LU506047B1

LU506047B1 - Dimming system and self-powering method thereof

Info

Publication number: LU506047B1
Application number: LU506047A
Authority: LU
Inventors: Shiju E
Original assignee: Univ Zhejiang Normal
Priority date: 2023-01-09
Filing date: 2024-01-08
Publication date: 2024-07-08
Also published as: CN116224639A

Abstract

The present disclosure belongs to the dimming field and relates to a dimming system and a self-powering method thereof, to implement a self-powered dimming film. The dimming system includes an electret generator, a rectifying apparatus, a reset switch, a dimming film structure, and a voltage management module. The electret generator can convert an external mechanical stimulus into electric energy. An output terminal of the electret generator is connected to an input terminal of the rectifying apparatus. An output terminal of the rectifying apparatus is connected to the dimming film structure. The reset switch, the dimming film structure, and the voltage management module are connected in parallel. In this way, the self-powered dimming system without an external power supply can be obtained. The self-powered dimming film prepared in the present disclosure does not need an external power supply. A transmittance of the dimming film structure can be adjusted and controlled through an external stimulus. An initial optical state of the dimming film can be switched by rotating a polarizer. An application range is greatly expanded. Therefore, the dimming film can be applied to fields such as buildings, automobiles, and electronics.

Description

DIMMING SYSTEM AND SELF-POWERING METHOD THEREOF

LU506047

TECHNICAL FIELD

The present disclosure relates to the technical field of intelligent dimming, and specifically, to a dimming system and a self-powering method thereof.

BACKGROUND

The liquid crystal dimming film is an electronic light control product. When there is no electric field, an electronically controlled dimming polymer dispersed liquid crystal (PDLC) film can achieve a good effect of switching between transparent and fogging.

The liquid crystal dimming film is obtained by injecting a liquid crystal/polymer mixed material between two transparent conductive films. When there is no electric field, the liquid crystal dimming film is in an opaque state. After electrification, liquid crystals in the film are orderly arranged under an action of an electric field such that the film is in a transparent state.

Rapid switching between an on state and an off state can be implemented under the action of the electric field.

It can be learned that performance of the liquid crystal dimming film is closely related to its power supply. However, an application range of the liquid crystal dimming film is greatly limited due to a need for an external voltage source.

Related literature (Wang J, Meng C, Wang C T, et al, A fully self-powered, ultra-stable cholesteric smart window triggered by instantaneous mechanical stimuli, Nano Energy, 2021, 85:105976) has reported a method for charging a cholesteric liquid crystal smart window through a triboelectric nanogenerator. The smart window can switch from transparent to fogging. Diffuse reflection of incident light can be implemented through the fogging effect, to achieve concealment. However, due to material and structural constraints, there are still the following problems: 1. Achieving the fogging effect requires the generator to repeatedly charge the smart window and a voltage across a dimming film to reach 12 V. 2. The dimming film cannot return to a transparent state in power-off mode and can return to an initial state only by applying additional mechanical load on a surface of the dimming film. 3. An initial optical state of the smart window can be only the transparent state. 4. A transmittance of the dimming film cannot be gradually or selectively adjusted by adjusting a magnitude of supplied power as needed.

SUMMARY OF PRESENT INVENTION

In view of this, an objective of the present disclosure is to provide a dimming system and a self-powering method thereof to implement self-powering of the dimming system and an adjustable visible light transmittance by overcoming the following technical problems in the LU506047 background that dimming cannot be completely realized in power-off mode in an existing self- powered liquid crystal dimming film. À high voltage needs to be generated in the dimming film.

Additional load needs to be applied to the dimming film. Consequently, an application range is limited.

To solve the above problems, a first objective of the present disclosure is to provide a dimming system. The dimming system includes: a dimming film structure; an electret generator including first substrates arranged oppositely, two first electrode layers bonded to opposite sides of the first substrates, and a charged electret film connected to a surface of one of the first electrode layers, where the charged electret film is located between the two first electrode layers; a rectifier circuit having two opposite input terminals electrically connected to the first electrode layers of the electret generator respectively and two opposite output terminals electrically connected to the dimming film structure; a reset switch connected in parallel to the dimming film structure; and a voltage management module connected in parallel to the reset switch and configured to store charges generated by the electret generator and provide overvoltage protection for the dimming film structure, where the voltage management module powers the dimming film structure and maintains a voltage across the dimming film structure when there is no external stimulus.

Optionally, the dimming film structure includes a dimming film, light-transmitting substrates sandwiched on upper and lower surfaces of the dimming film, second electrode layers attached to the light-transmitting substrates and located on sides close to the dimming film, and polarizers pasted to the light-transmitting substrates and located on sides away from the dimming film, and the opposite output terminals of the rectifier circuit are electrically connected to the second electrode layers of the dimming film structure respectively.

Optionally, the voltage management module includes an external capacitor and a Zener diode connected in parallel, and the external capacitor and the Zener diode are connected in parallel to the second electrode layers; and when there is a continuous external stimulus, the Zener diode is configured to release excess charges between the second electrode layers to prevent an excessive voltage across the dimming film structure from damaging a liquid crystal structure of the dimming film.

Optionally, the reset switch includes two substrates with third electrode layers, the third electrode layers are printed on opposite surfaces of the substrates, and the third electrode layers are respectively connected to the output terminals of the rectifier circuit.

Optionally, a material of the light-transmitting substrate is a transparent substrate, and a material of the second electrode layer is a transparent electrode.

Optionally, an electret material of the charged electret film is any one of polyvinylidene LU506047 fluoride, a perfluoroethylene propylene copolymer, polyimide, polychlorotrifluoroethylene, polypropylene, polyethylene, a cycloolefin copolymer, soluble polytetrafluoroethylene, ethylene tetrafluoroethylene, and parylene.

A second objective of the present disclosure is to provide a self-powering method for the above dimming system and including the following steps:

S100: preparing an electret generator, a rectifier circuit, a reset switch, a dimming film structure, and a voltage management module:

S200: electrically connecting the electret generator to the reset switch, the dimming film structure, and the voltage management module through the rectifier circuit:

S300: rotating a relative angle of two polarizers to select an initial transmittance of a dimming film; and

S400: adjusting a light-transmitting state of the dimming film, where the light-transmitting state of the dimming film includes a first switching mode and a second switching mode; the first switching mode is switching the dimming film from the light-transmitting state to a dark state; and the second switching mode is switching the dimming film from the dark state to the light- transmitting state.

Optionally, in S400, Operation steps of the first switching mode include: making the dimming film initially in the light-transmitting state; pressing the electret generator such that the electret generator injects charges to second electrode layers of the dimming film structure to form a voltage across the dimming film, a stable voltage between the second electrode layers deflects liquid crystal molecules of the dimming film, and the dimming film darkens; and pressing the reset switch to reset the dimming film to the light-transmitting state.

Optionally, in S400, Operation steps of the second switching mode include: adjusting an angle between polarization directions of the two polarizers to 45 degrees such that the dimming film is in a translucent state; and pressing the electret generator to switch the dimming film to a transparent state; and pressing the reset switch to reset the dimming film to the dark state.

Optionally, charging methods of an electret material of the electret generator include corona charging, friction charging, contact polarization, liquid polarization, and high temperature polarization.

Compared with the prior art, the present disclosure has the following beneficial effects: 1. Inthe present disclosure, different amounts of positive charges are induced between upper and lower electrodes in first electrode layers through an electret generator. When a distance between an electret and the upper and lower electrodes is changed, a potential difference between the two electrodes changes, and electrons flow between the upper and lower electrodes. The flow of the electrons between the first electrode layers can be converted into 06047 a direct current (DC) pulse by connecting a rectifier circuit. A capacitor structure composed of a dimming film and second electrode layers can be charged by connecting the rectifier circuit and a dimming film structure. Charges can be stably maintained on the two second electrode layers of the dimming film structure due to a reverse surge action of the rectifier circuit, to form a stable voltage. In this way, liquid crystal molecules deflect and the dimming film darkens, to implement a dimming function. 2. In the prior art, implementing such an effect requires the generator to repeatedly charge the dimming film and a voltage across the dimming film to reach 12 V. The following problem in the prior art is also resolved: The dimming film cannot return to a transparent state in power- off mode. Further, an application range of the dimming film is expanded. A limitation that an initial optical state of the dimming film can be only the transparent state in the prior art is completely resolved.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic structural diagram of a dimming system according to an embodiment of the present disclosure;

Fig. 2 is a schematic structural diagram of a dimming film structure according to an embodiment of the present disclosure;

Fig. 3 is a schematic diagram of a transmittance adjustment principle of a dimming film structure according to an embodiment of the present disclosure;

Fig. 4 is a schematic diagram of light-transmitting states of a dimming system whose initial state is a transparent state in different trigger modes according to an embodiment of the present disclosure;

Fig. 5 is a schematic diagram of light-transmitting states of a dimming system whose initial state is a dark state in different trigger modes according to an embodiment of the present disclosure;

Fig. 6 is a schematic diagram of visible light transmittances of a dimming system whose initial state is a transparent state in different trigger modes according to an embodiment of the present disclosure;

Fig. 7 is a schematic diagram of output performance of an electret generator according to

Embodiment 1 of the present disclosure;

Fig. 8 is a schematic diagram of output performance of an electret generator according to

Embodiment 2 of the present disclosure;

Fig. 9 is a schematic diagram of relationships between a voltage and a transmittance of a dimming film and a quantity of times of pressing an electret generator according to an embodiment of the present disclosure;

Fig. 10 is a schematic diagram of relationships between different capacitances of an external capacitor and a voltage of a dimming film according to an embodiment of the present LU506047 disclosure; and

Fig. 11 is a flowchart of a self-powering method of a dimming system according to an embodiment of the present disclosure. 5 Reference numerals: 1-electret generator; 11-charged electret film; 12-first electrode layer; 13-first substrate: 2-rectifier circuit 3-reset switch; 31-substrate; 32-third electrode layer, 4-dimming film structure; 41-light-transmitting substrate; 42-second electrode layer; 43-dimming film; 44-polarizer, 5-voltage management module: 51-external capacitor; 52-Zener diode.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The following clearly and completely describes the technical solutions of the present disclosure with reference to accompanying drawings. Apparently, the described embodiments are merely some rather than all of the embodiments of the present disclosure. All other embodiments obtained by those skilled in the art based on the embodiments of the present disclosure without creative efforts shall fall within the protection scope of the present disclosure.

In the description of the present disclosure, it should be noted that orientations or position relationships indicated by terms such as "upper", "lower", “left”, “right”, "inner", and “outer” are orientation or position relationships shown in the accompanying drawings, and these terms are only used to facilitate description of the present disclosure and simplify the description, but not to indicate or imply that the mentioned apparatus or components must have a specific orientation or must be established and operated in a specific orientation, and thus these terms cannot be understood as a limitation to the present disclosure. In addition, the terms such as "first", "second", and "third" are used only for the purpose of description and cannot be understood to indicate or imply relative importance.

In the description of the present disclosure, it should be noted that, unless otherwise clearly specified, meanings of terms "install", "connected with", and "connected to" should be understood in a board sense. For example, the connection may be a fixed connection, a removable connection, or an integral connection; may be a mechanical connection or an electrical connection; may be a direct connection or an indirect connection by using an intermediate medium; may be intercommunication between two components; or may be a wired connection or a wireless connection. Those of ordinary skill in the art may understand specific meanings of the foregoing terms in the present disclosure based on a specific situation.

In addition, the technical features involved in the various implementations of the present LU506047 disclosure described below may be combined with each other as long as they do not constitute a conflict with each other.

As shown in figures 1 - 10, an embodiment of the present disclosure provides a dimming system. The dimming system includes an electret generator 1, a rectifier circuit 2, a reset switch 3, a dimming film structure 4, and a voltage management module 5.

The electret generator 1 includes first substrates 13 arranged oppositely, first electrode layers 12, and a charged electret film 11. The first electrode layers 12 are bonded to opposite sides of the first substrates 13. The charged electret film 11 is connected to a surface of one of the first electrode layers 12. The charged electret film 11 is located between the two first electrode layers 12.

In this embodiment, the charged electret film 11 is connected to a lower surface of the first electrode layer 12. Space between the charged electret film 11 and a lower electrode of the first electrode layer 12 may be filled with any dielectric material to suppress breakdown and improve output performance.

In a preferred implementation in the embodiments of the present disclosure, the electret generator 1 in this embodiment is an energy conversion apparatus, and may alternatively be a friction generator, a thermoelectric generator, a dielectric elastomer generator, or the like. Any apparatus capable of converting an ambient environment stimulus into electrical energy may be used to replace the electret generator 1 in the embodiments of the present disclosure to meet different application environment requirements.

The rectifier circuit 2 has two opposite input terminals electrically connected to the first electrode layers 12 of the electret generator 1 respectively and two opposite output terminals electrically connected to second electrode layers 42 of the dimming film structure 4 respectively.

Further, the rectifier circuit 2 in this embodiment may be replaced by any electronic device having a unidirectional conduction function, such as a diode.

The reset switch 3 is connected in parallel to the dimming film structure 4.

The voltage management module 5 is connected in parallel to the reset switch 3, and is configured to store charges generated by the electret generator 1 and provide overvoltage protection. When there is no external stimulus, the voltage management module 5 powers the dimming film structure 4 and maintains a voltage across the dimming film structure 4. When there is a continuous external stimulus, the voltage management module 5 releases excess charges to prevent a liquid crystal material of the dimming film structure 4 from being damaged by a high voltage.

In the embodiments of the present disclosure, a specific implementation process of preparing the electret generator 1 is as follows:

First, the first electrode layer 12 is prepared on a side of the charged electret film 11, and negative corona polarization is performed on an electret through a high voltage source of -10 kV. Preferably, the electret used herein has an area of 5 cm? and a thickness of 50 um. LU506047

Then, the side of the charged electret film 11 with the first electrode layer 12 is fastened to the first substrate 13.

As a best preferred mode of this embodiment, the first substrate 13 is made of polyethylene terephthalate (PET) and bonded and fastened through a conventional adhesive.

Finally, the charged electret film 11 and the first substrate 13 with the first electrode layer 12 constitute an electromechanical conversion apparatus in this embodiment.

In the embodiments of the present disclosure, an electret material of the electret generator 1 includes but is not limited to polyvinylidene fluoride (PVDF), a perfluoroethylene propylene copolymer (FEP), polyimide (PI), polychlorotrifluoroethylene (PCTFE), polypropylene (PP), polyethylene (PE), a cycloolefin copolymer (COC), soluble polytetrafluoroethylene (PFA), ethylene tetrafluoroethylene (E-TFE), parylene, and the like.

In the embodiments of the present disclosure, charging methods of the electret material of the electret generator 1 include corona charging, friction charging, contact polarization, liquid polarization, and high temperature polarization.

It should be explained in detail herein that for those skilled in the art, the electret material is a material that can be semi-permanently charged. This is existing common knowledge.

Referring to figure 2, in the embodiments of the present disclosure, the dimming film structure 4 includes light-transmitting substrates 41, the second electrode layers 42, a dimming film 43, and polarizers 44.

The light-transmitting substrates 41 are sandwiched on upper and lower surfaces of the dimming film 43. The second electrode layers 42 are printed on the light-transmitting substrates 41 and located on sides close to the dimming film 43. The polarizers 44 are pasted to the light- transmitting substrates 41 and located on sides away from the dimming film 43. The opposite output terminals of the rectifier circuit 2 are electrically connected to the second electrode layers 42 of the dimming film structure 4 respectively.

In addition, the dimming film 43 in this embodiment is a liquid crystal dimming layer. A liquid crystal of the dimming film 43 may be a twisted nematic (TN) or super-twisted nematic (STN) liquid crystal. Certainly, a mixture of the two types of liquid crystals or a little cholesteric liquid crystal may alternatively be used. Specifically, the TN liquid crystal is preferred in the embodiments of the present disclosure. The TN liquid crystal is a TN liquid crystal material that is optically active and has a twist angle of 90 to 110 degrees.

It should be further explained herein that if the TN liquid crystal is used as a material of a liquid crystal layer, polarization layers need to be disposed on sides of a conductive layer.

Polarized light is formed after incident light passes through the outer polarization layer. When passing through the liquid crystal layer, the polarized light is rotated by the twisted liquid crystal.

When absorption axis directions of the two polarization layers are perpendicular to each other, rotated polarized light can smoothly pass through the inner polarization layer. In this case, a heat-insulation and sun-shading variable liquid crystal film has a high transmittance. When an LU506047 electric field is applied to the liquid crystal layer, liquid crystal molecules tend to be in a non- twisted state from a twisted state, and a polarization direction of light passing through the outer polarization layer is maintained. Therefore, light cannot completely pass through the inner polarization layer. In this case, the heat-insulation and sun-shading variable liquid crystal film has a low transmittance.

In addition, a horizontal relative angle between the upper and lower polarizers 44 can be manually adjusted to adjust a desired transmittance variation range of the dimming film 43.

In the embodiments of the present disclosure, a specific implementation process of preparing the dimming film structure 4 is as follows:

First, the transparent second electrode layers 42 are prepared on the two light-transmitting substrates 41. A material of the light-transmitting substrate 41 is light-transmitting glass. A material of the second electrode layer 42 is indium tin oxide (ITO). Specifically:

In this embodiment, the material of the light-transmitting substrate 41 is a transparent substrate, and the material of the second electrode layer 42 is a transparent electrode. The transparent substrate is preferably transparent glass. The transparent electrode is preferably any one of fluorine-doped tin oxide, ITO, and a metal nanowire, and further preferably ITO.

It should be noted that ITO used in this embodiment is sputtered on transparent glass through magnetron sputtering. ITO has a visible light transmittance higher than 60% and a sheet resistance lower than 600 ohms/square. This is a conventional technical means for those skilled in the art.

Then, the dimming film 43 is disposed between the two second electrode layers 42. The polarizers 44 are respectively pasted to outermost layers of the two light-transmitting substrates 41. The two polarizers 44 are parallel to each other.

Finally, the horizontal relative angle between the two polarizers 44 is rotated to select an initial transmittance of the dimming film 43. It should be noted that when an angle between polarization directions of the two polarizers 44 is approximately 90 degrees, the dimming film 43 is in a light-transmitting state.

Referring to figure 1, in the embodiments of the present disclosure, the dimming film 43 is made of a TN liquid crystal material. Certainly, any liquid crystal material responsive to an electric field or a liquid crystal mixture may alternatively be used.

The dimming film 43 has a structure using a liquid crystal. In the dimming film 43 using the liquid crystal, a liquid crystal cell is manufactured by sandwiching a liquid crystal material between transparent film materials having transparent electrodes, and the liquid crystal cell is sandwiched between the polarizers 44 for manufacturing.

Therefore, in the dimming film 43, an electric field applied to the liquid crystal is changed to change an orientation of the liquid crystal such that external light is blocked or transmitted and an amount of transmitted light is variable, to control transmission of the external light. When the horizontal relative angle between the two polarizers 44 is adjusted, the desired transmittance LU506047 variation range of the dimming film 43 can be adjusted.

Preferably, in this embodiment, an area of the dimming film 43 is 10x10 cm”.

In addition, it can be understood that the polarizer 44 is a multilayer film material capable of converting unpolarized light into polarized light, and is a conventional material in the art.

Referring to figure 1, in the embodiments of the present disclosure, the reset switch 3 includes two substrates 31 with third electrode layers 32. The third electrode layers 32 are printed on opposite surfaces of the substrates 31. The third electrode layers 32 are respectively connected to the output terminals of the rectifier circuit 2.

Specifically, the reset switch 3 has a piezoresistive switch structure for controlling conduction of the third electrode layers 32. In this embodiment, the reset switch 3 is composed of the two substrates 31 with the third electrode layers 32. The reset switch 3 is pressed such that the second electrode layers 42 in the dimming film structure 4 can be conducted, to reset an initial state of the dimming film 4.

Referring to figure 1, in this embodiment, the electret generator 1 may be connected to the reset switch 3 and the dimming film structure 4 through the rectifier circuit 2. The rectifier circuit 2 is configured to rectify mains power into first DC power for output. The rectifier circuit 2 may be a rectifier bridge, a rectifier diode, or another component having a rectification function.

In an optional implementation, the rectifier circuit 2 is a bridge rectifier circuit, as shown in figure 1. Because a specific connection manner is a conventional experimental operation in the art, it is not described herein.

It can be learned from an electrostatic induction principle that because the electret material of the electret generator 1 is negatively charged, different amounts of positive charges are induced between upper and lower electrodes in the first electrode layers 12. When a distance between the electret and the lower electrode is changed, a potential difference between the upper and lower electrodes in the first electrode layers 12 is changed, and electrons flow between the upper and lower electrodes.

Referring to figure 1, the electron flow can be converted into a DC pulse by connecting to a rectifier bridge of the rectifier circuit 2. Then, the rectifier bridge of the rectifier circuit 2 is connected to the dimming film structure 4. Under an action of the electret generator 1, the second electrode layers 42 in the dimming film structure 4 can be charged. The charges can be stably maintained on the two electrodes of the dimming film structure 4 due to a reverse surge action of the rectifier bridge, to form a stable voltage. In this way, the liquid crystal molecules deflect and the dimming film 4 darkens, to implement a dimming function.

Referring to figure 1, in the embodiments of the present disclosure, the voltage management module 5 includes an external capacitor 51 and a Zener diode 52 connected in parallel. The external capacitor 51 and the Zener diode 52 are connected in parallel to the second electrode layers 42. A function of the external capacitor 51 is to store the charges generated by the electret generator 11; and when there is no external stimulus, power the LU506047 dimming film structure 4, to maintain a voltage across the dimming film 4 and ensure an optical state. À function of the Zener diode 52 is to release excess charges between the upper and lower electrode layers of the dimming film 4 to prevent the liquid crystal molecules from being damaged by the voltage exceeding a threshold.

When there is a continuous external stimulus, the Zener diode 52 is configured to release the excess charges between the second electrode layers 42 to prevent an excessive voltage across the dimming film structure 4 from damaging a liquid crystal structure of the dimming film 43.

In a preferred implementation in the embodiments of the present disclosure, the first electrode layer 12 and the third electrode layer 32 are made of a same material, which is a conductive material with a specific optical transmittance. The material includes but is not limited to copper, gold, aluminium, silver and a nanowire thereof, a carbon tube, and other electrode materials.

Referring to figure 11, another embodiment of the present disclosure further provides a self- powering method of a dimming system. Based on the foregoing dimming system, the self- powering method includes the following steps:

In S100, an electret generator 1, a rectifier circuit 2, a reset switch 3, a dimming film structure 4, and a voltage management module 5 are prepared.

In S200, the electret generator 1 is electrically connected to the reset switch 3, the dimming film structure 4, and the voltage management module 5 through the rectifier circuit 2.

IN Saoo, à horizontal relative angle of two polarizers 44 is rotated to select an initial transmittance of a dimming film 43.

In S400, à light-transmitting state of the dimming film 43 is adjusted. The light-transmitting state of the dimming film 43 includes a first switching mode and a second switching mode.

The first switching mode is switching the dimming film 43 from the light-transmitting state to a dark state.

The second switching mode is switching the dimming film 43 from the dark state to the light- transmitting state.

Specifically, in the embodiments of the present disclosure, in Sao, operation steps of the first switching mode include:

The dimming film 43 is initially in the light-transmitting state.

The electret generator 1 is pressed such that the electret generator 1 is adapted to charge second electrode layers 42 of the dimming film structure 4, and the dimming film structure 4 gradually darkens. A stable voltage between the second electrode layers 42 deflects liquid crystal molecules of the dimming film 43. The dimming film structure 4 has its visible light transmittance decreased, that is, darkens. The reset switch 3 is pressed to reset the dimming film structure 4 to the light-transmitting state.

Specifically, in the embodiments of the present disclosure, in Sao, operation steps of the LU506047 second switching mode include:

An angle between polarization directions of the two polarizers 44 is adjusted to 45 degrees such that the dimming film 43 is in a translucent state.

The electret generator 1 is pressed to switch the dimming film structure 4 to a transparent state. The reset switch 3 is pressed to reset the dimming film structure 4 to the dark state.

Embodiment 1:

In Embodiment 1 of the present disclosure, a dimming system includes an electret generator 1, a rectifier circuit 2, a reset switch 3, a dimming film structure 4, and a voltage management module 5. A charged electret film 11 used in the electret generator 1 is made of

FEP and has an area of 5 cm? and a thickness of 12.5 um. A used dimming film 43 has an area of 10x10 cm? and a capacitance of 92 nF. A used external capacitor 51 has a capacitance of 10 nF. A used Zener diode 52 has a model of 1N739 and achieves a stable voltage of 9.1 V.

When the electret generator 1 is pressed, a horizontal relative angle of two polarizers 44 is approximately 90 degrees. That is, an initial state of the dimming film 43 is as shown in figure 4.

In an operation mode shown in figure 4, the dimming film structure 4 switches from a visible light transmitting state to an opaque state. A change of a transmittance of the dimming film 43 with a wavelength shown in figure 6 can be obtained.

Referring to figure 7, when the electret generator 1 is pressed, there is a potential difference between upper and lower electrodes in first electrode layers 12 of the electret generator 1. When the electret generator 1 is completely pressed and released through an external force of 10 N, an open circuit voltage generated by the electret generator 1 is 280 V, and an amount of unidirectionally transferred charges is 180 nC. The charges are injected between upper and lower electrodes in second electrode layers 42 of the dimming film 43 and into the external capacitor 51 through a rectifier bridge of the rectifier circuit 2. A voltage across the dimming film is 3.1 V.

Embodiment 2: figure 8 is a diagram of a voltage output characteristic and a charge output characteristic of an electret generator 1. In comparison with Embodiment 1, a difference lies in that a charged electret film 11 used in the electret generator 1 is made of polytetrafluoroethylene (PTFE) and has an area of 5 cm? and a thickness of 50 um. The other parameters are the same as those in

Embodiment 1.

In an operation mode shown in figure 5, a dimming film 43 is disposed between two second electrode layers 42. Two polarizers 44 are respectively pasted to outermost layers of the two second electrode layers 42. A horizontal relative angle between the two polarizers 44 is rotated to select an initial transmittance. At this time, an angle between polarization directions of the two polarizers 44 is 45 degrees, and the dimming film is in a translucent state. When the electret LU506047 generator 1 is pressed, the dimming film 4 switches to a transparent state. When the reset switch 3 is pressed, the dimming film returns to the translucent state.

Referring to figure 8, when the electret generator 1 is completely pressed and released through an external force of 10 N, an open circuit voltage generated by the electret generator 1 is 60 V, and an amount of unidirectionally transferred charges is 70 nC.

The charges are injected between the upper and lower second electrode layers 42 of the dimming film 43 and into the external capacitor 51 through a rectifier circuit 2. A voltage across the dimming film 43 is 1.2 V.

As the electret generator 1 is continuously pressed, the voltage across the dimming film 43 continuously increases. Due to a voltage stabilization effect of a Zener diode 52, the voltage cannot further increase until it reaches a saturation voltage of 9.1 V.

Referring to figure 9, a transmittance of the dimming film 43 and a transmittance of a dimming film structure 4 at a wavelength of 500 nm continuously decrease as the voltage across the dimming film 43 increases. A visible light transmittance of the dimming film 43 can be adjusted by adjusting the electret generator 1. The visible light transmittance can be adjusted by changing a magnitude of a press force, a size of the electret generator 1, a quantity of stacked electret generators 1, and a material.

Embodiment 3:

Conditions in Embodiment 3 are the same as those in Embodiment 1, except that a capacitance of an external capacitor 51 is changed. The external capacitor 51 is a CBB capacitor.

Referring to figure 10, a voltage of a dimming system connected to the external capacitor 51 with different capacitances is increased to 4 V. A voltage across a dimming film 43 slowly decreases over time. The voltage of the dimming film 43 connected to the external capacitor 51 decreases more slowly.

Compared with the dimming film 43, the external capacitor 51 has a good power retention capability at 9.1 V or lower. When the voltage across the dimming film 43 decreases, the external capacitor 51 provides charges to it to maintain the voltage across the dimming film 43.

As the capacitance of the external capacitor 51 increases, the voltage across the dimming film 43 decreases more slowly. This ensures a low visible light transmittance for a long time.

Embodiment 4:

Implementation conditions in Embodiment 4 are the same as those in Embodiment 1. Two polarizers 44 are orthogonal to each other. In this embodiment, when one of the polarizers 44 is rotated to the left by approximately 45°, that is, an angle between polarization directions of the two polarizers are approximately 45°, an initial optical state of a dimming film structure 4 is a translucent state. LU506047

Referring to figure 11, when an electret generator 1 is pressed, the dimming film structure 4 switches from the translucent state to a transparent state. Further, when one of the polarizers 44 is rotated to the left by 90°, the initial optical state of the dimming film structure 4 gradually changes to yellow. When the electret generator 1 is pressed, the dimming film structure 4 switches from yellow to the transparent state.

Although the present disclosure is disclosed as described above, the protection scope of the present disclosure is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present disclosure. Such changes and modifications shall fall within the protection scope of the present disclosure.

Claims

1. A dimming system, comprising: — a dimming film structure (4); — an electret generator (1) comprising — first substrates (13) arranged oppositely, — two first electrode layers (12) bonded to opposite sides of the first substrates (13), and — a charged electret film (11) connected to a surface of one of the first electrode layers (12), wherein the charged electret film (11) is located between the two first electrode layers (12); — a rectifier circuit (2) having two opposite input terminals electrically connected to the first electrode layers (12) of the electret generator (1) respectively and two opposite output terminals electrically connected to the dimming film structure (4); — a reset switch (3) connected in parallel to the dimming film structure (4); and — a voltage management module (5) connected in parallel to the reset switch (3) and configured to store charges generated by the electret generator (1) and provide overvoltage protection for the dimming film structure (4), wherein the voltage management module (5) powers the dimming film structure (4) and maintains a voltage across the dimming film structure (4) when there is no external stimulus.

2. The dimming system according to claim 1, wherein the dimming film structure (4) comprises — a dimming film (43), — light-transmitting substrates (41) sandwiched on upper and lower surfaces of the dimming film (43), — second electrode layers (42) attached to the light-transmitting substrates (41) and located on sides close to the dimming film (43), and — polarizers (44) pasted to the light-transmitting substrates (41) and located on sides away from the dimming film (43), wherein the opposite output terminals of the rectifier circuit (2) are electrically connected to the second electrode layers (42) of the dimming film structure (4) respectively.

3. The dimming system according to claim 2, wherein the voltage management module (5) comprises an external capacitor (51) and a Zener diode (52) connected in parallel, wherein — the external capacitor (51) and the Zener diode (52) are connected in parallel to the second electrode layers (42); and

— when there is a continuous external stimulus, the Zener diode (52) is configured to LU506047 release excess charges between the second electrode layers (42) to prevent an excessive voltage across the dimming film structure (4) from damaging a liquid crystal structure of the dimming film (43).

4. The dimming system according to claim 3, wherein the reset switch (3) comprises two substrates (31) with third electrode layers (32), wherein — the third electrode layers (32) are printed on opposite surfaces of the substrates (31), and — the third electrode layers (32) are respectively connected to the output terminals of the rectifier circuit (2).

5. The dimming system according to any one of claims 2 to 4, wherein — a material of the light-transmitting substrate (41) is a transparent substrate, and — a material of the second electrode layer (42) is a transparent electrode.

6. The dimming system according to claim 5, wherein an electret material of the charged electret film (11) is any one of polytetrafluoroethylene, a perfluoroethylene propylene copolymer, polyimide, polychlorotrifluoroethylene, polypropylene, polyethylene, a cycloolefin copolymer, soluble polytetrafluoroethylene, ethylene tetrafluoroethylene, and parylene.

7. A self-powering method of a dimming system, based on the dimming system according to any one of claims 2 to 6 and comprising the following steps: S100: preparing an electret generator (1), a rectifier circuit (2), a reset switch (3), a dimming film structure (4), and a voltage management module (5); S200: electrically connecting the electret generator (1) to the reset switch (3), the dimming film structure (4), and the voltage management module (5) through the rectifier circuit (2); S300: rotating a relative angle of two polarizers (44) to select an initial transmittance of a dimming film (43); and S400: adjusting a light-transmitting state of the dimming film (43), wherein the light- transmitting state of the dimming film (43) comprises a first switching mode and a second switching mode; wherein — the first switching mode is switching the dimming film (43) from the light-transmitting state to a dark state; and

— the second switching mode is switching the dimming film (43) from the dark state to the, 506047 light-transmitting state.

8. The self-powering method of a dimming system according to claim 7, wherein in step S400, operation steps of the first switching mode comprise: — making the dimming film (43) initially in the light-transmitting state; — pressing the electret generator (1) such that the electret generator (1) injects charges to second electrode layers (42) of the dimming film structure (4) to form a voltage across the dimming film (43), a stable voltage between the second electrode layers (42) deflects liquid crystal molecules of the dimming film (43), and the dimming film (43) darkens; and — pressing the reset switch (3) to reset the dimming film (43) to the light-transmitting state.

9. The self-powering method of a dimming system according to claim 7, wherein in step S400, operation steps of the second switching mode comprise: — adjusting an angle between polarization directions of the two polarizers (44) to 45 degrees such that the dimming film (43) is in a translucent state; and — pressing the electret generator (1) to switch the dimming film (43) to a transparent state; and pressing the reset switch (3) to reset the dimming film (43) to the dark state.

10. The self-powering method of a dimming system according to claim 8 or 9, wherein charging methods of an electret material of the electret generator (1) comprise corona charging, friction charging, contact polarization, liquid polarization, and high temperature polarization.