JP5606819B2 - The camera module - Google Patents

Description

  The present invention relates to a camera module mounted on an electronic device such as a mobile phone, and more particularly to a camera module having a camera shake correction function in addition to an autofocus function.

  In recent years, the majority of mobile phones have a camera module incorporated in the mobile phone. Since a camera module mounted on a mobile phone must be housed in the mobile phone, there is a great demand for reduction in size and weight compared to a digital camera.

  Among such camera modules, a type that realizes an auto focus (AF) function by driving a lens with a lens driving device has been increasingly used in electronic devices such as mobile phones. ing. There are various types of lens driving devices, such as a type using a stepping motor, a type using a piezoelectric element, a type using a VCM (Voice Coil Motor), and is already on the market.

  On the other hand, in a situation where a mobile phone equipped with a camera module having an autofocus function has become commonplace, a camera shake correction function has attracted attention as a further function for differentiation. The camera shake correction function is widely used in the world for digital cameras and video cameras, but it is difficult to mount on mobile phones due to size problems. However, new camera shake correction mechanisms that can be miniaturized are also being proposed, and it is expected that camera modules for mobile phones equipped with camera shake correction functions will increase in the future.

  Patent Document 1 discloses a camera module with a camera shake correction function that is conscious of being mounted on a mobile phone. Patent Document 1 describes an optical image stabilization mechanism (OIS: Optical Image Stabilizer).

  In Patent Document 1, a conventional AF camera module called a photographing unit (movable module) is supported by four suspension wires and driven in two axial directions perpendicular to the optical axis to correct camera shake. . As a driving mechanism for the photographing unit, magnets are respectively disposed on the four outer peripheral side surfaces of the cover portion on which the photographing unit is mounted, and a coil is disposed on the fixed body side yoke so as to face each magnet. As a result, the photographing unit can be driven independently of the two axes perpendicular to the optical axis with respect to the fixed body side yoke.

JP 2009-288770 A (published on Dec. 10, 2009)

  In the example of Patent Document 1, the entire AF camera module is driven for camera shake correction, and the OIS movable portion becomes heavy. In addition, the imaging unit includes an image sensor, and sufficient camera shake correction cannot be performed even if the lens system and the image sensor are integrally driven in a direction perpendicular to the optical axis. In order to reduce the weight of the OIS movable part and obtain a correction effect, for example, an image sensor is arranged on the OIS fixed part side, or the AF driving magnet and the OIS drive to reduce the weight of the OIS movable part and the number of parts Even if a common magnet is used, the entire movable portion of the AF and the fixed portion of the AF become the OIS movable portion, and thus the OIS movable portion cannot be reduced in weight. The fact that the OIS movable part is heavy has a problem that power is required for driving first. In the OIS, since the OIS movable part is driven at a frequency of about 100 Hz for camera shake correction, it is desirable to reduce the weight of the OIS movable part.

  Secondly, when the camera is held such that the optical axis is not parallel to the direction of gravity, the OIS movable part shifts due to its own weight. For this reason, particularly when the image sensor is arranged on the OIS fixed part side for weight reduction, the optical axis of the lens is shifted with respect to the image sensor, and the image deviated from the direction aimed by the photographer. I will shoot. In order to avoid such a situation, a DC correction current is usually applied to the coil to return the OIS movable part to the original optical axis position detected by a position sensor or the like. However, when such correction is performed, a correction current is always required even in a preview state before and after shooting, and there is a problem that power consumption as a camera module or a mobile phone equipped with the camera module increases. .

Further, in the example of Patent Document 1, the AF movable portion is supported on the AF fixing portion by the AF spring, and the AF fixing portion is supported on the OIS fixing portion by the OIS spring (suspension wire). . A schematic representation of such a configuration is a two-degree-of-freedom vibration model as shown in FIG. m ₁ is the mass of the AF movable portion, m ₂ is the mass of the OIS movable portion excluding the AF movable portion (ie, the mass of the AF fixed portion), and k ₁ is the lateral direction of the AF spring supporting the AF movable portion ( spring constant direction) perpendicular to the optical axis, k ₂ is the spring constant of the bending direction of the suspension wires supporting the OIS movable section (direction perpendicular to the optical axis). If the displacement of the AF movable part and the OIS movable part is x ₁ and x ₂ with the natural length position of each spring as a reference, in the example of Patent Document 1, the OIS driving force f ₀ corresponds to the OIS movable part (m ₂ ). For simplicity, the viscosity term is omitted. The equation of motion for this model is as follows.

m ₁ (d ² x ₁ / dt ² ) + k ₁ (x ₁ −x ₂ ) = 0
m ₂ (d ² x ₂ / dt ² ) + k ₁ (x ₂ −x ₁ ) + k ₂ x ₂ = f ₀
Solving these simultaneous equations by Laplace transform gives the following.

X ₁ / F ₀ = k ₁ / ((m ₁ s ² + k ₁ ) × (m ₂ s ² + k ₁ + k ₂ ) −k ₁ ² )
Here, s is a variable of Laplace transform, and X ₁ , X ₂ , and F ₀ are functions after Laplace transform of x ₁ , x ₂ , and f ₀ , respectively. Further, since X ₁ indicates the displacement of the lens, only the expression relating to X ₁ is shown, but the expression relating to X ₂ can also be derived by a similar solution.

Here, when converted into the frequency domain as s ² = −ω ² and ω = 2π × f (f is a frequency), a Bode diagram of this vibration system is obtained. FIG. 13 shows a Bode diagram of this system. The horizontal axis is frequency, and the gain scale is shown on the left side of the vertical axis and the phase scale is shown on the right side of the vertical axis. If the above equation is calculated as it is, the gain becomes infinite at the resonance point, and the result of calculation with an appropriate viscosity term is shown in FIG.

As can be inferred from the above equation, X ₁ / F ₀ is a quadratic term in which the numerator is a constant and the denominator is s ² . Therefore, there are two resonance points where the denominator = 0, that is, X ₁ / F ₀ → ∞. In particular, the secondary resonance on the high frequency side has a large gain peak and the phase rotates 180 degrees, so that it may cross the 0 dB line again after passing the cutoff frequency of the servo system. It is not desirable because it leads to connection. To prevent oscillation, reduce the gain of the entire servo system, or decreasing the gain of the secondary resonance in a filter or the like, (a higher k ₁₎ or mechanically increasing the frequency of the secondary resonant response, such as Is required. Lowering the gain leads to a decrease in image stabilization function, the higher the k ₁ to the operation of the AF can adversely affect.

  Further, the results shown in FIG. 13 are based on the assumption that an OIS driving force (acting via an AF spring) is applied to the center of gravity of the AF movable part. Since the rotational moment acts on the AF movable part, the AF spring also resonates in the torsion mode (rotation about an axis perpendicular to the optical axis). A Bode diagram when a torsional mode resonance occurs is shown in FIG. Although depending on the structure, the torsional resonance usually occurs at a slightly lower frequency than the secondary resonance, and when viewed from the gain peak, the lower peak and the upper peak are seen close to each other. Such a resonance peak is also undesirable because it leads to instability of the servo system.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to reduce the weight of the OIS movable part and to directly apply an OIS driving force to the optical part including the imaging lens. It is possible to eliminate high-order resonance peaks that lead to instability of the servo system, or to suppress high-order resonance peaks, and with a compact optical camera shake correction function that can also be installed in mobile phones It is to provide a camera module.

A camera module according to the present invention includes an optical unit including an imaging lens, an intermediate support, a fixed support, and an image sensor that is fixed to the fixed support. And in order to solve said subject, the said optical part and the said intermediate support body are connected, and the said optical part is supported with respect to the said intermediate support body so that a displacement in the direction perpendicular | vertical to an optical axis is possible. A first support part; a second support part that connects the intermediate support and the fixed support; and supports the intermediate support so as to be displaceable in the optical axis direction with respect to the fixed support; and the optical A first coil fixed to the part, a magnet fixed to the intermediate support, and a second coil fixed to the fixed support, the first coil, Electromagnetic force acting between the magnets Ri, the optical unit is displaced in a direction perpendicular to the optical axis, by an electromagnetic force acting between the second coil and the magnet is characterized in Rukoto displaces the intermediate support in the optical axis direction.

  According to the above configuration, the intermediate support, the first support, and the optical unit supported by the intermediate support can be displaced in the optical axis direction for the autofocus (AF) function. The optical unit can be displaced in a direction perpendicular to the optical axis for optical image stabilization (OIS). Therefore, the OIS movable part driven for optical camera shake correction includes limited members such as an optical part, and does not include the intermediate support body and the second support part. Therefore, it is possible to reduce the weight of the OIS movable unit that is driven for optical camera shake correction. Therefore, the correction current for correcting the optical axis shift due to the weight of the OIS movable part can be reduced, and the power consumption of the camera module can be reduced.

  According to the above configuration, the OIS movable portion does not include the intermediate support that is supported by the second support so as to be displaceable in the optical axis direction. Therefore, the OIS is not interposed between the intermediate support and the second support. An OIS driving force can be applied directly to the movable part. Therefore, a higher-order resonance peak can be suppressed as compared with the conventional structure in which the OIS driving force is applied to the optical unit via the second support portion (AF spring). Therefore, it is easy to control the displacement of the optical part, and the stability of the servo system can be improved.

  A first driving mechanism including a first coil and a first magnet, wherein one of the first coil and the first magnet is fixed to the optical unit, and the other is the intermediate support or the The first driving mechanism may be configured to displace the optical unit in a direction perpendicular to the optical axis by an electromagnetic force acting between the first coil and the first magnet. .

  According to the above configuration, the OIS driving force is directly applied to the OIS movable portion by the electromagnetic force acting between the first coil and the first magnet without using the intermediate support body and the second support portion. Can do. Therefore, the higher order resonance peak of the optical member can be suppressed.

  Further, the first coil may be fixed to the optical unit.

  According to said structure, since an OIS movable part is provided with a comparatively lightweight coil instead of a magnet, an OIS movable part can be further reduced in weight.

  A second drive mechanism including a second coil and a second magnet, wherein one of the second coil and the second magnet is fixed to the intermediate support, and the other is fixed to the fixed support; The second drive mechanism may be configured to displace the intermediate support in the optical axis direction by electromagnetic force acting between the second coil and the second magnet.

  According to the above configuration, the mass of the AF movable portion that is displaceable in the optical axis direction is increased as compared with the conventional configuration, but the space outside the second support (AF spring) (outside the second drive mechanism) The first drive mechanism (OIS drive mechanism) is not restricted in this space. Therefore, the space outside the intermediate support can be widely used for the AF driving mechanism, and a large driving force can be generated using a strong magnet or the like.

  A first drive mechanism including a first coil and a first magnet; and a second drive mechanism including a second coil and a second magnet. The first coil is fixed to the optical unit. The first magnet and the second magnet are fixed to the intermediate support, the second coil is fixed to the fixed support, and the first drive mechanism includes the first coil and the first magnet. The optical unit is displaced in a direction perpendicular to the optical axis by an electromagnetic force acting between the second support mechanism and the second drive mechanism. The second driving mechanism causes the intermediate support to be moved by the electromagnetic force acting between the second coil and the second magnet. It is good also as a structure displaced in an optical axis direction.

  According to said structure, since the arrangement | positioning space | interval of a 1st magnet and a 2nd coil can be enlarged, it can suppress that the magnetic flux from a 1st magnet leaks into a 2nd coil.

  A first coil fixed to the optical unit; a third magnet fixed to the intermediate support; and a second coil fixed to the fixed support. The intermediate support is displaced by electromagnetic force acting between the second coil and the third magnet by displacing the optical part in a direction perpendicular to the optical axis by electromagnetic force acting between the first coil and the third magnet. The structure which displaces a body to an optical axis direction may be sufficient.

  According to the above configuration, the OIS driving force and the AF driving force can be generated by the third magnet. Therefore, the magnet for OIS driving and the magnet for AF driving can be shared. Therefore, the number of parts can be reduced, the cost can be reduced, and the camera module can be downsized.

  Further, the first support portion may be configured to act to hold the optical portion at a predetermined position on a plane perpendicular to the optical axis with respect to the intermediate support body by an elastic force.

  Further, the first support portion may be composed of at least four suspension wires.

  According to said structure, an optical part can be supported by a simple structure so that a displacement in the direction of 2 axis | shafts perpendicular | vertical to an optical axis is possible. Also, by using a suspension wire as the first support part, it becomes possible to sufficiently increase the spring constant in the length direction (stretching direction) relative to the spring constant in the bending direction (bending direction), and Resistance to twisting (tilt) can be increased.

  As described above, in the camera module according to the present invention, the OIS movable unit driven for optical camera shake correction includes a limited member such as an optical unit, and does not include the intermediate support and the second support. . Therefore, it is possible to reduce the weight of the OIS movable unit that is driven for optical camera shake correction. Therefore, the correction current for correcting the optical axis shift due to the weight of the OIS movable part can be reduced, and the power consumption of the camera module can be reduced.

  Further, since the OIS movable portion does not include an intermediate support that is supported by the second support portion so as to be displaceable in the optical axis direction, the OIS movable portion is directly connected to the OIS movable portion without using the intermediate support and the second support portion. An OIS driving force can be applied. Therefore, a higher-order resonance peak can be suppressed as compared with the conventional structure in which the OIS driving force is applied to the optical unit via the second support portion (AF spring). Therefore, it is easy to control the displacement of the optical part, and the stability of the servo system can be improved.

It is a perspective view which shows the structure of the camera module with an optical camera-shake correction function which concerns on embodiment of this invention. It is AA arrow sectional drawing of the camera module of FIG. FIG. 3 is a cross-sectional view of the camera module of FIG. It is a principal part perspective view which shows the structure of the coil for OIS and the magnet for OIS of FIG. It is a principal part perspective view which shows the structure of the coil for AF of FIG. 1, and the magnet for AF. It is the figure which represented typically the vibration model of the camera module of embodiment of this invention. It is an example of the Bode diagram regarding the displacement of the imaging lens in the camera module of the embodiment of the present invention. It is another example of the Bode diagram regarding the displacement of the imaging lens in the camera module of the embodiment of the present invention. It is sectional drawing equivalent to FIG. 2 which shows the structure of the camera module with a camera-shake correction function which concerns on another embodiment of this invention. It is CC sectional view taken on the line of the camera module of FIG. FIG. 10 is a perspective view of the main part showing the configuration of the OIS coil and the OIS magnet of FIG. 9. It is the figure which represented typically the vibration model of the camera module with the conventional optical camera-shake correction function. It is an example of the Bode diagram regarding the displacement of the imaging lens in the conventional camera module with an optical camera shake correction function. It is another example of the Bode diagram regarding the displacement of the imaging lens in the conventional camera module with an optical camera shake correction function.

[Embodiment 1]
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to FIGS.

(Configuration of camera module)
FIG. 1 is a perspective view showing the structure of a camera module 100 with an optical image stabilization function of the present embodiment. The camera module 100 includes an optical unit 3 including a plurality of imaging lenses, an optical unit driving device 5 disposed outside the optical unit 3 in order to drive the optical unit 3 in an optical axis direction and a direction perpendicular to the optical axis. And an imaging unit 8 that images light that has passed through the optical unit 3. The optical unit driving device 5 and the imaging unit 8 are stacked in the optical axis direction. In the following description, for the sake of convenience, the optical unit 3 side (subject side) is the upper side, and the imaging unit 8 side is the lower side.

  First, the overall structure of the camera module 100 will be described with reference to FIGS. 2 is a cross-sectional view taken along the line AA showing the structure of the camera module 100 of FIG. 1, and is a cross-sectional view of the center portion of the camera module 100 cut in the optical axis direction. FIG. 3 is a cross-sectional view of the camera module 100 of FIG. In FIG. 2, the position of the optical axis is indicated by a broken line.

  The optical unit 3 includes a plurality (four in FIG. 2) of imaging lenses 1 and a cylindrical lens barrel 2 that holds the plurality of imaging lenses 1 inside. The optical unit 3 is an imaging optical system that forms a subject image, and guides light from the outside to the imaging element 6 of the imaging unit 8 via the plurality of imaging lenses 1. The optical axis of the imaging lens 1 coincides with the axis of the lens barrel 2. The optical unit 3 is supported so as to be displaceable in an optical axis direction and a biaxial direction perpendicular to the optical axis with respect to the imaging element 6 of the imaging unit 8.

  The optical unit driving device 5 includes a lens holder 4, an intermediate support 10, a fixed support 12, a base member 13, a suspension wire (first support) 9 that connects the lens holder 4 and the intermediate support 10, and an intermediate support. 10 and an AF spring (second support portion) 11 a that connects the fixed support 12 and the AF spring (second support portion) 11 b that connects the intermediate support 10 and the base member 13.

  The lens holder 4 holds the lens barrel 2 inside and is driven integrally with the optical unit 3. A square flange portion 4a is formed at the upper end portion (end portion on the subject side) of the lens holder 4, and one end of the suspension wire 9 is fixed to each of the four corner portions of the flange portion 4a. The other end of each suspension wire 9 is fixed to the intermediate support 10.

  The suspension wire 9 is a thin rod-shaped member made of metal or the like. The suspension wire 9 is easily bent (bent) in a direction perpendicular to the wire axis (longitudinal direction), but the spring constant in the longitudinal direction along the wire axis is high, and the expansion and contraction in the longitudinal direction can be almost ignored. By supporting the lens holder 4 with the four suspension wires 9 arranged in parallel to the optical axis, the optical unit 3 can be displaced in the biaxial direction perpendicular to the optical axis with respect to the intermediate support 10. When the OIS driving force is not applied, the optical unit 3 is held at a predetermined position on a plane perpendicular to the optical axis by the elastic force of the four suspension wires 9.

  The intermediate support 10 is a hollow, rectangular member that is open at the top and bottom, and is disposed so as to surround the optical unit 3 and the lens holder 4. At the lower end of the intermediate support 10, a support portion 10 a that protrudes inside the hollow is formed. One end of each suspension wire 9 is fixed to the flange portion 4 a of the lens holder 4, and the other end of each suspension wire 9 is fixed to the support portion 10 a of the intermediate support 10. The intermediate support 10 is supported by the AF springs 11 a and 11 b so as to be displaceable in the optical axis direction with respect to the fixed support 12 and the base member 13.

  The AF springs 11a and 11b are metal springs that are widely used in existing AF camera modules and whose inner side and outer side are connected by an arm portion of a spiral plate spring. The AF spring 11a and the AF spring 11b are arranged in pairs at a predetermined interval on the upper and lower portions of the intermediate support 10 so as to surround the intermediate support 10. Of the pair of AF springs 11a and 11b, the inner end of the AF spring 11a disposed above is fixed to the upper portion of the intermediate support 10, and the outer end of the AF spring 11a disposed above is It is fixed to the fixed support 12. The inner end of the AF spring 11b disposed below is fixed to the lower portion of the intermediate support 10, and the outer end of the AF spring 11b disposed below is fixed to the base member 13. The AF springs 11 a and 11 b apply a downward force to the intermediate support 10 so that the lower end of the intermediate support 10 abuts a part of the surface of the base member 13 in a state where no current flows through the AF coil described later. Act on. A leaf spring support structure having a spring arm, such as the AF springs 11a and 11b, can be efficiently arranged in the upper and lower spaces of the AF drive mechanism, and is therefore effective in reducing the size of the camera module, particularly in reducing the thickness.

  Since the AF springs 11a and 11b support the intermediate support 10 so as to be displaceable only in the optical axis direction, the spring constant in the direction perpendicular to the optical axis is significantly larger than the spring constant in the optical axis direction. It is configured as follows. Therefore, the intermediate support 10 supported by the AF springs 11a and 11b is not easily tilted. In order to increase the spring constant in the direction perpendicular to the optical axis, the thickness (dimension in the optical axis direction) and width of the arm portion of the leaf spring can be increased and the length can be shortened. If everything is done, the spring constant in the direction of the optical axis also increases, which affects the AF characteristics. In order to increase the spring constant in the direction perpendicular to the optical axis so as not to affect the AF characteristics, the effect of the spring constant as the first power of the width and the third power of the thickness is used. The AF springs 11a and 11b may be configured so that the size of the arm portion is reduced (thickness is reduced) and the width of the arm portion in the plane perpendicular to the optical axis is increased. By doing so, the spring constant in the lateral direction (direction perpendicular to the optical axis) of the AF springs 11a and 11b can be increased without unnecessarily increasing the spring constant in the optical axis direction of the AF springs 11a and 11b. And the tilt of the AF movable part can be reduced.

  The fixed support 12 is made of a yoke and has a rectangular box shape surrounding the four sides of the intermediate support 10. An opening is provided at a position of the fixed support 12 corresponding to the upper side of the optical unit 3. The fixed support 12 may include a holding member (not shown) such as a resin provided integrally with the yoke. The outer end of the AF spring 11 a is fixed to the inside of the fixed support 12. The lower part of the fixed support 12 is fixed to the upper part of the base member 13.

  The base member 13 is a rectangular member disposed below the fixed support 12, and an opening 13 a penetrating in the vertical direction is formed at the center of the base member 13. The base member 13 includes a recess on the bottom surface side, and includes an IR cut filter 18 disposed in the recess on the bottom surface side so as to close the opening 13a. Due to the base member 13 and the IR cut filter 18, the base member 13 also serves as a sensor cover that covers the image sensor 6. In the present embodiment, the IR cut filter 18 is made of lid glass, but is not limited thereto. In addition, the base member 13 includes a protrusion 13b that protrudes downward in a part of the outer side of the bottom surface side recess. By assembling the protrusion 13b of the base member 13 in contact with the upper surface of the image sensor 6, the optical unit 3 (that is, the image pickup lens 1) can be positioned with high accuracy with respect to the image sensor 6 in the optical axis direction. The tilt after assembly of the optical unit 3 with respect to the image sensor 6 can be reduced. An outer end portion of the AF spring 11 b disposed below is fixed to the base member 13.

  The imaging unit 8 includes a substrate 7 and an imaging element 6 mounted on the substrate 7. The image sensor 6 receives light that has arrived via the optical unit 3 and performs photoelectric conversion to obtain a subject image formed on the image sensor 6. The upper surface of the substrate 7 and the lower surface of the base member 13 are fixed with an adhesive. Here, a slight gap is provided between the substrate 7 and the base member 13 in order to bring the imaging element 6 into contact with the protrusion 13b of the base member 13, and by filling the gap with adhesive. Bonding between the base member 13 and the substrate 7 is performed.

(OIS drive mechanism of optical part)
Next, the OIS drive mechanism of the optical unit 3 will be described. The OIS function for displacing the optical unit 3 in the direction perpendicular to the optical axis is realized by an OIS drive mechanism including an OIS coil 14 and an OIS magnet 15.

  The OIS coil 14 is arranged and fixed on the outer side surface of the lens holder 4, specifically, on each of the four side surfaces outside the lens holder 4. Each OIS coil 14 is arranged so that the axis of the coil is perpendicular to the side surface of the lens holder 4. Further, an OIS magnet 15 is disposed and fixed on the inner side surface of the intermediate support 10 so as to face each OIS coil 14. By passing an electric current through the OIS coil 14, an electromagnetic force generated between the OIS magnet 15 acts on the lens holder 4, and the lens holder 4 (and the optical unit 3) is driven in a direction perpendicular to the optical axis ( Can be displaced). The OIS coil 14 disposed on one side surface of the lens holder 4 is combined with the OIS coil 14 disposed on the opposite side surface to form a first direction perpendicular to the optical axis (the optical axis and the relevant axis). A force is applied in a direction perpendicular to the axis of the OIS coil 14. The set of the remaining two OIS coils 14 applies a force in a second direction perpendicular to the optical axis (a direction perpendicular to the optical axis and the first direction).

  FIG. 4 is a perspective view of the main part showing the positional relationship between the OIS coil 14 and the OIS magnet 15 facing it. The OIS coil 14 is wound in a substantially oval (vertically long in the optical axis direction) donut shape. An OIS magnet having a two-pole structure on the side of the intermediate support 10 so that opposite magnetic poles face each of two longitudinal windings of the OIS coil 14 (locations where the winding is along the optical axis direction). 15 is arranged. A current flows in each of the longitudinal winding portions of the OIS coil 14 in the opposite direction, and the magnetic poles of the OIS magnet 15 facing the two longitudinal winding portions are also in the opposite directions. Therefore, when a current is passed through the OIS coil 14, the two longitudinal winding portions receive a force in the same direction, and the lens holder 4 and the optical unit 3 are integrated with the OIS coil 14 in the lateral direction (optical axis). And is driven (displaced) in a direction perpendicular to the axis of the OIS coil 14.

  The OIS movable part driven by the OIS drive mechanism includes an optical part 3, a lens holder 4, and an OIS coil 14. Compared to the conventional configuration, the OIS movable part of the present embodiment does not include the intermediate support 10 or the like, and thus becomes lighter.

(AF drive mechanism of optical part)
Next, the AF driving mechanism of the optical unit 3 will be described. The AF function for displacing the optical unit 3 and the intermediate support 10 that supports the optical unit 3 in the optical axis direction is realized by an AF driving mechanism including an AF coil 16 and an AF magnet 17.

  An AF coil 16 is arranged and fixed on the outer side surface of the intermediate support 10. The AF coil 16 is wound so as to surround the intermediate support 10, and the axis of the AF coil 16 coincides with the optical axis. In addition, an AF magnet 17 is disposed and fixed on the inner side surface of the fixed support 12 so as to face the AF coil 16. By passing an electric current through the AF coil 16, an electromagnetic force generated between the AF magnet 17 acts on the intermediate support 10 and is connected to the intermediate support 10 and the intermediate support 10 by the suspension wire 9. The lens holder 4 (and the optical unit 3) can be integrally driven (displaced) in the optical axis direction.

  FIG. 5 is a perspective view of the main part showing the positional relationship between the AF coil 16 and the AF magnet 17. The AF coil 16 is wound in a square shape so as to surround the intermediate support 10 (not shown in FIG. 5). An AF magnet 17 is disposed so as to face each side surface of the AF coil 16 wound in a square shape. The AF magnets 17 are arranged so that the magnetic poles with the same polarity face inward (the magnetic poles with the same polarity face the AF coil 16). When a current is passed through the AF coil 16, the windings on the four sides facing each AF magnet 17 receive a force in the same direction, and are integrated with the AF coil 16 and the intermediate support 10 (and the optical unit 3). ) Is driven (displaced) in the optical axis direction.

  The AF movable part driven by the AF drive mechanism includes an intermediate support 10, an OIS magnet 15, and an AF coil 16 in addition to the OIS movable part. Therefore, compared to the conventional configuration, since the intermediate support 10 and the like are added to the AF movable portion, the mass of the AF movable portion is increased. However, since a large and powerful AF magnet 17 can be disposed using a wide space outside the intermediate support 10, a sufficient driving force for AF driving can be ensured. Therefore, there is no particular disadvantage compared to the conventional configuration. Note that the AF drive mechanism is not limited to this configuration, and the AF movable unit can be driven in the optical axis direction by using a configuration in which the configuration of the coil and magnet shown in FIG. it can.

  For the OIS drive mechanism and the AF drive mechanism, the combination of mounting the coil or magnet on the movable portion side or mounting on the fixed portion side is free, and the configuration in which the coil and magnet in the illustrated configuration are replaced is possible. It can also be used. However, since the magnet has a larger mass than the coil, it is more energy efficient to mount the coil on the movable part side and the magnet on the fixed part side.

  As for the OIS drive mechanism, the OIS coil is mounted on the OIS movable part, the OIS magnet is mounted on the fixed support, and the OIS movable part is moved relative to the fixed support by the electromagnetic force acting between them. It may be displaced in a direction perpendicular to. With this configuration, the OIS magnet is provided on the fixed support, so that the AF movable portion can be reduced in weight.

  In the present embodiment, the AF coil 16 is mounted on the intermediate support 10 side to reduce the weight of the AF movable part. However, the OIS magnet 15 is provided on both the inner and outer surfaces immediately adjacent to the AF coil 16. And the AF magnet 17 are arranged. Therefore, the AF coil 16 is easily affected by the magnetic flux from both magnets. Therefore, contrary to this, it may be desirable in terms of design to arrange an AF magnet on the intermediate support 10 side and an AF coil on the fixed support 12 side. This configuration will be described later as another embodiment.

(OIS function and AF function)
With the above configuration, the optical unit driving device 5 can drive the optical unit 3 in a total of three axes directions, that is, the optical axis direction and two axes perpendicular to the optical axis, by electromagnetic force. By driving the optical unit 3 triaxially with respect to the image sensor 6 of the imaging unit 8, both an autofocus (AF) function and an optical camera shake correction (OIS) function are realized.

  As for the AF function, the optical unit 3 is moved up and down with respect to the image sensor 6 from the infinity end to the macro end (that is, the plurality of image pickup lenses 1 are displaced in the optical axis direction with respect to the image sensor 6). It will be realized. Note that the infinity end of the imaging lens 1 means a position that focuses on a subject at infinity, and the macro end of the imaging lens 1 refers to a subject at a desired macro distance (for example, 10 cm). Means the position to focus on.

  As for the OIS function, the optical unit 3 is moved in a direction perpendicular to the optical axis with respect to the image sensor 6 according to the amount and direction of camera shake (that is, the plurality of imaging lenses 1 are perpendicular to the optical axis with respect to the image sensor 6). This is realized by relative displacement in a proper direction). A gyro sensor (not shown), an acceleration sensor, etc. are mounted on a camera module or a mobile phone equipped with a camera module. And identify the direction. The OIS control system controls the displacement in the direction perpendicular to the optical axis of the imaging lens 1 according to the specified amount and direction of camera shake. If a position sensor (Hall element or photo reflector) that detects the position of the OIS movable part (or optical part 3) with respect to the image sensor 6 is mounted in the camera module, a gyro sensor that detects angular velocity is installed. Since the position of the optical unit 3 (that is, the position of the imaging lens 1) can be controlled according to the detection signal, closed loop control can be performed to improve the correction accuracy of camera shake correction.

  With the configuration as described above, a camera module with an optical image stabilization function is configured. However, the configuration is not limited to the above. The description in the present embodiment does not limit the shape of the coil and the structure of the magnetic circuit, and limits a new idea for downsizing, weight reduction, high thrust, or the like. It is not something to add.

  The first point of the main feature of the present invention is that the OIS movable part including the imaging lens is supported by an elastic support member so as to be displaceable in a direction perpendicular to the optical axis in order to realize the OIS function. It is included in the AF movable part to support the AF movable part so as to be displaceable in the optical axis direction. By configuring in this way, the mass of the OIS movable part can be reduced, and the correction current for supporting the OIS movable part by electromagnetic force in order to correct the optical axis shift due to its own weight can be reduced. Therefore, the power consumption of the camera module can be reduced.

  Conventionally, the technology of an AF drive mechanism of a camera module having only an AF function without an OIS function has already been established and refined. The conventional design of the camera module having the OIS function and the AF function is performed by applying the established AF driving mechanism technology (module) to the camera module having the AF driving mechanism from the outside. This was done by adding a drive mechanism. Therefore, conventionally, the idea of the present invention that the OIS movable part is incorporated into the AF movable part has not been born.

  In a relatively large camera module such as a digital camera, a part of the AF lens forming the imaging optical system for the AF function is displaced in the optical axis direction, and another part of the OIS lens is used for the OIS function. The AF function and the OIS function were realized by moving the lens in a direction perpendicular to the optical axis. Therefore, the optical unit is not configured to be displaceable in three axes, and the AF lens and the OIS lens are independently supported by the fixed support. Such a configuration is disadvantageous for miniaturization, and it is difficult to miniaturize it so that it can be mounted on a mobile phone.

  The second point of the present invention is to directly apply an OIS driving force acting in two axial directions perpendicular to the optical axis to the OIS movable portion including the imaging lens. In the conventional configuration in which the OIS movable portion includes the AF movable portion, the OIS driving force acts on the imaging lens via the AF spring. According to the second point of the present invention, since the OIS driving force is directly applied to the imaging lens, it is higher in order than the conventional structure in which the imaging lens is driven via the AF spring. The resonance peak can be easily controlled and the stability of the servo system can be improved. This effect will be described in detail below. Since the AF driving force acts to hold the imaging lens 1 at a predetermined distance from the imaging device, the OIS acts to dynamically control the position of the imaging lens 1 according to external vibration (hand shake). Unlike driving force, it is difficult to generate resonance or the like. Therefore, there is no problem even if the AF movable part includes the OIS movable part.

(Vibration analysis by OIS drive)
FIG. 6 is a diagram illustrating a vibration model schematically representing the configuration of the camera module of the present embodiment. The vibration model in one direction perpendicular to the optical axis of the present embodiment is a two-degree-of-freedom vibration model as shown in FIG. m ₁ is the mass of the OIS movable portion, m ₂ is the mass of the AF movable portion excluding the OIS movable portion, and k ₁ is a spring in the bending direction (direction perpendicular to the optical axis) of the suspension wire supporting the OIS movable portion. constant, k ₂ is the spring constant in the lateral direction (direction perpendicular to the optical axis) of the AF spring which supports the AF movable portion. If the displacements of the OIS movable part and the AF movable part are respectively x ₁ and x ₂ with reference to the natural length position of each spring, in this embodiment, the OIS driving force f ₀ is applied to the OIS movable part (corresponding to m ₁ ). The reaction (−f ₀ ) of the OIS driving force f ₀ acts on the intermediate support. That is, the reaction (−f ₀ ) acts on the AF movable part (corresponding to m ₂ ) excluding the OIS movable part. In addition, in the form which arrange | positions the magnet for OIS not to an intermediate support body but to a fixed support body, a reaction does not act on an intermediate support body. For simplicity, the viscosity term is omitted. If you create an equation of motion for this model,
m ₁ (d ² x ₁ / dt ² ) + k ₁ (x ₁ −x ₂ ) = f ₀
m ₂ (d ² x ₂ / dt ² ) + k ₁ (x ₂ −x ₁ ) + k ₂ x ₂ = −f ₀
Solving these simultaneous equations by Laplace transform,
X ₁ / F ₀ = (m ₂ s ² + k ₂ )
/ ((M ₁ s ² + k ₁ ) × (m ₂ s ² + k ₁ + k ₂ ) −k ₁ ² )
It becomes. Here, s is a variable of Laplace transform, and X ₁ , X ₂ , and F ₀ are functions after Laplace transform of x ₁ , x ₂ , and f ₀ , respectively.

Here, when the numerical value of one design example of the camera module 100 of the present embodiment is used as each constant, the vibration system is converted into the frequency domain as s ² = −ω ² and ω = 2π × f (f is a frequency). The Bode diagram is obtained. FIG. 7 shows a Bode diagram showing the displacement of the imaging lens of this system. The horizontal axis is frequency, and the gain scale is shown on the left side of the vertical axis and the phase scale is shown on the right side of the vertical axis. In addition, the corresponding axis is indicated by an arrow attached to each line in the Bode diagram. If the above equation is calculated as it is, the gain becomes infinite at the resonance point, and FIG. 7 shows the calculation result given an appropriate viscosity term. Although also can be inferred from the above _equation, X 1 / _{F 0} is the first-order terms of the molecule ^{s 2,} the denominator is set to the second order term of ^{s 2.} Therefore, there are two resonance points where the denominator = 0, that is, X ₁ / F ₀ → ∞, and one reverse resonance point where the numerator = 0. The resonance point on the numerator side and the resonance point on the high frequency side on the denominator side are paired, and their frequencies are close but slightly shifted. Therefore, on the Bode diagram, the downward gain peak f ₁ and the upward gain Each peak f ₂ exists. In the design example, the frequency of the downward gain peak is lower, and the phase peak appearing in the phase is an upwardly convex peak. Therefore, since the phase is not delayed, the servo system can be stabilized.

The difference between the downward gain peak frequency and the upward gain peak frequency varies depending on the ratio of the mass m ₁ of the OIS movable part and the mass m ₂ of the AF movable part excluding the OIS movable part, and depending on the design, the two are brought close to each other. The peak can be reduced. FIG. 8 shows a Bode diagram of the vibration system in such a design example. Compared with the result shown in FIG. 7, the frequency of the downward gain peak and the frequency of the upward gain peak are close, and the peak itself is also small.

  The results shown in FIG. 7 and FIG. 8 are based on the assumption that the OIS driving force is applied to the center of gravity position of the OIS movable part, but when the center of gravity position and the position of the OIS driving force are shifted, Since a rotational moment acts on the OIS movable part, resonance of the suspension wire torsion mode (rotation about an axis perpendicular to the optical axis) also occurs. However, the torsional mode here is a mode in which the OIS movable part is tilted (the optical axis is tilted), and in order for such vibration to occur, the suspension wire needs to expand and contract. As described above, the spring constant of expansion and contraction of the suspension wire is very high, and the frequency at which such a torsional resonance peak appears can be set high. Note that the vibration mode of rotation about an axis parallel to the optical axis is not a problem because it usually does not occur if the OIS coils arranged in pairs with the optical axis in between are arranged symmetrically.

[Embodiment 2]
Another embodiment of the present invention will be described below. For convenience of explanation, members / configurations having the same functions as those in the drawings described in the first embodiment are given the same reference numerals, and detailed descriptions thereof are omitted. This embodiment will be described with reference to FIGS. In the present embodiment, the OIS magnet and the AF magnet are shared by a single magnet.

(Configuration of camera module)
FIG. 9 is a cross-sectional view similar to FIG. 1, and is a cross-sectional view showing the structure of the camera module 200 by cutting the central portion of the camera module 200 of the present embodiment in the optical axis direction. FIG. 10 is a cross-sectional view of the camera module 200 of FIG. Unlike the first embodiment, the intermediate support 10 includes one magnet 19 on each of the four sides. The magnet 19 is disposed and fixed so as to penetrate the intermediate support 10. The fixed support (yoke) 12 includes one AF coil 16 on the inner side surface. The AF coil 16 is wound along the inner side surface of the fixed support 12 (the axis of the AF coil is parallel to the optical axis), and is fixed to the fixed support 12.

  The inner surface (optical axis side) of the magnet 19 faces the OIS coil 14, and the outer surface (opposite side of the optical axis) of the magnet 19 faces the AF coil 16. The magnet 19 has one magnetic pole on the inner surface facing the OIS coil 14 and another magnetic pole on the outer surface facing the AF coil 16.

  FIG. 11 is a perspective view of a principal part showing a positional relationship between the OIS coil 14 of the camera module 200 and the magnet 19 facing the OIS coil 14. Unlike the structure of the first embodiment shown in FIG. 4, the OIS magnet 19 of the second embodiment shown in FIG. 11 is not a two-pole structure, but a single pole having a single magnetic pole on the surface facing the OIS coil 14. A magnet with a structure. Therefore, the position of the magnet 19 with respect to the OIS coil 14 is shifted and arranged so that only one long side of the OIS coil 14 faces the magnetic pole of the OIS magnet 19.

(OIS function and AF function)
The camera module 200 can drive the optical unit 3 in two axial directions perpendicular to the optical axis by passing a current through the OIS coil 14, and can also drive the optical unit 3 by flowing a current through the AF coil 16. 3. The AF movable part including the intermediate support 10 and the magnet 19 can be driven in the optical axis direction. As described above, the camera module 200 performs OIS driving using the magnetic flux toward the inner side (optical axis side) of the magnet 19 and performs AF driving using the magnetic flux toward the outer side (opposite side to the optical axis). .

  In this embodiment, the use of the magnet 19 having a single pole structure as the OIS magnet causes a driving force to be generated only on one long side of the OIS coil, so that the driving efficiency is reduced. The role of the AF magnet can be assigned to the single magnet 19. Therefore, the cost can be reduced by reducing the number of parts, and the camera module can be reduced in size and weight.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

  The present invention can be suitably used particularly for camera modules mounted on various electronic devices including communication devices such as portable terminals.

DESCRIPTION OF SYMBOLS 1 Imaging lens 2 Lens barrel 3 Optical part 4 Lens holder 4a Flange part 5 Optical part drive device 6 Imaging element 7 Board | substrate 8 Imaging part 9 Suspension wire (1st support part)
10 Intermediate support 11a, 11b AF spring (second support)
12 fixed support 13 base member 14 coil for OIS 15 magnet for OIS 16 coil for AF 17 magnet for AF 18 IR cut filter 19 magnet 100, 200 camera module

Claims (3)

An optical camera shake correction camera module including an optical unit including an imaging lens, an intermediate support, a fixed support, and an image sensor fixed to the fixed support,
A first support unit that connects the optical unit and the intermediate support, and supports the optical unit so that the optical unit can be displaced in a direction perpendicular to the optical axis with respect to the intermediate support;
Connecting the said intermediate support and the fixed support member, relative to the stationary support, a second support portion that movably supports the intermediate support in the optical axis direction,
A first coil fixed to the optical unit;
A magnet fixed to the intermediate support;
A second coil fixed to the fixed support,
The intermediate support is displaced by an electromagnetic force acting between the first coil and the magnet, and the optical portion is displaced in a direction perpendicular to the optical axis by the electromagnetic force acting between the first coil and the magnet. the camera module according to claim Rukoto is displaced in the optical axis direction. 2. The camera according to claim 1 , wherein the first support portion acts to hold the optical portion at a predetermined position in a plane perpendicular to the optical axis with respect to the intermediate support body by an elastic force. module. The first support portion, a camera module according to claim 1 or 2, characterized in that it consists of at least four suspension wires.

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