WO2023065876A9

WO2023065876A9 - Rear cover, electronic device, and preparation method for rear cover

Info

Publication number: WO2023065876A9
Application number: PCT/CN2022/117787
Authority: WO
Inventors: 沈奎; 郜成杰; 王超
Original assignee: 荣耀终端有限公司
Priority date: 2021-10-21
Filing date: 2022-09-08
Publication date: 2023-06-22
Also published as: CN114994963A; WO2023065876A1

Abstract

A rear cover (120), an electronic device (1000), and a preparation method for the rear cover (120). The rear cover (120) has diversified appearance effects and can meet the appearance requirements of users. The rear cover (120) comprises a transparent cover plate (10), a composite liquid crystal membrane (20) and a decorative membrane (30). A composite liquid crystal layer (25) and the decorative membrane (30) are located on the same side of the transparent cover plate (10), and the composite liquid crystal membrane (20) is located between the transparent cover plate (10) and the decorative membrane (30). The composite liquid crystal membrane (20) comprises the composite liquid crystal layer (25), wherein the composite liquid crystal layer (25) comprises an organic polymer matrix (26) and a plurality of liquid crystal droplets (27); and the liquid crystal droplets (27) are dispersed in the organic polymer matrix (26). Each liquid crystal droplet (27) comprises a liquid crystal molecule (28) and a dichroic dye molecule (29), wherein the dichroic dye molecule (29) is linked to the liquid crystal molecule (28) and can deflect along with the deflection of the liquid crystal molecule (28).

Description

Back cover, electronic device and method for preparing back cover

This application claims the priority of the Chinese patent application with the application number 202111226129.0 and the application title "Back Cover, Electronic Device and Back Cover Preparation Method" filed with the China Patent Office on October 21, 2021, the entire contents of which are incorporated by reference in this application.

technical field

The present application relates to the technical field of electronic equipment, in particular to a back cover, an electronic equipment and a method for preparing the back cover.

Background technique

With the continuous development of science and technology, electronic devices such as mobile phones are widely used in people's daily life and work, and have become indispensable daily necessities for people. At present, the back cover of electronic equipment is generally made of plastic, metal, glass or ceramics. The appearance effect of the back cover is fixed, resulting in a single appearance decoration of the back cover, which cannot meet the appearance requirements of users.

Contents of the invention

The embodiments of the present application provide a back cover, an electronic device and a method for preparing the back cover, which are used to increase the variety of appearance and decoration of the back cover, so as to meet the user's appearance requirements.

In a first aspect, the present application provides a back cover, which includes a transparent cover plate, a composite liquid crystal film and a decorative film. The composite liquid crystal layer and the decorative film are located on the same side of the transparent cover, and the composite liquid crystal film is located between the transparent cover and the decorative film. The composite liquid crystal film includes a composite liquid crystal layer, and the composite liquid crystal layer includes an organic macromolecule matrix and a plurality of liquid crystal droplets, and the plurality of liquid crystal microdroplets are dispersed in the organic polymer matrix. Each liquid crystal droplet includes liquid crystal molecules and dichroic dye molecules, and the dichroic dye molecules are connected with the liquid crystal molecules and can deflect along with the deflection of the liquid crystal molecules. Wherein, when the composite liquid crystal layer is in the state of astigmatism, the rear cover presents the first appearance effect. When the composite liquid crystal layer is in the light-transmitting state, the rear cover presents the second appearance effect.

The back cover shown in this application uses a composite liquid crystal film to realize the diversity of appearance decoration of the back cover. The dichroic dye molecules in the composite liquid crystal layer can be deflected with the deflection of the liquid crystal molecules to achieve the "guest-host effect". On the basis of transparent changes, the color change can be realized synchronously, and the haze and color of the back cover can be changed synchronously, so that the appearance effect of the back cover can be switched between the first appearance effect and the second appearance effect. Increase the diversity of appearance and decoration of the back cover, solve the problem of single appearance effect of the existing back cover, meet the appearance needs of users, and increase the shielding effect of the composite liquid crystal layer on the decorative diaphragm in the state of astigmatism, and improve the performance of the back cover in composite The appearance effect of the liquid crystal layer in the astigmatic state and the light-transmitting state is different. In addition, dichroic dyes of different colors can be adaptively used according to individual needs, which is conducive to enhancing the designability of the back cover and realizing personalized customization of the appearance of the back cover.

In one embodiment, the composite liquid crystal film of the rear cover further includes a first transparent conductive layer and a second transparent conductive layer, and the first transparent conductive layer and the second transparent conductive layer are respectively located on opposite sides of the composite liquid crystal layer. Wherein, the first transparent conductive layer is located between the transparent cover plate and the composite liquid crystal layer, and the second transparent conductive layer is located between the composite liquid crystal layer and the decorative film.

When the voltage difference between the first transparent conductive layer and the second transparent conductive layer is equal to zero, the composite liquid crystal diaphragm is in a power-off state, the liquid crystal molecules in the composite liquid crystal layer are arranged in disorder, and the dichroic dye molecules deflect along with the liquid crystal molecules In disordered arrangement, the composite liquid crystal layer is in a state of astigmatism, and the light not only scatters under the action of liquid crystal molecules and propagates in multiple directions, but also is reflected by dichroic dye molecules and propagates in multiple directions.

When the voltage difference between the first transparent conductive layer and the second transparent conductive layer is greater than zero or less than zero, the composite liquid crystal membrane is in the energized state, the liquid crystal molecules in the composite liquid crystal layer are arranged in an orderly manner, and the dichroic dye molecules follow the liquid crystal The molecules are deflected and arranged in an orderly manner, and the composite liquid crystal layer is in a light-transmitting state, and the light can pass through the composite liquid crystal layer directly, and the propagation direction remains unchanged.

In one embodiment, the back cover further includes a flexible circuit board, the flexible circuit board is electrically connected to the first transparent conductive layer and the second transparent conductive layer, and the flexible circuit board is used to transmit electrical signals to the first transparent conductive layer and the second transparent conductive layer. The transparent conductive layer is used to change the voltage difference between the first transparent conductive layer and the second transparent conductive layer, so that the composite liquid crystal layer can be switched between a light-scattering state and a light-transmitting state.

In one embodiment, the composite liquid crystal film of the rear cover further includes a first transparent substrate and a second transparent substrate. The first transparent substrate is located between the first transparent conductive layer and the transparent cover, and the first transparent substrate carries the first transparent conductive layer. The second transparent substrate is located between the second transparent conductive layer and the decorative film, and the second transparent substrate carries the second transparent conductive layer.

In one embodiment, the back cover includes a transparent adhesive layer, and the transparent adhesive layer is bonded between the transparent cover plate and the first transparent substrate, so as to realize the assembly between the transparent cover plate and the composite liquid crystal film.

In one embodiment, the decorative film includes a transparent carrier and a transparent adhesive layer, and the transparent adhesive layer is bonded between the transparent carrier and the second transparent substrate to realize the assembly between the decorative film and the composite liquid crystal film .

In one embodiment, the decorative film includes an ink layer, and the ink layer is located on a side of the transparent carrier away from the transparent adhesive layer.

In one embodiment, the decorative film further includes a texture layer and an optical coating, the texture layer and the optical coating are located between the transparent carrier and the ink layer, the optical coating covers the surface of the texture layer away from the transparent carrier, the texture layer and the optical coating Work together to increase the glare effect of the back cover.

In one embodiment, the first appearance effect comprises the same color as the dichroic dye molecule, and the second appearance effect is a different color than the first appearance effect.

In one embodiment, the back cover is provided with a camera hole, and along the thickness direction of the back cover, the camera hole penetrates through the transparent cover plate, the composite liquid crystal layer and the decorative film.

In a second aspect, the present application provides an electronic device, the electronic device includes a processor and a back cover, and the processor is electrically connected to the back cover. The back cover includes a transparent cover plate, a composite liquid crystal film and a decorative film. The composite liquid crystal layer and the decorative film are located on the same side of the transparent cover, and the composite liquid crystal film is located between the transparent cover and the decorative film. The composite liquid crystal film includes a composite liquid crystal layer, and the composite liquid crystal layer includes an organic macromolecule matrix and a plurality of liquid crystal droplets, and the plurality of liquid crystal microdroplets are dispersed in the organic polymer matrix. Each liquid crystal droplet includes liquid crystal molecules and dichroic dye molecules, and the dichroic dye molecules are connected with the liquid crystal molecules and can deflect along with the deflection of the liquid crystal molecules. Wherein, when the composite liquid crystal layer is in the state of astigmatism, the rear cover presents the first appearance effect. When the composite liquid crystal layer is in the light-transmitting state, the rear cover presents the second appearance effect.

In the electronic device shown in this application, the back cover uses a composite liquid crystal diaphragm to realize the diversity of the appearance decoration of the back cover, and the dichroic dye molecules in the composite liquid crystal layer can deflect along with the deflection of the liquid crystal molecules, realizing the "guest-host effect". The color change can be realized synchronously on the basis of the change from haze to transparency, so as to achieve the effect of synchronous change of the haze and color of the back cover, which can not only increase the variety of appearance and decoration of the back cover, but also solve the problem of single appearance effect of the existing back cover To meet the user's appearance requirements, it can also increase the shielding effect of the composite liquid crystal layer on the decorative film when the composite liquid crystal layer is in the astigmatism state, and improve the difference in the appearance of the back cover when the composite liquid crystal layer is in the astigmatism state and the light transmission state. In addition, dichroic dyes of different colors can be adaptively used according to individual needs, which is conducive to enhancing the designability of the back cover and realizing personalized customization of the appearance of the back cover.

It can be understood that the functional interaction between the user and the electronic device can also be realized by utilizing the appearance change of the rear cover. Among them, the interactive function includes but is not limited to notification reminder functions such as call reminder, message reminder, alarm clock ringing or Bluetooth connection. Exemplarily, the back cover has the first appearance effect and the second appearance effect. When the user uses the electronic device, he does not need to unlock the electronic device, and can directly determine which application scenario the electronic device is in based on the appearance effect presented by the back cover. . For example, when the back cover of the electronic device faces the user, and the electronic device is in a sleep state, the back cover presents the first appearance effect. When the electronic device receives a new message, the processor switches the back cover from the first appearance effect to the second appearance effect through the flexible circuit board, and the user can know that the electronic device has received a new message according to the change in the appearance effect of the back cover. Not only can the user's experience be improved, but also the setting of the message prompt light in the electronic device can be omitted, which is beneficial to realize the light and thin design of the electronic device.

In one embodiment, the rear cover further includes a flexible circuit board, one end of the flexible circuit board is electrically connected to the first transparent conductive layer and the second transparent conductive layer, and the other end is electrically connected to the processor, and the flexible circuit board is used to connect the processor The sent electrical signal is transmitted to the first transparent conductive layer and the second transparent conductive layer to change the voltage difference between the first transparent conductive layer and the second transparent conductive layer, so that the composite liquid crystal layer is in the astigmatic state and the light-transmitting state switch between.

In one embodiment, the electronic device further includes a circuit board, the processor is installed on the circuit board, and the flexible circuit board is electrically connected to the circuit board to realize the electrical connection with the processor.

In one embodiment, the back cover is provided with a camera hole, and along the thickness direction of the back cover, the camera hole runs through the transparent cover plate, the composite liquid crystal layer and the decorative film.

In a third aspect, the present application provides a method for preparing a back cover, including:

forming a first transparent conductive layer on the first transparent substrate;

forming a second transparent conductive layer on the second transparent substrate;

A composite liquid crystal layer is formed between the first transparent conductive layer and the second transparent conductive layer, wherein the composite liquid crystal layer includes liquid crystal molecules and dichroic dye molecules, and the dichroic dye molecules are connected with the liquid crystal molecules and can follow the liquid crystal The deflection of the molecules deflects;

Attaching the decorative film to the surface of the second transparent substrate away from the second transparent conductive layer;

Attach the transparent cover to the surface of the first transparent substrate away from the first transparent conductive layer.

In one embodiment, after the step of forming the first transparent conductive layer on the first transparent substrate and before the step of forming a composite liquid crystal layer between the first transparent conductive layer and the second transparent conductive layer, the preparation of the back cover The method further includes: forming a first electrical signal input terminal on the surface of the first transparent conductive layer;

After the step of forming the second transparent conductive layer on the second transparent substrate, and before the step of forming a composite liquid crystal layer between the first transparent conductive layer and the second transparent conductive layer, the preparation method of the rear cover further includes: The surfaces of the two transparent conductive layers form a second electrical signal input terminal.

In one embodiment, after the step of attaching the decorative film to the surface of the second transparent substrate away from the second transparent conductive layer, and after attaching the transparent cover plate to the surface of the first transparent substrate away from the first transparent conductive layer, Before the step of layering the surface, the preparation method of the rear cover further includes: connecting the flexible circuit board to the first electrical signal input terminal and the second electrical signal input terminal.

Description of drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will describe the drawings required for the embodiments of the present application.

FIG. 1 is a schematic structural diagram of an electronic device provided in an embodiment of the present application;

Fig. 2 is a schematic structural diagram of a back cover in the electronic device shown in Fig. 1;

Fig. 3 is the sectional structure schematic diagram that the back cover shown in Fig. 2 is cut along I-I place;

Fig. 4 is a schematic diagram of the optical path when the composite liquid crystal diaphragm in the back cover shown in Fig. 3 is in a power-off state;

Fig. 5 is a schematic diagram of the optical path when the composite liquid crystal diaphragm in the rear cover shown in Fig. 3 is in an electrified state;

Fig. 6 is a process flow diagram of a method for preparing a rear cover provided by an embodiment of the present application;

FIG. 7 is a schematic structural view of forming a first transparent conductive layer on the surface of the first transparent substrate in the method for preparing the back cover shown in FIG. 6;

FIG. 8 is a structural schematic diagram of etching the first transparent conductive layer to form a first through hole in the method for preparing the back cover shown in FIG. 6;

Fig. 9 is a schematic structural diagram of forming a first electrical signal input terminal in the method for preparing the back cover shown in Fig. 6;

Fig. 10 is a schematic structural view of forming a second transparent conductive layer on the surface of the second transparent substrate in the method for preparing the back cover shown in Fig. 6;

FIG. 11 is a structural schematic diagram of etching a second transparent conductive layer to form a second through hole in the method for preparing the rear cover shown in FIG. 6;

Fig. 12 is a schematic structural view of forming a second electrical signal input terminal in the method for preparing the back cover shown in Fig. 6;

Fig. 13 is a composite liquid crystal layer formed between the first transparent conductive layer and the second transparent conductive layer in the preparation method of the back cover shown in Fig. 6, to form a structural representation of the composite liquid crystal diaphragm;

Fig. 14 is a schematic structural view of attaching the transparent adhesive layer to the surface of the first transparent substrate away from the first transparent conductive layer in the preparation method of the back cover shown in Fig. 6;

Fig. 15 is a schematic structural view of attaching the decorative film to the surface of the second transparent substrate away from the second transparent conductive layer in the preparation method of the back cover shown in Fig. 6;

Fig. 16 is a schematic structural view of the second laser engraving process in the preparation method of the back cover shown in Fig. 6;

FIG. 17 is a schematic structural diagram of connecting a flexible circuit board in the manufacturing method of the back cover shown in FIG. 6 .

Detailed ways

Please refer to FIG. 1 . FIG. 1 is a schematic structural diagram of an electronic device 1000 provided in an embodiment of the present application.

The electronic device 1000 may be a mobile phone, a tablet computer, a notebook computer, a car machine, a smart watch, a smart bracelet, a POS machine (point of sales terminal, point of sale terminal) and other electronic products. Next, the embodiment of the present application is described by taking the electronic device 1000 as a mobile phone as an example. Wherein, for the convenience of description, define the width direction of the electronic device 1000 as the X-axis direction, the length direction of the electronic device 1000 as the Y-axis direction, the thickness direction of the electronic device 1000 as the Z-axis direction, and the X-axis direction, the Y-axis direction and the Z-axis direction. The directions are perpendicular to each other.

The electronic device 1000 includes a casing 100 , a display module 200 , a circuit board 300 , a processor 400 , a speaker module 500 and a camera module 600 . The casing 100 is provided with a sound hole 1001 , and the sound hole 1001 communicates with the inside and outside of the casing 100 . The display module 200 is installed on the casing 100 . The circuit board 300 , the processor 400 and the speaker module 500 are installed inside the casing 100 . The processor 400 is mounted on the circuit board 300 and is electrically connected to the circuit board 300 . Wherein, the circuit board 300 may be a main board (main board) of the electronic device 1000, and the processor 400 may be a CPU (central processing unit, central processing unit) of the electronic device 1000. The speaker module 500 is electrically connected with the processor 400 for receiving the audio signal sent by the processor 400, and vibrates and emits sound according to the audio signal. The camera module 600 is installed in the casing 100 and exposed relative to the casing 100 . The camera module 600 is electrically connected to the processor 400, and is used for receiving information collection signals sent by the processor 400, collecting light outside the electronic device 1000, and forming corresponding image data.

Please also refer to FIG. 2 . FIG. 2 is a schematic structural diagram of the rear cover 120 in the electronic device 1000 shown in FIG. 1 .

The casing 100 includes a middle frame 110 and a rear cover 120 , and the rear cover 120 is installed on the middle frame 110 . The middle frame 110 is provided with a speaker hole 1001 . Exemplarily, there is one speaker hole 1001 . In some other embodiments, there may be more than two speaker holes 1001 , and this application does not specifically limit the number of speaker holes 1001 . Wherein, the rear cover 120 may be a battery cover of the electronic device 1000 . The rear cover 120 is provided with an imaging hole 1201 , and the imaging hole 1201 penetrates through the rear cover 120 along the thickness direction of the rear cover 120 . Specifically, the rear cover 120 is installed on one side of the middle frame 110 . The imaging hole 1201 communicates with the inside and outside of the casing 100 . Exemplarily, the rear cover 120 can be detachably installed on the middle frame 110 , so as to facilitate maintenance and replacement of internal components or modules of the electronic device 1000 .

The display module 200 is installed on the other side of the middle frame 110 . That is, the display module 200 is installed on the side of the middle frame 110 away from the rear cover 120 . That is, the display module 200 and the rear cover 120 are respectively installed on opposite sides of the middle frame 110 . When the user uses the electronic device 1000, the display module 200 is placed facing the user, and the rear cover 120 is placed facing away from the user. Wherein, the display module 200 includes a cover plate and a display screen (not shown) fixed on the cover plate. The cover plate can be made of transparent materials such as glass. The display screen may be a display screen such as LCD (liquid crystal display, liquid crystal display) or OLED (organic light-emitting diode, organic light-emitting diode display), and is used for displaying information such as images or text.

In this embodiment, the camera module 600 is exposed relative to the rear cover 120 to serve as a rear camera module of the electronic device 1000 . Specifically, the camera module 600 passes through the camera hole 1201 of the rear cover 120 . Wherein, part of the camera module 600 is located inside the casing 100 , part of the camera module 600 is located in the camera hole 1201 , and part of the camera module 600 protrudes relative to the rear cover 120 . It should be noted that the exposure of the camera module 600 relative to the rear cover 120 means that the rear cover 120 does not completely cover the camera module 600 . In some other embodiments, the camera module 600 may not protrude relative to the back cover 120. At this time, the camera module 600 may not pass through the camera hole 1201 of the back cover 120, and part of the camera module 600 is located in the housing 100. Inside, part of the camera module 600 is located in the camera hole 1201 , or, the camera module 600 is completely accommodated inside the casing 100 .

It should be noted that in existing electronic equipment, the back cover is generally made of plastic, metal, glass or ceramics, and the appearance effect of the back cover is fixed, resulting in a single appearance and decoration of the back cover, which cannot meet the needs of users. Appearance needs. Next, the rear cover 120 of the electronic device 1000 shown in the embodiment of the present application will be described.

Please also refer to FIG. 3 . FIG. 3 is a schematic cross-sectional view of the rear cover 120 shown in FIG. 2 along line I-I. Wherein, "cutting along the I-I" refers to cutting along the plane where the I-I line is located, and the related descriptions below can be understood in the same way.

The rear cover 120 includes a transparent cover plate 10 , a composite liquid crystal film 20 , a decorative film 30 , a transparent adhesive layer 40 and a flexible circuit board 50 . The composite liquid crystal film 20 , the decorative film 30 and the transparent adhesive layer 40 are located on the same side of the transparent cover 10 . The composite liquid crystal film 20 is located between the transparent cover 10 and the decorative film 30 . The transparent adhesive layer 40 is bonded between the transparent cover plate 10 and the composite liquid crystal film 20 . The flexible circuit board 50 is electrically connected between the composite liquid crystal diaphragm 20 and the circuit board 300 (as shown in FIG. 1 ), so as to realize the electrical connection between the back cover 120 and the circuit board 300, and then realize the back cover 120 and the processor 400. (As shown in Figure 1) the electrical connection between. The flexible circuit board 50 can transmit electrical signals to the composite liquid crystal diaphragm 20 to realize the transformation of the appearance effect (such as color or pattern) of the back cover 120, improve the variety of appearance and decoration of the back cover 120, and meet the user's appearance requirements. In some other embodiments, the electronic device 1000 may also include the flexible circuit board 50, but the rear cover 120 does not include the flexible circuit board 50, that is, the flexible circuit board 50 is not part of the rear cover 120, which is not specifically limited in this embodiment of the present application. .

In this embodiment, the transparent cover 10 is made of glass. In some other embodiments, the transparent cover plate 10 can also be made of transparent materials such as PC (polycarbonate, polycarbonate) or PMMA (polymethyl methacrylate, polymethacrylate). Specific limits.

It should be understood that the "transparency" mentioned in the embodiments of the present application means that the transmission of light will not be blocked, that is, the light can pass through. For example, the transparent cover 10 means that when light enters the transparent cover 10, the light will not be blocked by the transparent cover 10, that is, the light can pass through the transparent cover 10 and continue to propagate. At this time, the transparent cover 10 may have no base color, It may also have a basic color, which is not specifically limited in the present application, and the "transparency" mentioned in the following text can be understood in the same way.

The composite liquid crystal film 20 is located on the bottom side of the transparent cover 10 . In other words, the transparent cover 10 is located on the top side of the composite liquid crystal film 20 to protect the composite liquid crystal film 20 . Wherein, the composite liquid crystal film 20 may cover part of the bottom surface of the transparent cover 10 , or the composite liquid crystal film 20 may cover the entire bottom surface of the transparent cover 10 . In this embodiment, the composite liquid crystal film 20 may be a PDLC (polymer-dispersed liquid crystal, polymer-dispersed liquid crystal) dimming film. Specifically, the composite liquid crystal film 20 includes a first transparent substrate 21, a first transparent conductive layer 22, a second transparent substrate 23, a second transparent conductive layer 24 and a composite liquid crystal layer 25, and the first transparent conductive layer 22 is located on the second transparent conductive layer. The bottom side of a transparent substrate 21 , the second transparent conductive layer 24 is located on the top side of the second transparent substrate 23 , and the composite liquid crystal layer 25 is located between the first transparent conductive layer 22 and the second transparent conductive layer 24 .

It should be noted that the orientation terms such as "top" and "bottom" involved in this application are described with reference to the orientation shown in the drawings, and "bottom" is defined as "bottom" facing the positive direction of the Z axis, and "bottom" is defined as "bottom" facing the negative direction of the Z axis. The orientation is "top", which does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operate in a particular orientation, and thus should not be construed as a limitation on the application. It should be understood that the "side" mentioned in this application when describing the positional relationship between the layer structures refers to the orientation along the thickness direction of the layer structure, that is, the orientation towards the top or bottom surface of the layer, such as A Located on the side of B means that A is located on the top or bottom side of B, and the description of "side" can be understood in the same way later.

In this embodiment, the first transparent substrate 21 is made of PET (polyethylene terephthalate, polyethylene terephthalate). Wherein, the thickness of the first transparent substrate 21 is between 20 μm˜100 μm, for example, the thickness of the first transparent substrate 21 is 23 μm. In some other embodiments, the first transparent substrate 21 can also be made of materials such as TAC (triacetyl cellulose, triacetyl cellulose), PVA (polyvinyl alcohol, polyvinyl alcohol), PC or PMMA, and/or, The thickness of a transparent substrate 21 may also be other values, and the application does not specifically limit the material and thickness of the first transparent substrate 21 .

The first transparent conductive layer 22 is located on the bottom side of the first transparent substrate 21 . Specifically, the first transparent conductive layer 22 is located on the bottom surface of the first transparent substrate 21 . In other words, the bottom surface of the first transparent substrate 21 carries the first transparent conductive layer 22 . In this embodiment, the first transparent conductive layer 22 is made of ITO (indium tin oxide, tin-doped indium oxide). Wherein, the thickness of the first transparent conductive layer 22 is between 20 nm˜400 nm, for example, the thickness of the first transparent conductive layer 22 is 30 nm. Exemplarily, the first transparent conductive layer 22 may be formed on the bottom surface of the first transparent substrate 21 by vacuum coating.

In some other embodiments, the first transparent conductive layer 22 can also use IZO (indium zinc oxide, indium zinc oxide), AZO (aluminum zinc oxide, aluminum-doped zinc oxide) or ATO (antimony tin oxide, antimony tin oxide), etc. TCO (transparent conductive oxide, transparent conductive oxide), and/or, the thickness of the first transparent conductive layer 22 also can be other values, and/or, the first transparent conductive layer 22 can also be formed on the first transparent conductive layer 22 by other processes. As for the bottom surface of a transparent substrate 21 , the present application does not specifically limit the material, thickness and formation process of the first transparent conductive layer 22 .

Both the second transparent substrate 23 and the second transparent conductive layer 24 are located on the bottom side of the first transparent conductive layer 22 . In this embodiment, the second transparent substrate 23 is made of PET. Wherein, the thickness of the second transparent substrate 23 is between 20 μm˜100 μm, for example, the thickness of the second transparent substrate 23 is 23 μm. In some other embodiments, the second transparent substrate 23 can also be made of materials such as TAC, PVA, PC or PMMA, and/or, the thickness of the second transparent substrate 23 can also be other values. The material and thickness of the second transparent substrate 23 are not specifically limited.

The second transparent conductive layer 24 is located on the top side of the second transparent substrate 23 . Specifically, the second transparent conductive layer 24 is located on the bottom surface of the second transparent substrate 23 . In other words, the top surface of the second transparent substrate 23 carries the second transparent conductive layer 24 . In this embodiment, the second transparent conductive layer 24 is made of ITO. Wherein, the thickness of the second transparent conductive layer 24 is between 20 nm˜400 nm, for example, the thickness of the second transparent conductive layer 24 is 30 nm. Exemplarily, the second transparent conductive layer 24 can be formed on the top surface of the second transparent substrate 23 by vacuum coating. In some other embodiments, the second transparent conductive layer 24 can also be made of TCO such as IZO, AZO or ATO, and/or, the thickness of the second transparent conductive layer 24 can also be other values, and/or, the second The transparent conductive layer 24 can also be formed on the top surface of the second transparent substrate 23 through other processes, and the application does not specifically limit the material, thickness and formation process of the second transparent conductive layer 24 .

Please refer to FIG. 4 and FIG. 5 together. FIG. 4 is a schematic diagram of the optical path when the composite liquid crystal diaphragm 20 in the rear cover 120 shown in FIG. 20 is a schematic diagram of the optical path when it is in the power-on state. Wherein, the solid lines with arrows in FIG. 5 and FIG. 6 represent optical paths.

It should be understood that the power-off state of the composite liquid crystal film 20 means that both the first transparent conductive layer 22 and the second transparent conductive layer 24 are powered off, and there is no gap between the first transparent conductive layer 22 and the second transparent conductive layer 24. There is a voltage difference. Composite liquid crystal film 20 being in the energized state means that both the first transparent conductive layer 22 and the second transparent conductive layer 24 are energized, and the voltage difference between the first transparent conductive layer 22 and the second transparent conductive layer 24 is greater than zero or less than 0.

The composite liquid crystal layer 25 is located between the first transparent conductive layer 22 and the second transparent conductive layer 24 . Exemplarily, the thickness of the composite liquid crystal layer 25 is 18 μm. The composite liquid crystal layer 25 includes an organic polymer matrix 26 and a plurality of liquid crystal microdroplets 27 , and the plurality of liquid crystal microdroplets 27 are dispersed in the organic polymer matrix 26 . Wherein, the organic polymer matrix 26 is network-like, and the organic polymer matrix 26 is formed by polymerizing prepolymers under the action of cross-linked products. In addition, the organic polymer matrix 26 may also include a plurality of glass microspheres (not shown in the figure), and the diameter of the glass microspheres is between 15 μm and 50 μm to ensure the thickness of the composite liquid crystal layer 25 .

A plurality of liquid crystal droplets 27 are uniformly dispersed in the organic polymer matrix 26 . Each liquid crystal droplet 27 includes liquid crystal molecules 28 and dichroic dye molecules 29 . Wherein, the liquid crystal molecules 28 are liquid crystal molecules that can be deflected under the action of an electric field, such as nematic liquid crystal molecules or cholesteric liquid crystal molecules. It should be understood that the nematic liquid crystal refers to the liquid crystal in the nematic phase, which is composed of rod-like molecules with a large aspect ratio, and the molecular center of mass has no long-range order. Cholesteric liquid crystals are derived from cholesterol derivatives. Such liquid crystal molecules are flat and arranged in layers. The molecules in the layers are parallel to each other, and the long axes of the molecules are parallel to the plane of the layers. The direction of the long axes of the molecules in different layers changes slightly. The normal direction of is arranged in a helical structure. The dichroic dye molecules 29 are connected with the liquid crystal molecules 28 and can be deflected with the deflection of the liquid crystal molecules 28 . Exemplarily, the dichroic dye molecules 29 can be connected to the liquid crystal molecules 28 through chemical bonding in which the dichroic dye groups are linked on the branch chains of the liquid crystal molecules 28, or the dichroic dye molecules 29 can be connected physically The connection mode is connected with the liquid crystal molecules 28 . In some other embodiments, the dichroic dye molecules 29 can also be dispersed in the organic polymer matrix 26 .

It should be noted that dichroic dyes have different extinction coefficients for parallel and vertically polarized light. Dichroic dyes are dyes that can absorb light. A dichroic dye may be a dye that absorbs light outside a wavelength range of a specific color (eg, red) and reflects light of a wavelength range of a specific color (eg, red). Taking the specific color as red as an example, dichroic dyes can absorb light of other colors outside the wavelength range of red light and reflect red light.

In addition, as shown in FIG. 3 , the composite liquid crystal film 20 also includes a first electrical signal input terminal 20 a and a second electrical signal input terminal 20 b. The first electrical signal input terminal 20 a is disposed on the bottom surface of the first transparent conductive layer 22 and is electrically connected to the first transparent conductive layer 22 . The second electrical signal input terminal 20 b is disposed on the top surface of the second transparent conductive layer 24 and is electrically connected to the second transparent conductive layer 24 . Exemplarily, both the first electrical signal input terminal 20a and the second electrical signal input terminal 20b may be made of silver paste. Wherein, the first electrical signal input terminal 20a and the second electrical signal input terminal 20b are both used to receive electrical signals to change the voltage difference between the first transparent conductive layer 22 and the second transparent conductive layer 24, so that the composite liquid crystal film Slice 20 switches between an off state and an on state.

As shown in FIG. 4, when the voltage difference between the first transparent conductive layer 22 and the second transparent conductive layer 24 is zero, that is, when there is no voltage difference between the first transparent conductive layer 22 and the second transparent conductive layer 24, The composite liquid crystal diaphragm 20 is in a power-off state, the liquid crystal molecules 28 in the composite liquid crystal layer 25 are disorderly arranged, the dichroic dye molecules 29 are disorderly arranged as the liquid crystal molecules 28 deflect, and the composite liquid crystal layer 25 is in an astigmatism state. At this time, the light is not only scattered by the liquid crystal molecules 28 to propagate in multiple directions, but also reflected by the dichroic dye molecules 29 to propagate in multiple directions.

As shown in Figure 5, when the voltage difference between the first transparent conductive layer 22 and the second transparent conductive layer 24 is greater than zero or less than zero, that is, there is a voltage difference between the first transparent conductive layer 22 and the second transparent conductive layer 24 , the composite liquid crystal diaphragm 20 is in the energized state, the liquid crystal molecules 28 in the composite liquid crystal layer 25 are arranged in an orderly manner, the dichroic dye molecules 29 are arranged in an orderly manner with the deflection of the liquid crystal molecules 28, and the composite liquid crystal layer 25 is in a light-transmitting state . At this time, the light can directly pass through the composite liquid crystal layer 25 and keep the direction of propagation unchanged.

Please refer to FIG. 3 , the decorative film 30 is located on the bottom side of the composite liquid crystal film 20 . That is, the decorative film 30 is located on the side of the composite liquid crystal film 20 away from the transparent cover 10 . The decorative film 30 includes a transparent carrier 31, a textured layer 32, an optical coating 33, an ink layer 34 and a transparent adhesive layer 35. The textured layer 32, the optical coating 33 and the ink layer 34 are all located on the bottom side of the transparent carrier 31. The transparent adhesive Layer 35 is located on the top side of transparent carrier 31 . Specifically, the texture layer 32 is located on the bottom surface of the transparent carrier 31 , and the optical coating 33 covers the bottom surface of the texture layer 32 and can cooperate with the texture layer 32 to increase the glare effect of the decorative film 30 . The ink layer 34 is located on the bottom surface of the optical coating 33 . The transparent adhesive layer 35 is located on the top surface of the transparent carrier 31 and is used for bonding with the second transparent substrate 23 to realize the assembly between the composite liquid crystal film 20 and the decorative film 30 . Exemplarily, the transparent carrier 31 is made of PET, and the thickness of the transparent carrier 31 is 50 μm. The thickness of the texture layer 32 is between 8 μm˜10 μm, for example, the thickness of the texture layer 32 is 10 μm. The thickness of the optical coating 33 is 100 nm. The ink layer 34 is made of ink material, and the thickness of the ink layer 34 is 30 μm. The transparent adhesive layer 35 is OCA adhesive, and the thickness of the transparent adhesive layer 35 is between 20 μm and 25 μm.

The transparent adhesive layer 40 is bonded between the transparent cover plate 10 and the composite liquid crystal film 20 . Specifically, the transparent adhesive layer 40 is bonded between the transparent cover plate 10 and the first transparent substrate 21 . Wherein, the top surface of the transparent adhesive layer 40 is bonded to the transparent cover 10 , and the bottom surface of the transparent adhesive layer 40 is bonded to the first transparent substrate 21 . Wherein, the thickness of the transparent adhesive layer 40 is between 25 μm and 30 μm. Exemplarily, the transparent adhesive layer 40 can be made of OCA. In some other embodiments, the thickness of the transparent adhesive layer 40 can also be other values, and/or, the transparent adhesive layer 40 can also be made of other materials. Specific limits.

The flexible circuit board 50 is electrically connected to the first transparent conductive layer 22 and the second transparent conductive layer 24 . Specifically, one end of the flexible circuit board 50 is electrically connected to the first electrical signal input terminal 20 a and the second electrical signal input terminal 20 b to realize electrical connection with the first transparent conductive layer 22 and the second transparent conductive layer 24 . In this embodiment, the flexible circuit board 50 includes a first electrical signal output terminal 51 , a second electrical signal output terminal 52 and a third electrical signal output terminal 53 . The first electrical signal output terminal 51 is electrically connected to the first electrical signal input terminal 20 a to realize the electrical connection between the flexible circuit board 50 and the first transparent conductive layer 22 . The second electrical signal output terminal 52 is electrically connected to the second electrical signal input terminal 20 b to realize the electrical connection between the flexible circuit board 50 and the second transparent conductive layer 24 . The third electrical signal output terminal 53 is electrically connected to the circuit board 300 (as shown in FIG. 1 ), so as to realize the electrical connection between the flexible circuit board 50 and the circuit board 300 . In other words, the circuit board 300 is electrically connected to the first transparent conductive layer 22 and the second transparent conductive layer 24 through the flexible circuit board 50, so as to input electrical signals to the first transparent conductive layer 22 and the second transparent conductive layer 24 through the flexible circuit board 50, Furthermore, the voltage difference between the first transparent conductive layer 22 and the second transparent conductive layer 24 is changed, so that the composite liquid crystal film 20 is switched between the power-off state and the power-on state.

When the processor 400 powers off the first transparent conductive layer 22 and the second transparent conductive layer 24 through the flexible circuit board 50, and the composite liquid crystal film 20 is in a power-off state, the composite liquid crystal layer 25 is in a state of astigmatism, and the light is not only in the liquid crystal molecules Scattering occurs under the action of 28 and is also reflected by dichroic dye molecules 29 . At this time, the human eye can see that the rear cover 120 presents the first appearance effect. Wherein, the first appearance effect includes the same color as the dichroic dye molecule 29 . When the processor 400 powers on the first transparent conductive layer 22 and the second transparent conductive layer 24 through the flexible circuit board 50, and the composite liquid crystal diaphragm 20 is in the electrified state, the composite liquid crystal layer 25 is in the light-transmitting state, and light can pass through directly. Composite liquid crystal layer 25 , at this time, liquid crystal molecules 28 and dichroic dye molecules 29 will not affect the propagation of light, and human eyes can see that the rear cover 120 presents the second appearance effect. Wherein, the color of the second appearance effect is different from the color of the first appearance effect.

Exemplarily, taking the color of the dichroic dye molecule 29 as red as an example, the transformation of the appearance effect of the rear cover 120 will be described. When the processor 400 powers off the first transparent conductive layer 22 and the second transparent conductive layer 24 through the flexible circuit board 50, and the composite liquid crystal film 20 is in a power-off state, the composite liquid crystal layer 25 is in an astigmatism state, and the human eye can see The back cover 120 is seen in matte red. When the processor 400 powers on the first transparent conductive layer 22 and the second transparent conductive layer 24 through the flexible circuit board 50, and the composite liquid crystal film 20 is in the electrified state, the composite liquid crystal layer 25 is in the light-transmitting state, and the human eye can see It can be seen that the rear cover 120 presents the appearance effect of the decorative film 30 .

In the embodiment of the present application, the composite liquid crystal film 20 is used to realize the diversity of appearance and decoration of the rear cover 120, and the dichroic dye molecules 29 in the composite liquid crystal film 20 can deflect along with the deflection of the liquid crystal molecules 28, realizing the "guest-host effect" , the change of color can be realized synchronously on the basis of the change from haze to transparency, so as to achieve the effect of synchronous change of haze and color of the rear cover 120 . It can not only increase the variety of appearance effects of the back cover 120, solve the problem of single appearance effect of the existing back cover, but also increase the shielding effect of the composite liquid crystal layer 25 on the decorative film 30 when the composite liquid crystal layer 25 is in the astigmatism state, and improve the performance of the back cover 120 in composite The appearance effect of the liquid crystal layer 25 in the astigmatic state and the light-transmitting state is different. Among them, the haze is the percentage of the transmitted light intensity that deviates from the incident light at an angle of more than 2.5° to the total transmitted light intensity, and the greater the haze, the lower the transparency. In addition, dichroic dyes of different colors can also be adaptively used according to individual needs, which is beneficial to enhance the designability of the back cover 120 and realize personalized customization of the appearance of the back cover 120 .

It can be understood that the electrical signal of the processor 400 is transmitted to the composite liquid crystal film 20 through the flexible circuit board 50 , which not only realizes the change of the appearance of the back cover 120 , but also realizes the functional interaction between the user and the electronic device 1000 . Wherein, the interactive function includes but is not limited to notification reminder functions such as call reminder, message reminder, alarm clock ringing or Bluetooth connection. Exemplarily, the back cover 120 has a first appearance effect and a second appearance effect. When a user uses the electronic device 1000, he does not need to unlock the electronic device 1000, and can directly judge whether the electronic device 1000 is based on the appearance effect presented by the back cover 120. In what application scenario. For example, when the back cover 120 of the electronic device 1000 faces the user and the electronic device 1000 is in a sleep state, the back cover 120 presents the first appearance effect. When the electronic device 1000 receives a new message, the processor 400 switches the back cover 120 from the first appearance effect to the second appearance effect through the flexible circuit board 50, for example, the processor 400 switches the color of the back cover 120 from white to Red, at this time, the user can know that the electronic device 1000 has received a new message according to the change of the appearance effect of the rear cover 120, which can not only improve the user experience, but also save the setting of the message indicator light in the electronic device 1000, which is conducive to realizing the electronic device 1000. The thin and light design of the device 1000.

Please refer to FIG. 6 . FIG. 6 is a process flow diagram of a method for preparing a rear cover provided in an embodiment of the present application.

The embodiment of the present application provides a method for preparing a back cover, including:

Step S101 , forming a first transparent conductive layer 22 on the surface of the first transparent substrate 21 . Specifically, as shown in FIG. 7 , a first transparent conductive layer 22 is formed on the bottom surface of the first transparent substrate 21 . In this embodiment, the first transparent substrate 21 is made of PET, the thickness of the first transparent substrate 21 is between 20 μm and 100 μm, the first transparent conductive layer 22 is made of ITO, and the thickness of the first transparent conductive layer 22 is Between 20nm and 400nm. Exemplarily, a vacuum coating process is used to deposit the first transparent conductive layer 22 on the bottom surface of the first transparent substrate 21 . Subsequently, the first transparent conductive layer 22 is annealed at 150° C. for 30 minutes, and finally the square resistance of the first transparent conductive layer 22 is between 500Ω˜1000Ω.

Step S102 , etching the first transparent conductive layer 22 to form a first through hole 221 . Specifically, as shown in FIG. 8 , the first transparent conductive layer 22 is etched to expose the first transparent substrate 21 in a region about 3 mm away from the edge of the first transparent conductive layer 22 to form a first through hole 221 . The design of the first through hole 221 can not only prevent the first transparent conductive layer 22 from being short-circuited due to deformation during the subsequent laser forming process, but also form a clearance area to prevent the first transparent conductive layer 22 from affecting the normal operation of the antenna in the electronic device 1000. Work.

Step S103, forming the first electrical signal input terminal 20a. Specifically, as shown in FIG. 9 , a first electrical signal input terminal 20 a is formed on the bottom surface of the first transparent conductive layer 22 . In this embodiment, the first electrical signal input terminal 20a is made of silver paste, and the area of the first electrical signal input terminal 20a is about 0.3mm*0.4mm. Specifically, silver paste is printed on the bottom surface of the first transparent conductive layer 22a with a printing area of about 0.3 mm*0.4 mm, and then baked at 130° C. for 15 minutes to form the first electrical signal input terminal 20 a. Wherein, the projection of the first electrical signal input terminal 20 a on the first transparent conductive layer 22 a does not overlap with the first through hole 221 . The first electrical signal input terminal 20 a is to enhance the electrical conductivity and prepare for the subsequent electrical connection between the first transparent conductive layer 22 and the flexible circuit board 50 .

Step S201 , forming a second transparent conductive layer 24 on the surface of the second transparent substrate 23 . Specifically, as shown in FIG. 10 , a second transparent conductive layer 24 is formed on the top surface of the second transparent substrate 23 . In this embodiment, the material and thickness of the second transparent substrate 23 can be the same as that of the first transparent substrate 21, and the material and thickness of the second transparent conductive layer 24 can be the same as the material and thickness of the first transparent conductive layer 22. The thickness is the same, and the formation process of the second transparent conductive layer 24 is the same as that of the first transparent conductive layer 22 , which will not be repeated here.

Step S201 , etching the second transparent conductive layer 24 to form a second through hole 241 . In this embodiment, the forming process of the second through hole 241 is the same as the forming process of the first through hole 221 , which will not be repeated here. As shown in Figure 11, the position of the second through hole 241 is adapted to the position of the first electrical signal input terminal 20a. It is arranged facing to each other so that the subsequent first electrical signal input terminal 20a is press-fitted with the flexible circuit board 50 .

Step S203, forming the second electrical signal input terminal 20b. Specifically, as shown in FIG. 12 , a second electrical signal input terminal 20 b is formed on the top surface of the second transparent conductive layer 24 . In this embodiment, the forming process of the second electrical signal input terminal 20b is the same as that of the first electrical signal input terminal 20a, and will not be repeated here. Wherein, the position of the second electrical signal input terminal 20b matches the position of the first through hole 221 (as shown in FIG. 8 ). The input terminal 20 b is arranged facing to each other, so that the subsequent second electrical signal input terminal 20 b is press-fitted with the flexible circuit board 50 .

It should be noted that step S101 and step S201 can be performed simultaneously or successively; step S102 and step S202 can be performed simultaneously or successively; step S103 and step S203 can be performed simultaneously or successively. This is not specifically limited.

Step S4, preparing a composite liquid crystal material. Specifically, the liquid crystal material, the dichroic dye, the prepolymer, the cross-linking agent and the glass microspheres are mixed in a certain proportion and stirred evenly to form a composite liquid crystal material. Wherein, the liquid crystal material may be a nematic liquid crystal material or a cholesteric liquid crystal material. The size of the glass microspheres is between 15 μm and 50 μm.

In step S5 , a composite liquid crystal layer 25 is formed between the first transparent conductive layer 22 and the second transparent conductive layer 24 to form a composite liquid crystal film 20 . Specifically, as shown in FIG. 13, the composite liquid crystal material prepared in step S4 is coated between the first transparent conductive layer 22 and the second transparent conductive layer 24, and then the first transparent substrate 21 and the second transparent substrate 23 Precise positioning and continuous lamination of roll-to-roll, and UV curing after lamination. Wherein, the curing strength is between 10mW and 18mW, and the curing time is 2min. It should be noted that, at this time, the prepolymer is polymerized under the action of the crosslinking agent to form a networked organic polymer matrix 26 (as shown in FIG. 4 ). Since the liquid crystal molecules 28 cannot be compatible with the network organic polymer matrix 26 and phase separation occurs, the liquid crystal molecules 28 are uniformly dispersed in the network in the form of liquid crystal droplets 27 to form a composite liquid crystal film 20 .

In steps S4 and S5, the composite liquid crystal membrane 20 is formed by adding a dichroic dye to the liquid crystal material, and the dichroic dye molecules 29 can be deflected along with the deflection of the liquid crystal molecules 28 to realize the "guest-host effect", so that the subsequent The prepared back cover 120 can simultaneously realize the color change on the basis of the change from haze to transparency, achieve the effect of synchronous change of the haze and color of the back cover 120 , and realize the diversity of the appearance and decoration of the back cover 120 .

Step S6 , attaching the transparent adhesive layer 40 to the surface of the first transparent substrate 21 away from the first transparent conductive layer 22 . In this embodiment, the transparent adhesive layer 40 is OCA glue, and the thickness of the transparent adhesive layer 40 is between 25 μm and 30 μm. Specifically, as shown in FIG. 14 , after plasma treatment is performed on the top surface of the first transparent substrate 21 in the composite liquid crystal film 20 , a transparent adhesive layer 40 is bonded. Wherein, the transparent adhesive layer 40 is used for subsequent lamination with the transparent cover plate 10 .

Step S7, performing the first laser engraving process. Specifically, laser engraving is performed on the composite liquid crystal film 20 bonded with the transparent adhesive layer 40 , and the radium engraving forms a shape slightly larger than the preset size of the back cover.

Step S8 , attaching the decorative film 30 to the surface of the second transparent substrate 23 away from the second transparent conductive layer 24 . As shown in Figure 15, in this embodiment, the decorative film 30 includes a transparent adhesive layer 35, a transparent carrier 31, a texture layer 32, an optical coating 33 and an ink layer 34, and the transparent adhesive layer 35 is located on the top surface of the transparent carrier 31 , the texture layer 32 , the optical coating 33 and the ink layer 34 are sequentially stacked on the bottom surface of the transparent carrier 31 . Wherein, the transparent adhesive layer 35 is OCA adhesive, and the thickness of the transparent adhesive layer 35 is between 20 μm and 25 μm. The transparent carrier 31 is made of PET, and the thickness of the transparent carrier 31 is 50 μm. The thickness of the texture layer 32 is between 8 μm˜10 μm, for example, the thickness of the texture layer 32 is 10 μm. The thickness of the optical coating 33 is 100 nm. The ink layer 34 is made of ink material, and the thickness of the ink layer 34 is 30 μm. Specifically, the decorative film 30 is attached to the bottom surface of the second transparent substrate 23 in the composite liquid crystal film 20 . Wherein, the transparent adhesive layer 35 is attached to the bottom surface of the second transparent substrate 23 .

Step S9, performing the second laser engraving process. Specifically, as shown in FIG. 16 , the composite liquid crystal film 20 bonded with the transparent adhesive layer 40 and the decorative film 30 is subjected to laser engraving treatment, and the laser is shot out of the camera area (not shown), the first electrical signal input terminal 20a and the second electrical signal input terminal 20b.

Step S10 , connecting the flexible circuit board 50 . Specifically, as shown in FIG. 17, the layer structure covering the first electrical signal input terminal 20a and the second electrical signal input terminal 20b after laser engraving is removed, and the outflowing composite liquid crystal material is wiped off, and the first electrical signal input terminal 20b of the flexible circuit board 50 is The electrical signal output terminal 51 is press-fitted with the first electrical signal input terminal 20a to conduct, and the second electrical signal output terminal 52 is press-fitted with the second electrical signal input terminal 20b for conduction.

Step S11, performing a lighting test. Specifically, the flexible circuit board 50 is energized, and the above-mentioned assembled diaphragm is subjected to a lighting test under a verified voltage, and related optical data are tested.

Step S12 , attaching the transparent cover plate 10 to the surface of the transparent adhesive layer 40 away from the first transparent substrate 21 . Specifically, as shown in FIG. 3 , the transparent cover plate 10 is attached to the surface of the first transparent substrate 21 away from the first transparent conductive layer 22 through the transparent adhesive layer 40 .

Claims

A rear cover, characterized in that it includes a transparent cover plate, a composite liquid crystal layer and a decorative film, the composite liquid crystal layer and the decorative film are located on the same side of the transparent cover plate, and the composite liquid crystal layer is located on the same side of the transparent cover plate Between the transparent cover plate and the decorative film, the composite liquid crystal layer includes liquid crystal molecules and dichroic dye molecules, and the dichroic dye molecules are connected with the liquid crystal molecules and can follow the liquid crystal The deflection of the molecules deflects;

When the composite liquid crystal layer is in the state of astigmatism, the back cover presents the first appearance effect;

When the composite liquid crystal layer is in a light-transmitting state, the rear cover presents a second appearance effect.
The rear cover according to claim 1, wherein the rear cover further comprises a first transparent conductive layer and a second transparent conductive layer, the first transparent conductive layer is located between the transparent cover plate and the composite liquid crystal. Between layers, the second transparent conductive layer is located between the composite liquid crystal layer and the decorative film;

When the voltage difference between the first transparent conductive layer and the second transparent conductive layer is equal to zero, the composite liquid crystal layer is in the astigmatic state;

When the voltage difference between the first transparent conductive layer and the second transparent conductive layer is greater than zero or less than zero, the composite liquid crystal layer is in the light-transmitting state.
The back cover according to claim 2, wherein the back cover further comprises a flexible circuit board, the flexible circuit board is electrically connected to the first transparent conductive layer and the second transparent conductive layer, and the flexible circuit board is electrically connected to the first transparent conductive layer and the second transparent conductive layer. The flexible circuit board is used to transmit electrical signals to the first transparent conductive layer and the second transparent conductive layer, so as to change the voltage difference between the first transparent conductive layer and the second transparent conductive layer.
The back cover according to claim 2 or 3, wherein the back cover further comprises a first transparent substrate and a second transparent substrate, the first transparent substrate is located between the first transparent conductive layer and the second transparent substrate. Between the transparent cover plates, the second transparent substrate is located between the second transparent conductive layer and the decorative film.
The rear cover according to claim 4, wherein the rear cover comprises a transparent adhesive layer, and the transparent adhesive layer is bonded between the transparent cover plate and the first transparent substrate.
The rear cover according to claim 4 or 5, wherein the decorative film comprises a transparent carrier and a transparent adhesive layer, and the transparent adhesive layer is bonded to the transparent carrier and the second transparent lining. between the bottom.
The rear cover according to claim 6, wherein the decorative film includes an ink layer, and the ink layer is located on a side of the transparent carrier away from the transparent adhesive layer.
The rear cover according to claim 7, wherein the decorative film further comprises a texture layer and an optical coating, and both the texture layer and the optical coating are located between the transparent carrier and the ink layer , the optical coating covers the surface of the texture layer away from the transparent carrier.
The rear cover according to any one of claims 1 to 8, wherein the first appearance effect includes the same color as the color of the dichroic dye molecule, and the second appearance effect is a different color than the first skin effect described.
The rear cover according to any one of claims 1 to 8, wherein the rear cover is provided with an imaging hole, and along the thickness direction of the rear cover, the imaging hole penetrates the transparent cover, the The composite liquid crystal layer and the decorative film.
An electronic device, characterized in that the electronic device comprises a processor and the back cover according to any one of claims 1 to 10, and the processor is electrically connected to the back cover.
A preparation method for a back cover, characterized in that it comprises:

forming a first transparent conductive layer on the first transparent substrate;

forming a second transparent conductive layer on the second transparent substrate;

A composite liquid crystal layer is formed between the first transparent conductive layer and the second transparent conductive layer, wherein the composite liquid crystal layer includes liquid crystal molecules and dichroic dye molecules, and the dichroic dye molecules are combined with The liquid crystal molecules are connected and can be deflected with the deflection of the liquid crystal molecules;

attaching the decorative film to the surface of the second transparent substrate away from the second transparent conductive layer;

Attaching the transparent cover to the surface of the first transparent substrate away from the first transparent conductive layer.
The preparation method of the back cover according to claim 12, characterized in that, after the step of forming a first transparent conductive layer on the first transparent substrate, and after the step of forming the first transparent conductive layer and the second transparent conductive layer Before the step of forming a composite liquid crystal layer between layers, the preparation method of the back cover further includes: forming a first electrical signal input terminal on the surface of the first transparent conductive layer;

After the step of forming a second transparent conductive layer on the second transparent substrate and before the step of forming a composite liquid crystal layer between the first transparent conductive layer and the second transparent conductive layer, the preparation of the back cover The method further includes: forming a second electrical signal input terminal on the surface of the second transparent conductive layer.
The preparation method of the back cover according to claim 13, characterized in that after the step of attaching the decorative film to the surface of the second transparent substrate away from the second transparent conductive layer, and after the step of attaching the transparent Before the step of attaching the cover plate to the surface of the first transparent substrate away from the first transparent conductive layer, the preparation method of the rear cover further includes: attaching the flexible circuit board to the first electrical signal input terminal and The second electrical signal input terminal is connected.