JP2007121853A - Imaging device - Google Patents

Abstract

An imaging apparatus having a compact configuration and capable of increasing the driving force of an actuator is provided.
In a magnet 32 of an actuator 30, a thickness t at a position A facing a corner of a yoke 31 constituting a part of a housing is shifted from another position C (for example, a position shifted by 45 ° from the position A). ), The magnetic flux density can be increased by that amount, whereby the driving force of the actuator 30 can be increased. In addition, this configuration can effectively use the space and contribute to the downsizing of the imaging device 50.
[Selection] Figure 3

Description

  The present invention relates to an imaging apparatus, and more particularly to an imaging apparatus suitable for use in an imaging apparatus using a solid-state imaging device such as a CCD image sensor or a CMOS image sensor.

  2. Description of the Related Art In recent years, an image pickup apparatus equipped with an autofocus mechanism (hereinafter referred to as an AF mechanism) is mounted along with improvement in performance of an image pickup apparatus using a charge coupled device (CCD) type or a complementary metal oxide semiconductor (CMOS) type solid-state image pickup device. Mobile phones are becoming popular.

Patent Document 1 discloses a lens driving device that can be used in such an imaging apparatus, and that can be used to drive the lens in the optical axis direction by arranging an actuator around the lens.
JP 2004-280031 A

  By the way, in the general voice coil motor used for the imaging device described in Patent Document 1, the magnet disposed around the coil has a hollow cylindrical shape, whereas the space for installing the imaging device is used. Are often prepared in a rectangular tube shape. In such a case, there is a problem that the installation space cannot be effectively used, and the driving force of the voice coil motor is low for the maximum size of the imaging device.

  The present invention has been made in view of the problems of the related art, and an object thereof is to provide an imaging apparatus having a compact configuration and capable of increasing the driving force of an actuator.

An imaging apparatus according to claim 1 is provided.
A housing,
An imaging lens including at least one movable lens movable in the optical axis direction with respect to the housing;
An actuator for moving the movable lens,
The thickness of the magnet of the actuator in the direction orthogonal to the optical axis of the imaging lens differs according to the circumferential position.

  In general, it is known that the magnetic flux density can be increased by increasing the thickness of the magnet. Therefore, according to the present invention, when the space for installing the imaging device is a non-cylindrical shape (for example, a rectangular tube shape), the actuator magnet is orthogonal to the optical axis of the imaging lens so as to be adapted thereto. By making the wall thicknesses different in the direction to perform, it is possible to effectively use the space and to secure the driving force of the actuator.

  According to a second aspect of the present invention, in the invention according to the first aspect, the yoke of the actuator has a polygonal cross section in a direction perpendicular to the optical axis of the imaging lens, and the magnet of the actuator Since the thickness at the position facing at least one corner of the yoke is thicker than the thickness at other positions, the magnetic flux density can be increased by the thickness, Thus, the driving force of the actuator can be increased. In addition, since the thickness of a part of the magnet is increased by using a space that is not used, the space can be effectively used, contributing to the downsizing of the imaging apparatus. The “position facing the corner” means a position within a range of ± 20 ° around the optical axis with respect to the position closest to the corner.

  According to a third aspect of the present invention, in the invention of the first or second aspect, the center of gravity of the magnet substantially coincides with the optical axis of the imaging lens when the cross section in the direction perpendicular to the optical axis of the imaging lens is taken. Therefore, it is possible to secure a balance during driving.

  An imaging device according to a fourth aspect of the present invention is the imaging device according to any one of the first to third aspects, wherein the magnet has a plurality of fan-shaped or rectangular cross sections in a direction perpendicular to the optical axis of the imaging lens. The second divided portion at a position rotated by 45 degrees around the optical axis from the first divided portion having the thickest thickness in the direction perpendicular to the optical axis has a thickness in the direction perpendicular to the optical axis as compared with the first divided portion. It is characterized by being thin.

  According to a fifth aspect of the present invention, in the invention of the fourth aspect, the four first divided portions and the four second divided portions are alternately arranged in the circumferential direction. And

  According to the present invention, it is possible to provide an imaging apparatus that has a compact configuration and can increase the driving force of an actuator.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of an image pickup apparatus 50 including the image pickup apparatus according to the present embodiment. FIG. 2 is a cross-sectional view of the image pickup apparatus 50 shown in FIG. FIG. FIG. 3 is a view of the imaging device 50 of FIG. 2 taken along the line III-III and viewed in the direction of the arrow.

  The imaging apparatus 50 includes a CMOS image sensor 51 as a solid-state imaging device having a photoelectric conversion unit 51a, an imaging lens 10 as an imaging lens that causes the photoelectric conversion unit 51a of the image sensor 51 to capture a subject image, and an image sensor. IR cut filter F disposed between 51 and imaging lens 10, substrate 52 having external connection terminal 54 (FIG. 1) for holding image sensor 51 and transmitting and receiving electrical signals, and imaging lens An assembly housing 20 to be supported and an actuator (also referred to as a focus actuator) 30 for driving a focusing lens are provided, and these are integrally formed. The height Δ in the optical axis direction of the imaging apparatus 50 is 10 mm or less.

  In the image sensor 51, a photoelectric conversion unit 51a as a light receiving unit in which pixels (photoelectric conversion elements) are two-dimensionally arranged is formed in the center of a plane on the light receiving side. A processing circuit (not shown) is formed. Such a signal processing circuit includes a drive circuit unit that sequentially drives each pixel to obtain a signal charge, an A / D conversion unit that converts each signal charge into a digital signal, and a signal that forms an image signal output using the digital signal. It consists of a processing unit and the like. A number of pads (not shown) are arranged near the outer edge of the plane on the light receiving side of the image sensor 51, and are connected to the substrate 52 via wires W. The image sensor 51 converts the signal charge from the photoelectric conversion unit 51 a into an image signal such as a digital YUV signal, and outputs the image signal to a predetermined circuit on the substrate 52 via the wire W. Here, Y is a luminance signal, U (= R−Y) is a color difference signal between red and the luminance signal, and V (= BY) is a color difference signal between blue and the luminance signal. Note that the image sensor is not limited to the above CMOS image sensor, and other devices such as a CCD may be used.

  The substrate 52 includes a support flat plate 52a that supports the image sensor 51 and the outer cylinder 21 on one plane, and a flexible substrate 52b (FIG. 1) having one end connected to the support flat plate 52a.

  The support flat plate 52a has a large number of signal transmission pads provided on the surface thereof, which are connected to the wires W from the image sensor 51 described above and to the flexible substrate 52b.

  As described above, one end of the flexible substrate 52b is connected to the support flat plate 52a, and the support flat plate 52a and an external circuit (for example, a host device on which an imaging device is mounted) are connected via an external connection terminal 54 provided at the other end. Control circuit), and a voltage and a clock signal for driving the image sensor 51 are supplied from an external circuit, and a digital YUV signal can be output to the external circuit. Furthermore, the intermediate portion in the longitudinal direction of the flexible substrate 52b is flexible or easily deformable, and the deformation gives freedom to the orientation and arrangement of the external output terminals with respect to the support flat plate 52a.

  An assembly housing 20 made of a light-shielding member is disposed so as to surround the image sensor 51, and is attached to a lower cylinder 21A in which a lower end is bonded to the substrate 52 using an adhesive B and an upper part of the lower cylinder 21A. The outer cylinder 21 including the short cylinder-shaped upper cylinder 21 </ b> B and a yoke 31 attached to the outer cylinder 21 are included.

  In FIG. 2, an IR cut filter F is attached to a flange portion 21a extending from the inner periphery of the lower cylinder 21A in the direction perpendicular to the optical axis.

  The movable cylinder 22 movably arranged with respect to the assembly housing 20 includes a short large cylindrical portion 22a, a long small cylindrical portion 22b connected to the upper end thereof, and a small flange portion 22c formed on the upper end thereof. A holding member 22e is provided which includes a large flange portion 22d extending in the radial direction from the lower end of the large cylindrical portion 22a, and is attached so as to close the large cylindrical portion 22a. The movable cylinder 22 holds the fixed lens in the order of the first lens L1, the second lens L2, the third lens L3, and the fourth lens L4 from the object side. A stopper SP is provided on the upper surface of the flange portion 21a, and the movement of the movable cylinder 22 is restricted by contacting the holding member 22e. A central opening of the small flange portion 22c is an aperture stop S.

  The flange portion L1f of the first lens L1 is abutted and fitted so as to include the upper portion of the flange portion L2f of the second lens L2. Further, the flange portion L3f of the third lens L3 is abutted and fitted so as to contain the lower portion of the flange portion L2f of the second lens L2. The outer diameters of the first lens L1 and the second lens L2 are slightly smaller than the outer diameter of the third lens L3. Accordingly, when the lenses L1 to L3 are assembled in the small cylindrical portion 22b in a manner described later, the optical axis of the lens with respect to the moving cylinder 22 is the inner peripheral surface of the small cylindrical portion 22b and the outer diameter of the third lens L3. The optical axis of the third lens L3 and the optical axes of the first lens L1 and the second lens L2 are accurately positioned by the fitting between the flange portions by fitting.

  On the other hand, the flange portion L4f of the fourth lens L4, which is the most image side lens, is fitted against the inner periphery of the large cylindrical portion 22a, thereby positioning the optical axis of the fourth lens L4 with respect to the movable barrel 22. It can be done with high accuracy. The holding member 22e is attached to the lower surface of the flange portion L4f of the fourth lens L4.

  An actuator 30 is disposed outside the small cylindrical portion 22b of the moving cylinder 22 in the direction perpendicular to the optical axis. The actuator 30 is bonded to the upper end of the large flange portion 22d of the moving cylinder 22 and extends in the optical axis direction. The actuator 30 is wound in the circumferential direction around the optical axis, and the upper cylinder 21B. A magnet 32 disposed so as to enclose the coil 33, and a yoke 31 that supports the magnet 32 and covers the upper periphery from the upper side to the inner periphery of the coil 33, with a lower end attached to the upper tube 21B. It is made up of.

  2 and 3, the yoke 31 has a rectangular outer wall 31a, a cylindrical inner wall 31b, and a top wall 31c connecting the upper edge of the outer wall 31a and the upper edge of the inner wall 31b. As shown in FIG. 3, the magnet 32 is divided into four in the circumferential direction to form divided portions 32a. Each divided portion 32a has a substantially triangular prism shape, and a space between the outer wall 31a and the inner wall 31b. It has a shape that fills Accordingly, the thickness t of the divided portion 32a is the thickest at the position facing the corner of the outer wall 31a.

  In FIG. 2, a spring member 27 having a shape in which donut discs having different diameters are connected to each other with the connecting positions shifted in phase is fixed to the vicinity of the lower end of the upper cylindrical portion 21B, and the inner peripheral side is held as a holding member. It is fixed to the lower surface of 22e. On the other hand, a spring member 28 having a shape similar to that of the spring member 27 has its outer peripheral side fixed to the upper surface of the yoke 31 and its inner peripheral side fixed to the upper end of the movable cylinder 22. The spring members 27 and 28 generate an urging force in response to the movement cylinder 22 moving in the optical axis direction.

  The plus terminal of the coil 33 of the actuator 30 is connected to the spring member 27 via a wiring H1 + that passes through the large flange portion 22d of the movable cylinder 22 and extends on the outer wall of the holding member 22e. Further, the spring member 27 is connected to the substrate 52 through H2 + that penetrates the outer wall of the upper cylinder 21B and extends the outer wall of the lower cylinder 21A. Further, the negative terminal of the coil 33 is connected to the spring member 28 via a wiring H <b> 1 that extends through the outer wall of the small cylindrical portion 22 b of the movable cylinder 22. The spring member 28 is connected to the substrate 52 via H2- extending through the outer wall of the yoke 31, the upper cylinder 21B, and the lower cylinder 21A. The driving principle of the voice coil motor is well known and will be omitted. However, the magnetic force generated by supplying electric power to the coil 33 from the outside via the spring members 27 and 28 and the wirings H1 +, H2 +, H1- and H2-. Thus, the coil 33 can be displaced with respect to the magnet 32 in accordance with the supplied electric power.

  The imaging lens 10 has, in order from the object side, an aperture stop S, a first lens L1 having a positive refractive power and a convex surface facing the object side, a second lens L2 having a negative refractive power, and a positive refractive power. The third lens L3 and the fourth lens L4 having negative refractive power are included. In the present embodiment, the lenses L1, L2, L3, and L4 constitute a focusing lens (also referred to as a movable lens). However, since the outer diameters of the lenses L1 to L3 are smaller than those of the lens L4, the outer diameters thereof. The large actuator 30 can be mounted using the difference.

  The imaging lens 10 is used to form a subject image on a solid-state imaging device using the aperture stop S and the lenses L1, L2, L3, and L4 as an optical system. The aperture stop S is a member that determines the F number of the entire imaging lens system.

  The IR cut filter F held by the flange portion 21a of the outer cylinder 21 between the imaging lens 10 and the image sensor 51 is a member formed in, for example, a substantially rectangular shape or a circular shape.

  Further, a light-shielding mask SM is disposed between the first lens L1 and the second lens L2 and between the second lens L2 and the third lens L3, so that the outside of the lens effective diameter close to the solid-state imaging device. It is possible to prevent unnecessary light from being incident on the light source and to suppress generation of ghosts and flares.

  A usage mode of the imaging apparatus 50 described above will be described. FIG. 4 is a diagram illustrating a state in which the imaging device 50 is installed in a mobile phone 100 as a mobile terminal. FIG. 5 is a control block diagram of the mobile phone 100.

  In the imaging device 50, for example, the object-side end surface of the outer cylinder 21 in the imaging lens is provided on the back surface of the mobile phone 100 (the liquid crystal display unit side is the front surface), and is arranged at a position corresponding to the lower side of the liquid crystal display unit. Established.

  The external connection terminal 54 of the imaging device 50 is connected to the control unit 101 of the mobile phone 100 and outputs an image signal such as a luminance signal or a color difference signal to the control unit 101 side.

  On the other hand, as shown in FIG. 5, the mobile phone 100 controls each part in an integrated manner, and supports and inputs a control part (CPU) 101 that executes a program corresponding to each process, and a number and the like with keys. An input unit 60, a display unit 70 for displaying captured images and videos in addition to predetermined data, a wireless communication unit 80 for realizing various information communication with an external server, and a mobile phone 100 By a storage unit (ROM) 91 that stores necessary data such as system programs, various processing programs, and terminal IDs, and various processing programs and data executed by the control unit 101, or processing data, or the imaging device 50 And a temporary storage unit (RAM) 92 that is used as a work area for temporarily storing imaging data and the like.

  When the photographer holding the mobile phone 100 directs the optical axis of the imaging lens 10 of the imaging device 50 toward the subject, an image signal is captured by the image sensor 51. For example, by performing image plane AF processing or the like, The focus shift can be detected. Since the control unit 101 supplies power to the actuator 30 so as to drive the lenses L1 to L4 in a direction to eliminate this focus shift, the wirings H1 +, H2 +, H1-, H2- are connected from the external connection terminal 54. The electric power is supplied to the coil 33 through this. Since the generated magnetic force and the biasing force of the deformed spring members 27 and 28 are balanced, the lenses L1 to L4 can be moved and held together with the movable barrel 22 to the optimum focusing position. Autofocus operation can be realized. If the driving force of the actuator 30 disappears due to the interruption of the power supply, the movable cylinder 22 returns to the original position.

  When the photographer presses the button BT shown in FIG. 4 at a desired photo opportunity, the release is performed, and the image signal is taken into the imaging device 50. The image signal input from the imaging device 50 is transmitted to the control system of the mobile phone 100 and stored in the storage unit 92 or displayed on the display unit 70, and further, video information is transmitted via the wireless communication unit 80. Will be transmitted to the outside.

  According to the present embodiment, in the magnet 32 of the actuator 30, the thickness t at the position A facing the corner portion of the yoke 31 constituting a part of the housing is set to the other position C (for example, from the position A to 45). Therefore, the magnetic flux density can be increased accordingly, and the driving force of the actuator 30 can be increased accordingly. In addition, such a configuration can effectively use the space and contribute to the downsizing of the imaging device 50. Further, in the present embodiment, the magnet 32 has an axisymmetric arrangement with the optical axis as the center, and the thickness in the direction perpendicular to the optical axis is axisymmetrically thick. They can be matched to ensure a balance during driving.

  FIG. 6 is a view similar to FIG. 3 according to a modification of the present embodiment. For example, in order to increase the outer diameter of the lens in order to obtain higher optical performance, the diameter of the coil 33 needs to be increased. In such a case, if a cylindrical magnet is used as in the prior art, the maximum dimension of the actuator will increase. On the other hand, according to this modification, the diameter of the coil 33 can be increased without increasing the maximum dimension of the actuator.

  More specifically, in FIG. 6, as the diameter of the coil 33 is increased, the cross section in the direction perpendicular to the optical axis of the divided portion 32 a of the magnet 32 is reduced and pushed into the corner portion of the yoke 31. Also in this modified example, the thickness t of the position A facing the corner portion of the yoke 31 that constitutes a part of the housing is set to be larger than the thickness of the other position C (for example, the circumferential end of the divided portion 32a). Since the thickness is increased, a high magnetic flux density can be obtained even with the small divided portion 32a, and thereby the driving force of the actuator 30 can be increased.

  FIG. 7 is a view similar to FIG. 3 according to another modification of the present embodiment. The magnet 32 in the present modification includes a first divided portion 32a having a thickness t whose cross section in the direction perpendicular to the optical axis is fan-shaped and a second divided portion ta (<t) whose cross section in the direction perpendicular to the optical axis is fan-shaped. The division part 32a ′ is configured to be alternately arranged four by four in the circumferential direction. The thick first divided portion 32a is arranged at a position facing the corner of the rectangular support flat plate 52a so as not to protrude outward from the side in the direction perpendicular to the optical axis. The second divided portion 32a ′ at a position rotated 45 degrees around the optical axis from the thickest first divided portion 32a has a smaller thickness in the direction perpendicular to the optical axis than the first divided portion 32a. The outer wall 31a of the yoke 31 has a substantially cylindrical shape such that irregularities are periodically generated in the circumferential direction along the outer peripheral surfaces of the divided portions 32a and 32a '.

  According to this modification, the magnetic flux density of the magnet is increased by arranging the first divided portion 32a having a thick wall thickness t, as compared with the case where the second divided portion 32a ′ having a thin wall thickness t ′ is disposed on the entire circumference. And the driving force of the actuator 30 can be increased. Further, since the yoke 31 is arranged so as not to project outward from the rectangular support flat plate 52a in the direction orthogonal to the optical axis, the space can be effectively used while having a high driving force. .

  FIG. 8 is a view similar to FIG. 3 according to another modification of the present embodiment. As shown in FIG. 8, the magnet 32 in the present modification includes a first divided portion 32 a having a thickness t having a rectangular cross section in the optical axis orthogonal direction, and a thickness t ′ having a rectangular cross section in the optical axis orthogonal direction. (<T) 2nd division part 32a 'is set as the structure arrange | positioned 4 each alternately in the circumferential direction. The thick divided portion 32a is arranged at a position facing the corner of the rectangular support flat plate 52a, and the thin second divided portion 32a ′ is in the direction orthogonal to the optical axis along each side of the support flat plate 52a. The second divided portion 32a ′ at a position rotated by 45 degrees around the optical axis from the first divided portion 32a having the largest thickness in the direction perpendicular to the optical axis is arranged so as not to protrude outward. The thickness in the direction perpendicular to the optical axis is thinner than that of the dividing portion 32a. The outer wall 31a of the yoke 31 has a substantially octagonal cylindrical shape along the outer peripheral surface of the divided portions 32a and 32a '.

  According to this modification, the magnetic flux density of the magnet is increased by arranging the first divided portion 32a having a thick wall thickness t, as compared with the case where the second divided portion 32a ′ having a thin wall thickness t ′ is disposed on the entire circumference. And the driving force of the actuator 30 can be increased. Further, since the yoke 31 is disposed so as not to project outward from the rectangular support flat plate 52a in the direction orthogonal to the optical axis, the space can be used effectively while having a high driving force. .

  The present invention has been described above with reference to the embodiments. However, the present invention should not be construed as being limited to the above-described embodiments, and can be modified or improved as appropriate. For example, the movable lens may be any one or more of the lenses L1 to L4, and the total number of lenses is not limited to four.

It is a perspective view of the imaging device 50 concerning this Embodiment. It is the figure which cut | disconnected the imaging device 50 of FIG. 1 by the surface containing an II-II line | wire, and looked at the arrow direction. It is the figure which cut | disconnected the imaging device 50 of FIG. It is a figure which shows the state equipped with the imaging device 50 in the mobile telephone 100 as a portable terminal. 3 is a control block diagram of the mobile phone 100. FIG. It is a figure similar to FIG. 3 concerning the modification of this Embodiment. It is a figure similar to FIG. 3 concerning another modification of this Embodiment. It is a figure similar to FIG. 3 concerning another modification of this Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Imaging lens 20 Assembly housing | casing 21 Outer cylinder 21A Lower cylinder 21B Upper cylinder 21a Flange part 21b Recessed part 22 Moving cylinder 22a Large cylindrical part 22b Small cylindrical part 22c Small flange part 22d Large flange part 22e Holding member 27 Spring member 28 Spring member 30 Actuator 31 Yoke 31a Outer wall 31b Inner wall 31c Top wall 32 Magnet 32a, 32a ′ Dividing part 33 Coil 50 Imaging device 51 Image sensor 51a Photoelectric conversion part 52 Substrate 54 External connection terminal 60 Input part 70 Display part 80 Wireless communication part 92 Storage part DESCRIPTION OF SYMBOLS 100 Mobile phone 101 Control part B Adhesive BT Button F Cut filter H1 +, H2 +, H1-, H2- Wiring L1-L4 Lens S Aperture stop SP Stopper W Wire

Claims (5)

A housing,
An imaging lens including at least one movable lens movable in the optical axis direction with respect to the housing;
An actuator for moving the movable lens,
The imaging apparatus according to claim 1, wherein a thickness of the magnet of the actuator in a direction orthogonal to the optical axis of the imaging lens differs according to a circumferential position.   The actuator yoke has a polygonal cross-section in a direction perpendicular to the optical axis of the imaging lens, and the actuator magnet has a wall thickness at a position facing at least one corner of the yoke. The imaging apparatus according to claim 1, wherein the imaging apparatus is thicker than a thickness of the position.   3. The image pickup apparatus according to claim 1, wherein the center of gravity of the magnet substantially coincides with the optical axis of the image pickup lens when the cross section in the direction perpendicular to the optical axis of the image pickup lens is taken.   The magnet is composed of a plurality of divided portions having a fan-shaped or rectangular cross section in a direction perpendicular to the optical axis of the imaging lens, and from the first divided portion having the thickest thickness in the direction perpendicular to the optical axis around the optical axis. The imaging device according to any one of claims 1 to 3, wherein the second dividing unit at a position rotated by 45 degrees has a smaller thickness in the direction perpendicular to the optical axis than the first dividing unit. The imaging apparatus according to claim 4, wherein the four first division units and the four second division units are alternately arranged in a circumferential direction.

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