Strain-sensing VCM elastic piece, driving assembly, camera module, and electronic device

Abstract

The present invention provides a strain-sensing VCM elastic piece, a driving assembly, a camera module, and an electronic device. The elastic piece comprises an inner connecting part, an outer connecting part, and an elastic arm connected to the outer connecting part and the inner connecting part. The outer connecting part is arranged in the circumferential direction of the outer side of the inner connecting part. The strain-sensing VCM elastic piece further comprises a strain resistor structure. The strain resistor structure comprises a first strain resistor layer, and a first insulating layer and a second strain resistor layer arranged on the elastic arm. The first strain resistor layer and the second strain resistor layer each comprise a plurality of strain resistors, and a Wheatstone bridge detection circuit formed between the strain resistors. According to the present invention, a piezoresistive circuit is manufactured on the surface of the VCM elastic piece, the resistance value of the piezoresistive circuit on the elastic piece is changed due to the stretching of the elastic piece by a focusing movement of a lens, and is then converted into an electric signal by means of a measuring circuit to be output, thereby sensing the displacement of the lens, achieving precise positioning of the lens.

Description

Strain sensing VCM shrapnel, drive components, camera modules and electronic equipment Technical Field

[0001] The present invention relates to the technical field of voice coil motors, and in particular to a strain sensing VCM spring, a drive assembly, a camera module, and an electronic device. Background Art

[0002] With the rapid development of the camera industry, products equipped with cameras are becoming more and more popular, including mobile phone cameras, IPAD cameras, etc., becoming indispensable equipment in people's lives.

[0003] The VCM (voice coil motor) is the main component of the camera focus drive. VCM can be divided into open-loop and closed-loop types. The open-loop VCM adjusts the current in the induction coil to push the lens to the appropriate position through the electromagnetic thrust and the constraint balance of the upper and lower springs. This method is simple to manufacture and low in cost, but has poor positioning accuracy and slow positioning speed. The closed-loop VCM adds a Hall sensor device to the open-loop type. The Hall sensor is used to accurately locate the lens position. This method has high accuracy and fast and good focusing effect, but the assembly process is complex and the price is high. In addition, the layout space required for the Hall sensor and its supporting magnets and coils is large, resulting in a relatively large internal volume of the motor, which is not conducive to the requirements of light, thin and miniaturized electronic products. Summary of the Invention

[0004] Based on this, the purpose of the present invention is to provide a strain-sensing VCM spring, a drive component, a camera module and an electronic device to solve the problems existing in the prior art.

[0005] The present invention proposes a strain-sensing VCM spring piece, comprising an internal connection part, an external connection part, and an elastic arm connecting the external connection part and the internal connection part, wherein the external connection part is arranged along the outer circumference of the internal connection, and the strain-sensing VCM spring piece also includes a strain resistor structure, wherein the strain resistor structure includes a first strain resistor layer and a first insulating layer and a second strain resistor layer arranged on the elastic arm, wherein the first strain resistor layer and the second strain resistor layer each include multiple strain resistors, and a Wheatstone bridge detection circuit is formed between each of the strain resistors, wherein the Wheatstone bridge detection circuit is used to calculate the corresponding detection voltage based on the input voltage and the change value of each strain resistor, and calculate the displacement of the elastic arm based on the detection voltage, the input voltage and the length of the elastic arm.

[0006] Furthermore, the first strain resistor layer is provided at one end of the elastic arm away from the second strain resistor layer, and a second insulating layer is provided between the first strain resistor layer and the elastic arm.

[0007] Furthermore, the external connection portion includes a connection body, the first strain resistor layer is provided on the connection body and is arranged close to the second strain resistor layer, and the second strain resistor layer is insulated from the connection body.

[0008] Furthermore, the first strain resistor layer includes a first strain resistor and a second strain resistor, the second strain resistor layer includes a third strain resistor and a fourth strain resistor, the first strain resistor is connected in series with the fourth strain resistor, the second strain resistor is connected in series with the third strain resistor, and the first strain resistor and the second strain resistor are connected in parallel with the second strain resistor and the third strain resistor.

[0009] Furthermore, the calculation formula of the detection voltage is as follows:

[0010] ;

[0011] Where, Indicates the input voltage, 、 、 、 Respectively represent the change values ​​of the first strain gauge resistor, the second strain gauge resistor, the third strain gauge resistor and the fourth strain gauge resistor, 、 、 、 Respectively represent the resistance values ​​of the first strain gauge resistor, the second strain gauge resistor, the third strain gauge resistor, and the fourth strain gauge resistor before the change;

[0012] The calculation formula of the displacement of the elastic arm is:

[0013] ;

[0014] Where, Indicates the length of the elastic arm, represents the piezoresistive coefficient.

[0015] Furthermore, the Wheatstone bridge detection circuit further includes a differential pressure detector, one end of which is respectively connected to the first strain resistor and the fourth strain resistor, and the other end of which is respectively connected to the second strain resistor and the third strain resistor.

[0016] Furthermore, the first strain resistor layer and the second strain resistor layer have a width ranging from 1 μm to 1 mm and a thickness ranging from 5 nm to 20 nm.

[0017] The present invention also proposes a driving assembly, comprising a shell, a carrier fixed in the shell, and an upper spring sheet and a lower spring sheet respectively fixed at both ends of the carrier, wherein the upper spring sheet and the lower spring sheet adopt the above-mentioned strain sensing VCM spring sheet.

[0018] The present invention also provides a camera module, comprising a lens, an imaging sensor and the above-mentioned driving assembly.

[0019] The present invention also provides an electronic device, comprising the above-mentioned camera module.

[0020] Compared with the prior art, the present invention has the following beneficial effects: by providing a first strain resistor layer and a second strain resistor layer on the elastic arm of the VCM spring, a piezoresistive circuit is formed on the VCM spring, and a Wheatstone bridge detection circuit is formed between the strain resistor layers to realize a closed-loop focus control. Due to the stretching of the spring by the lens focus movement, the resistance value of the piezoresistive circuit on the spring changes, which is then converted into an electrical signal output by the measurement circuit, thereby sensing the displacement of the lens and realizing precise positioning of the lens position, thereby replacing the complex Hall sensor closed-loop motor solution and achieving spatial miniaturization. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG1 is a schematic diagram of the overall structure of a strain sensing VCM spring in a first embodiment of the present invention;

[0022] FIG2 is an enlarged schematic diagram of the cross section taken along line AA' in FIG1 ;

[0023] FIG3 is a circuit diagram of a Wheatstone bridge detection circuit in a first embodiment of the present invention;

[0024] FIG4 is a schematic diagram of a multi-circuit design of a strain resistor layer in a cross section taken along line AA′ in the first embodiment of the present invention;

[0025] FIG5 is a schematic diagram of the overall structure of a strain sensing VCM spring in a second embodiment of the present invention;

[0026] FIG6 is a front view of a strain sensing VCM spring in accordance with a second embodiment of the present invention;

[0027] FIG7 is a top view of a strain sensing VCM spring in a second embodiment of the present invention;

[0028] FIG8 is an enlarged schematic diagram of the cross section along line BB′ in FIG7 .

[0029] Description of main component symbols:

[0030] Internal connection part 100 Second insulating layer 430 External connection part 200 Third strain resistor 510 Elastic arm 300 Fourth strain resistor 520 First strain resistor 410 First insulating layer 530 Second strain resistor 420 Pressure difference detector 600

[0031] The following specific embodiments will further illustrate the present invention in conjunction with the above-mentioned drawings. Modes for Carrying Out the Invention

[0032] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the accompanying drawings. The drawings illustrate several embodiments of the present invention. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the present invention.

[0033] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be an intermediate element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one skilled in the art to which this invention pertains. The terms used in this specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0035] Example 1

[0036] Please refer to Figures 1 to 2, which show a strain-sensing VCM spring in a first embodiment of the present invention, including an internal connection part 100, an external connection part 200, an elastic arm 300 and a strain resistance structure, wherein the external connection part 200 is arranged along the outer circumference of the internal connection part 100, and the elastic arm 300 is respectively connected to the internal connection part 100 and the external connection part 200. The strain resistance structure includes a first strain resistance layer and a first insulating layer 530 and a second strain resistance layer provided on the elastic arm 300. The first strain resistance layer and the second strain resistance layer are both composed of two strain resistors, and a Wheatstone bridge detection circuit is formed between the two strain resistors of the first strain resistance layer and the two strain resistors of the second strain resistance layer.

[0037] It should be noted that the insulating layer can be made by PVD / CVD, coating, printing, spraying, lamination, etc., and its material can be metal / non-metal oxide, nitride, organic insulating layer such as Pi, Pi-like, epoxy resin and other materials, and the insulating layer pattern is formed by photolithography or laser processing or printing; the strain resistor layer is formed by sputtering, printing, spraying, electroplating and other directions, and then the circuit pattern is formed by photolithography or laser laser. The strain resistor layer can be Cu, CuNi, NiCr, Ag, Au, Pt, nanosilver wire, graphene, piezoresistive ink, etc., preferably Constantan (Cu / Ni) alloy. Considering the temperature effect, the optimal range of Cu / Ni ratio is between 40%:60% and 60%:40%; in this embodiment, the Wheatstone bridge detection circuit is used to calculate the corresponding detection voltage according to the input voltage and the change value of each strain resistor, and calculate the displacement of the elastic arm according to the detection voltage, input voltage and the length of the elastic arm.

[0038] It can be understood that by forming a piezoresistive circuit on the shrapnel, when the lens focuses and moves, the resistance of the piezoresistive circuit of the upper or lower shrapnel will change when the VCM shrapnel is stretched or compressed. At this time, the displacement of the lens can be sensed by measuring the electrical signal output of the circuit, thereby achieving precise positioning of the lens position.

[0039] In this embodiment, the external connection portion 200 includes a connection body, a first strained resistor layer disposed on the connection body and adjacent to the second strained resistor layer, and the second strained resistor layer is insulated from the connection body. The first strained resistor layer includes a first strained resistor 410 and a second strained resistor 420, and the second strained resistor layer includes a third strained resistor 510 and a fourth strained resistor 520. The first strained resistor 410 and the fourth strained resistor 520 are connected in series, and the second strained resistor 420 and the third strained resistor 510 are connected in series. The first strained resistor 410 and the second strained resistor 420 are connected in parallel with the second strained resistor 420 and the third strained resistor 510 (as shown in FIG3 ). The width of the first and second strained resistor layers ranges from 1 μm to 1 mm, and the thickness ranges from 5 nm to 20 nm. Preferably, the ratio of the third strained resistor to the second strained resistor is equal to or close to the ratio of the first strained resistor to the fourth strained resistor, which can be achieved through line width or trace length.

[0040] In this embodiment, the Wheatstone bridge detection circuit further includes a differential pressure detector 600 , one end of which is connected to the first strain resistor 410 and the fourth strain resistor 520 , and the other end is connected to the second strain resistor 420 and the third strain resistor 510 .

[0041] Furthermore, the calculation formula of the detection voltage is as follows:

[0042] ;

[0043] Where, Indicates the input voltage, 、 、 、 Respectively represent the change values ​​of the first strain gauge resistor, the second strain gauge resistor, the third strain gauge resistor and the fourth strain gauge resistor, 、 、 、 They respectively represent the resistance values ​​of the first strain resistor, the second strain resistor, the third strain resistor and the fourth strain resistor before change; it should be noted that, in this embodiment, when the strain resistor is not strained (tensile strain and compressive strain), its corresponding change value is 0.

[0044] The calculation formula of the displacement of the elastic arm is:

[0045] ;

[0046] Where, Indicates the length of the elastic arm, represents the piezoresistive coefficient.

[0047] It should be noted that the first strain resistor layer in this embodiment is arranged on the external connection part 200 and does not participate in the strain when the lens focuses and moves. The arrangement of two strain resistors can make the pressure difference detector 600 more sensitive to the detection signal. It can be understood that in some optional embodiments, the first strain resistor layer can be composed of one strain resistor, and the other is provided separately through the peripheral circuit and does not play a strain role. When the strain resistor size of the first strain resistor layer or the second strain resistor layer is used to change the line width and line thickness of the strain resistor layer, a single-line mode (as shown in Figure 2) and a multi-line mode (as shown in Figure 4) can be adopted.

[0048] Example 2

[0049] Please refer to Figures 5 to 8, which show a strain-sensing VCM spring in a second embodiment of the present invention. The strain-sensing VCM spring in this embodiment differs from the strain-sensing VCM spring in the first embodiment in that: the first strain resistor layer is arranged at one end of the elastic arm 300 away from the second strain resistor layer, and a second insulating layer 430 is provided between the first strain resistor layer and the elastic arm 300.

[0050] It can be understood that the first strain resistor layer and the second strain resistor layer are both arranged on the elastic arm 300. When the lens focuses and moves, the sensing states of the first strain resistor 410 and the second strain resistor 420 of the first strain resistor layer are opposite to those of the third strain resistor 510 and the fourth strain resistor 520 of the second strain resistor layer, so that the strain information can be detected more accurately and the sensing sensitivity of the strain resistor is improved. At the same time, being arranged on the elastic arm can eliminate the error caused by temperature change on the strain resistor.

[0051] In summary, the strain-sensing VCM spring in the above-mentioned embodiment of the present invention forms a piezoresistive circuit on the VCM spring by providing a first strain resistor layer and a second strain resistor layer on the spring arm of the VCM spring, and a Wheatstone bridge detection circuit is formed between the strain resistor layers to realize a closed-loop focus control. As the lens focus movement stretches the spring, the resistance of the piezoresistive circuit on the spring changes, which is then converted into an electrical signal output by the measurement circuit, thereby sensing the displacement of the lens and realizing precise positioning of the lens position, thereby replacing the complex Hall sensor closed-loop motor solution and achieving spatial miniaturization.

[0052] Example 3

[0053] On the other hand, an embodiment of the present invention further proposes a driving assembly, including a shell, a carrier fixed in the shell, and an upper spring piece and a lower spring piece respectively fixed at both ends of the carrier, wherein the upper spring piece and the lower spring piece adopt the above-mentioned strain sensing VCM spring piece.

[0054] Example 4

[0055] Another aspect of the present invention provides a camera module, including a lens, an imaging sensor, and the aforementioned driving assembly.

[0056] Example 5

[0057] Another aspect of the present invention provides an electronic device including the camera module described above.

[0058] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0059] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A strain sensing VCM spring, characterized in that: The invention comprises an inner connection part, an outer connection part and an elastic arm connecting the outer connection part and the inner connection part, wherein the outer connection part is arranged along the outer circumferential direction of the inner connection, the strain sensing VCM spring piece also comprises a strain resistance structure, wherein the strain resistance structure comprises a first strain resistance layer and a first insulating layer and a second strain resistance layer arranged on the elastic arm, the outer connection part comprises a connection body, the first strain resistance layer is arranged on the connection body and is arranged close to the second strain resistance layer, the second strain resistance layer is insulated from the connection body, the first strain resistance layer and the second strain resistance layer each comprise a plurality of strain resistances, and strain resistances are formed between the strain resistances. Wheatstone bridge detection circuit, the first strain resistor layer includes a first strain resistor and a second strain resistor, the second strain resistor layer includes a third strain resistor and a fourth strain resistor, the first strain resistor is connected in series with the fourth strain resistor, the second strain resistor is connected in series with the third strain resistor, the first strain resistor and the second strain resistor are connected in parallel with the second strain resistor and the third strain resistor, wherein the Wheatstone bridge detection circuit is used to calculate the corresponding detection voltage according to the input voltage and the change value of each of the strain resistors, and calculate the displacement of the elastic arm according to the detection voltage, the input voltage and the length of the elastic arm.

2. The strain sensing VCM spring according to claim 1, characterized in that: The first strain resistor layer is disposed at one end of the elastic arm away from the second strain resistor layer, and a second insulating layer is disposed between the first strain resistor layer and the elastic arm.

3. The strain sensing VCM spring according to claim 1, characterized in that: The calculation formula of the detection voltage is as follows: ； In the formula, Indicates the input voltage, 、 、 、 Respectively represent the change values ​​of the first strain resistor, the second strain resistor, the third strain resistor and the fourth strain resistor, 、 、 、 Respectively represent the resistance values ​​of the first strain resistor, the second strain resistor, the third strain resistor and the fourth strain resistor before the change; The calculation formula of the displacement of the elastic arm is: ； In the formula, Indicates the length of the elastic arm, Represents the piezoresistance coefficient.

4. The strain sensing VCM spring according to claim 1, characterized in that: The Wheatstone bridge detection circuit also includes a differential pressure detector, one end of which is respectively connected to the first strain resistor and the fourth strain resistor, and the other end of which is respectively connected to the second strain resistor and the third strain resistor.

5. The strain sensing VCM spring according to claim 1, characterized in that: The first strain resistor layer and the second strain resistor layer have a width ranging from 1 μm to 1 mm and a thickness ranging from 5 nm to 20 nm.

6. A drive assembly, characterized in that: It comprises a shell, a carrier fixed in the shell, and an upper spring sheet and a lower spring sheet respectively fixed at two ends of the carrier, wherein the upper spring sheet and the lower spring sheet are the strain sensing VCM spring sheets as described in any one of claims 1 to 5.

7. A camera module, characterized in that: It comprises a lens, an imaging sensor and the driving assembly as claimed in claim 6.

8. An electronic device, characterized in that: Including the camera module described in claim 7.

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