JP5163587B2 - Actuator, drive device, and imaging device - Google Patents

Description

  The present invention relates to an actuator, and a driving device and an imaging device using the actuator.

  A micro camera unit (MCU) mounted on a mobile phone or the like is required to be small and thin. Conventionally, in such an MCU, a voice coil motor (VCM) has been the mainstream as an actuator for performing so-called autofocus (AF) control by moving a lens. However, it is difficult to further reduce the thickness of the MCU using the VCM.

  Therefore, in order to realize the downsizing of the actuator, it is conceivable to employ an actuator using a so-called bimetal. Since this bimetal is driven in response to heat, it has not been adopted for actuators in terms of high power consumption and low responsiveness. However, the downsizing of the MCU tends to alleviate the disadvantages related to power consumption and responsiveness, and a camera module employing an actuator using a bimetal has been proposed (for example, Patent Document 1).

JP 2007-193248 A

  By the way, in a bimetal, a larger displacement is obtained, so that the difference of the thermal expansion coefficient of the material which comprises two layers is large. As a combination of materials for increasing the difference in thermal expansion coefficient, for example, there is a combination of 20Ni-6Mn-Fe having a relatively high thermal expansion coefficient and 36Ni-Fe having a relatively low thermal expansion coefficient. Can be mentioned.

  However, the materials suitable for these bimetals have low thermal conductivity, so that the temperature once increased in response to heating in the bimetal cannot be easily lowered, resulting in a decrease in response speed during cooling. Therefore, when moving the optical lens of the MCU, a certain amount of time is required to move the optical lens moved in one direction in the opposite direction. As a result, AF control cannot be performed in a short time. In addition, when performing AF control, servo control is performed to stop the optical lens at the in-focus position, but the position of the optical lens is set to a desired position because of the low responsiveness when bimetal is cooled. It is difficult to stop in a short time.

  And the improvement of the responsiveness at the time of cooling of such a bimetal is not considered at all by the technique of the said patent document 1. FIG. Such a problem is common to actuators that generate a driving force by bending using a difference in coefficient of thermal expansion.

  The present invention has been made in view of the above problems, and provides an actuator with good response that generates a driving force by bending using a difference in coefficient of thermal expansion, and a driving device and an imaging device using the actuator. For the purpose.

  In order to solve the above problems, an actuator according to a first aspect includes a first layer, a second layer having a larger coefficient of thermal expansion than the first layer, and a larger heat conduction than the first and second layers. A plurality of layers including a third layer having a rate are stacked, and a movable portion that deforms in response to heating is provided. Further, the actuator is configured to be integrated with the third layer or to be in contact with the third layer, and has a thermal conductivity higher than that of the first and second layers. And a fixed part to which the movable part is fixed.

  The actuator according to the second aspect is the actuator according to the first aspect, wherein the third layer is provided between the first layer and the second layer.

  The actuator which concerns on a 3rd aspect is an actuator which concerns on the 1st or 2nd aspect, Comprising: The said thermal radiation area | region has a 2nd heat capacity larger than the 1st heat capacity of the said movable part.

  The actuator which concerns on a 4th aspect is an actuator which concerns on a 3rd aspect, Comprising: The said thermal radiation area | region has a 2nd surface area larger than the 1st surface area of the said movable part.

  The actuator according to a fifth aspect is the actuator according to any one of the first to fourth aspects, wherein the third layer is made of at least one material of copper, nickel, and aluminum. .

  The actuator according to a sixth aspect is the actuator according to any one of the first to fifth aspects, wherein the heat conducting portion is made of at least one material of copper, nickel, and aluminum. .

  The actuator according to a seventh aspect is the actuator according to any one of the first to sixth aspects, wherein the plurality of layers further include a patterned heater layer.

  A drive device according to an eighth aspect includes an actuator according to any one of the first to seventh aspects, an adjacent layer joined to the heat dissipation area, and a movement target that is a target moved by the actuator. With things.

  A drive device according to a ninth aspect includes the actuator according to any one of the first to seventh aspects, and a moving object that is an object to be moved by deformation of the movable portion.

  An imaging apparatus according to a tenth aspect includes the actuator according to any one of the first to seventh aspects, an imaging element, and an optical system that guides light from a subject to the imaging element, and the imaging element and At least one of the optical systems is moved by deformation of the movable part.

  Even with the actuator according to any of the first to seventh aspects, the cooling rate of the movable part is increased by the heat conduction from the third layer having a high thermal conductivity to the heat conduction part, and therefore the difference in the thermal expansion coefficient is utilized. It is possible to provide an actuator with good responsiveness that generates a driving force by the curved portion.

  According to the actuator which concerns on a 2nd aspect, the cooling rate of a movable part can be raised, ensuring the quantity which a movable part can deform | transform.

  The actuator according to any of the third and fourth aspects can further increase the cooling rate of the movable portion.

  With the drive device according to the eighth aspect, the cooling rate of the movable part can be increased by heat dissipation through the adjacent layer.

  According to the drive device according to the ninth aspect, the cooling rate of the movable part is increased by the heat conduction from the third layer having a large thermal conductivity to the heat conduction part, and therefore, by the curvature utilizing the difference in the thermal expansion coefficient. It is possible to provide a driving device using an actuator that generates a driving force and has good response.

  According to the imaging device according to the tenth aspect, the cooling rate of the movable part is increased by the heat conduction from the third layer having a large heat conductivity to the heat conduction part, and therefore, by the curvature utilizing the difference in the coefficient of thermal expansion. An imaging device using an actuator that generates a driving force and has excellent response can be provided.

It is a schematic diagram which shows schematic structure of the mobile telephone carrying the camera module which concerns on one Embodiment of this invention. It is a cross-sectional schematic diagram paying attention to the 1st housing | casing which concerns on one Embodiment of this invention. It is a cross-sectional schematic diagram of the camera module which concerns on one Embodiment of this invention. It is the external view which looked at the camera module which concerns on one Embodiment of this invention from the side. It is the external view which looked at the camera module which concerns on one Embodiment of this invention from the side. It is a cross-sectional schematic diagram of a lens group. It is a cross-sectional schematic diagram of a lens group. It is the external view which looked at the 1st lens constituent layer from the lower part. It is the external view which looked at the 2nd lens constituent layer from the upper part. It is a figure for demonstrating the shape of a spacer layer. It is the external view which looked at the lens position adjustment layer from the upper part. It is a cross-sectional schematic diagram of a lens position adjustment layer. It is the external view which looked at the actuator layer from the upper part. It is the external view which looked at the actuator layer from the side. It is a figure for demonstrating the layer structure of an actuator layer. It is a figure which shows the shape of the high thermal expansion layer which comprises an actuator layer. It is a figure which shows the shape of the heat conductive layer which comprises an actuator layer. It is a figure which shows the shape of the low thermal expansion layer which comprises an actuator layer. It is a figure which shows the shape of the insulating layer which comprises an actuator layer. It is a figure which shows the shape of the heater layer which comprises an actuator layer. It is an upper surface external view which shows the detailed structure of an actuator layer. It is a figure for demonstrating the operation example of a movable part. It is a figure for demonstrating the operation example of a movable part. It is the external view which looked at the 2nd parallel spring from the downward direction. It is a figure which shows the 2nd parallel spring with which the lens group was mounted | worn. It is the external view which looked at the 1st parallel spring from the lower part. It is a figure which shows the 1st parallel spring with which the lens group was mounted | worn. It is a flowchart which shows the manufacturing process of a camera module. It is a figure which shows typically a mode that the prepared sheet | seat etc. are laminated | stacked and joined. It is a figure which shows the time-dependent change of the lens position by natural cooling. It is a figure which shows the aspect which moves the image pick-up element which concerns on one modification of this invention.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

<(1) Schematic configuration of mobile phone>
FIG. 1 is a schematic diagram showing a schematic configuration of a mobile phone 100 equipped with a camera module 500 according to an embodiment of the present invention. In FIG. 1 and the drawings after FIG. 1, three axes XYZ orthogonal to each other are appropriately attached in order to clarify the orientation relationship.

  As shown in FIG. 1, the mobile phone 100 is configured as a foldable mobile phone, and includes a first housing 200, a second housing 300, and a hinge part 400. Each of the first casing 200 and the second casing 300 has a plate-like substantially rectangular parallelepiped shape and serves as a casing for storing various electronic members. Specifically, the first casing 200 includes a camera module 500 and a display, and the second casing 300 includes a control unit that electrically controls the mobile phone 100 and an operation member such as a button. Have. In addition, the hinge part 400 connects the 1st housing | casing 200 and the 2nd housing | casing 300 so that rotation is possible. For this reason, the mobile phone 100 can be folded.

  In addition, the current supply driver 600, the electric resistance detection unit 700, and the contrast detection unit 800 are mounted on the first casing 200. The current supply driver 600 controls supply of current to the heater layer 155 (FIG. 20) of the camera module 500. The electrical resistance detector 700 detects electrical resistance in the heater layer 155. The contrast detector 800 detects the contrast of the image signal obtained by the image sensor 181 (FIG. 3) of the camera module 500. The second casing 300 is equipped with a focus control unit 310 on a circuit board that performs overall control of the overall operation of the mobile phone 100. The focus control unit 310 controls the amount of current supplied to the heater layer 155 via the current supply driver 600 in accordance with the input of signals from the electrical resistance detection unit 700 and the contrast detection unit 800, so that the camera module AF control for adjusting the in-focus state of 500 is executed.

  FIG. 2 is a schematic cross-sectional view focusing on the first casing 200 of the mobile phone 100. As shown in FIG. 1 and FIG. 2, the camera module 500 is a small imaging device, so-called micro camera unit, having an XY cross section of about 5 mm square and a thickness (depth in the Z direction) of about 3 mm. (MCU).

  Hereinafter, the configuration of the camera module 500, the manufacturing process of the camera module 500, the AF control in the camera module 500, and the responsiveness in the camera module 500 will be sequentially described.

<(2) Configuration of camera module>
FIG. 3 is a schematic cross-sectional view of the camera module 500, and the direction indicated by the arrow AR1 in FIG. 3 corresponds to the + Z direction. In the drawings subsequent to FIG. 3, an arrow AR <b> 1 indicating a direction corresponding to the + Z direction is appropriately attached in order to clarify the orientation relationship. 4 and 5 are side views of the camera module 500 as viewed from the side.

  As shown in FIG. 3, the camera module 500 includes an optical unit KB in which a lens group 20 as a photographing optical system is movably provided, and an imaging unit PB that acquires a photographed image related to a subject image. Yes.

  The imaging unit PB has a configuration in which, for example, an imaging element layer 18 having an imaging element 181 such as a COMS sensor or a CCD sensor, and a cover glass layer 17 are stacked in this order in the + Z direction. The cover glass layer 17 may include a filter layer that cuts infrared rays (IR).

  The optical unit KB includes a lid layer 10, a first frame layer 11, a first parallel spring (upper parallel spring) 12, a second frame layer 13, a second parallel spring (lower parallel spring) 14, an actuator layer 15, and lens position adjustment. The layer 16 and the lens group 20 are provided. The lid layer 10, the first frame layer 11, the first parallel spring 12, the second frame layer 13, the second parallel spring 14, the actuator layer 15, the lens position adjustment layer 16, and the lens group 20 are all in a wafer state (wafer Produced by level). These manufacturing processes will be described later.

  In the optical unit KB, the lens position adjusting layer 16, the actuator layer 15, the second parallel spring 14, the second frame layer 13, the first parallel spring 12, the first frame layer 11, and the lid layer 10 are arranged in this order in the + Z direction. The lens group 20 is held between the second parallel spring 14 and the first parallel spring 12. The first parallel spring 12, the second parallel spring 14, and the actuator layer 15 cooperate with each other to move the lens group 20 in the direction along the Z axis.

  In the camera module 500, the lid layer 10, the first and second frame layers 11 and 13, the lens position adjustment layer 16, the cover glass layer 17, and the imaging element layer 18 serve as a fixing portion for the lens group 20. The camera module 500 and the optical unit KB are manufactured in a wafer state (at the wafer level), and four side surfaces thereof (side surfaces parallel to the Z axis in FIGS. 4 and 5) are cut surfaces formed by dicing. ing. And in this cut surface, the laminated structure of the multiple layer which comprises the optical unit KB and the imaging part PB is exposed.

  Here, the lens group 20 is supported by the first and second parallel springs 12 and 14 coupled to the fixed portion. More specifically, the second parallel spring 14 is interposed between the actuator layer 15 and the lens group 20 on the −Z side (the side on which the image sensor 181 is disposed) of the lens group 20. Further, a first parallel spring 12 is interposed between the first frame layer 11 and the lens group 20 on the + Z side (the side where the lid layer 10 is disposed) of the lens group 20. That is, the lens group 20 is sandwiched between the first parallel spring 12 and the second parallel spring 14. Here, since the lens group 20 is clamped by the first and second parallel springs 12 and 14, the posture of the lens group 20 is maintained regardless of the movement of the lens group 20, and the optical axis of the lens group 20 is substantially constant. Retained.

  Further, the first and second parallel springs 12 and 14 apply a force in a direction opposite to the moving direction of the lens group 20 (that is, the + Z direction) when the lens group 20 as the moving object moves in the + Z direction. The lens group 20 is given. When the lens group 20 moves in the −Z direction, the direction of the force applied to the lens group 20 by the first and second parallel springs 12 and 14 is the moving direction of the lens group 20 (that is, −Z). Direction).

  Further, in a non-driving state in which the lens group 20 is not moving in the + Z direction (for example, a stationary state before driving), the lens group 20 is moved by the elastic force of the first and second parallel springs 12 and 14 from the lens position adjusting layer 16. The lens group 20 is supported by the lens position adjusting layer 16 by being pressed against the upper end surface of the protrusion 162. In this non-driven state, the lens group 20 is disposed at a predetermined position on the most −Z side of the range (displaceable range) that can be displaced along the Z axis and is stationary.

  The predetermined position is, for example, a position where the focal point of the optical unit KB is disposed on the + Z side surface (hereinafter also referred to as “imaging surface”) on which a large number of pixel circuits are arranged in the image sensor 181. Is set. Here, the focal point of the optical unit KB refers to a point where light beams emitted from the optical unit KB gather at one point when parallel light beams enter the optical unit KB from the + Z side.

  Further, as described above, in the non-driven state, the lens group 20 is pressed against the lens position adjustment layer 16 by the elastic force of the first and second parallel springs 12 and 14, and thus is strong against the camera module 500. Even when an impact is applied, the posture of the lens group 20 is maintained.

  The actuator layer 15 as an actuator has movable parts 15 a and 15 b (FIG. 13) that generate drive displacement in the + Z direction, and is disposed on the −Z side of the lens group 20. The movable portions 15 a and 15 b are in contact with the first protrusion 201 protruding to the −Z side of the lens group 20, and the drive displacement generated in the movable portions 15 a and 15 b is transmitted to the lens group 20 via the first protrusion 201. Is done. That is, the actuator layer 15 moves the lens group 20 that is a moving object in a predetermined direction (here, the + Z direction). In a scene where the drive displacement in the + Z direction in the movable portions 15a and 15b is reduced, the lens group 20 is moved in a direction opposite to the predetermined direction (−Z by the elastic force of the first and second parallel springs 12 and 14). Direction).

  The side wiring 21 is a thin conductive member disposed on one of the four side surfaces of the camera module 500. As shown in FIGS. 4 and 5, the side wiring 21 electrically connects the heater layer 155 (FIG. 20), the current supply driver 600, and the electric resistance detection unit 700 via the imaging element layer 18. . Note that an insulating portion 14ep is provided between the second parallel spring 14 and the side wiring 21 so that the side wiring 21 and the second parallel spring 14 are not short-circuited.

  As described above, in the camera module 500, the lens group 20 that is a moving object is coupled to the first and second parallel springs 12 and 14 disposed at positions facing each other via the lens group 20, The first and second parallel springs 12 and 14 are elastically deformed in a direction perpendicular to the lens group 20 (+ Z direction), and hold the posture of the lens group 20. The lens group 20 receives a driving force from the movable portions 15a and 15b of the actuator layer 15 and displaces the position along the Z axis. Therefore, the optical unit KB provided in the camera module 500 can displace the lens group 20 in the optical axis direction (+ Z direction) of the lens group 20, and the camera module 500 can be used as a driving device for displacing the lens group 20. Make it work.

<(2-1) Lens group>
The lens group 20 is manufactured at a wafer level using a glass substrate as a base material, and is formed by, for example, superposing two or more lenses. In the present embodiment, a case where the lens group 20 is configured by overlapping two optical lenses is illustrated. In the present embodiment, the lens group 20 functions as an imaging lens that guides light from the subject to the imaging element 181.

  6 and 7 are schematic cross-sectional views of the lens group 20, and the direction indicated by the arrow AR2 corresponds to the + Z direction. 8 is a bottom external view of the lens group 20 when the lens group 20 is viewed from below (−Z side), and FIG. 9 is a top external view of the lens group 20 when the lens group 20 is viewed from above (+ Z side). It is.

  As shown in FIGS. 6 and 7, the lens group 20 includes a first lens constituent layer LY1 having a first lens G1, a second lens constituent layer LY2 having a second lens G2, and a spacer layer RB. . Then, the first lens constituent layer LY1 and the second lens constituent layer LY2 are coupled via the spacer layer RB. Here, the outer edges of the non-lens portions of the first and second lens constituent layers LY1, LY2 have a substantially square shape.

  Further, as shown in FIGS. 6 to 8, the first lens constituting layer LY1 having the first lens G1 has a first non-lens portion that does not function as a lens on the one main surface (here, −Z side). A protrusion 201 is provided. Furthermore, as shown in FIGS. 6, 7, and 9, a non-lens portion that does not function as a lens is provided on one main surface (here, + Z side) of the second lens constituent layer LY <b> 2 having the second lens G <b> 2. A second protrusion 202 is provided.

  FIG. 10 is a view of the spacer layer RB as viewed from above (+ Z side), focusing on the shape of the spacer layer RB. As shown in FIG. 10, the spacer layer RB is provided along the outer edge of the non-lens portion of the first and second lens constituting layers LY1 and LY2, and the outer edge and the inner edge of the XY cross section are rectangular in shape. It has a configuration. Then, the optical axis of the lens group 20 is set in a direction along the Z axis.

<(2-2) About each functional layer>
Below, the detail of each functional layer which comprises the camera module 500 is demonstrated. For each functional layer, the −Z side surface is referred to as one main surface, and the + Z side surface is referred to as the other main surface.

<(2-2-1) Image sensor layer>
As shown in FIG. 3, the image sensor layer 18 receives light from the subject that has passed through the optical unit KB, and generates an image signal related to the image of the subject, its peripheral circuit, and the image sensor 181. It is a member provided with the outer peripheral part which surrounds. The image sensor 181 is configured by arranging a large number of pixel circuits. Note that a solder ball HB for performing reflow soldering is provided on one main surface (the surface on the −Z side) of the imaging element layer 18. Although not shown here, various types of wiring for applying a signal to the image sensor 181 and reading a signal from the image sensor 181 are connected to one main surface of the image sensor layer 18. A terminal is provided.

  The current supply driver 600, the electric resistance detection unit 700, and the contrast detection unit 800 are formed on the imaging element layer 18, and the side surface wiring 21 is patterned on the side surface of the camera module 500 cut by dicing. The current supply driver 600 and the electric resistance detection unit 700 may be electrically connected to the actuator layer 15. Further, a focus control unit 310 that controls the operation of the actuator layer 15 may be formed in the imaging element layer 18. In addition, the current supply driver 600, the electrical resistance detection unit 700, and the contrast detection unit 800 are provided, for example, on the circuit board of the second casing 300, and the contrast detection unit 800 captures an image by soldering using a reflow method. While being electrically connected to the element layer 18, the current supply driver 600 and the electric resistance detection unit 700 may be electrically connected to the actuator layer 15 via the imaging element layer 18.

<(2-2-2) Cover glass layer>
As shown in FIG. 3, the cover glass layer 17 has a substantially flat plate shape and an XY cross section having a substantially square shape, and is made of transparent glass or the like. The cover glass layer 17 is bonded to the other main surface (+ Z side surface) of the image sensor layer 18 and has a function of protecting the image sensor 181. The image sensor substrate 178 is configured with the cover glass layer 17 bonded to the image sensor layer 18.

<(2-2-3) Lens position adjustment layer>
The lens position adjustment layer 16 is configured by using a resin material, is disposed between the image sensor 181 and the lens group 20, and is a member that adjusts the distance between the image sensor 181 and the lens group 20. Specifically, the lens position adjustment layer 16 defines the position (initial position) of the lens group 20 in the non-driven state. The lens position adjustment layer 16 is generated using, for example, a method of etching a resin.

  FIG. 11 is a top view of the lens position adjusting layer 16 as seen from above (+ Z side). FIG. 11 is a cross-sectional view of the lens position adjusting layer 16 as viewed in the direction of the arrow at the cut surface XII-XII of the lens position adjusting layer 16. As shown in FIGS. 11 and 12, the lens position adjustment layer 16 includes a frame body 161 and a protrusion 162.

  The frame 161 is a substantially rectangular annular portion that constitutes the outer peripheral portion of the lens position adjusting layer 16, and has a plate-like shape substantially parallel to the XY plane. The frame 161 forms a hole (through-hole) 16H penetrating in the direction along the Z axis, and the + Y side plate-like member and the −Y side plate-like member constituting the frame 161 are: Each plate-like portion has a portion (convex portion) 161T protruding from the lower portion to the through-hole 16H side. Further, one main surface of the frame body 161 is bonded to the adjacent cover glass layer 17, and the other main surface of the frame body 161 is connected to the adjacent actuator layer 15 (specifically, the frame body 15 f of the actuator layer 15 ( FIG. 13)).

  The protrusion 162 is erected upward (in the + Z direction) in the vicinity of the inner edge of the convex portion 161T provided on the frame body 161. The projection 162 is a plate-like portion having a substantially rectangular board surface substantially parallel to the XZ plane, and the longitudinal direction of the projection 162 is a direction substantially parallel to the X axis, and the short direction of the projection 162 Is a direction substantially parallel to the Z-axis. The end surface on the + Z side of the protrusion 162 has a function of placing the lens group 20 at the initial position when the lens group 20 comes into contact therewith.

  In FIG. 11, a region (pixel array region) in which a plurality of pixel circuits constituting the image sensor 181 are arranged, that is, an outer edge of the front surface (imaging surface) of the image sensor 181 is indicated by a broken line. As shown in FIG. 11, the imaging surface is configured such that the relationship of (short side length) :( long side length) :( diagonal length) = 3: 4: 5 is established. . The protrusion 162 is disposed at a position that sandwiches the optical path from the subject through the lens group 20 to the pixel array region of the image sensor 181 in the direction in which the width of the pixel array region is the narrowest. That is, the protrusion 162 is installed so as not to adversely affect the photographing and increase the size of the apparatus.

<(2-2-4) Actuator layer>
FIG. 13 is a top view of the actuator layer 15 as seen from above (+ Z side). FIG. 14 is a side view of the actuator layer 15 as seen from the side. FIG. 15 is a diagram schematically showing the layer structure of the actuator layer 15. 16 to 20 are diagrams showing the configuration of each layer constituting the actuator layer 15.

  As shown in FIG. 13, the actuator layer 15 includes a frame body 15 f constituting an outer peripheral portion, and two plate-like movable portions that protrude from the frame body 15 f with respect to a hollow portion inside the frame body 15 f. 15a and 15b. That is, the movable parts 15a and 15b are fixed to the frame 15f as a fixed part. One main surface of the frame 15f is bonded to the adjacent lens position adjustment layer 16 (specifically, the frame 161), and the other main surface of the frame 15f is the adjacent second parallel spring 14. (Specifically, it is joined to the fixed frame 141 (FIG. 24)).

  As shown in FIG. 15, the actuator layer 15 includes a high thermal expansion layer 151 (FIG. 16), a heat conduction layer 152 (FIG. 17), a low thermal expansion layer 153 (FIG. 18), an insulating layer 154 (FIG. 19), The heater layer 155 (FIG. 20) is laminated in this order from the −Z side to the + Z side. That is, so-called bimetal (Bi-metallic strip) is employed in the movable portions 15a and 15b. Although not shown here, an insulating film is preferably formed on the upper surface (+ Z side surface) of the heater layer 155 for the purpose of preventing a short circuit between the heater layer 155 and the second parallel spring 14. .

As shown in FIG. 16, the high thermal expansion layer 151 has two plate-like shapes protruding from the frame portion 151 f with respect to the frame portion 151 f constituting the frame body 15 f and the hollow portion inside the frame portion 151 f. Protruding portions 151a and 151b are provided. Here, the protruding portion 151a constitutes the movable portion 15a, and the protruding portion 151b constitutes the movable portion 15b. Further, the high thermal expansion layer 151 is made of a material having a larger coefficient of thermal expansion than the material constituting the low thermal expansion layer 153. The material constituting the high thermal expansion layer 151, for example, iron-nickel-manganese alloy thermal expansion coefficient is 20 × 10 ^-6 / ℃, manganese-copper thermal expansion coefficient is 30 × 10 ^-6 / ℃ nickel alloy, any of the thermal expansion coefficient of 18 × 10 ^-6 / ℃ iron-nickel-chromium alloys is, and thermal expansion coefficient of 18 × 10 ^-6 / ℃ iron-molybdenum-nickel alloy is 1 One material is enough. However, the thermal conductivity of these materials is relatively low. For example, the thermal conductivity of an iron / nickel / manganese alloy is about 8.8 W · m ⁻¹ · K ⁻¹ .

As shown in FIG. 17, the heat conductive layer 152 protrudes from the frame portion 152 f to the frame portion 152 f constituting the frame body 15 f and the hollow portion inside the frame portion 152 f, as with the high thermal expansion layer 151. Two plate-like projecting portions 152a and 152b are provided. In addition, the heat conductive layer 152 is made of a material having a higher thermal conductivity than the material forming the high thermal expansion layer 151 and the low thermal expansion layer 153. The material constituting the heat conducting layer 152, for example, copper and copper alloys thermal conductivity of 105.5W · m ^-1 · K ^-1, heat conductivity in 204W · m ^-1 · K ^-1 Any one of aluminum and nickel having a thermal conductivity of 90 W · m ⁻¹ · K ⁻¹ may be used.

As shown in FIG. 18, the low thermal expansion layer 153 protrudes from the frame portion 153f with respect to the frame portion 153f constituting the frame body 15f and the hollow portion inside the frame portion 153f, similarly to the high thermal expansion layer 151. Two plate-like projecting portions 153a and 153b are provided. Here, the projecting portion 153a constitutes the movable portion 15a, and the projecting portion 153b constitutes the movable portion 15b. As a material constituting the low thermal expansion layer 153, for example, an iron / nickel alloy having a thermal expansion coefficient of 1.1 × 10 ⁻⁶ / ° C. is preferably employed. However, the thermal conductivity of this material is relatively low, about 8.8 W · m ⁻¹ · K ⁻¹ .

  As shown in FIG. 19, the insulating layer 154 protrudes from the frame portion 154f with respect to the frame portion 154f constituting the frame body 15f and the hollow portion inside the frame portion 154f, like the high thermal expansion layer 151. Provided with two projecting portions 154a and 154b. Here, the projecting portion 154a constitutes the movable portion 15a, and the projecting portion 154b constitutes the movable portion 15b. The insulating layer 154 is made of an insulator such as silica (silicon dioxide).

  The heater layer 155 is patterned on the insulating layer 154 and is made of a metal having high conductivity such as platinum. As shown in FIG. 20, in the heater layer 155, the wiring portion 1551, the heater portion 155b, the wiring portion 1552, the heater portion 155a, and the wiring portion 1553 are extended in this order, and are sequentially electrically connected. The The wiring portions 1551, 1552, and 1553 constitute the frame 15f, the heater portion 155a constitutes the movable portion 15a, and the heater portion 155b constitutes the movable portion 15b.

  In addition, the wiring portions 1551, 1552, and 1553 are configured to be wider and have lower electrical resistance than the heater portions 155a and 155b. Therefore, when a voltage is applied between one end of the heater layer 155 (here, the end surface on the −Y side of the wiring portion 1551) and the other end (here, the end surface on the −Y side of the wiring portion 1553), The heater portions 155a and 155b having high resistance generate heat due to their own Joule heat. That is, the heater portions 155a and 155b as the heat generating portions generate heat in response to current supply. Note that the wiring portions 1551, 1552, and 1553 are preferably made of a metal having a low resistivity, such as gold or copper, from the viewpoint of reducing power consumption.

  With respect to the actuator layer 15, first, a sheet (actuator layer sheet) in which chips corresponding to the actuator layer 15 are formed in a predetermined arrangement is generated, and then the actuator layer sheet is subjected to a dicing process to be described later. Is divided into shapes. The actuator layer sheet is manufactured by the following process, for example. First, the material plate of the high thermal expansion layer 151, the material plate of the heat conductive layer 152, and the material plate of the low thermal expansion layer 153 are pressed or rolled in a state where they are stacked in this order, so that 3 A laminar sheet is created. Next, the thin plate having the three-layer structure is cut into a predetermined shape, and a silicon oxide film corresponding to the insulating layer 154 is formed on the thin plate (three-layer thin plate) after the cut by plasma CVD or the like. Next, on the silicon oxide film, (i) formation of a resist film having a desired pattern by photolithography technology, (ii) formation of a metal film (platinum, copper, gold, etc.) by vapor deposition (or sputtering), etc., and (iii) Removal of unnecessary portions (resist film or the like) by a lift-off method or the like is sequentially performed as appropriate, whereby a wiring pattern corresponding to the heater layer 155 is formed. Note that the wiring pattern corresponding to the heater layer 155 may be formed by screen printing or the like. Finally, the shapes of the movable portions 15a and 15b corresponding to the chips of the actuator layers 15, that is, hollow portions are formed by etching or pressing.

  FIG. 21 is a top view showing a detailed configuration of the actuator layer 15 when the actuator layer 15 is viewed from above (+ Z side). As shown in FIG. 21, the heater layer 155 is formed on the other main surface (+ Z side surface) of the actuator layer 15. Specifically, the heater portion 155a extends from one end portion (fixed end) fixed to the frame 15f of the movable portion 15a to the vicinity of the other end portion (free end) FT of the movable portion 15a. It is folded in the vicinity of the free end FT and extends from the vicinity of the free end FT to the fixed end. Similarly, the heater portion 155b extends from one end portion (fixed end) fixed to the frame 15f of the movable portion 15b to the vicinity of the other end portion (free end) FT of the movable portion 15b. It is folded near the free end FT and extends from the free end FT to the fixed end. Further, one end (specifically, the end surface on the −Y side of the wiring portion 1551) and the other end (the end surface on the −Y side of the wiring portion 1553) of the heater layer 155 are exposed on the side surface of the camera module 500 in the dicing process. To do. The exposed side of the heater layer 155 is provided with the side wiring 21 (FIGS. 3 to 5), so that voltage and current are supplied through the side wiring 21.

  FIGS. 22 and 23 are schematic views showing a mode in which the movable portions 15a and 15b are deformed in response to heat generated by the heater portions 155a and 155b. In addition, since the deformation | transformation aspect of movable part 15a, 15b is respectively the same, in FIG.22 and FIG.23, the deformation | transformation aspect of the movable part 15a is shown as an example, Here, deformation | transformation of the movable part 15a is shown. An embodiment will be described as an example.

  As shown in FIG. 22, the movable portion 15a has a flat shape when the heater portion 155a is not generating heat. On the other hand, as shown in FIG. 23, the protruding portion 151a of the high thermal expansion layer 151 expands more than the protruding portion 153a of the low thermal expansion layer 153 due to heat generated in response to energization to the heater portion 155a. Here, the amount of heat generated by the heater 155a exceeds the amount of heat released from the protruding portion 153a to the surrounding atmosphere and the frame 15f, so that the temperature of the movable portion 15a increases. If the thickness of the movable part 15a is made very thin, such as about 30 to 50 μm, the temperature of the movable part 15a rises in a relatively short time. When the temperature of the movable portion 15a rises, the difference in expansion between the projecting portion 151a and the projecting portion 153a causes deformation that causes the movable portion 15a to warp, above the free end FT (+ Z direction). ) Occurs.

  On the other hand, when the energization to the heater portion 155a is stopped, the heat of the movable portion 15a is rapidly transmitted to the frame body 15f due to the presence of the heat conductive layer 152, and the movable portion 15a is rapidly cooled by heat radiation from the frame body 15f. The At this time, the upward displacement (+ Z direction) of the free end FT is reduced, and the movable portion 15a returns to a flat shape as shown in FIG.

  In such an actuator layer 15, the heat conductive layer 152 is configured integrally with the projecting portions 152a and 152b constituting the movable portions 15a and 15b and the frame portion 152f as the heat conducting portion constituting the frame 15f. Has been. For this reason, when the heating of the heaters 155a and 155b is finished from the state in which the movable parts 15a and 15b are heated by the heat generated by the heaters 155a and 155b, the heat of the movable parts 15a and 15b passes through the heat conductive layer 152. Via the frame body 15f. At this time, heat is radiated not only from the surfaces of the movable portions 15a and 15b but also from the surface of the frame 15f. The frame body 15f is joined to the second parallel spring 14 and the lens position adjusting layer 16 which are functional layers (adjacent layers) adjacent to the actuator layer 15, respectively. For this reason, heat dissipation through the frame 15f and the adjacent layer is promoted, and the cooling rate of the movable portions 15a and 15b is increased. That is, the frame body 15f functions as a region (heat dissipation region) that dissipates heat in order to promote cooling of the movable portions 15a and 15b.

  In order to promote heat dissipation in the heat dissipation region and increase the cooling rate of the movable portions 15a and 15b, the movable portions 15a and 15b can be sufficiently absorbed by the heat dissipation region. It is preferable that the heat capacity of the frame 15f be set to be larger than the heat capacity. That is, it is preferable that the volume of the frame body 15f as the heat dissipation region is set to be larger than the volume of the movable portions 15a and 15b. Here, since the thicknesses of the movable portions 15a and 15b and the frame body 15f are constant, it is preferable that the surface area of the frame body 15f is set larger than the surface area of the movable portions 15a and 15b. .

  In the actuator layer 15, a heat conductive layer 152 is provided between the high thermal expansion layer 151 and the low thermal expansion layer 153. For this reason, the heat of the high thermal expansion layer 151 and the low thermal expansion layer 153 is easily transmitted to the heat conductive layer 152, and cooling of the movable parts 15a and 15b is promoted. Further, the presence of such a heat conductive layer 152 secures a space between the high thermal expansion layer 151 and the low thermal expansion layer 153, so that the movable portion due to the difference in expansion between the projecting portion 151a and the projecting portion 153a can be obtained. Warpage of the portions 15a and 15b is promoted. That is, it is possible to increase the displacement of the free end FT with less heating. Therefore, the heat conduction layer 152 is provided between the high thermal expansion layer 151 and the low thermal expansion layer 153, so that the deformable amount of the movable portions 15a and 15b is secured and the cooling rate of the movable portions 15a and 15b is increased. It is done.

  Further, regarding the actuator layer 15, when the heating rate, cooling rate, and power consumption are comprehensively determined, the thickness of the high thermal expansion layer 151, the thickness of the heat conductive layer 152, and the thickness of the low thermal expansion layer 153 are 2: 1. : A form having a relationship of 2 is preferable.

<(2-2-5) Second parallel spring>
FIG. 24 is an external view of the lower surface of the second parallel spring 14 when the second parallel spring 14 is viewed from below (−Z direction). FIG. 25 is a view showing the second parallel spring 14 joined to the lens group 20. As shown in FIG. 24, the second parallel spring 14 is an elastic member having a fixed frame body 141 and an elastic portion 142, and is a layer (elastic layer) forming a spring mechanism. In addition, as a raw material of the 2nd parallel spring 14, SUS type metal material or phosphor bronze etc. are employ | adopted, for example.

  The fixed frame 141 constitutes the outer peripheral portion of the second parallel spring 14 and is joined to the frame 15 f of the adjacent actuator layer 15. Here, the distance between the heater layer 155 of the actuator layer 15 and the second parallel spring 14 is usually only about 10 μm. For this reason, if the side wiring 21 that supplies voltage and current to the heater layer 155 is simply provided from the imaging element layer 18 to the actuator layer 15 by printing, for example, the side wiring 21 extends to the fixed frame 141. . That is, the side wiring 21 and the second parallel spring 14 are short-circuited.

  Therefore, in order to prevent this short circuit, a notch 143 that is recessed at the outer edge near the four corners of the fixed frame 141 of the second parallel spring 14 is provided. The notch 143 is an epoxy system used for joining when the second frame layer 13 and the second parallel spring 14 are joined and when the second parallel spring 14 and the actuator layer 15 are joined. Insulating part 14ep (FIGS. 3 to 5) is formed by filling an adhesive such as resin. Due to the presence of the insulating portion 14ep, unnecessary short circuit due to contact between the side wiring 21 and the second parallel spring 14 is prevented.

  The elastic part 142 has a connection part PG1 with the fixed frame 141 and a joint part PG2 with the lens group 20, and the connection part PG1 and the joint part PG2 are connected by a plate-like member EB. Then, as shown in FIG. 25, the second parallel spring 14 is joined to the lens group 20 at a joint portion PG2 provided in the elastic portion 142. Here, the first protrusion 201 contacts the free end FT of the actuator layer 15 through the gap between the fixed frame 141 of the second parallel spring 14 and the plate member EB. That is, the second parallel spring 14 has a shape that does not contact the first protrusion 201 of the lens group 20.

  Then, as the lens group 20 is moved in the + Z direction with respect to the fixed frame body 141, the positions of the connecting portion PG1 and the joint portion PG2 in the Z direction shift, and the plate-like member EB undergoes bending deformation (flexure deformation). Bend. That is, the second parallel spring 14 can be elastically deformed in the optical axis direction (± Z direction) of the lens group 20 by elastic deformation of the plate-like member EB, and functions as a spring mechanism.

  The second parallel spring 14 is manufactured using a SUS metal material or phosphor bronze. For example, when the second parallel spring 14 is made of a SUS-based metal material, a resist in the shape of a parallel spring is patterned on the metal material by a photolithography technique, and dipped in an iron chloride-based etching solution to be wet. Etching is performed to form a parallel spring pattern.

<(2-2-6) Second frame layer>
As shown in FIG. 3, the second frame layer 13 is a ring-shaped member in which the outer edge and the inner edge of the XY cross section are each substantially rectangular, and forms a hollow portion that penetrates along the Z-axis. The second frame layer 13 surrounds the lens group 20 from the side by arranging the lens group 20 in the hollow portion. In addition, resin, glass, etc. are mentioned as a raw material which comprises the 2nd frame layer 13, The 2nd frame layer 13 is manufactured by what is called a press method using a metal metal mold | die, the injection molding method, etc. The lower end surface (one main surface) located on the −Z side of the second frame layer 13 is joined to the fixed frame body 141 of the adjacent second parallel spring 14. Further, the upper end surface (other main surface) located on the + Z side of the second frame layer is joined to the adjacent first parallel spring 12 (specifically, the fixed frame body 121 (FIG. 26) of the first parallel spring 12). Is done.

<(2-2-7) First parallel spring>
FIG. 26 is an external view of the lower surface of the first parallel spring 12 when the first parallel spring 12 is viewed from below (−Z direction). As shown in FIG. 26, the first parallel spring 12 is an elastic member having the same configuration and function as the second parallel spring 14 except that the notch 143 is not provided, and the fixed frame body. 121 and an elastic part 122. One main surface of the fixed frame 121 is joined to the other main surface of the adjacent second frame layer 13, and the other main surface of the fixed frame 121 is connected to the adjacent first frame layer 11 (in detail, the first 1 frame layer 11-lower end surface on the -Z side).

  FIG. 27 is a view showing the first parallel spring 12 joined to the lens group 20. As illustrated in FIG. 27, the joint portion PG <b> 2 provided in the elastic portion 122 is joined to the upper end surface on the + Z side of the protrusion 202 of the lens group 20. For this reason, when the lens group 20 is moved relative to the fixed frame 121 in the + Z direction, elastic deformation occurs in the plate-like member EB, and the first parallel spring 12 functions as a spring mechanism.

<(2-2-8) First frame layer>
As shown in FIG. 3, the first frame layer 11 is a ring-shaped member in which the outer edge and the inner edge of the XY cross section are each substantially rectangular like the second frame layer 13 and penetrates along the Z axis. Forming a hollow portion. The hollow portion of the first frame layer 11 becomes a space in which the plate-like member EB and the protruding portion 202 that are elastically deformed when the lens group 20 is moved in the + Z direction can move. The first frame layer 11 is formed by the same material and manufacturing method as the second frame layer 13. The lower end surface (one main surface) located on the −Z side of the first frame layer 11 is joined to the fixed frame body 121 of the adjacent first parallel spring 12. Moreover, the upper end surface (other end surface) located on the + Z side of the first frame layer is joined to the adjacent lid layer 10 (specifically, near the outer peripheral portion of the lid layer).

<(2-2-9) Lid layer>
As shown in FIG. 3, the outer edge of the XY cross section has a substantially square shape, and the lid layer 10 has a hole (through hole) 10 </ b> H penetrating in a direction parallel to the Z axis at a substantially center, and is substantially in the XY plane. It is a plate-like member having a parallel board surface. The through hole 10H is a hole for guiding light from the subject to the image sensor 181 through the lens group 20, and the lid layer 10 is formed by pressing a flat resin material or patterning the resin material. The through hole 10H is formed and manufactured by a method of etching later.

  In addition, although illustration is abbreviate | omitted in FIG. 3, on the upper surface (other main surface) side of the lid | cover layer 10 so that dust etc. may not penetrate | invade into the camera module 500 from the through-hole 10H of the lid | cover layer 10, A transparent protective layer composed of glass or the like is provided as appropriate.

<(3) AF control in camera module>
As shown in FIG. 1, a current supply driver 600, an electrical resistance detection unit 700, and a contrast detection unit 800 are mounted on the first casing 200, and the second casing 300 is in focus. A control unit 310 is mounted. The electrical resistance detection unit 700 detects the electrical resistance of the heater layer 155 and outputs a signal indicating the electrical resistance to the focusing control unit 310. The focusing control unit 310 detects the deformation of the movable parts 15a and 15b (specifically, the displacement of the free end FT) based on the electric resistance of the heater layer 155. The detection of the displacement of the free end FT is performed by utilizing the fact that the relationship between the shape and the electrical resistance in the heater layer 155 (specifically, the heater portions 155a and 155b) is uniquely determined. Then, the focus control unit 310 controls the current supplied to the heater layer 155 via the current supply driver 600 while detecting the displacement of the free end FT, so that the deformation amount of the movable units 15a and 15b, that is, free Control the displacement of the end FT. At this time, when the first protrusion 201 is pushed up by the free end FT, the lens group 20 is moved in the + Z direction, so that the separation distance between the lens group 20 and the image sensor 181 is changed, and the focal point of the optical unit KB. The position of is changed.

  The contrast detection unit 800 detects the contrast of the image signal obtained by the image sensor 181. For example, a numerical value obtained by accumulating differences in gradation values between adjacent pixels for the entire image is detected as an evaluation value indicating contrast. A signal indicating the evaluation value indicating the contrast is output to the focus control unit 310.

  When performing AF control, first, the separation distance between the lens group 20 and the image sensor 181 is sequentially set to a preset multi-step separation distance under the control of the focusing control unit 310, and each separation distance is set. An image signal is acquired by the image sensor 181 in the set state. In other words, the extension position of the lens group 20 in the + Z direction is set to a preset multistage position, and an image signal is output by the image sensor 181 at the time when the lens group 20 is disposed at each extension position. To be acquired. At this time, the focus control unit 310 controls the supply of current to the heater layer 155 via the current supply driver 600 while monitoring the electrical resistance of the heater layer 155 detected by the electrical resistance detection unit 700. Thus, the extended position of the lens group 20 is changed.

  Next, the focus control unit 310 detects a feeding position at which the evaluation value indicating the contrast is maximum based on the evaluation value indicating the contrast detected for each feeding position by the contrast detection unit 800. The state where the lens group 20 is disposed at the extended position where the evaluation value indicating the contrast is maximum corresponds to the state where the subject is in focus. Then, under the control of the focus control unit 310, the lens group 20 is moved to the extended position where the evaluation value indicating the contrast is maximized, thereby achieving focusing on the subject in the camera module 500. That is, AF control is realized.

  Here, the bimetal employed in the actuator layer 15 tends to cause the displacement of the free end FT in proportion to the temperature. Therefore, if no contrivance is made, the free end FT is displaced in response to a change in the environmental temperature. For example, in a mobile phone or the like, it is generally assumed that the mobile phone is used in a temperature range of about −20 to + 70 ° C. (use environment temperature range). For this reason, when an unintended displacement occurs in the free end FT in such a use environment temperature range, the lens group 20 moves without permission, and the lens group 20 cannot be stopped at a desired position. However, as described above, in the non-driven state, the lens group 20 is pressed against the lens position adjusting layer 16 by the elastic force of the first and second parallel springs 12 and 14, and therefore, within the operating environment temperature range, The free end FT is designed not to be displaced against the elastic force of the first and second parallel springs 12 and 14. In addition to such a device, when the free end FT is displaced within the operating environment temperature range, the movable portions 15a and 15b are swung so that the free end FT does not contact the first protrusion 201. A gap may be provided between the free end FT and the first protrusion 201.

<(4) Camera module manufacturing process>
Here, a manufacturing process of the camera module 500 will be briefly described. FIG. 28 is a flowchart showing the manufacturing process of the camera module 500. As shown in FIG. 28, (process A) generation of the lens group 20 (step SP1), (process B) sheet preparation (step SP2), (process C) assembly jig preparation (step SP3), (process D) First bonding of the sheet (step SP4), (Process E) Mounting of the lens group 20 (Step SP5), (Process F) Second bonding of the sheet (Step SP6), (Process G) Image sensor substrate 178 (Step SP7) and (process H) dicing (step SP8) are sequentially performed, and the camera module 500 is manufactured.

<(4-1) Lens Group Generation (Process A)>
In step SP1, the lens group 20 is generated. Here, first, a wafer in which a large number of lens groups 20 are arranged in a matrix (hereinafter also referred to as a “lens group wafer”) is manufactured, and a large number of lens groups 20 are separated into pieces by dicing. Group 20 is produced. The lens group wafer includes a wafer in which a large number of first lens constituent layers LY1 are arranged (first lens constituent layer wafer), a wafer in which a large number of spacer layers RB are arranged (spacer layer wafer), and a large number of second lenses. A wafer (second lens constituent layer wafer) on which the constituent layers LY2 are arranged is laminated and bonded together.

<(4-2) Preparation of sheet (Process B)>
In step SP2, a sheet relating to each functional layer constituting the camera module 500 is formed for each layer. Here, a disc-shaped sheet at the wafer level is prepared. A large number of chips corresponding to members related to the functional layer are formed in a matrix on the sheet for each functional layer. Specifically, in step SP2, the functions such as the lid layer 10, the first frame layer 11, the first parallel spring 12, the second frame layer 13, the second parallel spring 14, the actuator layer 15, and the lens position adjustment layer 16 are performed. Each sheet U10 to U16 in which a large number of chips related to the layers are formed in a predetermined arrangement, and a sheet (image pickup element) including chips related to the image pickup element substrate 178 formed by joining the cover glass layer 17 and the image pickup element layer 18 Substrate sheet) U178 is prepared. That is, eight sheets U10 to 16 and U178 are prepared.

<(4-3) Preparation of assembly jig (Process C)>
In step SP3, an assembly jig is prepared. The assembling jig is configured by providing a plurality of protrusions having substantially the same shape on a flat base in a predetermined arrangement. In the assembly jig, alignment marks for alignment are formed at two or more predetermined locations. The upper surface of the protrusion is configured to be substantially parallel to the main surface of the flat base. A unit corresponding to each camera module 500 is manufactured on the upper surface.

<(4-4) Sheet First Joining (Process D)>
In step SP4, three sheets U11 to U13 among the eight prepared sheets U10 to 16 and U178 are joined. Here, the first frame layer sheet U11, the first parallel spring sheet U12, and the second frame layer sheet U13 are aligned in the sheet shape so that the chips included in the sheets U11 to U13 are stacked on each other. (Alignment) is performed. And each sheet | seat U11-U13 is joined using an adhesive agent etc.

  FIG. 29 shows a state in which three sheets U11 to U13 are laminated and joined in step S4, a lens group 20 is attached in step S5, and four sheets U10 and U14 to U16 are laminated in step S6. It is a figure which shows typically a mode that it joins and a mode that the image pick-up element board | substrate sheet | seat U178 is joined by step SP7.

<(4-5) Attaching the lens group (Process E)>
In step SP5, the lens group 20 generated in step SP1 is attached to a hollow portion of each second frame layer 13 of the unit manufactured in step SP4 by a predetermined mounter. That is, the lens group 20 is inserted into each gap of the second frame layer sheet U13 having a lattice shape. Here, while the lens group 20 is pressed against the joint PG2, the end surface of the second protrusion 202 is joined to the one main surface side of the joint PG2. In addition, as this joining method, the method etc. which join using the adhesive agent (UV curing adhesive) hardened | cured by irradiation of an ultraviolet-ray are mentioned.

<(4-6) Sheet second joining (process F)>
In step SP6, four sheets U10 and U14 to U16 of the eight sheets U10 to 16 and U178 prepared in step SP2 are joined. Specifically, in step SP6, each chip included in the second parallel spring sheet U14 and the actuator layer sheet U15 is attached to the second frame layer sheet with respect to one main surface side of the units generated up to step SP5. Positioning (alignment) is performed while maintaining the sheet shape so as to be stacked on each chip included in U13. And each sheet | seat U14, U15 is joined using an adhesive agent etc. in order.

  Further, the sheet is so formed that each chip included in the lid layer sheet U10 is stacked with respect to each chip included in the first frame layer sheet U11 with respect to the other main surface side of the first frame layer sheet U11. Alignment (alignment) is performed in the shape. In this state, the lid layer sheet U10 is bonded to the other main surface side of the first frame layer sheet U11 using an adhesive or the like.

  Further, the sheet-like shape is formed so that each chip included in the lens position adjustment layer sheet U16 is stacked on each chip included in the actuator layer sheet U15 with respect to one main surface side of the actuator layer sheet U15. The alignment (alignment) is performed as it is. In this state, the lens position adjustment layer sheet U16 is bonded to one main surface side of the actuator layer sheet U15 using an adhesive or the like.

<(4-7) Mounting of image sensor substrate (process G)>
In step SP7, the lens is arranged so that the outer peripheral portion of the image sensor substrate 178 is bonded to the frame 161 of the lens position adjustment layer 16 of the unit formed by bonding the lens position adjustment layer 16 by step SP6. The other main surface of the imaging element substrate sheet U178 is joined to one main surface of the position adjustment layer sheet U16.

<(4-8) Dicing (Process H)>
In step SP8, a large number of lens groups 20 are inserted, and a laminated member formed by laminating eight sheets U10 to U16 and U178 is protected by a dicing tape or the like and then separated for each chip by a dicing device. . At this time, a large number of camera modules 500 are completed. In the middle of this dicing process, the side wiring 21 is formed. Specifically, when dicing along one direction is performed, each heater layer 155 is exposed at a cut surface corresponding to the side surface of each camera module 500. Therefore, a conductive material for forming the side wiring 21 is applied to the cut surface, and then dicing along the other direction is performed, so that a large number of camera modules 500 are completed.

<(5) Camera module responsiveness>
FIG. 30 is a diagram exemplifying a measurement result of the response of the camera module 500, specifically, the relationship between the passage of time and the change in the position of the lens group 20 during natural cooling of the bimetal. In FIG. 30, the horizontal axis indicates the passage of time, and the vertical axis indicates the extended position (lens position) of the lens group 20. In FIG. 30, the measurement results for the camera module 500 provided with the heat conductive layer 152 according to the present embodiment are indicated by black square plots and bold lines, and as a comparative example, the heat conductive layer 152 is provided. The measurement results for the camera modules that are not shown are indicated by a black circle plot and a broken line.

  Specifically, here, in the camera module 500 according to the present embodiment, the thickness of the high thermal expansion layer 151, the thickness of the thermal conductive layer 152, and the thickness of the low thermal expansion layer 153 have a relationship of 2: 1: 2. In addition, the thickness of the three layers was set to be about 30 μm in total. On the other hand, for the camera module according to the comparative example, the thickness of the high thermal expansion layer and the thickness of the low thermal expansion layer have a 1: 1 relationship, and the thickness of the two layers is set to be about 30 μm in total. It was. That is, both the present embodiment and the comparative example were set such that the bimetal thickness was constant.

  Further, here, the heater layer 155 from the state where the lens group 20 is disposed at a position extended about 200 μm in the + Z direction with reference to a predetermined position where the lens group 20 is pressed against the lens position adjusting layer 16. The relationship between the passage of time until the lens group 20 comes into contact with the lens position adjusting layer 16 and the extended position of the lens group 20 was measured by stopping the energization heating to naturally cool the bimetal.

  As shown in FIG. 30, in the camera module according to the comparative example, it took about 1 second for the lens group 20 to move by 200 μm in the −Z direction, whereas the camera module according to the present embodiment. In 500, it took about 0.5 seconds for the lens group 20 to move by 200 μm in the −Z direction. That is, it was found that the moving speed of the lens group 20 during bimetal cooling was increased to about twice due to the presence of the heat conductive layer 152.

  As described above, in the mobile phone 100 equipped with the camera module 500 according to the embodiment of the present invention, heat conduction from the projecting portions 152a and 152b having a large thermal conductivity to the frame portion 152f as the heat conducting portion results in The cooling rate of the movable parts 15a and 15b is increased. For this reason, it is possible to provide an actuator with good response that generates a driving force by bending using a difference in thermal expansion coefficient. Further, by using the frame 15f as a fixed portion joined to an adjacent layer in the actuator layer 15 as a heat dissipation region, the cooling rate of the movable portions 15a and 15b is provided without providing another member for heat dissipation. Can be increased. Therefore, the space is effectively used, and a high-performance actuator that is small in size is realized.

<(6) Modification>
It should be noted that the present invention is not limited to the above-described embodiment, and various changes and improvements can be made without departing from the gist of the present invention.

  For example, in the above embodiment, the heat conductive layer 152 is disposed between the high thermal expansion layer 151 and the low thermal expansion layer 153, but the present invention is not limited thereto. For example, an insulating layer is provided between the high thermal expansion layer 151 and the low thermal expansion layer 153, and the thermal conductive layer 152 is provided on one main surface side of the high thermal expansion layer 151 that is not the side on which the low thermal expansion layer 153 is provided. Alternatively, it may be provided on the other main surface side of the low thermal expansion layer 153 that is not the side on which the high thermal expansion layer 151 is provided. That is, regardless of the order in which the high thermal expansion layer, the low thermal expansion layer, and the heat conduction layer are laminated, the movable portion is configured by laminating a plurality of layers including the high thermal expansion layer, the low thermal expansion layer, and the heat conduction layer. It ’s fine.

  In the above embodiment, the projecting portions 152a and 152b and the frame portion 152f are integrally formed of the same material in the heat conductive layer 152, but the present invention is not limited to this. For example, the projecting portions 152a and 152b and the frame portion 152f are configured using different materials, and the projecting portions 152a and 152b and the frame portion 152f are in contact with each other, whereby the heat according to the one embodiment described above. A function similar to that of the conductive layer 152 may be realized. In addition, when employ | adopting such a structure, the raw material which comprises the frame part 152f should just have thermal conductivity larger than the raw material which comprises the high thermal expansion layer 151 and the low thermal expansion layer 153. FIG.

  In the above embodiment, the heater layer 155 is provided on the actuator layer 15, but the present invention is not limited to this. For example, the heater layer 155 may not be provided in the actuator layer 15, and the heater layer may be provided in another layer adjacent to the actuator layer 15, for example.

  In the embodiment described above, the plate-like first and second parallel springs 12 and 14 are employed as members for restricting the movement of the lens group 20, but the present invention is not limited to this. For example, various elastic members including a helical spring may be employed.

  In the above embodiment, the object moved by the movable parts 15a and 15b (moving object) is the lens group 20 as an optical system, but is not limited thereto. For example, other members such as an image sensor may be used as the moving object. For example, the lens group 20A corresponding to the optical system that guides light from the subject to the image sensor is fixed, and the image sensor layer is moved in the Z direction by a configuration similar to the configuration for moving the lens group 20 in the one embodiment. Also good.

  FIG. 31 is a diagram illustrating a conceptual diagram of one mode in which the lens group 20A is fixed and the imaging element layer 18A is moved back and forth in a direction along the optical axis Ax of the lens group 20A. In FIG. 31, an imaging unit PBA that moves the imaging element layer 18A back and forth along the optical axis Ax is depicted. In such a configuration, the image sensor layer 18A is moved back and forth along the optical axis Ax in accordance with the operation of the actuator layer, and the distance between the lens group 20A and the image sensor layer 18A is changed, so that AF control is performed. Is realized. As described above, AF control is realized when at least one of the image sensor and the optical system is moved in accordance with the bending deformation of the movable portions 15a and 15b. In any configuration, similar to the above-described embodiment, due to the heat conduction from the projecting portions 152a, 152b having a large thermal conductivity to the frame portion 152f as the heat conducting portion, the movable portions 15a, 15b The cooling rate is increased. For this reason, an imaging device using an actuator with good responsiveness that generates a driving force by bending using a difference in thermal expansion coefficient is realized.

  Moreover, the target object (moving target object) moved by the actuator is not limited to an element constituting the imaging apparatus such as an optical system or an imaging element. For example, the moving object may be another object such as an objective lens of an optical pickup lens. That is, the present invention can be applied to an actuator and a drive device in which a moving object is moved according to bending deformation of the actuator. In such a driving device, as in the above-described embodiment, the cooling of the movable portions 15a and 15b is performed by heat conduction from the projecting portions 152a and 152b having high thermal conductivity to the frame portion 152f as the heat conducting portion. Speed is increased. For this reason, the drive apparatus using the actuator with favorable responsiveness which produces a driving force by the curve using the difference in a thermal expansion coefficient is implement | achieved.

  In the above embodiment, the camera module 500 is mounted on the mobile phone 100. However, a configuration similar to the camera module 500 may be mounted on a compact digital camera.

  In the above embodiment, the two movable parts 15a and 15b are provided. However, the present invention is not limited to this, and the number of movable parts may be one or three or more.

  In the above embodiment, the movable parts 15a and 15b have a so-called cantilever structure in which one end is fixed to the frame 15f. However, the present invention is not limited to this. For example, what has what is called a doubly-supported beam structure in which both ends of the movable part are fixed to the frame is also conceivable.

  It goes without saying that all or a part of each of the above-described embodiment and various modifications can be appropriately combined within a consistent range.

12 First parallel spring 14 Second parallel spring 15 Actuator layer 15a, 15b Movable part 15f Frame body 16 Lens position adjustment layer 18, 18A Image sensor layer 20, 20A Lens group 21 Side wiring 100 Mobile phone 151 High thermal expansion layer 151a, 151b , 152a, 152b, 153a, 153b, 154a, 154b, 155a, 155b Projecting portion 151f, 152f, 153f, 154f, 155f Frame portion 152 Thermal conductive layer 153 Low thermal expansion layer 154 Insulating layer 155 Heater layer 1551, 1552, 1553 Wiring Unit 155a, 155b heater unit 181 imaging device 500 camera module

Claims (10)

A plurality of layers including a first layer, a second layer having a larger coefficient of thermal expansion than the first layer, and a third layer having a larger thermal conductivity than the first and second layers are stacked. A movable part that deforms in response to heating,
A heat dissipation region including a heat conducting portion configured integrally with the third layer or in contact with the third layer and having a higher thermal conductivity than the first and second layers; And having a fixed part to which the movable part is fixed,
An actuator comprising: The actuator according to claim 1,
The third layer is
An actuator provided between the first layer and the second layer. The actuator according to claim 1 or 2,
The heat dissipation area is
The actuator having a second heat capacity larger than the first heat capacity of the movable part. The actuator according to claim 3, wherein
The heat dissipation area is
The actuator having a second surface area larger than the first surface area of the movable part. The actuator according to any one of claims 1 to 4, wherein
The third layer is
An actuator comprising at least one material of copper, nickel, and aluminum. The actuator according to any one of claims 1 to 5, wherein
The heat conducting part is
An actuator comprising at least one material of copper, nickel, and aluminum. The actuator according to any one of claims 1 to 6, comprising:
The multiple layers are
The actuator further comprising a patterned heater layer. The actuator according to any one of claims 1 to 7,
An adjacent layer bonded to the heat dissipation area;
A moving object which is an object to be moved by the actuator;
A drive device comprising: The actuator according to any one of claims 1 to 7,
A moving object that is an object to be moved by deformation of the movable part;
A drive device comprising: The actuator according to any one of claims 1 to 7,
An image sensor;
An optical system for guiding light from a subject to the image sensor;
With
At least one of the image sensor and the optical system is moved by deformation of the movable part.

Images