuit with feedback can meet the power requirement of driving a whole liquid crystal panel by one IC, as the electronic window curtain is used more and more widely, the voltage regulation range of the Buck circuit is wider and wider, and the output voltage range of the conventional Buck circuit is limited and generally cannot be lower than 1V. Therefore, the requirement for a wider voltage regulation range of the electronic curtain liquid crystal panel cannot be satisfied, particularly the requirement for a low voltage range, for example, the requirement for a driving voltage lower than 1V cannot be satisfied.

Disclosure of Invention

In view of the above, the present invention provides a driving circuit, a driving method and an electronic curtain for a liquid crystal panel, which can meet the driving power requirement of the liquid crystal panel of the electronic curtain at a lower cost and provide a driving voltage in a lower voltage range.

The present invention provides a driving circuit of a liquid crystal panel based on the above object, including: the step-down conversion circuit for providing the driving voltage for the liquid crystal panel further comprises:

a first feedback circuit based on a negative feedback amplifying circuit;

and the output control circuit is used for switching on the first feedback circuit as the feedback circuit of the buck conversion circuit.

Wherein, first feedback circuit specifically includes:

the negative feedback input end of the negative feedback amplifying circuit is connected with the output end of the voltage reduction type conversion circuit;

the first voltage division circuit based on the series resistor is connected between the output end of the negative feedback amplifying circuit and the ground, and the connecting point between the resistors of the series resistor is connected with the feedback end of the buck conversion circuit;

the first switch is connected between a connection point between the resistors of the first voltage division circuit and a feedback end of the buck conversion circuit;

the second switch is arranged in a current path from the negative feedback input end of the negative feedback amplifying circuit to the first voltage division circuit; and

the output control circuit is specifically used for controlling the conduction of the first switch and the second switch, the first feedback circuit is connected to be a feedback circuit of the buck conversion circuit, and the buck conversion circuit outputs a driving voltage in a first range to the liquid crystal panel.

Or, the first feedback circuit specifically includes:

the negative feedback input end of the negative feedback amplifying circuit is connected with the output end of the voltage-reducing type conversion circuit;

the second switch is arranged between the positive feedback input end of the negative feedback amplifying circuit and the output end of the buck conversion circuit; and

Further, the circuit further comprises:

a second feedback circuit comprising a second voltage divider circuit based on a series resistance; and

the output control circuit is also used for switching on a second feedback circuit to be a current feedback circuit of the buck conversion circuit, and the buck conversion circuit outputs a driving voltage in a second range to the liquid crystal panel; the driving voltage in the first range is smaller than the driving voltage in the second range.

Wherein, the second feedback circuit specifically includes:

the second voltage division circuit and the third switch are connected between the output end of the buck conversion circuit and the ground in series;

the fourth switch is connected between a connection point between the resistors of the second voltage division circuit and the feedback end of the buck conversion circuit; and

the output control circuit is specifically used for controlling the third switch and the fourth switch to be switched off, the first switch and the second switch to be switched on, and the voltage-reducing type conversion circuit outputs a driving voltage in a first range to the liquid crystal panel; and controlling the third switch and the fourth switch to be switched on, switching off the first switch and the second switch, and outputting a driving voltage in a second range to the liquid crystal panel by the voltage-reducing conversion circuit.

The invention also provides a driving method of the liquid crystal panel, which comprises the following steps:

controlling a first feedback circuit in a driving circuit of the liquid crystal panel to be connected with a feedback circuit of a voltage reduction type conversion circuit in the driving circuit, and outputting driving voltage to the liquid crystal panel by the voltage reduction type conversion circuit;

wherein the first feedback circuit is based on a negative feedback amplification circuit.

More preferably, the first feedback circuit specifically includes: the negative feedback amplifier circuit, the first voltage division circuit based on the series resistor, the first switch and the second switch; and

in the method, the controlling a first feedback circuit in the driving circuit to be connected to a feedback circuit of a buck conversion circuit in the driving circuit, and outputting a driving voltage to the liquid crystal panel by the buck conversion circuit specifically includes:

controlling the first switch and the second switch to be conducted, connecting the first feedback circuit into a feedback circuit of the buck conversion circuit, and outputting a driving voltage in a first range to the liquid crystal panel by the buck conversion circuit;

the first voltage division circuit is connected between the output end of the negative feedback amplifying circuit and the ground, and the inter-resistor connecting point of the series resistor is connected with the feedback end of the buck conversion circuit;

the first switch is connected between a resistor connecting point of the first voltage division circuit and a feedback end of the buck conversion circuit;

the second switch is arranged in a current path from the negative feedback input end of the negative feedback amplifying circuit to the first voltage division circuit.

Or the positive feedback input end of the negative feedback amplifying circuit is connected with the output end of the buck conversion circuit;

the second switch is arranged between the positive feedback input end of the negative feedback amplifying circuit and the output end of the buck conversion circuit.

More preferably, the driving circuit further includes: a second feedback circuit; and

the method further comprises the following steps:

when the driving voltage required by the liquid crystal panel is the voltage in the second range, controlling a second feedback circuit to be connected with a current feedback circuit of the buck conversion circuit, and outputting the driving voltage in the second range to the liquid crystal panel by the buck conversion circuit;

wherein the second feedback circuit comprises a second voltage divider circuit based on a series resistance.

In addition, in another aspect of the present invention, an electronic window curtain is provided, which has a liquid crystal panel, and the liquid crystal panel adopts the driving circuit of the liquid crystal panel according to any one of the above embodiments.

And an electronic curtain having a liquid crystal panel, the liquid crystal panel employing the method of driving a liquid crystal panel according to any of the embodiments described above.

In the technical scheme of the embodiment of the invention, the feedback circuit based on the negative feedback amplifying circuit is provided for the Buck conversion circuit (Buck circuit), so that the voltage amplifying function of the amplifying circuit can be utilized to ensure that the output voltage V of the amplifying circuit_out' comparison with output voltage V of Buck circuit_outIs amplified by N times; thus, even if V_out' the lowest voltage is limited by the feedback voltage V of the Buck circuit_FBCannot reach V_FBThe following voltage range, but V_outIs V _out1/N of' may be lower than V_FBSo that the Buck circuit can output V_FBThe following voltage range. Therefore, compared with the existing feedback Buck circuit, the technical scheme of the invention can provide the driving voltage in a lower voltage range; meanwhile, the Buck circuit in the technical scheme of the invention can provide enough power for one IC to drive the whole liquid crystal panel, and can meet the drive power requirement of the liquid crystal panel of the electronic curtain at lower cost.

Preferably, the driving circuit of the embodiment of the present invention includes a multi-stage feedback circuit including a first feedback circuit and a second feedback circuit; the Buck circuit based on the first feedback circuit can output the driving voltage in the first range, and the Buck circuit based on the second feedback circuit can output the driving voltage in the second range, so that the range of the driving voltage supplied by the driving circuit is widened, and the driving circuit is wider in applicability.

Preferably, the first or second feedback circuit of the embodiment of the present invention is further connected to a trimming circuit, the output control circuit may control the regulated voltage output to the trimming circuit, and the regulated voltage acts on the feedback circuit, so as to change the output voltage of the Buck circuit. That is, the output control circuit can change the driving voltage output to the liquid crystal panel by changing the adjustment voltage. The output control circuit can control and adjust the driving voltage provided for the liquid crystal panel of the electronic curtain, so that the electronic curtain presents a plurality of semi-transparent transition states with different degrees between the transparent state and the non-transparent state, and the electronic curtain has better light transmission adjustability.

Drawings

FIG. 1 is a diagram of a prior art LCD panel driven by multiple ICs;

FIG. 2 is a diagram illustrating a prior art method for driving an entire liquid crystal panel with one IC;

FIG. 3 is a circuit diagram of a prior art Buck circuit with feedback;

fig. 4a and 4b are driving circuit diagrams of a liquid crystal panel of an electronic window covering according to an embodiment of the invention;

fig. 5 is a flowchart of a driving method of an electronic curtain liquid crystal panel according to an embodiment of the present invention;

fig. 6a and 6b are driving circuit diagrams of a liquid crystal panel of an electronic curtain according to a second embodiment of the present invention;

fig. 7 is a flowchart of a driving method of an electronic curtain liquid crystal panel according to a second embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to specific embodiments and the accompanying drawings.

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative only and should not be construed as limiting the invention.

As used herein, the singular forms "a", "an", "the" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may also be present. Further, "connected" or "coupled" as used herein may include wirelessly connected or wirelessly coupled. As used herein, the term "and/or" includes all or any element and all combinations of one or more of the associated listed items.

It should be noted that all expressions using "first" and "second" in the embodiments of the present invention are used for distinguishing two entities with the same name but different names or different parameters, and it should be noted that "first" and "second" are merely for convenience of description and should not be construed as limitations of the embodiments of the present invention, and they are not described in any more detail in the following embodiments.

The inventors of the present invention found that the feedback voltage V input to the feedback terminal of the Buck circuit_FBThe Buck circuit can normally work only by keeping about 0.5V; from the schematic diagram of the conventional feedback Buck circuit shown in FIG. 3, it can be seen that the output voltage V of the Buck circuit_outIs always greater than V_FB. In fact, based on the existing feedback Buck circuit, V_outIs generally greater than V_FBAt least 0.5V higher. That is, the minimum driving voltage of the output of the conventional feedback Buck circuit is limited by V_FBBut not to a voltage range of 1V or less.

Therefore, in the technical scheme provided by the embodiment of the invention, the inventor considers that a feedback circuit based on a negative feedback amplifying circuit can be provided for the Buck circuit, and the output voltage V of the amplifying circuit is enabled to be under the voltage amplifying action of the amplifying circuit_out' in comparison with V_outIs amplified by N times; thus, even if V_out' the lowest voltage is limited by V_FBCannot reach V_FBThe following voltage range, but V_outIs V _out1/N of' may be lower than V_FBSo that the Buck circuit can output V_FBThe following voltage range. Therefore, compared with the existing feedback Buck circuit, the technical scheme of the invention can provide the driving voltage in a lower voltage range; meanwhile, the Buck circuit in the technical scheme of the invention can provide enough power for one IC to drive the whole liquid crystal panel, so that the drive power requirement of the liquid crystal panel of the electronic curtain can be met at lower cost.

The technical solution of the embodiments of the present invention is described in detail below with reference to the accompanying drawings.

Example one

As shown in fig. 4a, a driving circuit for providing a driving voltage to a liquid crystal panel of an electronic window curtain according to an embodiment of the present invention includes: a Buck circuit 401, a first feedback circuit 402, and an output control circuit 403.

Wherein, the voltage output terminal of the Buck circuit 401 is connected with the IC of the liquid crystal panel of the electronic curtain to provide the driving voltage V for the liquid crystal panel_out. In practical applications, the Buck circuit 401 is usually integrated and packaged in one chip.

The first feedback circuit 402 is a feedback circuit based on a negative feedback amplification circuit.

The output control circuit 403 is configured to turn on the first feedback circuit 402 as a feedback circuit of the Buck circuit 401, and output a driving voltage to the liquid crystal panel from the Buck circuit 401. As mentioned above, the Buck circuit can output V due to the voltage amplification of the amplifying circuit in the feedback circuit_FBThe following voltage ranges of the driving voltages, so that a lower voltage range of the driving voltages can be provided. In practical applications, the output control circuit 403 may be implemented by a programmable single chip, a CPU, or a logic device.

Specifically, the first feedback circuit 402 may include: negative feedback amplifying circuit, first voltage divider circuit based on series resistance.

Wherein, the negative feedback input end of the negative feedback amplifying circuit is connected with the output end of the Buck circuit 401. Specifically, as shown in fig. 4a, the circuit configuration of the negative feedback amplifier circuit includes: amplifier, resistors R5, R6, R7. The resistor R6 is connected between the output end of the amplifier and the negative feedback end of the amplifier in a bridge mode; one end of the resistor R5 is connected with the negative feedback end of the amplifier, and the other end of the resistor R5 is connected with the output end of the Buck circuit 401 as the negative feedback end of the negative feedback amplifying circuit; resistor R7 is connected between the positive feedback terminal of the amplifier and ground.

The first voltage division circuit is connected between the output end of the negative feedback amplification circuit and the ground, and the inter-resistor connection point of the series resistor is connected with the feedback end of the Buck circuit 401. Specifically, the first voltage dividing circuit may employ a commonly used voltage dividing circuit based on a series resistance. As shown in fig. 4a, the first voltage divider circuit includes series resistors R3 and R4.

Further, in order to control the connection and disconnection relationship between the first feedback circuit 402 and the Buck circuit 401, the first feedback circuit 402 may further include: a first switch S3 and a second switch S4.

The first switch S3 is connected between the connection point between the resistors of the first voltage divider circuit and the feedback end of the Buck circuit 401; specifically, a first switch S3 is provided between the connection point of the resistors R3 and R4 and the feedback terminal of the Buck circuit 401.

The second switch S4 is disposed in the current path from the negative feedback input terminal of the negative feedback amplifying circuit to the first voltage dividing circuit. Specifically, a path from the output terminal of the Buck circuit 401, that is, from the negative feedback input terminal of the negative feedback amplifier circuit, through the resistors R5 and R6 to the resistor R3 of the first voltage divider circuit is a current path when the negative feedback amplifier circuit is used as the feedback circuit of the Buck circuit 401. A second switch S4 is provided in this path. That is, the second switch S4 may be disposed between the resistor R3 and the amplifier output terminal, or between the resistor R5 and the output terminal of the Buck circuit 401, or between the resistors R5 and R6, or between the resistor R6 and the amplifier output terminal.

The output control circuit 403 may specifically control the first switch S3 and the second switch S4 to be turned on, so as to turn on the first feedback circuit 402 as a feedback circuit of the Buck circuit 401, and the Buck circuit 401 outputs the driving voltage to the liquid crystal panel. Of course, the output control circuit 403 may also control the first switch S3 and the second switch S4 to be turned off, so as to disconnect the first feedback circuit 402 from the Buck circuit 401.

When the first feedback circuit 402 is turned on as a feedback circuit of the Buck circuit 401, the output voltage V of the Buck circuit 401 (i.e., the driving voltage of the liquid crystal panel)_outAnd a feedback terminal voltage V of the Buck circuit 401_FBThe relationship between them is shown in the following equation 1:

V_out＝V_FBx ((R3+ R4)/R4)/N (formula 1)

In the above formula 1, N is an amplification factor of the negative feedback amplification circuit, where N is 1+ R5/R6; R3-R6 are the resistance values of the resistors R3-R6.

As can be seen from the above equation 1, V_outMay be lower than V_FBThereby widening the low voltage range of the driving voltage, and enabling the low voltage range to reach the voltage range lower than 1V or even 0.5V.

As a preferred implementation, the driving circuit of the liquid crystal panel provided in the first embodiment of the present invention may employ a multi-stage feedback circuit to widen the range of the driving voltage supplied by the driving circuit, so that the driving circuit has a wider applicability. Therefore, as shown in fig. 4b, the driving circuit of the liquid crystal panel according to the first embodiment of the present invention may further include: a second feedback circuit 404.

The second feedback circuit 404 may employ a conventional feedback circuit, such as a series resistance based voltage divider circuit as shown in fig. 3.

Specifically, the second feedback circuit 404 includes a second voltage divider circuit based on a series resistance.

As shown in fig. 4b, the second feedback circuit 404 includes a second voltage divider circuit composed of series resistors R1 and R2, a third switch S1, and a fourth switch S2.

The second voltage division circuit and the third switch are connected in series between the output end of the Buck circuit 401 and the ground;

the fourth switch is connected between the connection point between the resistors of the second voltage divider circuit and the feedback terminal 401 of the Buck circuit.

Accordingly, the output control circuit 403 may turn on the first feedback circuit 402 as a current feedback circuit of the Buck circuit 401, and the Buck circuit 401 outputs the driving voltage in the first range to the liquid crystal panel, and further may turn on the second feedback circuit 404 as a current feedback circuit of the Buck circuit 401, and the Buck circuit outputs the driving voltage in the second range to the liquid crystal panel;

specifically, the output control circuit 403 may control the third switch and the fourth switch to be turned off, the first switch and the second switch to be turned on, so as to turn on the first feedback circuit 402 as the current feedback circuit of the Buck circuit 401, and the Buck circuit outputs a driving voltage in a first range to the liquid crystal panel; or the third switch and the fourth switch are controlled to be turned on, the first switch and the second switch are turned off, the second feedback circuit 404 is turned on to be a current feedback circuit of the Buck circuit 401, and the Buck circuit outputs a driving voltage in a second range to the liquid crystal panel.

When the second feedback circuit 404 is turned on as the feedback circuit of the Buck circuit 401, the output terminal voltage (i.e., the driving voltage of the liquid crystal panel) V of the Buck circuit 401_outAnd a feedback terminal voltage V of the Buck circuit 401_FBThe relationship between them is shown in the following equation 2:

V_out＝V_FBx ((R1+ R2)/R2) (equation 2)

In formula 2, R1 and R2 are resistances of the resistors R1 and R2 in the circuit shown in fig. 4b, respectively. Obviously, V in equation 2_outIs always greater than V_FB。

The driving voltage in the first range is smaller than the driving voltage in the second range. The driving voltage larger than the demarcation voltage value is a driving voltage in a first range, and the driving voltage smaller than or equal to the demarcation voltage value is a driving voltage in a second range. That is, for a first range of drive voltages, the demarcation voltage value is the voltage value at the upper end of its range; for the second range of drive voltages, the demarcation voltage value is the voltage value at the lower end of its range.

The value of the demarcation voltage may be set to an appropriate value by one skilled in the art according to the circuit characteristics of the first feedback circuit 402 and the second feedback circuit 404. For example, the demarcation voltage value may be 2V, the voltage greater than 2V may be the driving voltage in the second range, and the voltage less than or equal to 2V may be the driving voltage in the first range.

When a driving voltage larger than 2V, that is, a driving voltage in a second range, needs to be provided to the liquid crystal panel, the output control circuit 403 may control the third switch and the fourth switch to be turned on, the first switch and the second switch are turned off, the second feedback circuit 404 is turned on as the current feedback circuit of the Buck circuit 401, and the Buck circuit outputs the driving voltage in the second range, that is, the driving voltage larger than 2V, to the liquid crystal panel.

When a driving voltage smaller than or equal to 2V, that is, a driving voltage in a first range needs to be provided to the liquid crystal panel, the output control circuit 403 may control the first switch and the second switch to be turned on, the third switch and the fourth switch to be turned off, the first feedback circuit 402 is turned on as a current feedback circuit of the Buck circuit 401, and the Buck circuit outputs the driving voltage in the first range, that is, the driving voltage smaller than or equal to 2V, for example, a lower voltage such as 0.8V, 0.5V, etc., to the liquid crystal panel.

Of course, the driving voltage of the first range also has a lower voltage value, such as 0.1V; the second range of drive voltages will also have a voltage value at the upper end of the range. A person skilled in the art may empirically set a voltage value of the lower limit of the range for a driving voltage of the first range and a voltage value of the upper limit of the range for a driving voltage of the second range.

Preferably, the driving circuit of the first embodiment of the present invention can further provide a stepped driving voltage to the liquid crystal panel of the electronic curtain, so that the electronic curtain presents a plurality of semi-transparent transition states with different degrees between transparent and opaque states, and the electronic curtain has better light transmission adjustability.

The driving circuit shown in fig. 4a or 4b may further include: a first trimming circuit.

Specifically, the first trimming circuit includes a resistor R9. The resistor R9 is connected across the resistor-to-resistor connection of the first voltage divider circuit and the first voltage output terminal of the output control circuit 403.

Correspondingly, the output control circuit 403 is further configured to control the first voltage output terminal to output the first adjustment voltage when the liquid crystal panel is supplied with the driving voltage in the first range.

Further, as shown in fig. 4b, the driving circuit of the liquid crystal panel according to the embodiment of the present invention may further include: a second trimming circuit.

Specifically, the second trimming circuit includes a resistor R8. The resistor R8 is connected across the connection point between the resistors of the second voltage divider circuit and the first voltage output terminal of the output control circuit 403.

Correspondingly, the output control circuit 403 is further configured to control the second voltage output terminal to output the second adjustment voltage when the second range of driving voltage is provided for the liquid crystal panel.

In fact, the output control circuit 403 may control the driving circuit to output the driving voltage to the liquid crystal panel through programmed software, and the following describes in detail the control method of the driving circuit according to the embodiment of the present invention:

based on the above-described driving circuit, the most basic method for the output control circuit 403 to control the driving circuit to output the driving voltage to the liquid crystal panel is: and controlling a first feedback circuit in the driving circuit to be connected with a feedback circuit of a Buck circuit in the driving circuit, and outputting a driving voltage to the liquid crystal panel by the Buck circuit. That is, the output control circuit 403 controls the first and second switches to be turned on, so that the first feedback circuit is turned on as the feedback circuit of the Buck circuit, and the Buck circuit outputs the driving voltage of the first range to the liquid crystal panel.

More preferably, the output control circuit 403 may also control the drive circuit to output a wider range of drive voltages for the case where the drive circuit has a multi-stage feedback circuit: when judging that the driving voltage required by the liquid crystal panel is the voltage in the first range, the output control circuit 403 controls the first feedback circuit to be connected with the current feedback circuit of the Buck circuit, and the Buck circuit outputs the driving voltage in the first range to the liquid crystal panel; and when judging that the driving voltage required by the liquid crystal panel is the voltage in the second range, the output control circuit 403 controls the second feedback circuit to be switched on as the current feedback circuit of the Buck circuit, and the Buck circuit outputs the driving voltage in the second range to the liquid crystal panel.

Preferably, the output control circuit 403 according to the first embodiment of the present invention may further control the driving circuit to output a stepped driving voltage, and a specific method flow is shown in fig. 5, which may include the following steps:

s501: judging the range of the required driving voltage; if the driving voltage is within the first range, the following step S502 is performed, and if the driving voltage is within the second range, the following step S512 is performed.

In this step, the output control circuit 403 may determine the current required driving voltage of the liquid crystal panel according to the current requirement, for example, according to the received command or the detected illumination intensity; further, it is determined whether the currently required driving voltage belongs to the first range or the second range. If the driving voltage is within the first range, the following step S502 is performed, and if the driving voltage is within the second range, the following step S512 is performed.

S502: the output control circuit 403 controls the first feedback circuit to turn on as the current feedback circuit of the Buck circuit.

Specifically, the output control circuit 403 may control the first switch and the second switch to be turned on, the third switch and the fourth switch to be turned off, the first feedback circuit is turned on as a feedback circuit of the Buck circuit, and the Buck circuit outputs the driving voltage in the first range to the liquid crystal panel.

S503: the output control circuit 403 calculates and outputs the first adjustment voltage.

In this step, the output control circuit 403 calculates a first adjustment voltage according to the driving voltage required by the liquid crystal panel, the feedback voltage of the Buck circuit, the amplification factor of the negative feedback amplification circuit, the resistance value of the resistor in the first voltage division circuit, and the resistance value of the resistor in the first fine adjustment circuit;

then, according to the calculation result, the output control circuit 403 outputs a voltage to the first trimming circuit through the first voltage output terminal.

Specifically, the output control circuit 403 may calculate the first adjustment voltage according to the following equation 3:

V_out＝R3/(N×R9)×V_IN+(1+R3/(N×R4)-R3/(N×R9))×V_FB(formula 3)

In formula 3, V_outDriving voltage, V, required for the liquid crystal panel_INFor the first regulation of voltage, V_FBThe feedback voltage of the Buck circuit is shown, R9 is the resistance value of a resistor R9 in the first trimming circuit, and R3 and R4 are the resistance values of resistors R3 and R4 in the first voltage division circuit respectively; n is the amplification coefficient of the negative feedback amplification circuit, and is 1+ R5/R6; r5 and R6 are resistances of resistors R5 and R6 in the negative feedback amplifying circuit.

From equation 3, the first regulated voltage V can be seen_INDriving voltage V to liquid crystal panel_outThe relationship between them. The output control circuit can control the output toFirst regulating voltage V of first fine tuning circuit_INThe first regulated voltage acts on the first feedback circuit to make the output voltage of the Buck circuit, i.e. the driving voltage V of the liquid crystal panel_outWith a consequent change. The output control circuit can control and adjust the driving voltage in the first range provided for the liquid crystal panel of the electronic curtain, so that the electronic curtain presents a plurality of semi-transparent transition states with different degrees between penetration and fog, and the electronic curtain has better light transmission adjustability.

S512: the output control circuit 403 controls the second feedback circuit to turn on as the current feedback circuit of the Buck circuit.

Specifically, the output control circuit 403 may control the third switch and the fourth switch to be turned on, the first switch and the second switch to be turned off, the second feedback circuit is turned on as a feedback circuit of the Buck circuit, and the Buck circuit outputs a second range of driving voltage to the liquid crystal panel.

S513: the output control circuit 403 calculates and outputs the second adjustment voltage.

In this step, the output control circuit 403 may calculate a second adjustment voltage according to the driving voltage required by the liquid crystal panel, the feedback voltage of the Buck circuit, the resistance value of the resistor in the second voltage division circuit, and the resistance value of the resistor in the second trimming circuit;

then, according to the calculation result, the output control circuit 403 outputs a voltage to the second trimming circuit through the second voltage output terminal.

Specifically, the output control circuit 403 may calculate the second adjustment voltage according to the following equation 4:

V_out＝R1/R8×V_IN'+(1+R1/R2-R1/R8)×V_FB(formula 4)

In formula 4, V_outDriving voltage, V, required for the liquid crystal panel_IN' is a second regulated voltage, V_FBFor the feedback voltage of the Buck circuit, R8 is the resistance of the resistor R8 in the second trimming circuit, and R1 and R2 are the resistances of the resistors R1 and R2 in the second voltage divider circuit, respectively.

From equation 4, it can be seen that the second regulated voltage V_IN' Driving with liquid Crystal PanelVoltage V_outThe relationship between them. The output control circuit may control the second regulation voltage V output to the second trimming circuit_IN' the second regulated voltage is applied to the second feedback circuit to make the output voltage of Buck circuit, i.e. the driving voltage V of liquid crystal panel_outWith a consequent change. The output control circuit can control and adjust the driving voltage in the second range provided for the liquid crystal panel of the electronic curtain, so that the electronic curtain presents a plurality of semi-transparent transition states with different degrees between penetration and fog-like states, and the electronic curtain has better light transmission adjustability.

Example two

As shown in fig. 6a, the driving circuit for providing a driving voltage to a liquid crystal panel of an electronic window curtain according to the second embodiment of the present invention includes: buck circuit 601, first feedback circuit 602, output control circuit 603.

Wherein, the voltage output end of the Buck circuit 601 is connected with the IC of the liquid crystal panel of the electronic curtain to provide the driving voltage V for the liquid crystal panel_out. In practical applications, the Buck circuit 601 is usually integrated and packaged in one chip.

The first feedback circuit 602 is a feedback circuit based on a negative feedback amplification circuit.

The output control circuit 603 is configured to turn on the first feedback circuit 602 as a feedback circuit of the Buck circuit 601, and output a driving voltage from the Buck circuit 601 to the liquid crystal panel. As mentioned above, the Buck circuit can output V due to the voltage amplification of the amplifying circuit in the feedback circuit_FBThe following voltage ranges of the driving voltages, so that a lower voltage range of the driving voltages can be provided. In practical applications, the output control circuit 603 may be implemented by a programmable single chip, a CPU, or a logic device.

Specifically, the first feedback circuit 602 may include: negative feedback amplifying circuit, first voltage divider circuit based on series resistance.

The positive feedback input end of the negative feedback amplifying circuit in the first feedback circuit 602 is connected to the output end of the Buck circuit 601. Specifically, the circuit structure of the negative feedback amplifying circuit in the first feedback circuit 602, as shown in fig. 6a, includes: amplifier A601, resistors R605 and R606. Wherein, the resistor R605 is bridged between the output end of the amplifier A601 and the negative feedback end of the amplifier A601; the resistor R606 is connected between the negative feedback terminal of the amplifier a601 and ground.

The first voltage divider circuit of the first feedback circuit 602 is connected between the output terminal of the negative feedback amplifier circuit in the first feedback circuit 602 and the ground, that is, between the output terminal of the amplifier a601 and the ground, and the inter-resistor connection point of the series resistor is connected to the feedback terminal of the Buck circuit 601. Specifically, the first voltage dividing circuit may employ a commonly used voltage dividing circuit based on a series resistance. As shown in fig. 6a, the first voltage divider circuit includes series resistors R603 and R604.

Further, in order to control the connection and disconnection relationship between the first feedback circuit 602 and the Buck circuit 601, the first feedback circuit 602 may further include: a first switch S603 and a second switch S604.

The first switch S603 is connected between the connection point between the resistors of the first voltage divider circuit and the feedback end of the Buck circuit 601; specifically, a first switch S603 is provided between the connection point of the resistors R603 and R604 and the feedback terminal of the Buck circuit 601.

The second switch S604 is disposed between the positive feedback input terminal of the negative feedback amplifying circuit of the first feedback circuit 602 and the output terminal of the Buck circuit 601.

The output control circuit 603 may specifically control the first switch S603 and the second switch S604 to be turned on, so as to turn on the first feedback circuit 602 as a feedback circuit of the Buck circuit 601, and the Buck circuit 601 outputs the driving voltage to the liquid crystal panel. Of course, the output control circuit 603 may also control the first switch S603 and the second switch S604 to be turned off, so as to disconnect the first feedback circuit 602 from the Buck circuit 601.

When the first feedback circuit 602 is turned on as the feedback circuit of the Buck circuit 601, the voltage at the output terminal of the Buck circuit 601 (i.e., the driving voltage of the liquid crystal panel) V_outVoltage V at feedback terminal of Buck circuit 601_FBThe relationship between them is shown in the following equation 5:

V_out＝V_FBx ((R603+ R604)/R604)/N (formula 5)

In the above equation 5, N is an amplification factor of the negative feedback amplifier circuit of the first feedback circuit 602, where N is 1+ R605/R606; r603, R604, R605, R606 are resistance values of the above-described resistors R603, R604, R605, R606.

As can be seen from the above equation 5, V_outMay be lower than V_FBThereby widening the low voltage range of the driving voltage, and enabling the low voltage range to reach the voltage range lower than 1V or even 0.5V.

As a preferred implementation, the driving circuit of the liquid crystal panel provided in the second embodiment of the present invention may adopt a multi-stage feedback circuit to widen the range of the driving voltage supplied by the driving circuit, so that the driving circuit has a wider applicability. Therefore, as shown in fig. 6b, the driving circuit of the liquid crystal panel according to the second embodiment of the present invention may further include: a second feedback circuit 604.

The second feedback circuit 604 may employ a conventional feedback circuit, such as a series resistance based voltage divider circuit as shown in fig. 3.

Specifically, the second feedback circuit 604 includes a second voltage divider circuit based on a series resistance.

As shown in fig. 6b, the second feedback circuit 604 includes a second voltage divider circuit composed of series resistors R601 and R602, and a third switch S601 and a fourth switch S602.

The second voltage divider and the third switch S601 of the second feedback circuit 604 are connected in series between the output terminal of the Buck circuit 601 and ground;

the fourth switch S602 is connected between the connection point between the resistors of the second voltage divider of the second feedback circuit 604 and the feedback terminal 601 of the Buck circuit.

Accordingly, the output control circuit 603 may turn on the first feedback circuit 602 as the current feedback circuit of the Buck circuit 601, and the Buck circuit 61 outputs the driving voltage in the first range to the liquid crystal panel, and further may turn on the second feedback circuit 604 as the current feedback circuit of the Buck circuit 601, and the Buck circuit outputs the driving voltage in the second range to the liquid crystal panel;

specifically, the output control circuit 603 may control the third switch S601 and the fourth switch S602 to be turned off, the first switch S603 and the second switch S604 to be turned on, the first feedback circuit 602 is turned on as a current feedback circuit of the Buck circuit 601, and the Buck circuit outputs a first range of driving voltage to the liquid crystal panel; or the third switch S601 and the fourth switch S602 are controlled to be turned on, the first switch S603 and the second switch S604 are turned off, the second feedback circuit 604 is turned on as the current feedback circuit of the Buck circuit 601, and the Buck circuit outputs a driving voltage in a second range to the liquid crystal panel.

When the second feedback circuit 604 is turned on as the feedback circuit of the Buck circuit 601, the voltage V at the output terminal of the Buck circuit 601 (i.e., the driving voltage of the liquid crystal panel)_outVoltage V at feedback terminal of Buck circuit 601_FBThe relationship between them is shown in the following equation 6:

V_out＝V_FBx ((R601+ R602)/R602) (equation 6)

In equation 6, R601 and R602 are the resistances of the resistors R601 and R602 in the circuit shown in fig. 6b, respectively. Obviously, V in equation 6_outIs always greater than V_FB。

The value of the demarcation voltage may be set to an appropriate value by one skilled in the art according to the circuit characteristics of the first feedback circuit 602 and the second feedback circuit 604. For example, the demarcation voltage value may be 2V, the voltage greater than 2V may be the driving voltage in the second range, and the voltage less than or equal to 2V may be the driving voltage in the first range.

When a driving voltage larger than 2V, that is, a driving voltage in a second range needs to be provided to the liquid crystal panel, the output control circuit 403 may control the third switch S601 and the fourth switch S602 to be turned on, the first switch S603 and the second switch S604 to be turned off, the second feedback circuit 604 to be turned on as a current feedback circuit of the Buck circuit 601, and the Buck circuit outputs the driving voltage in the second range, that is, the driving voltage larger than 2V to the liquid crystal panel.

When a driving voltage smaller than or equal to 2V, that is, a driving voltage in a first range needs to be provided to the liquid crystal panel, the output control circuit 603 may control the first switch S603 and the second switch S604 to be turned on, the third switch S601 and the fourth switch S602 to be turned off, the first feedback circuit 602 is turned on as a current feedback circuit of the Buck circuit 601, and the Buck circuit outputs the driving voltage in the first range, that is, the driving voltage smaller than or equal to 2V, that is, a lower voltage such as 0.8V or 0.5V, to the liquid crystal panel.

Preferably, the driving circuit of the second embodiment of the present invention can further provide a stepped driving voltage to the liquid crystal panel of the electronic curtain, so that the electronic curtain presents a plurality of semi-transparent transition states with different degrees between transparent and opaque states, and the electronic curtain has better light transmission adjustability.

The driving circuit shown in fig. 6a or 6b may further include: a first trimming circuit; the first trimming circuit specifically includes a resistor R609. The resistor R609 is connected across the resistor-resistor junction of the first voltage divider of the first feedback circuit 602 and the first voltage output terminal of the output control circuit 603.

Correspondingly, the output control circuit 603 is further configured to control the first voltage output terminal to output the first adjustment voltage when the liquid crystal panel is provided with the driving voltage in the first range.

Further, as shown in fig. 6b, the driving circuit of the liquid crystal panel according to the second embodiment of the present invention may further include: a second trimming circuit. The second trim circuit includes a resistor R608. The resistor R608 is connected across the resistor-resistor connection of the second voltage divider of the second feedback circuit 604 and the first voltage output terminal of the output control circuit 603.

Correspondingly, the output control circuit 603 is further configured to control the second voltage output terminal to output the second adjustment voltage when the driving voltage in the second range is provided for the liquid crystal panel.

In fact, the output control circuit 603 can control the driving circuit to output the driving voltage to the liquid crystal panel through the programmed software, and the following describes the control method of the driving circuit according to the second embodiment of the present invention in detail:

based on the above-described driving circuit, the most basic method for the output control circuit 603 to control the driving circuit to output the driving voltage to the liquid crystal panel is: the first feedback circuit 602 in the drive circuit is controlled to turn on the feedback circuit which is the Buck circuit 601 in the drive circuit, and the Buck circuit 601 outputs the drive voltage to the liquid crystal panel. That is, the output control circuit 603 controls the first switch S603 and the second switch S604 to be turned on, so that the first feedback circuit 602 is turned on as a feedback circuit of the Buck circuit 601, and the Buck circuit outputs a first range of driving voltage to the liquid crystal panel.

More preferably, the output control circuit 603 can also control the driving circuit to output a wider range of driving voltages for the case where the driving circuit has a multi-stage feedback circuit: when the output control circuit 603 determines that the driving voltage required by the liquid crystal panel is a voltage in a first range, the output control circuit controls the first feedback circuit 602 to be switched on as a current feedback circuit of the Buck circuit 601, and the Buck circuit 601 outputs the driving voltage in the first range to the liquid crystal panel; and when the output control circuit 603 determines that the driving voltage required by the liquid crystal panel is a voltage in a second range, the output control circuit 603 controls the second feedback circuit 604 to be connected to a current feedback circuit of the Buck circuit 601, and the Buck circuit outputs the driving voltage in the second range to the liquid crystal panel.

Preferably, the output control circuit 603 according to the second embodiment of the present invention may further control the driving circuit to output a stepped driving voltage, and a specific method flow is shown in fig. 7, and may include the following steps:

s701: judging the range of the required driving voltage; if the driving voltage is within the first range, the following step S702 is performed, and if the driving voltage is within the second range, the following step S712 is performed.

In this step, the output control circuit 603 may determine the magnitude of the driving voltage currently required by the liquid crystal panel according to the current requirement, for example, according to the received command or the detected information such as the illumination intensity; further, it is determined whether the currently required driving voltage belongs to the first range or the second range. If the driving voltage is within the first range, the following step S702 is performed, and if the driving voltage is within the second range, the following step S712 is performed.

S702: the output control circuit 603 controls the first feedback circuit 602 to turn on the current feedback circuit which is the Buck circuit.

Specifically, the output control circuit 603 may control the first switch and the second switch to be turned on, the third switch and the fourth switch to be turned off, the first feedback circuit 602 is turned on as a feedback circuit of the Buck circuit 601, and the Buck circuit outputs a driving voltage in a first range to the liquid crystal panel.

S703: the output control circuit 603 calculates and outputs a first adjustment voltage.

In this step, the output control circuit 603 calculates a first adjustment voltage according to the driving voltage required by the liquid crystal panel, the feedback voltage of the Buck circuit, the amplification factor of the negative feedback amplification circuit, the resistance value of the resistor in the first voltage division circuit, and the resistance value of the resistor in the first fine adjustment circuit;

then, according to the calculation result, the output control circuit 603 outputs a voltage to the first trimming circuit through the first voltage output terminal.

Specifically, the output control circuit 603 may calculate the first adjustment voltage according to the following equation 7:

V_out＝R603/(N×R609)×V_IN+(1+R603/(N×R604)-R603/(N×R609))×V_FB(formula 7)

In the formula 7, V_outDriving voltage, V, required for the liquid crystal panel_INFor the first regulation of voltage, V_FBThe feedback voltage of the Buck circuit 601 is shown, R609 is the resistance value of the resistor R609 in the first trimming circuit, and R603 and R604 are the resistance values of the resistors R603 and R604 in the first voltage dividing circuit respectively; n is the amplification coefficient of the negative feedback amplification circuit, and is 1+ R605/R606; r605 and R606 are resistance values of resistors R605 and R606 in the negative feedback amplifying circuit.

From equation 7, it can be seen that the first regulated voltage V_INDriving voltage V to liquid crystal panel_outThe relationship between them. The output control circuit may control the first regulation voltage V output to the first trimming circuit_INThe first regulated voltage acts on the first feedback circuit to make the output voltage of the Buck circuit, i.e. the driving voltage V of the liquid crystal panel_outWith a consequent change. The output control circuit can control and adjust the driving voltage in the first range provided for the liquid crystal panel of the electronic curtain, so that the electronic curtain presents a plurality of semi-transparent transition states with different degrees between penetration and fog, and the electronic curtain has better light transmission adjustability.

S712: the output control circuit 603 controls the second feedback circuit to be switched on as the current feedback circuit of the Buck circuit.

Specifically, the output control circuit 603 may control the third switch and the fourth switch to be turned on, the first switch and the second switch to be turned off, the second feedback circuit is turned on as the feedback circuit of the Buck circuit 601, and the Buck circuit outputs the driving voltage of the second range to the liquid crystal panel.

S713: the output control circuit 603 calculates and outputs the second adjustment voltage.

In this step, the output control circuit 603 may calculate a second adjustment voltage according to the driving voltage required by the liquid crystal panel, the feedback voltage of the Buck circuit, the resistance value of the resistor in the second voltage division circuit, and the resistance value of the resistor in the second trimming circuit;

then, according to the calculation result, the output control circuit 603 outputs a voltage to the second trimming circuit through the second voltage output terminal.

Specifically, the output control circuit 603 may calculate the second adjustment voltage according to the following equation 8:

V_out＝R601/R608×V_IN'+(1+R601/R602-R601/R608)×V_FB(formula 8)

In the formula 8, V_outDriving voltage, V, required for the liquid crystal panel_IN' is a second regulated voltage, V_FBFor the feedback voltage of the Buck circuit 601, R608 is the resistance of the resistor R608 in the second trimming circuit, and R601 and R602 are the resistances of the resistors R601 and R602 in the second voltage dividing circuit, respectively.

From equation 8, it can be seen that the second regulated voltage V_IN' Driving voltage V with liquid crystal panel_outThe relationship between them. The output control circuit may control the second regulation voltage V output to the second trimming circuit_IN' the second regulated voltage is applied to the second feedback circuit to make the output voltage of Buck circuit, i.e. the driving voltage V of liquid crystal panel_outWith a consequent change. The output control circuit can control and adjust the driving voltage in the second range provided for the liquid crystal panel of the electronic curtain, so that the electronic curtain presents a plurality of semi-transparent transition states with different degrees between penetration and fog-like states, and the electronic curtain has better light transmission adjustability.

In the technical scheme of the invention, the feedback circuit based on the negative feedback amplifying circuit is provided for the Buck circuit, so that the voltage amplifying function of the amplifying circuit can be utilized to ensure that the output voltage V of the amplifying circuit_out' in comparison with V_outIs amplified by N times; thus, even if V_out' the lowest voltage is limited by V_FBCannot reach V_FBThe following voltage range, but V_outIs V _out1/N of' may be lower than V_FBSo that the Buck circuit can output V_FBThe following voltage range. Therefore, compared with the existing feedback Buck circuit, the technical scheme of the invention can provide the driving voltage in a lower voltage range; meanwhile, the Buck circuit in the technical scheme of the invention can provide enough power for one IC to drive the whole liquid crystal panel, so that the drive power requirement of the liquid crystal panel of the electronic curtain can be met at lower cost.

Preferably, in the driving circuit according to the above embodiment of the present invention, the driving circuit includes a multi-stage feedback circuit including a first feedback circuit and a second feedback circuit; the Buck circuit based on the first feedback circuit can output the driving voltage in the first range, and the Buck circuit based on the second feedback circuit can output the driving voltage in the second range, so that the range of the driving voltage supplied by the driving circuit is widened, and the driving circuit is wider in applicability.

Preferably, the first or second feedback circuit of the above embodiment of the present invention is further connected to a trimming circuit, the output control circuit can control the regulated voltage output to the trimming circuit, and the regulated voltage acts on the feedback circuit, so as to change the output voltage of the Buck circuit. That is, the output control circuit can change the driving voltage output to the liquid crystal panel by changing the adjustment voltage. The output control circuit can control and adjust the driving voltage provided for the liquid crystal panel of the electronic curtain, so that the electronic curtain presents a plurality of semi-transparent transition states with different degrees between the transparent state and the non-transparent state, and the electronic curtain has better light transmission adjustability.

In addition, in another aspect of the present invention, an electronic window curtain is provided, which has a liquid crystal panel, and is characterized in that the liquid crystal panel adopts the driving circuit of the liquid crystal panel according to any one of the above embodiments.

Those skilled in the art will appreciate that the present invention includes apparatus directed to performing one or more of the operations described in the present application. These devices may be specially designed and manufactured for the required purposes, or they may comprise known devices in general-purpose computers. These devices have stored therein computer programs that are selectively activated or reconfigured. Such a computer program may be stored in a device (e.g., computer) readable medium, including, but not limited to, any type of disk including floppy disks, hard disks, optical disks, CD-ROMs, and magnetic-optical disks, ROMs (Read-Only memories), RAMs (Random Access memories), EPROMs (Erasable programmable Read-Only memories), EEPROMs (Electrically Erasable programmable Read-Only memories), flash memories, magnetic cards, or optical cards, or any type of media suitable for storing electronic instructions, and each coupled to a bus. That is, a readable medium includes any medium that stores or transmits information in a form readable by a device (e.g., a computer).

It will be understood by those within the art that each block of the block diagrams and/or flowchart illustrations, and combinations of blocks in the block diagrams and/or flowchart illustrations, can be implemented by computer program instructions. Those skilled in the art will appreciate that the computer program instructions may be implemented by a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, implement the features specified in the block or blocks of the block diagrams and/or flowchart illustrations of the present disclosure.

Those of skill in the art will appreciate that various operations, methods, steps in the processes, acts, or solutions discussed in the present application may be alternated, modified, combined, or deleted. Further, various operations, methods, steps in the flows, which have been discussed in the present application, may be interchanged, modified, rearranged, decomposed, combined, or eliminated. Further, steps, measures, schemes in the various operations, methods, procedures disclosed in the prior art and the present invention can also be alternated, changed, rearranged, decomposed, combined, or deleted.

Those of ordinary skill in the art will understand that: the discussion of any embodiment above is meant to be exemplary only, and is not intended to intimate that the scope of the disclosure, including the claims, is limited to these examples; within the idea of the invention, also features in the above embodiments or in different embodiments may be combined, steps may be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity. Therefore, any omissions, modifications, substitutions, improvements and the like that may be made without departing from the spirit and principles of the invention are intended to be included within the scope of the invention.

Claims

1. A driving circuit of a liquid crystal panel, comprising: the step-down conversion circuit for providing the driving voltage for the liquid crystal panel is characterized by further comprising:

a first feedback circuit based on a negative feedback amplifying circuit;

2. The circuit according to claim 1, wherein the first feedback circuit comprises in particular:

3. The circuit according to claim 1, wherein the first feedback circuit comprises in particular:

4. The circuit of claim 2 or 3, further comprising:

5. The circuit according to claim 4, wherein the second feedback circuit comprises in particular:

6. The circuit of claim 5, further comprising:

the first fine tuning circuit comprises a resistor which is bridged between a resistor connecting point of the first voltage division circuit and a first voltage output end of the output control circuit;

a second trimming circuit comprising a resistor connected across the resistor-to-resistor connection of the second voltage divider circuit and the second voltage output terminal of the output control circuit; and

the output control circuit is also used for controlling a first voltage output end to output a first regulating voltage when the driving voltage in a first range is provided for the liquid crystal panel; and when the liquid crystal panel is provided with the driving voltage in the second range, controlling a second voltage output end to output a second regulating voltage.

7. A method for driving a liquid crystal panel, comprising:

8. The method according to claim 7, wherein the first feedback circuit comprises: the negative feedback amplifier circuit, the first voltage division circuit based on the series resistor, the first switch and the second switch; and

9. The method according to claim 7, wherein the first feedback circuit comprises: the negative feedback amplifier circuit, the first voltage division circuit based on the series resistor, the first switch and the second switch; and

the positive feedback input end of the negative feedback amplifying circuit is connected with the output end of the buck conversion circuit;

10. The method of claim 8 or 9, wherein the driving circuit further comprises: a second feedback circuit; and

the method further comprises the following steps:

when the driving voltage required by the liquid crystal panel is the voltage in the second range, controlling a second feedback circuit to be connected with a current feedback circuit of the buck conversion circuit, and outputting the driving voltage in the second range to the liquid crystal panel by the buck conversion circuit; wherein the driving voltage in the first range is smaller than the driving voltage in the second range;

11. The method of claim 10, wherein the second feedback circuit comprises: a second voltage division circuit, a third switch and a fourth switch; and

in the method, the controlling the second feedback circuit to be connected to the current feedback circuit of the buck conversion circuit specifically includes:

controlling the third switch and the fourth switch to be switched on, and switching off the first switch and the second switch;

the fourth switch is connected between the connection point between the resistors of the second voltage division circuit and the feedback end of the buck conversion circuit.

12. The method of claim 10, wherein the driving circuit further comprises: a first trimming circuit including a resistor connected to a connection point between resistors of the first voltage dividing circuit; and a second trimming circuit including a resistor connected to a connection point between the resistors of the second voltage dividing circuit; and

when the controlling the first feedback circuit in the driving circuit is turned on as a feedback circuit of a buck converter circuit in the driving circuit, the method further comprises: outputting a first regulation voltage to a first fine tuning circuit; and

when the controlling a second feedback circuit in the drive circuit turns on as a feedback circuit of a buck converter circuit in the drive circuit, the method further comprises: and outputting a second regulated voltage to a second trim circuit.

13. An electronic window curtain having a liquid crystal panel, characterized in that the liquid crystal panel employs a drive circuit of the liquid crystal panel according to any one of claims 1 to 6.

14. An electronic window curtain having a liquid crystal panel, characterized in that the liquid crystal panel employs the method for driving a liquid crystal panel according to any one of claims 7 to 12.