JP4751639B2 - Lens tube, imaging device including lens barrel - Google Patents

Description

  The present invention relates to a lens barrel that holds an optical element such as a lens element or an optical filter, and an imaging device including the lens barrel, and more specifically, a lens barrel and a lens barrel that incorporate an electromagnetic motor including a cylindrical rotor. The present invention relates to an imaging apparatus provided.

  The integration of image sensors and signal processing circuits such as CCD (Charge Coupled Device) and CMOS (Complementary Metal-Oxide Semiconductor) has been improved and can be provided at low cost. (Simply called “digital cameras”) is rapidly spreading.

  In recent years, mobile phone terminals equipped with digital cameras, personal information terminals (PDAs) and the like have gained popularity. Furthermore, in the future, further spread of digital cameras is expected in fields such as surveillance cameras and in-vehicle cameras. Such a digital camera includes an imaging device. In general, an imaging apparatus includes an optical system, a lens barrel that holds the optical system, and an imaging sensor.

  In recent years, digital cameras that perform zooming and focusing by electric drive are the mainstream. Electric zooming and focusing are performed by driving a holding mechanism for a predetermined lens element included in the optical system using a motor and moving the lens element in a direction parallel to the optical axis.

  Conventionally, the lens element holding mechanism is driven using a general-purpose brushless motor. However, when the holding mechanism is driven using a general-purpose brushless motor, there is a problem in that a space for arranging the motor must be provided in the lens barrel, which increases the size of the lens barrel. In addition, a transmission mechanism for transmitting the rotation of the motor is necessary, and there is a problem that the lens barrel is enlarged.

On the other hand, Patent Document 1 discloses a cylindrical fixed tube, a lens holding frame that holds a lens element in the fixed tube so as to be movable in the optical axis direction, and a guide rod that guides the lens holding frame in the optical axis direction. In a lens driving device comprising a (shaft), a magnet is arranged on the outer periphery of the lens holding frame to constitute a rotor, and a coil and a yoke are arranged on the outer circumference of the rotor to constitute a hollow motor. Has proposed. In the lens driving device described in Patent Document 1, the entire lens driving device can be made compact by decentering the center of the magnet and coil from the lens element held by the lens holding frame.
JP-A-5-196850

  In the lens driving device described in Patent Document 1, the inner diameter of the fixed cylinder is much larger than the outer diameter of the lens holding frame. For this reason, the lens driving device described in Patent Document 1 is not a compact lens barrel in a direction perpendicular to the optical axis of the lens element.

  An object of the present invention is to provide a lens barrel that is compact in a direction perpendicular to the optical axis of a lens element.

The above object is achieved by the following imaging device. An imaging apparatus that outputs an image of a subject as an electrical image signal, and includes an imaging optical system that includes a predetermined lens group and forms an optical image of the subject, and an optical that is formed by the imaging optical system An imaging sensor that receives an image and converts an optical image into an electrical image signal and a lens barrel that holds a part or all of the lens group of the imaging optical system, the lens barrel holding the lens group A lens frame, an electromagnetic motor for moving the lens frame along the optical axis of the imaging optical system, and at least one for engaging the lens frame and guiding the lens frame in a direction parallel to the optical axis of the lens group The electromagnetic motor is rotationally symmetric about a symmetric axis parallel to the optical axis. The electromagnetic motor is provided on the outer periphery of the lens frame and includes a rotation restricting portion that restricts the lens frame from rotating about the shaft. The lens frame includes a pair of magnetic circuits As the shaft and the optical axis of the lens group does not coincide, it is arranged by parallel decentration with respect to the magnetic circuit, the shaft and the rotation regulating portion, an inner magnetic circuit, center relative axis of symmetry of the magnetic circuit It is arranged at a position where the angle is less than 180 degrees, and the symmetry axis of the magnetic circuit is arranged at a position closer to the shaft and the rotation restricting portion than the optical axis of the lens group.

  With the above configuration, in the imaging apparatus having an electromagnetic motor for driving the lens group, the inside of the fixed barrel of the lens barrel can be made compact compared to the case where the symmetry axis of the magnetic circuit is aligned with the optical axis. . Therefore, the imaging device according to the present invention is compact in the direction perpendicular to the optical axis.

Preferably, the lens barrel includes a cylindrical fixed cylinder, the electromagnetic motor includes a cylindrical rotor having a lens frame disposed therein, and the magnetic circuit includes a stator provided in the fixed cylinder and the rotor, The coil provided in any one and the magnet provided in the other are included. Preferably, the magnetic circuit includes a coil wound around the lens frame and a magnet disposed outside the lens frame.

  According to the present invention, it is possible to provide a compact barrel in a direction perpendicular to the optical axis of the lens element. Further, according to the present invention, it is possible to provide a compact imaging device including the above-described lens barrel.

(Embodiment 1)
FIG. 1 is a longitudinal sectional view of the imaging apparatus according to the first embodiment. The imaging apparatus 100 according to Embodiment 1 includes an imaging optical system 110, an imaging sensor 120, and a lens barrel 130.

  The imaging optical system 110 includes a first zoom lens group 111, a second zoom lens group 112, and a focus lens in order from the subject side (left side in the figure) to the image side (right side in the figure) along the optical axis 101. A group 113 and a low-pass filter 114 are included. The imaging optical system 110 forms an optical image of the subject on the imaging sensor 120.

  The first zoom lens group 111 and the second zoom lens group 112 perform zooming to change the magnification of the optical image of the subject by moving along the optical axis 101 while changing the distance between them. The first zoom lens group 111 includes a lens element 111A and a lens element 111B. The second zoom lens group 112 includes a lens element 112A, a lens element 112B, and a lens element 112C.

  The focus lens group 113 performs focusing for adjusting the in-focus state of the optical image of the subject by moving along the optical axis 101. The focus lens group 113 includes one lens element 113A.

  The low-pass filter 114 has an optical characteristic of cutting a predetermined spatial frequency component from the optical image of the subject. The low-pass filter 114 reduces the false color and moire of the optical image of the subject based on the optical characteristics.

  The image sensor 120 is a CCD. The imaging sensor 120 converts the optical image formed by the imaging optical system 110 into an electrical image signal and outputs it. The image sensor 120 may be a CMOS.

  The lens barrel 130 includes a base 131, a first lens frame 132, a second lens frame 133, a third lens frame 134, a guide shaft 135A, a guide shaft 135B, a zoom cam barrel 136, and a focus cam barrel 137. The zoom motor 140, the focus motor 150, and the front cover 160 are included. The lens barrel 130 includes three bearing shafts 135C, a bearing shaft 135D, and a bearing shaft 135E that are not shown in FIG.

  FIG. 2 is a perspective view illustrating a part of the imaging apparatus according to the first embodiment. FIG. 2 shows a state in which the zoom cam cylinder 136, the focus cam cylinder 137, the zoom motor 140, the focus motor 150, and the front cover 160 are removed from the configuration of the imaging apparatus 100.

  In FIGS. 1 and 2, the base 131 has a substantially disc shape perpendicular to the optical axis 101. The base 131 has a rectangular opening at the center, and holds the low-pass filter 114 and the image sensor 120 in the opening in order from the subject side. The base 131 holds a guide shaft 135A, a guide shaft 135B, and bearing shafts 135C to 135E.

  The first lens frame 132 holds the first zoom lens group 111. The first lens frame 132 has a substantially cylindrical shape with the optical axis 101 as the central axis. The first lens frame 132 has a cam pin 132A protruding in the outer peripheral direction, a rotation restricting portion 132B, and a through hole 132C parallel to the optical axis 101 on the outer peripheral portion. The cam pin 132A engages with a cam groove (not shown) provided in the zoom cam cylinder 136. The rotation restricting portion 132B engages with the guide shaft 135B while forming a slight play in the direction orthogonal to the optical axis 101. The through hole 132C is fitted to the guide shaft 135A.

  The second lens frame 133 holds the second zoom lens group 112. The second lens frame 133 has a substantially cylindrical shape with the optical axis 101 as the central axis. The second lens frame 133 generally has the same configuration as the first lens frame 132. That is, the second lens frame 133 has a cam pin (not shown) protruding in the outer peripheral direction, a rotation restricting part (not shown), and a through hole (not shown) parallel to the optical axis 101 at the outer peripheral part. Have The cam pin engages with a cam groove (not shown) provided in the zoom cam cylinder 136. The rotation restricting portion engages with the guide shaft 135B. The through hole holds the guide shaft 135A through.

  The third lens frame 134 holds the focus lens group 113. The third lens frame 134 has a substantially cylindrical shape with the optical axis 101 as the central axis. The third lens frame 134 generally has the same configuration as the first lens frame 132. That is, the third lens frame 134 has a cam pin (not shown) protruding in the outer peripheral direction, a rotation restricting part (not shown), and a through hole (not shown) parallel to the optical axis 101 on the outer peripheral part. Have The cam pin engages with a cam groove (not shown) provided in the focus cam cylinder 137. The rotation restricting portion engages with the guide shaft 135B. The through hole holds the guide shaft 135A through.

  The zoom cam cylinder 136 and the focus cam cylinder 137 have a cylindrical shape. The zoom cam cylinder 136 and the focus cam cylinder 137 have the same central axis 102 and can rotate around the central axis 102. The central axis 102 is the center of a circumscribed circle formed by the three bearing shafts 135C to 135E in a plane perpendicular to the optical axis. That is, the three bearing shafts 135C to 135E function as rotational bearings for the zoom cam cylinder 136 and the focus cam cylinder 137. Here, the optical axis 101 of the imaging optical system 110 does not coincide with the central axis 102. The relationship between the optical axis 101 and the central axis 102 will be described in detail later.

  A zoom motor 140 and a focus motor 150 are disposed on the outer peripheral side of the zoom cam cylinder 136 and the focus cam cylinder 137. The zoom motor 140 includes a stator 141 and a rotor 142. The stator 141 includes a lens barrel 143 that functions as a stator yoke, and a stator coil 141A. The rotor 142 includes a rotor magnet 142A and a rotor yoke 142B. The rotor yoke 142B has a flange portion 142C for reducing leakage magnetic flux from the end portion of the rotor magnet 142A.

  The focus motor 150 includes a stator 151 and a rotor 152. The stator 151 includes a lens barrel 143 that functions as a common stator yoke with the zoom motor 140, and a stator coil 151A. The rotor 152 includes a rotor magnet 152A and a rotor yoke 152B. The rotor yoke 152B has a flange portion 152C for reducing leakage magnetic flux from the end portion of the rotor magnet 152A.

  FIG. 3 is an exploded perspective view of the zoom motor of the imaging apparatus according to the first embodiment. In FIGS. 1 and 3, the lens barrel 143 has a cylindrical shape formed around the central axis 102. The lens barrel 143 is made of a ferromagnetic material such as an electromagnetic steel plate, and is a fixed cylinder held by a base 131 and a front cover 160 described later.

  The stator coil 141 </ b> A is fixed to the inner peripheral surface of the lens barrel 143. In the stator coil 141 </ b> A, a plurality of small coils wound in a spiral shape are arranged at a predetermined pitch along the inner peripheral surface of the lens barrel 143. The rotor magnet 142A is a permanent magnet and has the same number of magnetic poles as the small coils of the stator coil 141A. The magnetic poles are arranged so that N poles and S poles alternate along the outer peripheral surface of the rotor yoke 142B. The rotor yoke 142B is made of a ferromagnetic material such as an electromagnetic steel plate, and is disposed between the rotor magnet 142A and the zoom cam cylinder 136.

  The lens barrel 143 and the stator coil 141A that function as a stator yoke, the rotor magnet 142A, and the rotor yoke 142B constitute a magnetic circuit. In the zoom motor 140, a magnetic circuit is driven by a current applied to a small coil of the stator coil 141A from outside at a predetermined timing, and the rotor magnet 142A and the rotor yoke 142B rotate to function as an electromagnetic motor.

  Although the configuration of the zoom motor 140 is shown in FIG. 3, the focus motor 150 has a configuration that is almost the same as the zoom motor 140.

  That is, the stator coil 151 </ b> A is fixed to the inner peripheral surface of the lens barrel 143. In the stator coil 151 </ b> A, a plurality of small coils wound in a spiral shape are arranged at a predetermined pitch along the inner peripheral surface of the lens barrel 143. The rotor yoke 152B is bonded to the outer peripheral surface of the focus cam cylinder 137. The rotor yoke 152B is made of a ferromagnetic material such as an electromagnetic steel plate.

  The rotor magnet 152A is bonded to the outer peripheral surface of the rotor yoke 152B. The rotor magnet 152A is a permanent magnet and has magnetic poles equal to the number of small coils of the stator coil 151A. The magnetic poles are alternately arranged with N and S poles along the outer peripheral surface of the rotor yoke 152B.

  The stator 151 including the lens barrel 143 and the stator coil 151 </ b> A functioning as a stator yoke, the rotor magnet 152 </ b> A, and the rotor yoke 152 </ b> B constitute a magnetic circuit of the focus motor 150. In the focus motor 150, a magnetic circuit is driven by a current applied to the small coil of the stator coil 151A from the outside at a predetermined timing, and the rotor magnet 142A and the rotor yoke 142B rotate to function as an electromagnetic motor.

  In FIG. 1, the front cover 160 has a disk shape perpendicular to the optical axis 101. The front cover 160 is fixed to the most subject side of the imaging apparatus 100. The front cover 160 has a through hole that supports the guide shaft 135A and the guide shaft 135B.

  The end of the lens barrel 143 on the subject side is supported by the front cover 160. Further, the end of the lens body 143 on the image side is supported by the base 131. Since the lens barrel 143 is supported by the front cover 160 and the base 131, the distance between the stator coil 141A and the rotor magnet 142A and the distance between the stator coil 151A and the rotor magnet 152A are appropriately maintained.

  In the above configuration, when zooming is performed, a drive current is applied from the outside to the small coil of the stator coil 141A of the zoom motor 140 at a predetermined timing. The magnetic circuit is driven by the application of the drive current, and the rotor 142 rotates around the central axis 102.

  As the rotor 142 rotates about the central axis 102, the zoom cam cylinder 136 rotates about the central axis 102. When the zoom cam cylinder 136 rotates around the central axis 102, the cam pin 132A provided on the first lens frame 132 is guided along the coupled cam groove. When the zoom cam cylinder 136 rotates around the optical axis, the zoom cam cylinder 136 is guided along a cam groove to which a cam pin provided on the second lens frame 133 is coupled.

  The first lens frame 132 is guided by the guide shaft 135A and moves in a direction parallel to the optical axis 101. At this time, in the first lens frame 132, since the rotation restricting portion 132B is engaged with the guide shaft 135B, the degree of freedom of rotation around the guide shaft 135A in the plane perpendicular to the optical axis 101 is restricted. . Therefore, when the zoom cam cylinder 136 rotates around the optical axis, the rotational motion is converted into a straight motion, and the first lens frame 132 moves in a direction parallel to the optical axis according to the phase of the cam groove. That is, the cam groove of the zoom cam cylinder 136 and the cam pin 132A of the first lens frame 132 constitute a conversion mechanism.

  Similarly, the rotation of the second lens frame 133 around the guide shaft 135A in the plane perpendicular to the optical axis 101 is restricted by the engagement between the rotation restricting portion and the guide shaft 135B. Therefore, when the zoom cam cylinder 136 rotates around the optical axis, the rotational motion is converted into a straight motion, and the second lens frame 133 moves in a direction parallel to the optical axis according to the phase of the cam groove.

  As the first lens frame 132 and the second lens frame 133 move, the first zoom lens group 111 and the second zoom lens group 112 move to a predetermined position in a direction parallel to the optical axis while changing the distance between them. . As a result, the imaging apparatus 100 can perform zooming.

  When focusing is performed, a drive current is applied to the small coil of the stator coil 151A of the focus motor 150 from the outside at a predetermined timing. By applying the drive current, an electromagnetic force is generated in the magnetic circuit, and the rotor 152 rotates around the optical axis.

  As the rotor 152 rotates about the optical axis, the focus cam cylinder 137 also rotates about the optical axis. When the focus cam cylinder 137 rotates around the optical axis, the focus cam cylinder 137 is guided along a cam groove to which a cam pin provided on the third lens frame 134 is coupled.

  Similarly, the degree of freedom of rotation of the third lens frame 134 around the guide shaft 135A in the plane perpendicular to the optical axis 101 is restricted by the engagement between the rotation restricting portion and the guide shaft 135B. Therefore, when the focus cam cylinder 137 rotates around the optical axis, the rotational motion is converted into a straight motion, and the third lens frame 134 moves in a direction parallel to the optical axis according to the phase of the cam groove.

  FIG. 4 is a perspective view for explaining the positional relationship among the first lens frame, the two guide shafts, and the three bearing shafts in the lens barrel of the imaging apparatus according to the first embodiment. FIG. 5 is a front view for explaining the positional relationship among the first lens frame, the two guide shafts, and the three bearing shafts in the lens barrel of the imaging apparatus according to the first embodiment. In FIG. 5, the AA cross section corresponds to the cross section of FIG. 1.

  4 and 5, the three bearing shafts 135C to 135E determine a circumscribed circle C1. The circumscribed circle C <b> 1 corresponds to the inner peripheral surface of the zoom cam cylinder 136. On the other hand, the virtual circle C0 is an inner peripheral surface of the zoom cam cylinder that is necessary when the optical axis 101 and the central axis 102 of the lens barrel 143, which is a fixed cylinder, coincide with each other, with the contact of the bearing shaft 135C as a reference. Corresponding to

  As can be seen from FIGS. 4 and 5, in the lens barrel according to the first embodiment, the diameter of the circumscribed circle C1 is smaller than the diameter of the virtual circle C0. In other words, the lens barrel according to Embodiment 1 does not match the optical axis 101 and the central axis 102 of the lens barrel 143 that is a fixed cylinder, but causes the inner circumferential surface of the zoom cam cylinder 136 to be eccentrically parallel to each other. Is configured compactly.

  Furthermore, in the lens barrel according to the first embodiment, the central angle θ1 formed between the guide shaft 135B engaged with the guide shaft 135A and the rotation restricting portion 132B and the central axis 102 is less than 180 degrees. The amount of eccentricity between the optical axis 101 and the central axis 102 of the lens barrel 143 which is a fixed cylinder is very large. Thus, since the lens barrel according to Embodiment 1 has a very large amount of eccentricity between the optical axis 101 and the central axis 102, the inner peripheral surface of the zoom cam cylinder 136 is particularly optically aligned as compared with the conventional example. Compact in the direction perpendicular to

  If the zoom cam cylinder 136 can be reduced, the fixed cylinder and other members disposed on the outer periphery of the zoom cam cylinder 136 can be reduced. Therefore, the entire lens barrel can be reduced in size. In the lens barrel according to the first embodiment, the central angle θ1 formed between the guide shaft 135B engaged with the guide shaft 135A and the rotation restricting portion 132B and the central shaft 102 is 90 degrees or less. The amount of eccentricity is extremely large.

  The central axis 102 is also a symmetric center of a magnetic circuit including the lens barrel 143 and the stator coil 141A, the rotor magnet 142A, and the rotor yoke 142B. The imaging apparatus according to Embodiment 1 has a driving electromagnetic motor by causing the optical axis 101 and the central axis 102 of the magnetic circuit constituting the driving electromagnetic motor to coincide with each other without causing them to decenter with respect to each other. In the configuration, the inner peripheral surface of the zoom cam cylinder 136 can be configured compactly.

(Embodiment 2)
FIG. 6 is a perspective view of a part of a lens barrel according to the second embodiment. FIG. 7 is a front view of a part of the lens barrel according to the second embodiment. Since the lens barrel according to the second embodiment has the same schematic configuration as that of the lens barrel 130 according to the first embodiment, the characteristic configuration will be described below focusing on the differences. 6 is a perspective view showing the structure around the first lens frame 232 that holds the first zoom lens group 111 in the lens barrel according to Embodiment 2, and FIG. 7 is a front view of the structure shown in FIG. Corresponds to the figure.

  The first lens frame 232 holds the first zoom lens group 111. The first lens frame 232 has a substantially cylindrical shape with the optical axis 101 as the central axis. The first lens frame 232 has a cam pin 232A protruding in the outer peripheral direction, a rotation restricting portion 232B, and a through hole 232C parallel to the optical axis 101 on the outer peripheral portion. The cam pin 232A engages with a cam groove (not shown) provided in the zoom cam cylinder 236. The rotation restricting portion 232B engages with the guide shaft 235B while forming a slight play in a direction orthogonal to the optical axis 101. The through hole 232C is fitted to the guide shaft 135A.

  The zoom cam cylinder 236 has a cylindrical shape. The zoom cam cylinder 236 can rotate around the central axis 102. The zoom cam cylinder 236 fixes the rotor yoke 142B to the outer peripheral portion, and further fixes the rotor magnet 142A to the outer peripheral portion. The rotor magnet 142A and the rotor yoke 142B constitute a magnetic circuit of the zoom motor 140 together with the lens barrel 143 and the stator coil 141A described in the first embodiment. Further, both end portions of the rotor magnet 142A in the direction parallel to the optical axis 101 are formed with bearing portions 142C that slide with external hollow bearings. Unlike the lens barrel 130 according to the first embodiment, the zoom cam cylinder 236 is different from the structure in which the zoom cam cylinder 236 is rotatably held by three bearing shafts 135C to 135E. It is rotatably held around the central shaft 102 by an external hollow bearing (not shown).

  In the imaging apparatus to which the lens barrel according to the second embodiment is applied, when the zoom motor 140 is driven and the zoom cam barrel 236 rotates, the first lens frame 232 moves in a direction parallel to the optical axis 101 and the first zoom is performed. The lens group 111 can be moved along the optical axis 101.

  FIG. 8 is a front view illustrating the positional relationship between the first lens frame and the two guide shafts in the lens barrel according to the second embodiment. In FIG. 8, a circle C <b> 1 corresponds to the inner peripheral surface of the zoom cam cylinder 236. The virtual circle C0 is formed on the inner peripheral surface required for the zoom cam cylinder when the optical axis 101 and the central axis 102 of the lens barrel 143, which is a fixed cylinder, coincide with each other, with the contact point of the guide shaft 235B as a reference. Correspond.

  As can be seen from FIG. 8, in the lens barrel according to the eighth embodiment, the diameter of the circle C1 is smaller than the diameter of the virtual circle C0. In other words, the lens barrel according to the second embodiment is configured so that the optical axis 101 and the central axis 102 of the lens barrel 143 that is a fixed cylinder do not coincide with each other, and the two are decentered in parallel to each other. Is configured compactly.

  Furthermore, in the lens barrel according to the second embodiment, the central angle θ1 formed between the guide shaft 135A and the guide shaft 235B engaged with the rotation restricting portion 232B and the central axis 102 is less than 180 degrees. The amount of eccentricity between the optical axis 101 and the central axis 102 of the lens barrel 143 which is a fixed cylinder is very large. Thus, since the lens barrel according to Embodiment 1 has a very large eccentricity between the optical axis 101 and the central axis 102, the inner peripheral surface of the zoom cam cylinder 236 is particularly compact compared to the conventional one. is there.

  If the zoom cam barrel 236 can be made smaller as in the lens barrel according to the second embodiment, the fixed barrel and other members arranged on the outer periphery of the zoom cam barrel 236 can be made smaller. Therefore, the entire lens barrel can be reduced in size. The lens barrel according to the second embodiment has a central angle formed between the guide shaft 235B engaged with the guide shaft 135A and the rotation restricting portion 232B and the central axis 102 is 90 degrees or less. The lead amount is extremely large.

  FIG. 11 is a graph showing the relationship between the diameter of the circle C1 corresponding to the inner peripheral surface of the zoom cam cylinder and the central angle θ1 in the lens barrel according to the second embodiment. In FIG. 11, the vertical axis of the graph represents the diameter of a circle C1 that is a circumscribed circle, and the horizontal axis represents the central angle θ1. As can be seen from FIG. 11, the smaller the central angle θ1, the smaller the diameter of the circle C1. Therefore, if the central angle θ1 is less than 180 degrees, the circle C1 can be reduced. However, considering the balance between the size reduction of the lens barrel and the effect of the rotation restriction, it is desirable that the center angle θ1 is less than 150 degrees, particularly less than 90 degrees.

  The central axis 102 is also a symmetric center of a magnetic circuit including the lens barrel 143 and the stator coil 141A, the rotor magnet 142A, and the rotor yoke 142B. The imaging apparatus according to Embodiment 2 has a driving electromagnetic motor by causing the optical axis 101 and the central axis 102 of the magnetic circuit constituting the driving electromagnetic motor to coincide with each other without causing them to decenter with respect to each other. In the configuration, the inner peripheral surface of the zoom cam cylinder 236 is configured to be compact.

(Embodiment 3)
FIG. 9 is a schematic diagram illustrating a configuration of a lens barrel according to the third embodiment. FIG. 9A corresponds to a front view, and FIG. 9B corresponds to a plan view. Unlike the lens barrels according to the first and second embodiments, the lens barrel according to the third embodiment drives a lens group using a voice coil motor.

  9A and 9B, the first lens frame 301 has a cylindrical shape. The first lens frame 301 holds the first lens group 111 inside. The optical axis of the first lens 111 and the central axis of the first lens frame 301 do not coincide with each other, and both are arranged eccentrically in parallel.

  The first lens frame 301 has two through holes provided in parallel to the optical axis 101. One through-hole 301A is engaged with the guide shaft 135A and guides the first lens frame 132 in a direction parallel to the optical axis. The other through-hole 301B (rotation restricting portion) is engaged with the guide shaft 135B with a slight play in the direction around the optical axis of the first lens frame 301. The first lens frame 301 has a coil 303 wound around its outer periphery. A magnet having a magnetic pole directed in a direction parallel to the optical axis 101 is disposed around the first lens frame 301. Therefore, the central axis 102 is a symmetrical center of a magnetic circuit composed of the coil 303 and the magnet 302.

  In the above configuration, when a current is supplied to the coil 303 from the outside, an electromagnetic force is generated in the magnetic circuit, and the first lens frame 301 is driven in a direction parallel to the optical axis 101 according to the direction of the current. .

  In the lens barrel according to the third embodiment, the optical axis 101 and the central axis 102 of the magnetic circuit constituting the driving electromagnetic motor are not aligned with each other, so that the first lens frame 301 is entirely decentered from each other. It is made compact. In particular, the lens barrel according to the third embodiment has a central angle θ1 formed between the guide shaft 235B that engages with the guide shaft 135A and the through-hole 301B and the central axis 102 is less than 180 degrees. The amount of eccentricity between the shaft 101 and the central shaft 102 is very large.

  As described above, in the lens barrel according to the third embodiment, the amount of eccentricity between the optical axis 101 and the central axis 102 is very large, so that the first lens frame 301 itself is particularly compact compared to the conventional case. . Further, the lens barrel according to the third embodiment is extremely compact because it does not require a cam barrel or a fixed barrel. In the lens barrel according to the third embodiment, the center angle formed between the guide shaft 135B that engages with the guide shaft 135A and the through hole 301B and the central axis 102 is 90 degrees or less, so the amount of eccentricity is small. It is extremely large.

(Embodiment 4)
FIG. 12 is a front view illustrating the positional relationship among the first lens frame, the guide shaft, and the rotation restricting portion in the lens barrel according to the fourth embodiment. Since the lens barrel according to the fourth embodiment has the same schematic configuration as that of the lens barrel 130 according to the first embodiment, the characteristic configuration will be described below focusing on the differences.

  In FIG. 12, a circle C1 corresponds to the inner peripheral surface of a zoom cam cylinder (not shown). The virtual circle C0 corresponds to the inner peripheral surface necessary for the zoom cam cylinder when the optical axis 101 and the central axis 102 of the lens barrel, which is a fixed cylinder, coincide with each other. The rotation restricting portion 335B has a rod-like configuration that fits into a through-hole provided on the fixed cylinder side and extends in the optical axis direction.

  FIG. 13 is a front view illustrating the positional relationship among the first lens frame, the guide shaft, and the rotation restricting portion in the lens barrel according to the modification of the fourth embodiment. The lens barrel according to the modified example includes two rotation restricting portions 435B and 435C that are arranged symmetrically with respect to the center axis 102 instead of the rotation restricting portion 335B. The configuration of each rotation restricting portion is the same as that of the rotation restricting portion 335B shown in FIG.

  As can be seen from FIGS. 12 and 13, in the lens barrel according to the fourth embodiment, the diameter of the circle C1 is smaller than the diameter of the virtual circle C0. In other words, the lens barrel according to the fourth embodiment has a compact inner peripheral surface of the zoom cam barrel by aligning the optical axis 101 and the central axis 102 of the lens barrel, which is a fixed barrel, without causing them to coincide with each other. It is configured.

  Furthermore, the lens barrel according to the fourth embodiment has a center angle θ1 formed between the guide shaft 135A and the rotation restricting portion 435B and the central axis 102 of less than 180 degrees. The amount of eccentricity with respect to the central axis 102 of a certain lens barrel is very large. As described above, in the lens barrel according to the fourth embodiment, the amount of eccentricity between the optical axis 101 and the central axis 102 is very large, so that the inner peripheral surface of the zoom cam cylinder is particularly compact compared to the conventional one. .

  In particular, in the lens barrel according to the modification of the fourth embodiment, the central angle θ2 formed between the guide shaft 135A and the rotation restricting portion 435C and the central axis 102 is also less than 180 degrees. Rotation can be regulated stably while increasing the amount of eccentricity with respect to the central axis 102 of the lens barrel, which is a fixed cylinder.

  Each embodiment described above can be modified as appropriate. For example, the configuration of the imaging optical system is not limited to a zoom lens system including three lens groups. It may be a zoom lens system composed of two or four or more lens groups. The lens barrel mechanism of Embodiments 1 to 4 may be applied according to the configuration of the zoom lens system.

  Further, the imaging optical system may be a single focus lens system. In this case, it is known that all the imaging optical systems are extended to perform focusing, or some lens groups are extended to perform focusing. However, these lens barrels are not limited to those described in the first to fourth embodiments. A lens barrel mechanism may be applied.

  In addition, the lens barrel of each embodiment is configured to engage the rotation restricting portion of the lens frame with a shaft arranged along a direction parallel to the optical axis, but is not limited thereto. For example, the rotation restricting portion may be engaged with a component such as a guide groove provided outside the lens frame and inside the cam cylinder along a direction parallel to the optical axis.

  Further, in the imaging devices according to Embodiment 1, Embodiment 2, and Embodiment 4, the magnetic circuit has a configuration in which the stator includes a stator coil and the rotor includes a rotor magnet. . As an electromagnetic motor, the stator may include a stator magnet and the rotor may include a rotor coil.

  FIG. 10 is a perspective view showing an example of a mobile phone terminal to which the imaging device of each embodiment is applied. The mobile phone terminal 400 is a foldable type and includes a hinge part 401. In this example, the imaging device 100 according to Embodiment 1 is provided in the hinge unit 401 of the mobile phone terminal 400. As described above, the imaging apparatus 100 is configured to be compact in the direction perpendicular to the optical axis by arranging the central axis of the fixed cylinder and the optical axis of the lens group in parallel eccentricity. 401 can be made compact. Therefore, the imaging apparatus 100 can make the mobile phone terminal 400 thin.

  Of course, it goes without saying that the imaging apparatus 100 may be arranged other than the hinge part 401 of the mobile phone terminal 400. Since the imaging device 100 is configured to be compact particularly in a direction perpendicular to the optical axis, it can contribute to miniaturization of the mobile phone terminal regardless of the position.

  The imaging apparatus 100 may be mounted on a device such as a digital still camera, a digital video camera, or a PDA (Personal Digital Assistance). Even if it is mounted on any device, it can contribute to the downsizing of those devices. Further, instead of the imaging device 100, the imaging devices of Embodiments 2 to 4 may be arranged in the above-described device.

  The lens barrel and the imaging apparatus of the present invention are suitable for digital still cameras, digital video cameras, mobile phone terminals with camera functions, PDAs, and the like, which are required to be downsized and highly functional.

1 is a longitudinal sectional view of an imaging apparatus according to Embodiment 1. FIG. FIG. 3 is a perspective view showing a part of the imaging apparatus according to Embodiment 1; 1 is an exploded perspective view of a zoom motor of the imaging apparatus according to Embodiment 1. FIG. The perspective view explaining the positional relationship between the first lens frame, the two guide shafts, and the three bearing shafts in the imaging apparatus according to Embodiment 1. FIG. The front view explaining the positional relationship between the first lens frame, the two guide shafts, and the three bearing shafts in the imaging apparatus according to the first embodiment. A perspective view of a part of an imaging apparatus according to Embodiment 2 Front view of a part of an imaging apparatus according to Embodiment 2 The front view explaining the positional relationship of a 1st lens frame and two guide shafts in the imaging device concerning Embodiment 2. FIG. Schematic diagram showing the configuration of the lens barrel according to the third embodiment. The perspective view which shows an example of the mobile telephone terminal to which an imaging device is applied In the lens barrel according to Embodiment 2, a graph showing the relationship between the diameter of the circle C1 corresponding to the inner peripheral surface of the zoom cam barrel and the central angle θ1. The front view explaining the positional relationship between a 1st lens frame, a guide shaft, and a rotation control part in the lens-barrel which concerns on Embodiment 4. FIG. The front view explaining the positional relationship between a 1st lens frame, a guide shaft, and a rotation control part in the lens-barrel which concerns on the modification of Embodiment 4. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Image pick-up device 101 Optical axis 102 Center axis 110 Imaging optical system 111 1st zoom lens group 112 2nd zoom lens group 113 Focus lens group 114 Low pass filter 120 Image sensor 130 Lens barrel 131 Base 132 First lens frame 132A Cam pin 132B Rotation restriction Part 132C Through-hole 133 Second lens frame 134 Third lens frame 135A Guide shaft 135B Guide shaft 135C Bearing shaft 135D Bearing shaft 135E Bearing shaft 136 Zoom cam barrel 137 Focus cam barrel 140 Zoom motor 141 Stator 142 Rotor 143 Lens body 150 Focus motor 151 Stator 152 Rotor 160 Front cover 232 First lens frame 232A Cam pin 232B Rotation restricting portion 232C Through hole 235B Guy Deshaft 236 Zoom cam cylinder 301 First lens frame 302 Magnet 303 Coil 335B Rotation restriction part 400 Mobile phone terminal 401 Hinge part 435B Rotation restriction part 435C Rotation restriction part

Claims (3)

An imaging device that outputs an image of a subject as an electrical image signal,
An imaging optical system that includes a predetermined lens group and forms an optical image of the subject;
An imaging sensor that receives an optical image formed by the imaging optical system and converts the optical image into the electrical image signal;
A lens barrel that holds a part or all of the lens group of the imaging optical system,
The lens barrel is
A lens frame for holding the lens group;
An electromagnetic motor for moving the lens frame along the optical axis of the imaging optical system;
At least one shaft engaged with the lens frame and guiding the lens frame in a direction parallel to the optical axis of the lens group;
A rotation restricting portion that is provided on an outer peripheral portion of the lens frame and restricts the lens frame from rotating around the shaft;
The electromagnetic motor includes a magnetic circuit that is rotationally symmetric about an axis of symmetry parallel to the optical axis,
The lens frame is arranged to be decentered parallel to the magnetic circuit so that the symmetry axis of the magnetic circuit does not coincide with the optical axis of the lens group,
The shaft and the rotation restricting portion are arranged inside the magnetic circuit at a position where a central angle with respect to the symmetry axis of the magnetic circuit is less than 180 degrees,
The imaging apparatus according to claim 1, wherein the symmetry axis of the magnetic circuit is disposed at a position closer to the shaft and the rotation restricting unit than the optical axis of the lens group. The lens barrel includes a cylindrical fixed cylinder,
The electromagnetic motor includes a cylindrical rotor having the lens frame disposed therein,
The magnetic circuit is:
The imaging device according to claim 1, comprising: a stator provided on the fixed cylinder; a coil provided on one of the rotors; and a magnet provided on the other. The magnetic circuit is:
The imaging device according to claim 1, comprising: a coil wound around the lens frame; and a magnet disposed outside the lens frame.

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