A gradient lighting device, its preparation method and application

Abstract

This invention discloses a gradient lighting device, its fabrication method, and its applications, relating to the field of electroluminescence technology. The functional layer provided by this invention includes a conductive underlayer, a dielectric layer, a light-emitting layer, and a transparent conductive layer. During operation, both the conductive underlayer and the transparent conductive layer are used to connect to the positive or negative terminals of the circuit, creating a potential difference that generates an electric field effect, driving the light-emitting coating of the transparent conductive layer to emit light. By adjusting the thickness of each layer in conjunction with parameters such as the controller's flicker frequency and operating frequency, a gradient lighting effect is achieved. If the thickness and controller parameters exceed the range defined by this invention, the gradient lighting effect will be lost.

Description

Technical Field

[0001] This invention relates to the field of electroluminescence technology, and more specifically, to a gradient lighting device, its preparation method, and its application. Background Technology

[0002] Electroluminescent coating (EL coating) is a functional coating that emits light by exciting luminescent materials with an electric field. It features low power consumption, flexibility, and uniform light emission, and is widely used in displays, backlighting, decoration, and industrial signage. The main purpose of forming an electroluminescent coating on brake calipers is to enhance the visual recognition, safety warnings, brand display, or temperature status feedback of the braking system through its luminescent properties and functionality.

[0003] Achieving gradient lighting effects is necessary under certain conditions, such as in ambulances. However, existing illuminated brake calipers cannot yet achieve gradient lighting effects.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a gradient lighting device, its preparation method and application, which aims to achieve the effect of gradient lighting.

[0006] This invention is implemented as follows:

[0007] In a first aspect, the present invention provides a gradient lighting device, comprising:

[0008] A substrate, on which a functional layer is disposed, the functional layer comprising a conductive bottom layer, a dielectric layer, a light-emitting layer and a transparent conductive layer disposed sequentially, wherein the conductive bottom layer and the transparent conductive layer are both used to connect the positive or negative electrode of the circuit; wherein the thickness of the conductive bottom layer, the dielectric layer, the light-emitting layer and the transparent conductive layer are each independently 10μm-60μm;

[0009] The controller is used to control the power supply to apply AC voltage to the conductive substrate and the transparent conductive layer; wherein, the switching signal frequency of the controller is less than 5Hz, and the operating frequency is 500Hz-2000Hz.

[0010] In an optional implementation, the applied AC voltage is 20V-130V, preferably 60V-130V;

[0011] Preferably, the thickness of the conductive substrate is 20μm-40μm, the thickness of the dielectric layer is 20μm-40μm, the thickness of the light-emitting layer is 20μm-40μm, and the thickness of the transparent conductive layer is 20μm-40μm.

[0012] Preferably, the switching signal frequency of the controller is 0.25Hz-2Hz.

[0013] In an optional embodiment, the raw materials used to form the conductive underlayer are metal powder and resin, wherein the mass fraction of the metal powder is 40%-60%.

[0014] Preferably, the metal powder is copper powder.

[0015] In an optional embodiment, the raw materials used to form the dielectric layer are ferroelectric materials and resin, wherein the mass fraction of the ferroelectric materials is 70%-90%.

[0016] Preferably, the ferroelectric material is selected from at least one of barium titanate, lead zirconate titanate, and lithium niobate.

[0017] In an optional embodiment, the raw materials used to form the light-emitting layer are pigments and resins, with the pigments having a mass fraction of 60%-80%.

[0018] Preferably, the pigment is selected from at least one of blue pigment, blue-green pigment, green pigment, orange-yellow pigment, and white pigment.

[0019] In an optional embodiment, the raw material used to form the transparent conductive layer is a high molecular polymer;

[0020] Preferably, the polymer is a polythiophene polymer;

[0021] More preferably, the polymer is PEDOT.

[0022] In an optional embodiment, the substrate is a brake caliper, and an insulating layer is provided between the brake caliper and the conductive substrate.

[0023] Preferably, the thickness of the insulating layer is 10μm-80μm;

[0024] Preferably, the raw material used to form the insulating layer is at least one of epoxy resin and polyester resin.

[0025] In an optional embodiment, a varnish layer is further disposed on the transparent conductive layer;

[0026] Preferably, the thickness of the varnish layer is 10μm-60μm;

[0027] Preferably, the material of the varnish layer is selected from at least one of hydroxyl acrylic resin and butyl acetate.

[0028] In a second aspect, the present invention provides a method for preparing any of the gradient lighting devices in the foregoing embodiments, comprising: preparing functional layers on a substrate and ensuring that the thickness of each layer meets the requirements;

[0029] The controller controls the power supply to apply AC voltage to the conductive bottom layer and the transparent conductive layer; the switching signal frequency of the controller is set to be less than 5Hz, and the operating frequency is 500Hz-2000Hz.

[0030] Thirdly, the present invention provides the application of any of the gradient lighting devices described in the foregoing embodiments in the manufacture of road transport devices.

[0031] The present invention has the following beneficial effects: The functional layer provided by the present invention includes a conductive bottom layer, a dielectric layer, a light-emitting layer, and a transparent conductive layer. During operation, both the conductive bottom layer and the transparent conductive layer are used to connect to the positive or negative electrode of the circuit, forming a potential difference that generates an electric field effect, driving the light-emitting coating of the transparent conductive layer to emit light. By adjusting the thickness of each layer in conjunction with parameters such as the controller's flashing frequency and operating frequency, a gradual light emission effect is achieved. If the thickness and controller parameters exceed the range defined by the present invention, the gradual lighting effect will be lost. Attached Figure Description

[0032] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 A schematic diagram of a gradient lighting device is provided for the present invention;

[0034] Figure 2 This is a diagram illustrating the light emission effect of Example 1;

[0035] Figure 3 This is a diagram illustrating the luminous effect of Comparative Example 3;

[0036] Figure 4 This is a diagram illustrating the luminous effect of Comparative Example 4;

[0037] Figure 5 This is a diagram illustrating the luminous effect of Comparative Example 5;

[0038] Figure 6 This is a diagram illustrating the luminous effect of Comparative Example 6;

[0039] Figure 7 This is a diagram showing the luminous effect of Comparative Example 7.

[0040] Icons: 101-Substrate; 102-Insulating layer; 103-Conductive bottom layer; 104-Dielectric layer; 105-Light-emitting layer; 106-Transparent conductive layer; 107-Varnish layer. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0042] like Figure 1 As shown, an embodiment of the present invention provides a gradient lighting device, including: a substrate 101, on which a functional layer is disposed, the functional layer including a conductive bottom layer 103, a dielectric layer 104, a light-emitting layer 105 and a transparent conductive layer 106 disposed sequentially, the conductive bottom layer 103 and the transparent conductive layer 106 are both used to connect the positive or negative electrode of the circuit, forming a potential difference to generate an electric field effect, driving the light-emitting coating to emit light.

[0043] The conductive bottom layer 103, dielectric layer 104, light-emitting layer 105, and transparent conductive layer 106 each have an independent thickness of 10μm-60μm. The thicknesses of these layers can be the same or different, and can be independently 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, or any value between these adjacent values. Preferably, the thicknesses of the conductive bottom layer 103, dielectric layer 104, light-emitting layer 105, and transparent conductive layer 106 are 20μm-40μm. Optimizing the thicknesses of these layers enhances the effect of gradient lighting.

[0044] The gradient lighting device also includes a controller for controlling the power supply to apply an AC voltage to the conductive substrate 103 and the transparent conductive layer 106. The controller can control the operating parameters of the power supply. Specifically, the controller can be a PWM controller, MOSFET / IGBT driver, etc. The power supply can be a vehicle-mounted 12V DC power supply. The controller converts the 12V DC power supply into 20-130V AC power supply, which is then transmitted to the substrate through wires and pins or wires and connectors, and finally connected to the positive and negative terminals of the lighting device.

[0045] Furthermore, the switching signal frequency (flicker frequency) of the controller is less than 5Hz, meaning the circuit will be periodically switched on, but each time for no more than 0.2 seconds. Specifically, the switching signal frequency of the controller refers to the frequency at which the controller actively switches power devices (such as transistors), i.e., the number of switching actions per unit time. The switching signal frequency of the controller can be 4.8Hz, 4.5Hz, 4.0Hz, 3.5Hz, 3.0Hz, 2.5Hz, 2.0Hz, 1.5Hz, 1.0Hz, 0.5Hz, etc., preferably 0.25Hz-2Hz.

[0046] Furthermore, the operating frequency is 500Hz-2000Hz, such as 500Hz, 800Hz, 1000Hz, 1300Hz, 1500Hz, 1800Hz, 2000Hz, etc. This operating frequency refers to the overall operating frequency of the controller or circuit system. If the operating frequency exceeds the above range, the product may not light up.

[0047] Furthermore, the applied AC voltage is 20V-130V, specifically 20V, 30V, 40V, 50V, 60V, 70V, 80V, 90V, 100V, 110V, 120V, 130V, etc. Too low a voltage will prevent the gradual light emission; the preferred voltage range is 60V-130V.

[0048] It should be noted that a gradient lighting effect can only be achieved in lighting brake caliper applications through the combination of the aforementioned layer thicknesses and the control of the switching signal frequency. The thickness of each coating layer must be controlled within the aforementioned range; excessively thick coatings will prevent the gradient lighting effect from being achieved, while excessively thin coatings cannot be reliably produced using existing processes. Furthermore, the controller's flashing frequency also needs to be controlled within a certain range; too fast a flashing frequency will result in the loss of the gradient effect. In summary, only when the coating thickness and flashing frequency are in a specific combination will a gradient lighting effect be produced.

[0049] The following explains the material and other parameters of each functional layer:

[0050] The conductive underlayer 103, also known as the backsheet layer, is directly sprayed onto the surface of an object to provide conductivity, used to connect the positive or negative terminals of a circuit. The backsheet material is a highly conductive, low-resistance material, such as metal powder, the type of which is not limited, for example, copper powder. Specifically, copper powder can be purchased from companies such as Shanghai Keyan Optoelectronic Technology Co., Ltd., Shenzhen Qizhicai Paint & Pigment Co., Ltd., and LeuchtstoffwerkBreitungen GmbH. In actual operation, the metal powder and resin can be mixed to form a slurry, which is then applied and cured to form a coating. In the slurry formed by the metal powder and resin, the mass fraction of the metal powder is 40%-60%, such as 40%, 50%, or 60%, and the resin used can be epoxy resin.

[0051] The dielectric layer 104 serves as an insulating layer, preventing short circuits and ensuring uniform current distribution on the surface to achieve uniform light emission. The material used can be a ferroelectric material, such as at least one of barium titanate, lead zirconate titanate, and lithium niobate, preferably barium titanate, which can be purchased from companies such as Shanghai Keyan Optoelectronic Technology Co., Ltd., Shenzhen Qizhicai Paint & Pigment Co., Ltd., and Leuchtstoffwerk Breitungen GmbH. In actual operation, the ferroelectric material and resin can be mixed to form a slurry, which is then applied by liquid spraying and curing to form a coating. In the slurry formed by the ferroelectric material and resin, the mass fraction of the ferroelectric material is 70%-90%, such as 70%, 80%, or 90%, and the resin used can be epoxy resin.

[0052] The luminescent layer 105 is used to determine the final color of light emission. Currently, a variety of colors are available, such as blue, blue-green, green, orange-yellow, and white pigments. Specific materials can be purchased from companies such as Shanghai Keyan Optoelectronic Technology Co., Ltd., Shenzhen Qizhicai Paint & Pigment Co., Ltd., and LeuchtstoffwerkBreitungen GmbH. In actual operation, the pigment and resin can be mixed to form a slurry, which is then applied by liquid spraying and curing to form a coating. In the slurry formed by pigment and resin, the mass fraction of pigment is 60%-80%, such as 60%, 70%, or 80%, and the resin used can be epoxy resin.

[0053] The transparent conductive layer 106 is used to connect the positive or negative electrode of the circuit, creating a potential difference between the backplate and the conductive coating, generating an electric field effect that drives the luminescent coating to emit light. The transparent conductive layer 106 is formed using a high-molecular polymer, such as polythiophene polymer, specifically PEDOT (poly(3,4-ethylenedioxythiophene)). The lighting brightness and frequency can be adjusted via AC power control.

[0054] In some embodiments, the substrate 101 is a brake caliper, and an insulating layer 102 is provided between the brake caliper and the conductive substrate 103. Since the brake caliper itself is conductive, an insulating layer 102 is necessary to prevent leakage. The thickness of the insulating layer 102 can be 10μm-80μm, such as 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, etc. The raw material used to form the insulating layer 102 is at least one of epoxy resin and polyester resin, and can be any one or more of these.

[0055] In some embodiments, a clear varnish layer 107 is further disposed on the transparent conductive layer 106, which serves to protect the functional coating. The thickness of the clear varnish layer 107 is 10μm-60μm, such as 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, etc. The material of the clear varnish layer 107 is selected from at least one of hydroxyl acrylic resin and butyl acetate, and the clear varnish layer 107 can be any one or more of the above.

[0056] Generally speaking, the process cannot complete the preparation of samples with a coating thickness of less than 10 μm; the thickness of each layer must be greater than or equal to 10 μm.

[0057] This invention provides a method for fabricating a gradient lighting device, comprising: fabricating a functional layer on a substrate 101 and ensuring that the thickness of each layer meets the requirements; using a controller to control the power supply to apply an AC voltage to the conductive bottom layer 103 and the transparent conductive layer 106; and setting the switching signal frequency of the controller to be less than 5Hz and the operating frequency to be 500Hz-2000Hz.

[0058] It should be noted that only through the combination of the thicknesses of the aforementioned layers and the control of the switching signal frequency can a gradual lighting effect be achieved in the application of lighting brake calipers.

[0059] The gradient lighting device provided in this invention can be used in the manufacture of road transport devices, such as vehicles, motorcycles, and ambulances. In an ambulance, the gradient frequency can be considered as the degree of urgency of the patient.

[0060] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0061] Before preparation, make the following preparations: (1) Spraying materials: electroluminescent paint, special power supply, 1 spray gun with a top bottle (the spray bottle is made of plastic); (2) Spraying substrate: insulating board; (3) Accessories: alcohol, thinner, copper foil tape, 3M 244 tape, multimeter, ultraviolet lamp, 600# and 2000# sandpaper, etc.

[0062] The brake caliper base material in the following embodiments or comparative examples is cast aluminum or cast iron, and its shape is as follows: Figure 2 As shown.

[0063] Example 1

[0064] This embodiment provides a gradient lighting device, the fabrication process of which is as follows:

[0065] (1) Preprocessing

[0066] The brake caliper surface is sandblasted with 40-80 mesh corundum abrasive to increase surface roughness and facilitate paint adhesion, with a target roughness of Ra 3.6 μm. Oil stains are removed using an 8% NaOH solution. After cleaning, a light etching process with an 8% HCl solution is performed to remove the oxide layer.

[0067] (2) Preparation of insulating layer 102

[0068] A mixture of high-solids, low-viscosity epoxy primer (75% solids content, epoxy paint 15553 purchased from Hempel) and polyimide (mass ratio 2:1) was sprayed onto the brake caliper to a thickness of 50 μm, and then baked at 60°C for 20 min to promote curing.

[0069] (3) Preparation of conductive substrate 103

[0070] Copper powder and epoxy resin were mixed to obtain a slurry with a copper powder mass fraction of 50% and a spraying thickness of 20 μm. After spraying, a low-temperature baking process was required at 80°C for 30 minutes.

[0071] (4) Fabrication of dielectric layer 104

[0072] A slurry was prepared by mixing barium titanate and epoxy resin, with a barium titanate mass fraction of 80%. The coating thickness was 20 μm. After coating, a low-temperature baking process was required, with a temperature of 80°C and a baking time of 30 min.

[0073] (5) Preparation of the light-emitting layer 105

[0074] Zinc sulfide and polyurethane were mixed to obtain a slurry, with zinc sulfide comprising 70% by mass. The coating thickness was 20 μm. After spraying, a low-temperature baking process was required, with the temperature set at 80°C and the time at 30 min.

[0075] (6) Preparation of transparent conductive layer 106

[0076] Commercially available PEDOT paint (purchased from Shanghai Keyan Optoelectronic Technology Co., Ltd., Shenzhen Qizhicai Paint & Pigment Co., Ltd., LeuchtstoffwerkBreitungen GmbH, etc.) was used, with a coating thickness of 20μm. After spraying, a low-temperature baking process was required at 80℃ for 30 minutes.

[0077] (7) Preparation of varnish layer 107

[0078] High-temperature and abrasion-resistant polyurethane varnish, specifically PPG 6178 from PPG Corporation, was used, with a coating thickness of 20 μm. After coating, a low-temperature baking process was required at 80°C for 30 minutes.

[0079] After the overall spraying is completed, it is cured at 100℃ for 2 hours.

[0080] (8) Connecting circuits

[0081] The controller, such as a PWM controller or MOSFET / IGBT driver, can be powered by a 12V DC vehicle power supply. The controller converts the 12V DC power to 20-130V AC power, which is then transmitted to the substrate via wires and pins or wires and connectors, ultimately connecting to the positive and negative terminals of the lighting device. The conductive bottom layer 103 is connected to the positive terminal, and the transparent conductive layer 106 is connected to the negative terminal, creating a potential difference that generates an electric field effect, driving the luminescent coating to emit light. The applied AC voltage is 130V, the operating frequency is 1000Hz, and the switching signal frequency is 0.5Hz.

[0082] The results show that the gradient lighting device prepared in this embodiment is as follows: Figure 2 As shown, a gradient light-emitting effect can be achieved, with a brightness greater than 50 candela. Effect description: If four points a, b, c, and d are marked sequentially on the surface of the device, the light-emitting sequence is that point a lights up first, followed by points b, c, and d in that order; when the device is turned off, point d turns off first, followed by points c, b, and a in that order.

[0083] It should be noted that the inventors explored the mechanism of gradual light emission as follows: by adjusting parameters such as the thickness of each layer and the frequency of the switching signal, the current transmission can be made to take a certain amount of time, rather than being completed instantaneously, thus achieving gradual light emission.

[0084] Example 2

[0085] The only difference from Example 1 is that the thickness of each of the conductive bottom layer 103, dielectric layer 104, light-emitting layer 105, and transparent conductive layer 106 is 10 μm.

[0086] The results show that the gradient lighting device prepared in this embodiment can achieve a gradient light emission effect, with a brightness greater than 40 candela (brightness lower than that of Example 1), obvious light emission effect, and the gradient light emission effect can be identified.

[0087] Example 3

[0088] The only difference from Example 1 is that the thickness of each of the conductive bottom layer 103, dielectric layer 104, light-emitting layer 105, and transparent conductive layer 106 is 60 μm.

[0089] The results show that the gradient lighting device prepared in this embodiment can achieve a gradient light emission effect, with a brightness greater than 30 candela (brightness lower than that of Example 1), a more obvious light emission effect, and the gradient light emission effect can be identified.

[0090] Example 4

[0091] The only difference from Example 1 is that the operating frequency is 2000Hz.

[0092] The results show that the gradient lighting device prepared in this embodiment can achieve a gradient light emission effect, with a brightness greater than 20 candela (brightness lower than that of Example 1), and the gradient light emission effect can be identified.

[0093] Example 5

[0094] The only difference from Example 1 is that the switching signal frequency is 5Hz.

[0095] The results show that the gradient lighting device prepared in this embodiment can achieve a gradient light emission effect, but the overall gradient time is relatively fast, making it more difficult to identify than in Embodiment 1, and the brightness is greater than 50 candela.

[0096] Comparative Example 1

[0097] The only difference from Example 1 is that the switching signal frequency is greater than 5Hz, specifically 10Hz.

[0098] The results showed that the flashing speed was too fast, and the gradual light-emitting effect could no longer be recognized by the naked eye.

[0099] Comparative Example 2

[0100] The only difference from Example 1 is that the switching signal frequency is 0Hz.

[0101] The results showed that there was no flickering effect and the luminous calipers remained off.

[0102] Comparative Example 3

[0103] The only difference from Example 1 is that the operating frequency is greater than 2000Hz, specifically 3000Hz.

[0104] The results showed that the brightness effect was poor, such as Figure 3 As shown, it is almost unrecognizable.

[0105] Comparative Example 4

[0106] The only difference from Example 1 is that the operating frequency is less than 500Hz, specifically 300Hz.

[0107] The results showed that the brightness effect was poor, such as Figure 4 As shown, the luminous effect is rather dim.

[0108] Comparative Example 5

[0109] The only difference from Example 1 is that the AC voltage is greater than 130V, specifically 200V.

[0110] The results show that: Figure 5 As shown, the brightness is greater than 50 candela, but this would affect the product's lifespan, so it is not considered.

[0111] Comparative Example 6

[0112] The only difference from Example 1 is that the AC voltage is less than 20V, specifically 10V.

[0113] The results show that: Figure 6 As shown, the overall brightness is too dim and has no practical application value; the brightness is 0.09 candela.

[0114] Comparative Example 7

[0115] The only difference from Example 1 is that the thickness of the conductive bottom layer 103, dielectric layer 104, light-emitting layer 105, and transparent conductive layer 106 is greater than 60 μm, specifically 80 μm.

[0116] The results show that: Figure 7 As shown, the product's luminous effect is weak and difficult to detect with the naked eye, with a brightness of approximately 0.15 candela.

[0117] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A gradient lighting device, characterized in that, include: A substrate, on which a functional layer is disposed, the functional layer comprising a conductive bottom layer, a dielectric layer, a light-emitting layer and a transparent conductive layer disposed sequentially, wherein the conductive bottom layer and the transparent conductive layer are both used to connect the positive or negative electrode of the circuit; wherein the thickness of the conductive bottom layer, the dielectric layer, the light-emitting layer and the transparent conductive layer are each independently 10μm-60μm; A controller is used to control the power supply to apply an AC voltage to the conductive substrate and the transparent conductive layer; wherein the switching signal frequency of the controller is less than 5Hz, and the operating frequency is 500Hz-2000Hz.

2. The gradient lighting device according to claim 1, characterized in that, The applied AC voltage is 20V-130V, preferably 60V-130V; Preferably, the thickness of the conductive bottom layer is 20μm-40μm, the thickness of the dielectric layer is 20μm-40μm, the thickness of the light-emitting layer is 20μm-40μm, and the thickness of the transparent conductive layer is 20μm-40μm. Preferably, the switching signal frequency of the controller is 0.25Hz-2Hz.

3. The gradient lighting device according to claim 1 or 2, characterized in that, The raw materials used to form the conductive underlayer are metal powder and resin, with the mass fraction of metal powder being 40%-60%. Preferably, the metal powder is copper powder.

4. The gradient lighting device according to claim 1 or 2, characterized in that, The raw materials used to form the dielectric layer are ferroelectric materials and resin, wherein the mass fraction of the ferroelectric materials is 70%-90%. Preferably, the ferroelectric material is selected from at least one of barium titanate, lead zirconate titanate, and lithium niobate.

5. The gradient lighting device according to claim 1 or 2, characterized in that, The raw materials used to form the light-emitting layer are pigments and resins, wherein the mass fraction of the pigments is 60%-80%; Preferably, the pigment is selected from at least one of blue pigment, blue-green pigment, green pigment, orange-yellow pigment, and white pigment.

6. The gradient lighting device according to claim 1 or 2, characterized in that, The raw material used to form the transparent conductive layer is a high molecular polymer; Preferably, the polymer is a polythiophene polymer; More preferably, the polymer is PEDOT.

7. The gradient lighting device according to claim 1 or 2, characterized in that, The substrate is a brake caliper, and an insulating layer is provided between the brake caliper and the conductive bottom layer; Preferably, the thickness of the insulating layer is 10μm-80μm; Preferably, the raw material used to form the insulating layer is at least one of epoxy resin and polyester resin.

8. The gradient lighting device according to claim 1 or 2, characterized in that, A varnish layer is also provided on the transparent conductive layer; Preferably, the thickness of the varnish layer is 10μm-60μm; Preferably, the material of the varnish layer is selected from at least one of hydroxyl acrylic resin and butyl acetate.

9. A method for preparing the gradient lighting device according to any one of claims 1-8, characterized in that, include: The functional layers are prepared on the substrate, and the thickness of each layer meets the requirements. The controller controls the power supply to apply an AC voltage to the conductive bottom layer and the transparent conductive layer; the switching signal frequency of the controller is set to be less than 5Hz, and the operating frequency is 500Hz-2000Hz.

10. The use of the gradient lighting device according to any one of claims 1-8 in the manufacture of road transport equipment.

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