JP2007101934A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging apparatus achieving miniaturization and the reduction of cost. <P>SOLUTION: The imaging apparatus is equipped with: a lens barrel 4 housing and holding a lens group 3 for forming a subject image on an imaging device 1; a bobbin 6 which is formed in parallel with the optical axis direction of the lens group 3, whose outer periphery a coil 7 is wound round, and which a guide hole 6a pierces through in an optical axis direction; a guide shaft 9 inserted in the guide hole 6a so as to make the bobbin 6 freely slide in the optical axis direction; a yoke 13 fit to the guide shaft 9 and formed to hold the coil inside; magnets 15a and 15b provided between the yoke 13 and the coil 7 and forming a magnetic circuit through the yoke 13, the guide shaft 9 and the coil 7; a supporting part 5 connecting the lens barrel 4 and the bobbin 6 so as to make them cooperate; and a locking means for setting the maximum moving distance of the lens barrel 4 in the optical axis direction by making overhanging parts 8a and 8b provided on the supporting part 5 abut on a notched part 14 provided on the yoke 13. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image pickup apparatus mounted on a mobile phone, a PDA, or the like, and particularly relates to an image pickup apparatus having an autofocus function.

  2. Description of the Related Art Conventionally, in an imaging apparatus having an autofocus function mounted on a small camera or the like, a stepping motor is used as a means for moving a lens in the optical axis direction in order to photograph an arbitrary subject from an infinite position to a close position. And DC motors were used. However, in recent years, imaging devices have come to be mounted on mobile phones, PDAs, and the like, and further reduction in size and weight of imaging devices is required.

  In order to meet the demand for reduction in size and weight, a voice coil motor in which a coil is arranged in a magnetic circuit composed of a magnet and a yoke is used instead of a stepping motor and a DC motor.

  As an imaging apparatus using such a voice coil motor, a guided part protrudes from a part of a side edge of a lens holding frame that holds a lens group, and a driven part protrudes from the opposite side of the guided part. A cylindrical bobbin extending in the optical axis direction is integrally formed at the tip of the driven part, a coil is wound around the bobbin, a drive coil is provided, and current is supplied to the drive coil, The guided part of the lens holding frame slides between the maximum movement distances determined by the position detection device and the iris device provided on the guide shaft, thereby photographing an arbitrary subject from an infinite position to a close position. There is something. (For example, see Patent Document 1)

JP 2000-137156 A

  Since the conventional imaging device is configured as described above, the maximum movement distance of the lens holding frame that holds the lens group is determined by the position detection device or the iris device. Therefore, a position detection device or the like must be mounted separately. Therefore, there has been a problem that the image pickup apparatus is large and expensive.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an imaging apparatus that can be miniaturized by eliminating the position detection apparatus as described above.

  An image pickup apparatus according to the present invention includes a lens barrel that houses and holds a lens group that forms a subject image on an image pickup element, and is formed in parallel to the optical axis direction of the lens group. A bobbin with a guide hole inserted in the axial direction, a guide shaft that is inserted into the guide hole and makes the bobbin slidable in the optical axis direction, and is fitted to the guide shaft and sandwiched between the coils. A yoke, a magnet provided between the yoke and the coil and forming a magnetic circuit via the yoke, the guide shaft and the coil; a support portion for connecting the lens barrel and the bobbin; This is provided with locking means for setting the maximum movement distance of the lens barrel in the optical axis direction by contact between the support portion and the yoke.

  According to the present invention, since the support portion for cooperating the lens barrel and the bobbin is in contact with the yoke, the structure is provided with the locking means for setting the maximum movement distance in the optical axis direction of the lens barrel. Since there is no need to use a position detection device that detects the distance, there is an effect that the imaging device can be downsized.

Embodiment 1
With respect to Embodiment 1 of the present invention, the configuration of an imaging apparatus will be described first with reference to FIGS. For convenience of explanation, the X, Y, and Z axis directions are defined and explained as shown in FIGS. The Z-axis direction indicates the optical axis direction, and the + Z-axis direction indicates the direction in which the subject is present.

  FIG. 1 is a top cross-sectional view of the imaging device as viewed from the top surface side, which is cut along the II plane in FIG. 2 to be described later and viewed in the −Z-axis direction. FIG. 2 is a front sectional view of the imaging apparatus as viewed from the front side. FIG. 1 is a view taken along the II-II plane and viewed in the Y-axis direction. FIG. 3 is a side cross-sectional view of the imaging apparatus as viewed from the side, and is taken along the III-III plane in FIG. 2 and viewed in the −X axis direction.

  In the + Z-axis direction of the printed circuit board 2 on which the imaging device 1 such as a CCD is mounted, a lens group 3 including a plurality of lenses for forming a subject image on the imaging device 1 is provided in the center of the optical axis. The outer periphery of the lens group 3 is held by a cylindrical lens barrel 4. Further, a support portion 5 extending in the + X-axis direction is fixed from an end portion in the −Z-axis direction of the outer peripheral side edge of the lens barrel 4. A square bobbin 6 extending in the + Z-axis direction is integrally formed at the end of the support portion 5 opposite to the lens barrel 4, and a coil 7 is wound around the outer periphery thereof. A guide hole 6a passes through substantially the center. Further, between the lens barrel 4 and the bobbin 6 of the support portion 5, an overhanging portion 8 that constitutes a locking means for setting the maximum movement distance of the lens barrel 4 extends from the support portion 5 in the Y direction. It has been.

  A guide shaft 9 is slidably inserted in the guide hole 6a of the bobbin 6 in the Z-axis direction. One end of the guide shaft 9 is fixed to the bottom 10a of the case 10 fixed on the printed circuit board 2 and opened in the + Z-axis direction, and the other end covers the opening of the case 10. For example, it is fixed to the lid 12 fixed to the case 10 using an adhesive 11. The lid 12 has an opening 12 a that surrounds the lens barrel 4.

  In addition, a U-shaped yoke 13 that opens in the + Z-axis direction with respect to the coil 7 and surrounds the coil 7 is provided in the case 10. The yoke 13 has a hole 13 a for inserting the guide shaft 9. The guide shaft 9 is inserted into the hole 13 a and is fixed to the case 10. The yoke 13 and the guide shaft 9 may be fitted to the extent that a magnetic circuit described later can be formed. Further, the overhanging portion 8 provided in the support portion 5 is in contact with the lower end of the yoke 13 on the side of the lens barrel 4 in the −Z-axis direction, and the operation of the support portion 5 in the + Z-axis direction is locked. The notch part 14 which comprises the latching means for setting is formed.

  Magnets 15a and 15b are provided between the coil 7 and the yoke 13 to contact the yoke 13 and form a magnetic circuit. The magnets 15a and 15b are magnetized with an S pole on the coil 7 side and an N pole on the yoke 13 side.

  Next, the operation will be described with reference to FIGS. 4 to 10 in addition to FIGS.

  FIG. 4 shows an example of a power waveform input to the coil 7 in order to perform autofocus by operating the lens barrel 4 holding the lens group 3 in the Z-axis direction (optical axis direction). . In FIG. 4, a pulse waveform power is input to the coil 7. The width of this pulse waveform is variable. The electric power input to the coil 7 is indicated by Duty (%) which is a ratio of the pulse ON time (B in FIG. 4) and the pulse ON + OFF time (A + B in FIG. 4). Duty (%) is a value from 0 to 100%, 0% indicates a state without input power (always indicates 0 mA in FIG. 4), and 100% indicates a state where input power is continuous (always 200 mA in FIG. 4). Show).

  5 and 6 are explanatory diagrams showing electromagnetic force generated in the coil 7 when the pulse waveform power shown in FIG. 4 is input to the coil 7 (except for Duty = 0%). 5 is viewed from the direction shown in FIG. 1, and FIG. 6 is viewed from the direction shown in FIG. 5 and 6, a coil current 20 flows through the coil 7 as shown in FIG. The coil current 20 is a current generated in the coil 7 when the pulse waveform power (except for Duty = 0%) shown in FIG. 4 is input. As shown in FIG. 6, magnetic circuits 21a and 21b are formed from the N poles of the magnets 15a and 15b to the S poles of the magnets 15a and 15b through the yoke 13, the guide shaft 9, the bobbin 6, and the coil 7. At this time, since the coil current 20 flows so as to cut off the magnetic circuits 21a and 21b, the electromagnetic force 22 acts on the coil 7 in the + Z-axis direction as shown in FIG. This electromagnetic force 22 is a driving force that moves the lens barrel 4 holding the lens group 3 in the + Z-axis direction via the bobbin 6 around which the coil 7 is wound and the support portion 5 on which the bobbin 6 is fixed. Become. The magnitude of the electromagnetic force 22 changes with the value of Duty (%) shown in FIG.

  FIG. 7 is an explanatory diagram showing an example of the relationship between the duty (%) and the lens barrel movement amount (mm). In FIG. 7, the horizontal axis indicates the Duty (%) shown in FIG. 4, and the range is 0 to 100%. 0% indicates a state where there is no input power, and 100% indicates a state where power is continuously input. The vertical axis indicates the amount of movement (mm) of the lens barrel, and the range is 0 to 0.5 mm. Here, 0 mm indicates the initial position, and 0.5 mm indicates the maximum movement distance. This maximum moving distance is the distance from the initial position until the overhang portions 8a and 8b, which are locking means provided on the support portion 5, abut on the notch portions 14, which are locking means provided on the yoke 13. It is. As shown in FIG. 7, the lens barrel 4 moves between 0 mm as the initial position and 0.5 mm as the maximum movement distance when Duty = 0 to 100% (especially 40 to 70%).

  FIG. 8 is an explanatory diagram showing an example of the relationship between the subject distance that can be photographed and the lens barrel movement amount (mm). In FIG. 8, the horizontal axis indicates the subject distance that can be photographed from the close position to the infinity position, and the vertical axis indicates the amount of movement (mm) of the lens barrel shown in FIG. As shown in FIG. 8, at the infinity position, the amount of movement of the lens barrel is small, the lens barrel 4 is at the initial position or a position near it, and at the proximity position, the amount of movement of the lens barrel is large, and the lens barrel 4 is at the maximum moving distance. It becomes the maximum movement position after movement or its vicinity. The amount of movement of the lens barrel changes according to the subject distance between the proximity position and the infinity position.

  FIG. 9 is an operation explanatory diagram sequentially illustrating shooting operations of the imaging apparatus. FIGS. 10A and 10B are explanatory views showing the imaging apparatus in which the lens barrel 4 is in the initial position. FIGS. 11A and 11B are explanatory views showing an imaging apparatus in which the lens barrel 4 is in the imaging position. FIGS. 12A and 12B are explanatory views showing the imaging apparatus in which the lens barrel 4 is at the maximum movement position in the + Z-axis direction. FIG. 13 is a detailed explanatory view showing a state in which the locking plate 8 is in contact with the yoke 13 at the maximum movement position.

  First, as shown in FIGS. 10A and 10B, the lens barrel 4 is in the initial position. This initial position indicates the position of the lens barrel 4 in a state where the imaging apparatus is supplied with power and is in an ON state but does not perform photographing. That is, FIG. 7 shows a case where Duty = 0%. At this time, the surface in the −Z-axis direction of the support portion 5 fixed to the lens barrel 4 is in contact with the yoke 13, and the lens barrel 4 is in a position closest to the image sensor 1. This initial position can also be the shooting position of the subject at infinity. (S1 in FIG. 9)

  Next, in order to photograph a desired subject, when the imaging device is pointed at the subject, the imaging device, for example, responds to the distance measurement result of a distance measuring device that measures the distance between the separately provided imaging device and the subject. Then, a predetermined duty (%) electric power for performing focus adjustment is input to the coil 7. Along with the magnitude of the electric power input to the coil 7, an electromagnetic force 22 having a predetermined magnitude acts on the coil 7 in the + Z-axis direction. The bobbin 6 around which the coil 7 is wound, the support part 5 fixed to the bobbin 6, the locking plate 8 fixed to the support part 5, and the lens barrel 4 holding the lens group 3 are shown in FIG. As shown in (a) and (b), it moves a predetermined distance in the + Z-axis direction. Then, the movement in the + Z-axis direction is stopped at the focus position at which the subject image is formed on the image sensor 1, and the subject is photographed (so-called autofocus photographing). (S2, S3 in FIG. 9)

  Further, when photographing a subject, the lens barrel 4 moves in the + Z-axis direction in accordance with the value of the duty (%) input to the coil 7, but the photographing range from the infinity position to the close position. As shown in FIGS. 12 (a), 12 (b), and 13, the yoke 3 is provided on the yoke 3 in order to ensure that the lens barrel 4 is not moved more than necessary in the + Z-axis direction by the electromagnetic force 22. The locking plate 8 fixed to the support portion 5 is brought into contact with the notch portion 14. Thereby, the maximum movement distance is set. The maximum moving distance can also be the shooting position of the closest subject.

  Then, after the photographing of the subject is completed, the duty tube 4 is set to the initial position as shown in FIGS. 10A and 10B with Duty = 0%. Although the movement of the lens barrel 4 to the initial position is not shown, the force of an elastic body such as a spring acting in the −Z axis direction is used. (S4 in FIG. 9)

  According to the first embodiment, the imaging apparatus is formed in parallel with the lens barrel 3 that houses and holds the lens group 3 that forms the subject image on the imaging element 1 and the optical axis direction of the lens group 3, and is arranged on the outer periphery. A coil 7 is wound, a bobbin 6 with a guide hole 6a inserted in the optical axis direction, a guide shaft 9 inserted in the guide hole 6a, which makes the bobbin 6 slidable in the optical axis direction, and a guide shaft 9 A yoke 13 formed so as to fit and sandwich the coil, and magnets 15a and 15b provided between the yoke 13 and the coil 7 and forming a magnetic circuit via the yoke 13, the guide shaft 9 and the coil 7. The lens barrel 4 and the bobbin 6 are connected to cooperate with each other, the projecting portions 8a and 8b provided on the support portion 5 and the notch 14 provided on the yoke 13 are brought into contact with each other. Configured to set the maximum movement range in the optical axis direction Because, since there is no need to use a position detector for detecting the maximum range of movement, the effect of miniaturization of the imaging device can be realized. In addition, the cost can be reduced.

Embodiment 2
According to the first embodiment, as shown in FIG. 13, the surface in the + Z-axis direction of the locking plate 8 having a substantially rectangular cross-sectional shape is in contact with the surface in the −Z-axis direction of the notch portion 14. However, as shown in FIG. 14, the cross-sectional shapes of the overhang portions 8 a and 8 b may be circular or elliptical, and may be brought into contact with the surface in the −Z-axis direction of the notch portion 14. In this case, since the protruding portions 8a and 8b having a circular cross section are in contact with the surface in the −Z-axis direction of the notch portion 14 by a line, in addition to the effect of the first embodiment, the variation in the movement amount of the lens barrel 4 is varied. It has an effect that can be reduced.

Embodiment 3
According to the second embodiment, the cross-sectional shape of the overhang portions 8a and 8b is circular or elliptical, and is shown in contact with the surface in the −Z-axis direction of the notch portion 14 by a line. 15, the surface in the −Z-axis direction of the notch portion 14 has a convex shape, and abuts on the surface in the + Z-axis direction of the overhang portions 8 a and 8 b having the substantially rectangular cross-sectional shape shown in the first embodiment. You may let them. Also in this case, since the notch portion 14 and the overhang portions 8a and 8b are in contact with each other with a line, the same effect as in the second embodiment is obtained.

Embodiment 4
According to the first embodiment, the notch portion 14 is formed in the −X axis direction. However, as shown in FIG. 16, the notch portion 14 is substantially perpendicular to the center line direction inside the longitudinal direction of the case 10. It may be bent. In this case, the imaging device shown in Embodiment 1 can be further reduced in size because the notch portion 14 does not extend in the −X axis direction.

  The projecting portions 8a and 8b having a circular cross-sectional shape shown in the second embodiment and the notch portion 14 having a convex surface in the −Z-axis direction shown in the third embodiment are applied to the fourth embodiment. It is also possible.

1 is a top cross-sectional view of an imaging apparatus according to Embodiment 1 of the present invention. 1 is a front sectional view of an imaging apparatus according to Embodiment 1 of the present invention. It is side surface sectional drawing of the imaging device which concerns on Embodiment 1 of this invention. It is an electric power waveform diagram input into the imaging device which concerns on Embodiment 1 of this invention. It is explanatory drawing which showed the relationship between the electric power input into the imaging device which concerns on Embodiment 1 of this invention, and the electromagnetic force which arises in a coil. It is explanatory drawing which showed the relationship between the electric power input into the imaging device which concerns on Embodiment 1 of this invention, and the electromagnetic force which arises in a coil. It is explanatory drawing which showed the relationship between the electric power input into the imaging device which concerns on Embodiment 1 of this invention, and a lens barrel movement amount. It is explanatory drawing which showed the relationship between the lens barrel movement amount of the imaging device which concerns on Embodiment 1 of this invention, and the to-be-photographed object distance. It is explanatory drawing which showed the imaging | photography operation | movement of the imaging device which concerns on Embodiment 1 of this invention. It is composition explanatory drawing which showed the case where the lens-barrel of the imaging device which concerns on Embodiment 1 of this invention exists in an initial position. It is composition explanatory drawing which showed an example in case the lens-barrel of the imaging device which concerns on Embodiment 1 of this invention exists in an imaging position. It is composition explanatory drawing which showed the case where the lens-barrel of the imaging device which concerns on Embodiment 1 of this invention exists in the maximum movement range. It is a detailed explanatory view showing the contact state of the notch portion of the yoke and the overhang portion of the support portion when the lens barrel of the imaging apparatus according to Embodiment 1 of the present invention is in the maximum movement range. It is a detailed explanatory view showing the contact state of the notch portion of the yoke and the protruding portion of the support portion when the lens barrel of the imaging apparatus according to Embodiment 2 of the present invention is in the maximum movement range. It is detailed explanatory drawing which showed the contact state of the notch part of a yoke and the protrusion part of a support part in case the lens-barrel of the imaging device which concerns on Embodiment 3 of this invention exists in the maximum movement range. It is detailed explanatory drawing which showed the contact state of the notch part of a yoke in case the lens-barrel of the imaging device which concerns on Embodiment 4 of this invention exists in the maximum movement range, and the overhang | projection part of a support part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image pick-up element 2 Printed circuit board 3 Lens group 4 Lens barrel 5 Support part 6 Bobbin 6a Guide hole 7 Coil 8a, 8b Overhang part 9 Guide shaft 10 Case 10a Bottom plate 11 Adhesive 12 Lid 12a Opening part 13 Yoke 13a Hole 14 Notch 15a, 15b magnet

Claims (3)

A lens group that forms a subject image on the image sensor;
A lens barrel for storing and holding the lens group;
A bobbin that is formed in parallel to the optical axis direction of the lens group, a coil is wound around the outer periphery, and a guide hole is provided in the optical axis direction;
A guide shaft that is inserted into the guide hole and makes the bobbin slidable in the optical axis direction;
A yoke that is fitted to the guide shaft and formed to sandwich the coil;
A magnet provided between the yoke and the coil and forming a magnetic circuit via the yoke, the guide shaft and the coil;
A support portion for connecting the lens barrel and the bobbin, and for cooperating the lens barrel and the bobbin;
An imaging apparatus comprising: a locking unit that sets a maximum moving distance of the lens barrel in the optical axis direction by contacting the support portion with the yoke.   The locking means includes an overhanging portion fixed to the support portion, and a cutout portion provided in the yoke, wherein the overhanging portion abuts at the maximum moving distance. Imaging device. The imaging apparatus according to claim 2, wherein a part of the yoke is bent inwardly, and the notch portion with which the protruding portion abuts is provided at the bent portion.

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