CN109073793B

CN109073793B - Liquid lens and processing method thereof and imaging module

Info

Publication number: CN109073793B
Application number: CN201880000897.4A
Authority: CN
Inventors: 蒋鹏
Original assignee: Shenzhen Goodix Technology Co Ltd
Current assignee: Shenzhen Goodix Technology Co Ltd
Priority date: 2018-07-06
Filing date: 2018-07-06
Publication date: 2021-06-22
Anticipated expiration: 2038-07-06
Also published as: WO2020006767A1; CN109073793A

Abstract

The application relates to the technical field of imaging module manufacturing, and provides a liquid lens, a processing method of the liquid lens and an imaging module. The liquid lens includes at least one layer of substrate; the substrate is provided with N substrate through holes, wherein N is a natural number greater than or equal to 1; a driving part connected with the lens driving circuit is arranged in each substrate through hole; the substrate is also provided with a first sealing layer and a second sealing layer, the first sealing layer, the second sealing layer and the substrate through hole form a lens cavity, and a liquid medium is arranged in the lens cavity; an insulating layer for isolating the liquid medium and the driving part is arranged in each substrate through hole. By adopting the embodiment of the application, the size of the product can be flexibly adjusted, processed and assembled more conveniently, the automatic batch production is easy, and the cost is reduced.

Description

Liquid lens and processing method thereof and imaging module

Technical Field

The application relates to the technical field of imaging equipment manufacturing, in particular to a liquid lens and a processing method and an imaging module thereof.

Background

With the rapid development of terminal services, simple and portable camera devices are increasingly popular with people. With the development of technology, various ultra-thin focus lenses have been developed, such as a variable focus camera including a voice coil focus motor for a mobile phone, a mechanical variable focus lens, and the like.

The inventor finds that the prior art has at least the following problems: the voice coil focusing device is small in size, so that the voice coil focusing device is inconvenient to assemble, and the cost of the whole camera module is high; the mechanical zoom lens has larger volume and is difficult to miniaturize and integrate; the existing electrowetting liquid lens has overlarge volume, is not suitable for microspur imaging and is not easy to be processed automatically in large batch; the disclosed electrowetting liquid lens is too large in volume and too long in focal length, and is not suitable for a microspur imaging occasion.

Disclosure of Invention

An object of some embodiments of the present application is to provide a liquid lens, a method for processing the same, and an imaging module, so that the size of the liquid lens can be flexibly adjusted, processed, and assembled more conveniently, and the liquid lens is easy for automatic mass production and beneficial to reducing the cost.

The embodiment of the application provides a liquid lens, which comprises at least one layer of substrate; the substrate is provided with N substrate through holes, wherein N is a natural number greater than or equal to 1; a driving part connected with a lens driving circuit is arranged in each substrate through hole; the substrate is also provided with a first sealing layer and a second sealing layer, the first sealing layer, the second sealing layer and the substrate through hole form a lens cavity, and a liquid medium is arranged in the lens cavity; and an insulating layer for isolating the liquid medium from the driving part is arranged in each substrate through hole.

The embodiment of the application further provides an imaging module, which comprises the liquid lens and the image sensor, wherein the image sensor is fixedly connected with the liquid lens, and the photosensitive area of the image sensor corresponds to the through hole of the substrate of the liquid lens.

The embodiment of the application also provides a liquid lens processing method, which comprises the following steps: providing a substrate; the substrate is provided with N substrate through holes, wherein N is a natural number greater than or equal to 1; a driving part connected with a lens driving circuit is arranged in the substrate through hole; forming an insulating layer on the driving part; forming a first sealing layer for sealing one end of the through hole of the substrate on the substrate; injecting a liquid medium into the substrate through hole; and forming a second sealing layer for sealing the other end of the through hole of the substrate on the substrate to obtain the single-layer liquid lens.

Compared with the prior art, the embodiment of the application forms the main structure of the liquid lens by forming the substrate through hole on the substrate, forming the driving part (namely, the driving electrode of the lens) and the insulating layer which are connected with the lens driving circuit in the substrate through hole, and then combining the first sealing layer and the second sealing layer which are arranged on the substrate to seal the substrate through hole to form the lens cavity. The main body structure of the lens can be manufactured by adopting a mature and stable plane processing technology related to a printed circuit board, and can be connected and assembled with peripheral circuits of an image sensor, a lens driving circuit and the like through the plane processing technology, so that the liquid lens and the peripheral circuits are more convenient to assemble, the liquid lens and the peripheral circuits are easier to realize array processing, and meanwhile, the plane processing technology can enable the product to be thinner in thickness, smaller in volume and lower in cost.

In addition, the driving part comprises a first metal layer and a conductive piece; the first metal layer is formed on the inner wall of the substrate through hole, and the conductive piece is installed in the substrate through hole in a tight fit mode; the surface of the conductive piece is an annular slope surface. The original curvature of the liquid medium can be determined by the slope of the annular slope surface of the conductive piece, so that the liquid lens with different original curvatures can be flexibly manufactured.

In addition, the driving part is a metal layer with an annular slope surface. The present embodiment can manufacture liquid lenses having different original curvatures in a more simplified process.

In addition, the liquid lens further comprises a bottom plate and a lens driving circuit; the bottom plate is stacked on the light-emitting side of the substrate, the bottom plate is provided with N bottom plate through holes, the bottom plate through holes are coaxially arranged with the substrate through holes, and the lens driving circuit is arranged on the bottom plate and electrically connected with the driving part. In the embodiment, the interconnection between the liquid lens and the lens driving circuit can be conveniently realized through the bottom plate, and the focal length can be conveniently adjusted by adjusting the thickness of the bottom plate.

In addition, the liquid lens further comprises a second metal layer formed on at least one surface of the substrate. The second metal layer of this embodiment may be used for electromagnetic shielding or forming a pad pattern layer, etc.

In addition, the base plate is flexible base plate, the income light side of flexible base plate is provided with the enhancement layer.

In addition, the substrate is provided with a black layer in the region except the lens cavity, so that stray light can be reduced.

In addition, the insulating layer is a black insulating layer. Stray light can be better reduced by the black insulating layer.

Drawings

One or more embodiments are illustrated by way of example in the accompanying drawings, which correspond to the figures in which like reference numerals refer to similar elements and which are not to scale unless otherwise specified.

FIG. 1 is a schematic diagram of a single layer, single hole liquid lens according to a first embodiment of the present application;

fig. 2 is a schematic structural view of an array type liquid lens according to a first embodiment of the present application;

FIG. 3 is a schematic view of a multilayer liquid lens according to a first embodiment of the present application;

FIG. 4 is a schematic diagram of a liquid lens according to a second embodiment of the present application;

FIG. 5 is a schematic structural diagram of an imaging module with a single-layer lens according to a third embodiment of the present application;

FIG. 6 is a schematic diagram of an imaging module of a multi-layered lens according to a third embodiment of the present application;

fig. 7 is a schematic structural diagram of an imaging module with a conductive member according to a third embodiment of the present application;

fig. 8 is a flowchart of a liquid lens processing method according to a fourth embodiment of the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, some embodiments of the present application will be described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.

Embodiments of the present application relate to a liquid lens, which may also be referred to as an Electrowetting (EW) liquid lens, and which may be used to converge and diverge light in an optical system. For example, the method can be applied to an optical detection device, and the optical detection device can be used for optical measurement, such as optical distance measurement, biological identification (including human face, optical fingerprint under screen, iris and the like) and the like; or may be applied to an optical imaging module such as a Charge-Coupled Device (CCD), a CMOS Image Sensor (CIS), or may also be applied to an optical field imaging module and laser modulation of a laser.

Referring to fig. 1 to 3, a liquid lens according to a first embodiment of the present application includes: the liquid lens comprises at least one layer of substrate 100, wherein the substrate 100 is provided with N substrate through holes 102, N is a natural number greater than or equal to 1, a driving part 103 connected with a lens driving circuit 120 is arranged in each substrate through hole 102, a first sealing layer 105 and a second sealing layer 106 are further arranged on the substrate 100, the first sealing layer 105, the second sealing layer 106 and the substrate through holes 102 form a lens cavity, a liquid medium is arranged in the lens cavity, and an insulating layer 104 used for isolating the liquid medium from the driving part 103 is arranged in each substrate through hole 102.

Specifically, the substrate 100 may be a Flexible substrate in a Flexible Printed Circuit (FPC) manufacturing process, or a rigid substrate in a Printed Circuit Board (PCB) manufacturing process, where the Flexible substrate may be suitable for processing a liquid lens with a thinner thickness and a smaller volume, and the rigid substrate may be suitable for processing a liquid lens with a larger size. The present embodiment is mainly described by taking an example of processing a liquid lens by using an FPC processing process, however, any liquid lens structure implemented by using a planar processing process such as an FPC or a PCB is within the protection scope of the present embodiment. The flexible substrate may be a Polyimide (PI) or Polyester (PE) film. The substrate 100 may be printed, optionally, a second metal layer 101 may be formed on the upper and lower surfaces of the substrate 100, the second metal layer 101 is, for example, a copper-clad layer, and the second metal layer 101 may be used for electromagnetic shielding and may also be used for forming a pad pattern layer.

The FPC processing technology can process through holes, blind holes, buried holes and the like. The holes in the FPC are mainly used to realize interlayer interconnection, and in this embodiment, the substrate through holes 102 are mainly used to provide driving electrodes of the liquid lens and to form a lens cavity. Specifically, one or more substrate through holes 102 may be formed in the substrate 100, and referring to fig. 2, the substrate through holes 102 may be arranged in an array manner or in other irregular manners. The substrate through hole 102 can be processed by laser drilling equipment, but is not limited to the laser drilling equipment, so that the liquid lens can be automatically processed in batches, the arrayed liquid lens can be conveniently realized, and meanwhile, the substrate through hole 102 is high in precision, more controllable in tolerance and high in arrayed processing consistency. The shape of the substrate through hole 102 may be circular, but is not limited thereto, and may also be rectangular, hexagonal, or the like in some examples. The size of the substrate through hole 102 can be set according to actual needs, for example, when the substrate through hole 102 is processed by laser drilling equipment, the diameter of the substrate through hole 102 can reach 20 micrometers (um), and therefore, the size of the liquid lens can be made smaller, and the substrate drilling process is mature and stable, compared with the existing stainless steel hollow circular tube structure, the size adjustment of the substrate through hole 102 is more flexible.

In this embodiment, the driving portion 103 is, for example, a metal layer with uniform thickness, such as a copper-clad layer, formed on the inner wall of each substrate through hole 102, and the copper-clad layer can be formed by an electroplating process in the FPC processing process, and specifically, an appropriate electroplating process, such as evaporation, sputtering, and water plating, can be selected according to the required thickness of the copper-clad layer, and is not described herein again. The driving portion 103 may be electrically connected to a lens driving circuit 120 (see below) through traces on the substrate 100. In this embodiment, the driving part 103 may extend to the upper and lower surfaces of the substrate 100, so that a three-dimensional driving electrode may be formed, but is not limited thereto. The driving part 103 can thus drive the liquid medium in the lens cavity to move along the direction of the equilibrium of surface tension and electric field force. Compared with the existing liquid lens with a metal packaging structure, the driving part 103 of the liquid lens of the embodiment has the advantages of mature and stable processing technology, low cost and suitability for automatic batch processing.

In this embodiment, the insulating layer 104 is formed on the surface of the driving portion 103, and can be used to isolate the driving portion 103 from the liquid medium, and can prevent the driving portion 103 from electrochemically reacting with the liquid medium when a driving signal is applied to the driving portion 103. Specifically, the insulating layer 104 may be a water-and oil-repellent insulating layer. In practical applications, the insulating layer 104 may be formed by: firstly, depositing an adhesion layer on the surface of the driving part 103, wherein the adhesion layer is made of parylene (Paracyclophane) with a thickness of several hundred nanometers, and then forming a polytetrafluoroethylene (Teflon) material layer with a proper thickness or other fluorine-containing plastics on the adhesion layer through an evaporation or baking process, so as to form an insulating layer 104; alternatively, a titanium dioxide hydrophobic layer may be formed on the adhesion layer by spraying to realize the insulating layer 104, and the surface of the titanium dioxide layer has a micro-nano hydrophobic structure similar to a lotus leaf, so that a better hydrophobic effect is achieved, but this should not be taken as a limitation, and any insulating layer capable of achieving a desired effect is within the protection scope of the present embodiment. The thickness of the insulating layer 104 can be set according to actual requirements, generally, the thickness of the insulating layer 104 can be selected from 500 nanometers (nm) to 50 micrometers (um), and in some examples, the thickness of the insulating layer 104 is, for example, 1um to 2um, so that a liquid lens with a small size can be obtained, which is beneficial to thinning of an imaging module using the liquid lens. In this embodiment, the liquid medium may include a non-polar liquid having different refractive indexes, such as transparent silicone oil, for example, methyl silicone oil or organic silicone oil, and a polar liquid, such as ionic water, or other high molecular ionic liquid, but is not limited thereto. In practical application, two liquids with different refractive indexes and relatively close densities can be selected as the liquid medium. In some examples, the liquid medium may also be two or more, for example three. Alternatively, it is also possible to obtain a black insulating layer by a blackening process, and provide the black insulating layer 104 on the driving portion 103. The black insulating layer can be obtained by adding a black pigment, for example, but not limited thereto, and the black insulating layer can reduce reflected stray light. The two liquid media within the lens cavity will self-stratify due to differences in surface tension, etc., and form a layer of naturally curved optical interface. Because the insulating layer 104 has different wettability to the transparent silicone oil and the ionic liquid, the comprehensive acting force of wettability of the insulating layer 104, the adhesion between molecules of the liquid medium, the surface tension of the liquid medium and the like can be far greater than the gravity of the liquid medium and the external impact force, so that the liquid medium in the lens cavity has a very stable optical structure. As in fig. 1 to 3, the liquid medium inside the transparent cavity forms a stable double-layer structure.

In this embodiment, the first sealing layer 105 and the second sealing layer 106 are used to seal the bottom and the top of the substrate through hole 102, respectively, and therefore need to have a certain waterproof and oilproof capability. The first sealing layer 105 and the second sealing layer 106 may be implemented by transparent plastic films, and the transparent plastic films may be formed on the upper and lower surfaces of the substrate 100 through a planar processing process, but not limited thereto, the first sealing layer 105 and the second sealing layer 106 may also be implemented by thin glass, for example, by adhering the thin glass to the upper and lower surfaces of the substrate 100 to seal the substrate through hole 102, and details thereof are not repeated here. In addition, the substrate 100 may support the first sealing layer 105 and the second sealing layer 106 during processing of the first sealing layer 105 and the second sealing layer 106, thereby facilitating the processing of the first sealing layer 105 and the second sealing layer 106. After the first sealing layer 105 is processed, a proper amount of liquid medium, such as transparent silicone oil and ionic liquid with equal volume, can be injected into the lens cavity, and then the second sealing layer 106 is processed, so as to obtain the single-layer liquid lens. The first sealant layer 105 and the second sealant layer 106 are also amenable to automated batch processing due to the planar processing technique.

It is worth mentioning that the liquid lens may further include a bottom plate 110 and a lens driving circuit 120. The base plate 110 is stacked on the light-emitting side of the substrate 100, the base plate 110 is provided with N base plate through holes 111, the base plate through holes 111 and the substrate through holes 102 are coaxially arranged, and the lens driving circuit 120 is disposed on the base plate 110 and electrically connected to the driving portion 103. Specifically, the bottom plate 110 may be a flexible substrate or a rigid substrate, and the bottom plate 110 may be disposed on the light emitting side of the substrate 100, for example, on the bottom surface of the substrate 100. The bottom plate 110 includes, for example, a supporting region overlapping with the substrate 100 and a carrying region extending from the supporting region, and the lens driving circuit 120 may be disposed on the carrying region of the bottom plate 110, so that the lens driving circuit 120 and the lens driving electrode (i.e., the driving portion 103) can be electrically connected through a planar processing process. Of course, an interface may be disposed on the substrate 100 to electrically connect to the lens driving circuit 120, so as to be compatible with the independent lens driving circuit 120. The bottom plate 110 not only can support the first sealing layer 105 to a certain extent, but also can be used to assist in determining the focal length of the liquid lens, for example, when a short focal length imaging is required, the thickness of the bottom plate 110 can be reduced, and when a larger focal length imaging is required, the thickness of the bottom plate 110 can be increased, so as to change the distance between the light-emitting surface of the liquid lens and an image sensor (see below). It is worth mentioning that in some examples, the set focal distance may also be achieved by the image sensor structure, for example, the image sensor chip may be sunk into the sensor substrate, so that the focal distance is determined by the thickness of part of the sensor substrate.

When the substrate 100 is a flexible substrate, a reinforcing layer 19 may be further disposed on the light incident side of the flexible substrate, and the reinforcing layer 19 may be a metal sheet or other plastic sheet with a certain strength, so as to improve the strength of the liquid lens. Optionally, the substrate 100 may be blackened, for example, a black layer, such as black paint, is sprayed on the light incident side of the substrate 100 except for the lens cavity, so as to reduce stray light.

Fig. 1 and 2 show a single-layer single-hole and multi-hole liquid lens, respectively, and fig. 3 shows a multi-layer liquid lens. Specifically, each layer of liquid lens can be manufactured separately, and then the multiple layers of liquid lenses are aligned and then fixedly connected to obtain the multiple layers of liquid lenses, wherein the substrate through holes 102 of each layer of liquid lens are coaxially aligned, and the multiple layers of liquid lenses can be bonded together in an adhering manner. Specifically, the diameters of the substrate through holes 102 of the liquid lenses of the respective layers may be the same, or may be sequentially decreased from top to bottom, or sequentially increased. Each layer of the multilayer liquid lens can be a single-hole liquid lens or an arrayed multi-hole liquid lens. It is worth mentioning that each hole lens in the liquid lens can focus independently, so that each layer of liquid lens can focus independently in the multilayer liquid lens, and the multilayer focusing combination can realize richer focusing effect.

Optionally, in the multilayer liquid lens structure, an intermediate substrate 130 may be further disposed between two adjacent layers of liquid lenses, an intermediate substrate through hole 131 is also required to be formed in the intermediate substrate 131, each intermediate substrate through hole 131 is disposed coaxially with the substrate through hole 102, and the intermediate substrate 130 may be used to assist in setting the focal length. In some examples, the intermediate substrate 130 may not be provided.

It should be noted that, with the liquid lens structure of the present embodiment, the diameter of the substrate through hole can be made very small, which not only can make the light entrance aperture of the liquid reach 0.4 mm or less, but also the focal length can reach 0.8 mm or less, so that the liquid lens structure can be applied to the micro-distance imaging occasions, such as optical fingerprint identification under a screen, while the existing liquid lens processing technology is difficult to implement.

Compared with the prior art, the main body structure of the liquid lens is obtained by processing the plane through FPC (flexible printed circuit) and PCB (printed circuit board) and other plane processing technologies, so that the product size is adjusted more flexibly, the product volume is smaller, the thickness is thinner, the array processing is easy to realize, the automation degree is high, the batch processing efficiency is high, the main body structure is more convenient to connect and assemble with peripheral circuits such as an image sensor and a lens driving circuit, and the cost is reduced.

A second embodiment of the present application is directed to a liquid lens, and is improved over the first embodiment, mainly in that, in the present embodiment, the driving portion has a specific surface shape, thereby facilitating the liquid lens to achieve a desired original curvature.

Referring to fig. 4, in the liquid lens of the present embodiment, the driving portion 103 includes a first metal layer 1030 and a conductive member 1031, the first metal layer 1030 is formed on an inner wall of the through substrate hole 102, the conductive member 1031 is tightly fitted in the through substrate hole 102, and a surface of the conductive member 1031 (i.e., a surface facing the liquid medium) is an annular slope surface.

The radius of the contact surface between two liquid media in the lens cavity, such as transparent silicone oil and ionic liquid, is called as the curvature radius, the curvature radius of the liquid medium is called as the original curvature when no driving signal is applied, when the driving signal is applied through the lens driving circuit 120, an electric field is applied to the liquid medium through the driving part, and the radius of the contact surface between the ionic liquid and the transparent silicone oil changes under the comprehensive action of the electric field force, the hydrophilic force of the insulating layer, the surface tension and the like, that is, the curvature radius changes, and accordingly the focal length of the liquid lens changes, thereby realizing the zoom function.

In this embodiment, the conductive member 1031 with an annular slope surface is embedded in the substrate through hole 102, so that the required original curvature can be adjusted according to the slope of the conductive member 1031, and therefore, by providing the conductive member with an annular slope surface with a specific slope, the required original curvature can be conveniently and accurately achieved. Specifically, the conductive member 1031 may be a micro-metal member, such as a micro-stainless steel member, or other device with good conductive performance. The conductive members 1031 may be embedded in the substrate through hole 102 in a zero-fit or interference fit manner, thereby ensuring good driving ability of the driving portion 103. In practical application, the slope of the annular slope surface can be 10-45 degrees, but is not limited thereto.

It should be noted that, in some examples, the driving portion 103 may also be a metal layer with an annular slope surface, and specifically, when the driving portion 103 is formed by electroplating, the thickness of the metal layer may be controlled by a mask template, so that the surface of the metal layer is formed as the annular slope surface with a desired slope, but is not limited thereto. It is worth mentioning that in some examples, the annular slope may also be implemented by the insulating layer 104, and since the thickness of the insulating layer with the annular slope structure may be larger, it may be necessary to increase the driving signal when zooming.

Compared with the previous embodiment, the liquid lens has the advantages that the annular slope surface structure is arranged in the through hole of the substrate, so that the required original curvature is convenient to realize, and the manufacturing flexibility of the liquid lens is improved.

The third embodiment of the present application relates to an imaging module, which can be used for realizing photographing or biological recognition, such as fingerprint recognition under a screen, and the present embodiment does not specifically limit the specific application of the imaging module.

Referring to fig. 5 to 7, the imaging module includes a liquid lens according to the first or second embodiment, and an image sensor 20. The image sensor 20 is fixedly connected with the liquid lens, and the light sensing area of the image sensor 20 corresponds to the substrate through hole 102 of the liquid lens.

Specifically, the image sensor 20 is disposed on a sensor substrate 21, and the sensor substrate 21 is fixedly connected to the liquid lens, for example, by adhesion. Wherein the light-sensing area of the image sensor 20 may be coaxially aligned with the substrate through-hole 102 of the liquid lens. The imaging module further includes a lens driving circuit 120, and the lens driving circuit 120 may be disposed on the bottom plate 110 of the liquid lens, or may be connected to the liquid lens as an independent component. Fig. 5 and 6 respectively show an imaging module including single-layer and multi-layer liquid prisms, and it should be noted that each layer of liquid prism may also be an arrayed liquid prism. Fig. 7 shows a single-layer, single-hole imaging module including a liquid prism having a driving portion with an annular slope surface, and the liquid prism in the imaging module shown in fig. 7 may also be a single-layer porous or multi-layer porous liquid prism.

Compared with the prior art, the main body structure of the liquid lens is obtained through the plane processing technology, so that the connection and assembly of the liquid lens and peripheral circuits of a lens driving circuit, an image sensor and the like can be conveniently realized through the plane processing technology such as sticking, the degree of automation is high, the assembly process is simplified, the processing period is shortened, and the cost is low.

A fourth embodiment of the present application relates to a liquid lens processing method for processing a liquid lens according to the first or second embodiment. Referring to fig. 8, the processing method includes steps 801 to 807. Please refer to fig. 1 to 3 for the structure of the liquid lens manufactured by the method of this embodiment.

Step 801: a substrate is provided.

Specifically, the substrate 100 may be a flexible substrate in an FPC processing process, or a hard substrate in a PCB processing process. This embodiment mainly takes the example of processing the liquid lens by using the FPC processing technique as an example. The flexible substrate may be a Polyimide (PI) or Polyester (PE) film. Compared with a hard substrate and a liquid lens in a metal packaging mode, the flexible substrate can be used for processing the liquid lens with smaller volume and thinner thickness. The substrate 100 may form traces, such as traces for connecting the lens driving circuit 120 and the driving part 103. At least one side of the substrate 100 may be formed with a second metal layer 101, for example, both sides of the substrate 100 may be formed with the second metal layer 101, the second metal layer 101 is, for example, a copper-clad layer, and the second metal layer 101 may be used for electromagnetic shielding and may also be used for forming a pad pattern layer.

Step 102: n substrate through holes are formed in the substrate, and N is a natural number greater than or equal to 1.

The FPC processing technology can process through holes, blind holes, buried holes and the like. The holes in the FPC are mainly used to realize interlayer interconnection, and in this embodiment, the substrate through holes 102 are mainly used to provide driving electrodes of the liquid lens and to form a lens cavity. Specifically, the substrate through hole 102 may be processed by a laser drilling device, but is not limited thereto, and any method capable of forming the substrate through hole 102 on the substrate 100 is within the scope of the present embodiment. Through holes of the substrate with the diameter of 20um can be processed by the laser drilling equipment, so that the liquid lens with very small size can be processed. In addition, the processing mode such as laser drilling easily realizes automatic batch processing to can conveniently realize the array liquid lens, the precision of base plate through-hole 102 is high simultaneously, and the tolerance is changeed and is controlled, and the array processing uniformity is high, and the base plate drilling technology is ripe, stable, compares current hollow pipe structure of stainless steel, and base plate through-hole 102 size adjustment is more nimble. The number of the substrate through holes 102 may be 1 as shown in fig. 1 or more than one as shown in fig. 2, and the plurality of substrate through holes 102 may be arranged in an array. The substrate through-hole 102 may be circular, rectangular, hexagonal, etc., and the shape of the substrate through-hole is not particularly limited in this embodiment.

Step 103: a driving part connected with the lens driving circuit is arranged in the substrate through hole.

Specifically, referring to fig. 1, the driving portion 103 is, for example, a metal layer with uniform thickness, such as a copper-clad layer, formed on the inner wall of each substrate through hole 102, and the copper-clad layer can be formed by an electroplating process in the FPC processing process, and an appropriate electroplating process, such as evaporation, sputtering, and water plating, can be specifically selected according to the required thickness of the copper-clad layer, and is not described herein again. In this embodiment, the driving part 103 may extend to the upper and lower surfaces of the substrate 100, so that a three-dimensional driving electrode may be formed, but is not limited thereto. Compared with the existing liquid lens with a metal packaging structure, the driving part 103 of the liquid lens of the embodiment has the advantages of mature and stable processing technology, low cost and suitability for automatic batch processing.

Referring to fig. 4, in one example, the driving portion 103 has a specific surface shape so as to facilitate the liquid lens to achieve a desired original curvature. Specifically, the driving part 103 may include a first metal layer 1030 and a conductive member 1031, a surface of the conductive member 1031 is an annular slope surface, and the first metal layer 1030 may be electrically connected to the lens driving circuit 120 through traces on the substrate 100. For the driving unit 103, step 103 specifically includes: first metal layer 1030 is formed on the inner wall of substrate through hole 102 by electroplating, and conductive member 1031 is embedded in substrate through hole 102. The first metal layer 1030 may be a copper-clad layer with a uniform thickness. The first metal layer 1030 may extend to upper and lower surfaces of the substrate 100, so that a three-dimensional spatial structure driving electrode may be formed. In this embodiment, the conductive member 1031 with an annular slope surface is embedded in the substrate through hole 102, so that the required original curvature can be adjusted according to the slope of the conductive member 1031, and therefore, by providing the conductive member with an annular slope surface with a specific slope, the required original curvature can be conveniently and accurately achieved. Specifically, the conductive member 1031 may be a micro-metal member, such as a micro-stainless steel member, or other device with good conductive performance. The conductive members 1031 may be embedded in the substrate through hole 102 in a zero-fit or interference fit manner, thereby ensuring good driving ability of the driving portion 103. In practical application, the slope of the annular slope surface can be 10-45 degrees, but is not limited thereto. It should be noted that, in some examples, the driving portion 103 may also be a metal layer with an annular slope surface, specifically, in step 103, the driving portion 103 is formed by depositing on the inner wall of the substrate through hole 102 through a masking process, and the thickness of the metal layer may be controlled through a masking template, so that the surface of the formed metal layer is an annular slope surface with a desired slope, but is not limited thereto. The annular slope surface structure is arranged in the through hole of the substrate, so that the required original curvature is convenient to realize, and the manufacturing flexibility of the liquid lens is improved.

Step 104: an insulating layer 104 is formed on the driving portion 103.

Specifically, the insulating layer 104 is formed on the surface of the driving portion 103 and can be used to isolate the driving portion 103 from the liquid medium. Specifically, the insulating layer 104 may be a water-and oil-repellent insulating layer. In practical applications, the insulating layer 104 may be formed by: firstly, depositing an adhesion layer on the surface of the driving part 103, wherein the adhesion layer is made of parylene (Paracyclophane) with a thickness of several hundred nanometers, and then forming a polytetrafluoroethylene (Teflon) material layer with a proper thickness or other fluorine-containing plastics on the adhesion layer through an evaporation or baking process, so as to form an insulating layer 104; alternatively, a titanium dioxide hydrophobic layer may be formed on the adhesion layer by spraying to realize the insulating layer 104, and the surface of the titanium dioxide layer has a micro-nano hydrophobic structure similar to a lotus leaf, so that a better hydrophobic effect is achieved, but this should not be taken as a limitation, and any insulating layer capable of achieving a desired effect is within the protection scope of the present embodiment. The thickness of the insulating layer 104 can be set according to actual needs, and in some examples, the thickness of the insulating layer 104 is, for example, 1um to 2um, so that a liquid lens with a small size can be obtained, which is beneficial to thinning of an imaging module using the liquid lens. Alternatively, it is also possible to obtain a black insulating layer by a blackening process, and provide the black insulating layer 104 on the driving portion 103. The black insulating layer can be obtained by adding a black pigment, for example, but is not limited thereto.

Step 105: a first sealing layer for sealing one end of the through-hole of the substrate is formed on the substrate.

Step 106: and injecting a liquid medium into the through hole of the substrate.

In particular, the liquid medium may be transparent silicone oil as well as ionic liquid. The two liquid media within the lens cavity will self-stratify due to differences in surface tension, etc., and form a layer of naturally curved optical interface. Because the insulating layer 104 has different wettability to the transparent silicone oil and the ionic liquid, the comprehensive acting force of wettability of the insulating layer 104, the adhesion between molecules of the liquid medium, the surface tension of the liquid medium and the like can be far greater than the gravity of the liquid medium and the external impact force, so that the liquid medium in the lens cavity has a very stable optical structure. As in fig. 1 to 3, the liquid medium inside the transparent cavity forms a stable double-layer structure.

Step 107: and forming a second sealing layer for sealing the other end of the through hole of the substrate on the substrate to obtain the single-layer liquid lens.

Specifically, the first sealing layer 105 and the second sealing layer 106 in the

steps

106 and 107 are used to seal the bottom and the top of the substrate through hole 102, respectively, so that they need to have certain waterproof and oilproof capabilities. The first sealing layer 105 and the second sealing layer 106 may be implemented by using transparent plastic films, or by using thin glass, for example, by adhering thin glass to the upper and lower surfaces of the substrate 100 to seal the substrate through-hole 102. In addition, the substrate 100 may support the first sealing layer 105 and the second sealing layer 106 during processing of the first sealing layer 105 and the second sealing layer 106, thereby facilitating the processing of the first sealing layer 105 and the second sealing layer 106. After the first sealing layer 105 is processed, a proper amount of liquid medium, such as transparent silicone oil and ionic liquid with equal volume, can be injected into the lens cavity, and then the second sealing layer 106 is processed, so as to obtain the single-layer liquid lens. The first sealant layer 105 and the second sealant layer 106 are also amenable to automated batch processing due to the planar processing technique.

It should be noted that the bottom plate 100 may be disposed on the light emitting side of the substrate 100, for example, the bottom plate is adhered to the substrate 100, and the lens driving circuit 120 is disposed on the bottom plate. The bottom plate 110 may have bottom plate through holes 111 with the same number as the substrate through holes 102, and the bottom plate through holes 111 are disposed coaxially with the substrate through holes 102. The bottom plate 110 not only can support the first sealing layer 105 to a certain extent, but also can be used to assist in determining the focal length of the liquid lens, for example, when a short focal length imaging is required, the thickness of the bottom plate 110 can be reduced, and when a larger focal length imaging is required, the thickness of the bottom plate 110 can be increased, so as to change the distance between the light-emitting surface of the liquid lens and the image sensor. It is worth mentioning that in some examples, the set focal distance may also be achieved by the image sensor structure, for example, the image sensor chip may be sunk into the sensor substrate, so that the focal distance is determined by the thickness of part of the sensor substrate.

When the substrate 100 is a flexible substrate, a reinforcing layer may be further disposed on the light incident side of the flexible substrate after step 807. The reinforcing layer 19 may be a metal sheet or other plastic sheet having a certain strength, thereby enhancing the strength of the liquid lens. Optionally, the substrate 100 may be blackened, for example, a black layer, such as black paint, is sprayed on the light incident side of the substrate 100 except for the lens cavity, so as to reduce stray light.

After step 807, a plurality of single-layer liquid lenses may be produced through steps 801 to 807, and stacked to form a multilayer liquid lens. Specifically, each layer of liquid lens can be manufactured separately, and then the multiple layers of liquid lenses are aligned and then fixedly connected to obtain the multiple layers of liquid lenses, wherein the substrate through holes 102 of each layer of liquid lens are coaxially aligned, and the multiple layers of liquid lenses can be bonded together in an adhering manner. Specifically, the diameters of the substrate through holes 102 of the liquid lenses of the respective layers may be the same, or may be sequentially decreased from top to bottom, or sequentially increased. Each layer of the multilayer liquid lens can be a single-hole liquid lens or an arrayed multi-hole liquid lens. It is worth mentioning that each hole lens in the liquid lens can focus independently, so that each layer of liquid lens can focus independently in the multilayer liquid lens, and the multilayer focusing combination can realize richer focusing effect.

It will be understood by those of ordinary skill in the art that the foregoing embodiments are specific examples for carrying out the present application, and that various changes in form and details may be made therein without departing from the spirit and scope of the present application in practice.

Claims

1. The liquid lens is characterized in that the liquid lens is a multilayer liquid lens and is applied to an optical imaging module;

each layer of liquid lens comprises a substrate, wherein the substrate is a flexible substrate in a flexible circuit board processing process or a hard substrate in a printed circuit board processing process;

the substrate is provided with N substrate through holes, wherein N is a natural number greater than or equal to 1;

a driving part connected with a lens driving circuit is arranged in each substrate through hole;

each layer of liquid lens further comprises a first sealing layer and a second sealing layer which are arranged on the substrate, the first sealing layer, the second sealing layer and the substrate through holes form a lens cavity, and a liquid medium is arranged in the lens cavity;

an insulating layer for isolating the liquid medium and the driving part is arranged in each substrate through hole;

the substrate through holes of each layer of liquid lens are coaxially aligned, an intermediate substrate is arranged between every two adjacent layers of liquid lenses, the intermediate substrate is provided with an intermediate substrate through hole, and the intermediate substrate through hole and the substrate through hole are coaxially arranged.

2. The liquid lens as claimed in claim 1, wherein the driving part includes a first metal layer and a conductive member;

the first metal layer is formed on the inner wall of the substrate through hole, and the conductive piece is installed in the substrate through hole in a tight fit mode; the surface of the conductive piece is an annular slope surface.

3. The liquid lens according to claim 1, wherein the driving portion is a metal layer having a surface with an annular slope.

4. The liquid lens of claim 1, wherein the liquid lens further comprises a base plate and a lens drive circuit;

the bottom plate is stacked on the light-emitting side of the substrate, the bottom plate is provided with N bottom plate through holes, the bottom plate through holes are coaxially arranged with the substrate through holes, and the lens driving circuit is arranged on the bottom plate and electrically connected with the driving part.

5. The liquid lens of claim 1, further comprising a second metal layer formed on at least one surface of the substrate.

6. The liquid lens according to claim 1, wherein the substrate is a flexible substrate having a reinforcing layer disposed on a light incident side thereof.

7. The liquid lens of claim 1, wherein a black layer is disposed on the substrate except for the lens cavity.

8. The liquid lens according to any one of claims 1 to 7, wherein the insulating layer is a black insulating layer.

9. An imaging module comprising a liquid lens according to any one of claims 1 to 8, and

and the image sensor is fixedly connected with the liquid lens, and a photosensitive area of the image sensor corresponds to the through hole of the substrate of the liquid lens.

10. The liquid lens processing method is characterized in that the liquid lens is a multilayer liquid lens and is applied to an optical imaging module, and the method comprises the following steps:

providing a substrate;

a driving part connected with a lens driving circuit is arranged in the substrate through hole;

forming an insulating layer on the driving part;

forming a first sealing layer for sealing one end of the through hole of the substrate on the substrate;

injecting a liquid medium into the substrate through hole;

forming a second sealing layer for sealing the other end of the through hole of the substrate on the substrate to obtain a single-layer liquid lens;

stacking a plurality of the single-layer liquid lenses to form the multilayer liquid lens; the substrate through holes of each layer of liquid lens are coaxially aligned, an intermediate substrate is arranged between every two adjacent layers of liquid lenses, the intermediate substrate is provided with an intermediate substrate through hole, and the intermediate substrate through hole and the substrate through hole are coaxially arranged.

11. The liquid lens processing method according to claim 10, wherein the driving portion includes a first metal layer and a conductive member; the surface of the conductive piece is an annular slope surface;

set up the drive division of being connected with lens drive circuit in the base plate through-hole specifically includes:

electroplating the inner wall of the through hole of the substrate to form the first metal layer;

and embedding the conductive piece in the through hole of the substrate.

12. The liquid lens processing method according to claim 10, wherein the driving portion is a metal layer whose surface is an annular slope;

and forming the driving part on the inner wall of the through hole of the substrate by deposition through a mask process.

13. The liquid lens processing method according to claim 10, wherein the substrate is a flexible substrate, and further comprising, after forming a second sealing layer for sealing the other end of the through-hole of the substrate on the substrate:

and arranging a reinforcing layer on the light incident side of the flexible substrate.