JP2007171704A - Lens drive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens drive which is used for an imaging apparatus and performs the focal position control of a lens group by driving the lens group with a voice coil motor and a DC motor, in which highly accurate lens position control inhibited in hysterisis as much as possible can be performed. <P>SOLUTION: The lens drive has: a lens group 1 which is slidable in an optical direction; the voice coil motor being a lens drive means driving the lens group 1; and a drive control section 10 being a drive control means which controls the lens drive means so that the moving operation of the lens group 1 from the repeated position of a U-turn operation or a movement start position to a prescribed stop position, just before the lens group 1 is stopped at the prescribed stop position in a focusing operation may always have the same prescribed moving direction and the same prescribed moving amount. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a lens driving device capable of accurately performing a focusing operation of a lens group of an imaging device.

  In a conventional imaging apparatus, a stepping motor, a DC motor, a voice coil motor, or the like is used to drive a lens group, and a lens driving device that controls these focusing operations is provided. When the lens group is driven using this stepping motor or the like, the lens driving device has a problem of hysteresis characteristics that the position of the lens group differs depending on the driving direction. Therefore, in order to correct the focus shift caused by the hysteresis characteristic, the drive direction in which the maximum focus evaluation value is detected and the drive direction when the lens group is moved to the in-focus position are made to coincide. The lens group is driven with a U-turn. Thereby, the influence of the hysteresis characteristic of the lens driving device could be reduced (for example, see Patent Document 1).

Japanese Patent Laid-Open No. 8-186852 (page 5, FIG. 12)

  As described above, the conventional lens driving device described in Patent Document 1 drives the lens group by making a U-turn so that the driving direction when the lens group is moved to the in-focus position is always the same direction. Although the influence of the hysteresis characteristics of the lens drive device could be reduced to some extent, it was not a satisfactory level for the recent strong demand for image quality of image pickup devices. There was a problem that accuracy was required.

  The present invention has been made to solve the above-described problems, and provides a lens driving device capable of sufficiently suppressing the hysteresis characteristic in the focusing operation of the lens group and performing highly accurate lens position control. The purpose is to provide.

  The lens driving device according to the present invention stops at a predetermined stop position in a focusing operation, a lens group that is slidable in the optical axis direction, a lens driving unit that drives the lens group in the optical axis direction. The lens so that the movement operation of the lens group immediately before the turn-back position or movement start position of the U-turn movement to the predetermined stop position always has the same predetermined movement direction and the same predetermined movement amount. Drive control means for controlling the drive means.

  According to the present invention, the movement operation of the lens group from the U-turn operation return position or the movement start position to the predetermined stop position immediately before stopping at the predetermined stop position is always the same predetermined movement direction. Since the drive control means controls the lens driving means so as to have the same predetermined movement amount, it is possible to sufficiently suppress the hysteresis characteristic in the focusing operation and perform extremely high-precision lens position control. There is an effect that can be done.

  Hereinafter, a lens driving device according to an embodiment of the present invention will be described by taking as an example the case where the lens driving means is a voice coil motor.

Embodiment 1 FIG.
FIGS. 1 to 3 show structural views of Embodiment 1 of the lens driving device according to the present invention. FIG. 1 is a perspective view, FIG. 2 is a top view, and FIG. 3 is a line AA shown in FIG. FIG.
1, 2, and 3 indicate the same or corresponding parts.
Below, it demonstrates using FIGS. 1-3.

  The direction of the optical axis OA of the lens group 1 including the small-diameter lens 1a and the large-diameter lens 1b shown in FIG. 3 is defined as the Z direction, and one direction in a plane orthogonal to the optical axis OA is defined as the Y direction. Also, the direction orthogonal to the Y direction in the plane orthogonal to the optical axis OA is defined as the X direction. Regarding the Z direction, the direction toward the subject is defined as upward (that is, + Z direction), and the direction toward the solid-state imaging device 2 is defined as downward (that is, −Z direction).

  The lens driving device is slidable with a substantially ring-shaped small-diameter frame portion 3 a that holds the small-diameter lens 1 a, a substantially ring-shaped large-diameter frame portion 3 b that holds the large-diameter lens 1 b, and the guide shaft 4. The lens movable member 3 includes a support portion 3d that is formed and has a guide hole 3c penetrating in the Z direction, and a coil holding portion 3e that holds the coil 5. The lower end of the guide shaft 4 is fitted in a hole portion of a yoke 7 fixed to the housing 6 of the imaging device.

  Since it is configured as described above, the lens movable member 3 can move in the Z direction along the guide shaft 4 by sliding between the guide shaft 4 and the guide hole 3c. The yoke 7 and the guide shaft 4 are each made of a magnetic material and constitute a magnetic circuit including a magnet 8a and a magnet 8b. The guide shaft 4 may be fitted to the yoke 7 as long as the magnetic lines of force of the magnets 8a and 8b can be passed.

  The coil holding part 3e of the lens movable member 3 is on the upper side of the support part 3d and is formed adjacent to the small diameter frame part 3a holding the small diameter lens 1a in the Y direction. A coil 5 is wound around the coil holding portion 3 e so as to surround the periphery of the guide shaft 4. The coil 5 is wound in a substantially rectangular shape so as to have two sides in the X direction and two sides in the Y direction.

  The yoke 7 is formed, for example, by bending a plate-like member into a U-shape, and extends upward from both the bottom portion 7a to which the lower end of the guide shaft 4 is fitted and the bottom portion 7a in the X direction as described above. It has the wall part 7b and the wall part 7c. Magnets 8a and 8b are respectively attached to the inner side surfaces of the wall 7b and the wall 7c so as to sandwich the coil 5 in the X direction. The magnet 8a and the magnet 8b face each other on the side of the coil 5 that extends in the Y direction.

  A magnetic piece 9 made of a magnetic material is fixed on the upper surface of the lens movable member 3 so as to be positioned above the coil 5. When the lens movable member 3 is within the movable range in the Z direction, the magnetic piece 9 is always disposed on the + Z side (that is, the subject side) from the center position in the Z direction of the magnet 8a and the magnet 8b. Has been.

  FIG. 4 is a schematic diagram for explaining a magnetic circuit of the lens driving device, and corresponds to a cross-sectional view (XZ cross-sectional view) taken along line BB in FIG. The same reference numerals as those in FIG. 1, FIG. 2, and FIG.

  The magnet 8 a and the magnet 8 b are arranged symmetrically in the X direction with respect to the guide shaft 4. The magnet 8a and the magnet 8b are both magnetized in the X direction so that the surface fixed to the yoke 7 is an N pole and the side facing the coil 5 is an S pole. As a result, the side of the coil 5 in the Y direction is located between the S pole of the magnet 8 a or the magnet 8 b and the guide shaft 4.

  The line of magnetic force from the N pole of the magnet 8a travels along the bottom 7a through the wall 7b of the yoke 7, and further passes through the guide shaft 4 through the coil holding part 3e and the coil 5, and the S of the magnet 8a. Reach the pole. Similarly, the line of magnetic force from the N pole of the magnet 8b travels along the bottom portion 7a through the wall portion 7c of the yoke 7, and further passes through the guide shaft 4 through the coil holding portion 3e and the coil 5 to reach the magnet. It reaches the south pole of 8b.

  When a current is passed through the coil 5, an electromagnetic force in the axial direction of the guide shaft 4 (that is, the Z direction) is generated in the coil 5 due to the action of the current and the magnetic field generated by the magnet 8a and the magnet 8b. Here, it is assumed that a current flows in the direction in which + Z direction (upward) electromagnetic force is generated in the coil 5.

  On the other hand, the magnetic piece 9 is always urged toward the center position in the Z direction of the magnet 8a and the magnet 8b (that is, the position having the highest magnetic flux density) by the magnetic field generated by the magnet 8a and the magnet 8b. The movable range of the lens movable member 3 is set so that the magnetic piece 9 is always located on the + Z direction side (subject side) from the center of the magnet 8a and the magnet 8b in the Z direction. The urging force in the −Z direction is always applied. From the viewpoint of obtaining a large urging force, the magnetic piece 9 is preferably made of a soft magnetic material such as nickel among the ferromagnetic materials.

When an electromagnetic force in the + Z direction is generated by passing a current in the coil 5 in a predetermined direction, the lens movable member 3 causes the guide shaft to resist the biasing force in the −Z direction that the magnetic piece 9 receives from the magnet 8a and the magnet 8b. 4 moves in the + Z direction. The magnitude of the electromagnetic force can be changed by changing the value of the current flowing through the coil 5, and the lens movable member 3 is moved to the guide shaft 4 until the position where the electromagnetic force in the + Z direction and the biasing force in the −Z direction are balanced. Can be moved along.

  When the current of the coil 5 is stopped, the electromagnetic force in the + Z direction disappears. Therefore, the lens movable member 3 is moved in the −Z direction by the biasing force in the −Z direction that the magnetic piece 9 receives from the magnets 8a and 8b (illustration is illustrated). However, it returns to the position where it abuts against the abutting surface to a position located on the + Z direction side of the center position of the magnet 8a and the magnet 8b in the Z direction.

  As described above, the voice coil motor, which is a lens driving means for driving the lens group 1 in the optical axis direction, is wound around the support portion 3d having the guide hole 3c slidably provided in the guide shaft 4 and the coil holding portion 3e. And a magnetic piece 9 for generating a biasing force in the −Z direction. This voice coil motor is controlled by a drive control unit 10 which is a drive control means shown in FIG.

  Here, the voice coil motor in the case where the magnetic piece 9 is used to generate the urging force in the −Z direction is shown, but an urging force such as a leaf spring can be generated instead of the magnetic piece 9. A member may be used.

  Further, when the lens movable member 3 is at the movement limit in the −Z direction, light from an object at infinity is imaged on the imaging surface of the solid-state imaging device 2 by the lens group 1. From this state, by moving the lens group 1 in the + Z direction (subject side), a subject image at a closer position can be formed on the solid-state imaging device. As a result, an arbitrary subject from infinity to a close position can be photographed with autofocus. The solid-state image sensor 2 is disposed on the circuit board 11, and an image signal photographed by the individual image sensor 2 is input to the circuit board 11.

  Next, a driving pattern of the voice coil motor according to the first embodiment of the lens driving device according to the present invention will be described.

  In general, as a driving method for finding a focus position of a lens, a focus evaluation value is confirmed while an image is captured, and the lens is moved. After the focus evaluation value is maximized, the lens is moved in the same direction to confirm that this peak is not a false peak, and after confirming that the focus evaluation value has decreased, the focus evaluation value is The lens is returned to the maximum position (see, for example, Patent Document 1). In this case, if there is hysteresis, the in-focus position will shift. In other words, as a lens driving device, when the subject is moved in the + Z direction where the subject is located and in the opposite -Z direction, a positional deviation occurs with respect to the lens position designated to stop. It becomes a problem. In the case of a voice coil motor, even if the same current value is applied to the coil to stop the lens at a predetermined position, the actual stop position of the lens is shifted from the predetermined position.

FIG. 5 is an explanatory diagram of drive patterns showing a drive pattern of the voice coil motor controlled by the drive control unit 10. In FIG. 5, the horizontal axis T represents time, and the vertical axis D represents the amount of current flowing through the coil 5. In addition, a shooting period T1 in FIG. 5 indicates a period during which the imaging apparatus provided with the lens driving device is shooting a subject, and a pause period T2 stops the shooting and transfers or focuses an image signal. Indicates the period of time.

  In the drive pattern shown in FIG. 5, when the current amount D is increased, the lens movable member 3 holding the lens group 1 moves from the image sensor 2 side toward the subject side, and when the current amount D is decreased, the lens is movable. The member 3 moves in the direction of the solid-state image sensor 2 from the subject side.

  In FIG. 5, the time T is up to 200 msec, which is a shooting period T1, and the lens group 1 needs to be stationary at a specified shooting position for shooting a subject. Therefore, the amount of current flowing through the coil 5 is kept constant, and the lens movable member 3 is stationary by the balance between the + Z direction electromagnetic force acting on the coil 5 and the −Z direction biasing force acting on the magnetic piece 9. Next, the period T from 200 msec to 205 msec is a rest period T2, and during this period, the lens is moved to the position of B1, which is the next imaging position, and the lens is stopped.

  By the way, the driving method of the voice coil motor shown in FIG. 5 is different from the driving method of the stepping motor (for example, see Patent Document 1). In FIG. 5, when the lens group 1 is moved from the image pickup position A1 to B1, it goes too far from the position of B1 to the position on the + Z direction side, which is the subject side, by a distance of D1, and returns to B1 from the excessive position. The moving drive method is adopted. This is because, in the case of a voice coil motor, a continuous operation without stepping like a stepping motor is performed, and the driving amount of the motor is directly used as the movement amount of the lens group 1 without having a speed reduction mechanism. When the positions of B1 and B1 are very close, the current difference flowing through the coil 5 becomes very small, and the frictional force between the guide shaft 4 and the guide hole 3c may not move accurately from A1 to B1. Therefore, a driving method is adopted in which the lens group 1 is once moved larger than the position of B1 to change the static friction to dynamic friction, thereby reducing the influence of friction when driving the lens group 1.

  Therefore, in the example of the driving pattern of FIG. 5, in order to move the lens group 1 from the imaging position corresponding to the current amount of A1 to the imaging position corresponding to the current amount of B1, First, as shown in the left half of FIG. 5, for example, as shown in the left half of FIG. By reducing the current amount, the current amount D supplied to the voice coil motor is controlled to move the lens group 1 to the imaging position corresponding to the current amount B1. Further, when the lens group 1 is moved in the −Z direction on the solid-state imaging device 2 side, as shown in the right half of FIG. 5, the imaging position corresponding to the current amount of B1 corresponds to the current amount of A1. In order to move the lens group 1 to the imaging position, the current amount for D1 is once increased and driven in the direction opposite to the position corresponding to A1, and then the current amount for D2 is decreased. Thus, the amount of current D supplied to the voice coil motor is controlled in order to move the lens group 1 to the imaging position corresponding to the amount of current A1.

  That is, in the drive pattern of FIG. 5, from the time when the lens group 1 is U-turned immediately before stopping at a predetermined stop position where the lens group 1 is to be stopped at the imaging position, that is, from the return position of the U-turn operation. The amount of current supplied to the voice coil motor is controlled so that the drive directions when moving to the respective imaging positions are always the same.

  6 uses the same lens driving device as the configuration shown in FIGS. 1 to 3 to control the amount of current D supplied to the voice coil motor by the drive control unit 10 based on an example of the drive pattern of FIG. It is a figure which shows the movement position L of the lens group 1 in a case. The current amount D increases from 0 to 100. As for the movement position L of the lens group 1, the positive direction is the subject side, and the negative direction is the solid-state imaging device 2 side. M1 is a case where the lens group 1 is moved toward the subject side indicated by the arrow 12, and is based on the driving pattern shown in the left half of FIG. M2 is the case where the lens group 1 is moved toward the solid-state imaging device 2 side indicated by the arrow 13, and is based on the drive pattern shown in the right half of FIG.

  According to FIG. 6, as in the driving pattern shown in FIG. 5, the driving direction when the lens group 1 is moved from the repeated position of the U-turn operation immediately before stopping to the imaging position to the imaging position is always the same direction. Even so, it is clear that hysteresis occurs. If such hysteresis occurs, when this lens driving device is used in the image pickup apparatus, the image will be out of focus.

  In the above description, the case where the lens group 1 has a drive pattern in which the lens group 1 always moves to the imaging position with a U-turn has been shown. However, from the movement start position that is the current position of the lens group 1 without a U-turn. Even if the amount of current supplied to the voice coil motor is controlled so that the drive direction when moving to the imaging position is always the same, hysteresis occurs as in the drive pattern of FIG.

  The cause of the occurrence of the hysteresis as described above cannot be clarified at all, but the influence of friction caused mainly by sliding between the guide shaft 4 and the guide hole 3c can be considered.

  When the lens group 1 is moved from the repeated position of the U-turn operation or the movement start position to the predetermined stop position immediately before stopping at the predetermined stop position to be the imaging position, the longer the movement distance, the longer the lens group 1 Since the moving speed of 1 is increased, acceleration is added and an overshoot from a predetermined stop position is increased. When trying to return to the predetermined stop position from the overshooted point, it stops at the point where it balances with the frictional force due to sliding and cannot return completely. On the contrary, when the moving distance is short, the moving speed of the lens group 1 does not increase so much, so the overshoot from the predetermined stop position is small, and the lens group 1 can be stopped at the predetermined stop position which is substantially the imaging position.

  As described above, the moving speed of the lens group 1 differs depending on the moving distance, and as a result, the amount of overshoot is different and stops at the point where it balances with the frictional force caused by sliding, thereby generating hysteresis. It is estimated to be.

  Therefore, in the movement operation of the lens group 1 from the return position of the U-turn operation immediately before stopping at the predetermined stop position or the movement start position to the predetermined stop position, not only the movement direction is always the same, If the amount of movement is the same, it is considered that hysteresis can be suppressed.

  FIG. 7 is a drive pattern explanatory view showing a drive pattern of the voice coil motor by the drive control unit 10 of Embodiment 1 of the lens driving device according to the present invention. The same reference numerals as those in FIG.

  In order to move the lens group 1 to the imaging position corresponding to the current amount of B1, the lens group 1 is in the imaging position corresponding to the current amount of B1 in the left half of FIG. The lens group 1 is moved to the imaging position corresponding to the current amount of B1 by increasing the current amount D and driving the current amount D so as to go too far, and then decreasing the current amount for D1. The point of controlling the amount of current D supplied to the voice coil motor in order to move it is the same as in FIG.

  However, as shown in the right half of FIG. 7, in order to move the lens group 1 from the imaging position corresponding to the current amount of B1 to the imaging position corresponding to the current amount of A1 with respect to further movement of the subject or the like. Then, after increasing the current amount D and driving in the opposite direction, the imaging position corresponding to the current amount of A1 is then decreased by decreasing the current amount corresponding to D1 when moving from A1 to B1. 5 is different from FIG. 5 in that the lens group 1 is moved to the position shown in FIG.

  That is, in the drive pattern of FIG. 7, unlike FIG. 5, imaging is performed from the time when the lens group 1 is U-turned immediately before stopping at a predetermined stop position where the lens group 1 is to be stopped at the imaging position. The amount of current supplied to the voice coil motor is controlled so that not only the drive direction when moving to a position always has the same predetermined direction, but also the movement distance at that time always has the same predetermined movement amount. is doing.

  FIG. 8 shows a case where the amount of current D supplied to the voice coil motor is controlled based on an example of the driving pattern of the first embodiment shown in FIG. 7 using the lens driving device having the configuration shown in FIGS. It is a figure which shows the movement position L of the lens group 1. The same reference numerals as those in FIG. 6 denote the same or corresponding parts, and thus description thereof is omitted.

  In FIG. 6, hysteresis was observed in a wide range of the movement position L. In FIG. 8, hysteresis at the positions of the arrows 14 and 15 and hysteresis at the positions of the arrows 16 and 17 remain. In the range of the moving position L, hysteresis is sufficiently suppressed. Therefore, if a lens driving device is used in the range of the moving position L, an imaging device using this lens driving device can perform lens position control with extremely high accuracy, and can achieve high accuracy without defocusing. It is possible to achieve image quality shooting.

  In the above description, the driving pattern in which the lens group 1 always moves to the imaging position with a U-turn has been shown. However, from the movement start position that is the current position of the lens group 1 without a U-turn, The same effect can be obtained by controlling the amount of current supplied to the voice coil motor so that the drive direction when moving to the imaging position is always the same and the movement distance is always the same. It goes without saying that

Embodiment 2. FIG.
In the lens driving device according to the first embodiment, the lens group 1 from the repeated position of the U-turn operation or the movement start position to the predetermined stop position immediately before the lens group 1 stops at the predetermined stop position that is the imaging position. The amount of current supplied to the voice coil motor as the lens driving means is controlled by the drive control unit 10 as the drive control means so that the movement operation always has the same predetermined movement direction and the same predetermined movement amount. However, in addition to this, if the reciprocating operation of at least one reciprocating half is performed before the moving operation of the lens group 1, the hysteresis can be further sufficiently suppressed.

  FIG. 9 is a drive pattern explanatory diagram showing a drive pattern of the voice coil motor by the drive control unit 10 of Embodiment 2 of the lens drive device according to the present invention. The same reference numerals as those in FIG. 7 denote the same or corresponding parts, and the description thereof will be omitted. In FIG. 9, in the movement operation of the lens group 1 from the repeated position of the U-turn operation immediately before stopping at the predetermined stop position that is the imaging position to the predetermined stop position, the direction of movement is opposite to that in FIG. Although the direction is the direction, the effect of the present invention should always be the same direction, and it does not matter which direction is aligned.

  As shown in the left half of FIG. 9, the lens group 1 is in the imaging position corresponding to the current amount of A1, and the lens group is in the imaging position corresponding to the current amount of B1 corresponding to the movement of the subject. In order to move 1, in addition to the U-turn operation shown in FIG. 7, before performing the U-turn operation, for example, when the time T is 200 msec to 220 msec, The amount of current D supplied to the coil motor is controlled. Further, as shown in the right half of FIG. 9, the lens group 1 was in the imaging position corresponding to the current amount of B1, and the imaging position corresponding to the current amount of A1 corresponding to the movement of the subject. In order to move the lens group 1, for example, the current amount D supplied to the voice coil motor is controlled so that the reciprocating operation is performed one and a half times in the time T from 500 msec to 515 msec. That is, in addition to the drive pattern shown in FIG. 7, the lens group 1 performs a reciprocating operation of at least one reciprocal half.

  FIG. 10 shows the amount of current supplied to the voice coil motor by the drive control unit 10 based on an example of the drive pattern of the second embodiment of FIG. 9 using the lens driving device having the configuration shown in FIGS. It is a figure which shows the movement position L of the lens group 1 at the time of controlling D. FIG. The same reference numerals as those in FIG. 8 denote the same or corresponding parts, and thus description thereof is omitted.

  In FIG. 8, hysteresis remains only at the positions indicated by the arrows 14 and 15 and at the positions indicated by the arrows 16 and 17, but in FIG. 10, the hysteresis is completely suppressed in the entire range of the moving position L. .

  As described above, the movement operation of the lens group 1 from the repeat position of the U-turn operation to the predetermined stop position immediately before the lens group 1 stops at the predetermined stop position that is the imaging position is always the same predetermined position. In addition to this, the amount of current supplied to the voice coil motor is set so as to perform at least one reciprocal half operation before the movement operation of the lens group 1. By controlling, an even more significant hysteresis suppression effect can be obtained, and an image pickup apparatus using this lens driving device can perform extremely high-precision lens position control, and can realize high-quality shooting without defocusing. .

Embodiment 3 FIG.
In the lens driving devices according to the first and second embodiments, the case where a voice coil motor is used as the lens driving unit of the lens group 1 is shown. However, as the lens driving unit, the DC motor and the DC motor are rotated. For example, even if a gear train is used, which is a linear motion drive mechanism that can be converted into a linear motion, the same drive pattern as that shown in the first and second embodiments is applied, so that sufficient hysteresis is obtained. It is possible to obtain a lens driving device capable of performing highly accurate lens position control with suppression.

  FIG. 11 is a configuration diagram of lens driving means comprising a DC motor and a gear train, which is lens driving means of Embodiment 3 of the lens driving device according to the present invention. The same reference numerals as those in FIG. 3 denote the same or corresponding parts, and the description thereof will be omitted.

  In the lens driving unit, the rotation of the DC motor 18 based on the control by the drive control unit 10 is appropriately decelerated by the first gear 19, the second gear 20, and the third gear 21, and the linear motion gear 22 Rotation is converted to linear motion. The linear motion gear 22 includes a lens movable member including a small-diameter frame portion 3a and a large-diameter frame portion 3b including a lens group 1 including a small-diameter lens 1a and a large-diameter lens 1b, and a support portion 3d having a guide hole 3c. It is fixed. The combination of the first gear 19, the second gear 20, the third gear 21, and the linear gear 22 constitutes a gear train and operates as a linear motion drive mechanism that converts the rotation of the DC motor 18 into linear motion.

  On the other hand, the lens movable member is slidably mounted on the guide shaft 4 fixed to the housing 6 through the guide hole 3c. Therefore, if the DC motor 18 is controlled by the drive control unit 10 in the same pattern as the drive pattern shown in the first and second embodiments, the DC motor 18 rotates according to the drive pattern, and the gear train is moved. Through this, the lens movable member holding the lens group 1 can be driven.

  Since the lens driving unit of the third embodiment is configured as described above, the hysteresis can be sufficiently suppressed in the focusing operation of the lens group 1 as in the first and second embodiments. An image pickup apparatus using this lens driving device can perform lens position control with extremely high accuracy, and can realize high-quality shooting without focus deviation.

  If a stepping motor is used, it is difficult to be affected by the friction of the sliding portion and it is easy to reduce the hysteresis. However, there is a problem that the noise of the motor itself is large because it operates stepwise. On the other hand, the lens driving device according to the present invention can sufficiently suppress hysteresis by using a motor that does not perform a step operation, such as a voice coil motor or a DC motor, as a lens driving means, not a stepping motor. Therefore, it is possible to obtain an effect that a low-noise lens driving device can be realized. However, since the voice coil motor is a linear motor that moves the lens movable member 3 directly in the direction of the guide shaft 4, an operating noise is generated between the shaft and the bearing during the reciprocating operation, but the reciprocating operation is performed while reducing hysteresis. By reducing the number of times, it is possible to suppress the generation of operation sounds. That is, the driving method of FIG. 9 described in the second embodiment is effective in improving the hysteresis, but the operation noise between the guide shaft 4 and the guide hole 3c which is a bearing is relatively loud. On the other hand, in the driving method of FIG. 7 described in the first embodiment, it is possible to suppress the generation of hysteresis while suppressing the operation sound, and it is possible to solve both the problem of hysteresis and the problem of operation sound. It is.

1 is a perspective view of Embodiment 1 of a lens driving device according to the present invention. It is a top view of Embodiment 1 of the lens driving device according to the present invention. It is YZ sectional drawing of Embodiment 1 of the lens drive device based on this invention. It is sectional drawing which shows the magnetic circuit of Embodiment 1 of the lens drive device based on this invention. It is drive pattern explanatory drawing which showed the drive pattern of the same voice coil motor as the conventional lens drive device. It is a figure which shows the electric current amount D at the time of controlling by an example of the drive pattern of the conventional voice coil, and the movement position L of the lens group 1. FIG. It is drive pattern explanatory drawing which showed the drive pattern of the voice coil motor of Embodiment 1 of the lens drive device based on this invention. It is a figure which shows the relationship between the electric current amount D and the movement position L of the lens group 1 at the time of controlling based on the drive pattern of the voice coil motor of Embodiment 1 of the lens drive device based on this invention. It is drive pattern explanatory drawing which showed the drive pattern of the voice coil motor of Embodiment 2 of the lens drive device based on this invention. It is a figure which shows the relationship between the electric current amount D and the movement position L of the lens group 1 at the time of controlling based on the drive pattern of the voice coil motor of Embodiment 2 of the lens drive device based on this invention. It is a block diagram of the linear drive mechanism of Embodiment 3 of the lens drive device based on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lens group 3 Lens movable member 3c Guide hole 4 Guide shaft 5 Coil 6 Case 7 Yoke 10 Drive control part 18 DC motor

Claims (4)

In the lens driving device that performs the focusing operation by stopping the lens group at a predetermined stop position in the optical axis direction,
The lens group slidable in the optical axis direction;
Lens driving means for driving the lens group in the optical axis direction;
Immediately before stopping at the predetermined stop position, the movement operation of the lens group from the repeated position of the U-turn operation or the movement start position to the predetermined stop position is always the same predetermined movement with the same predetermined movement direction. Driving control means for controlling the lens driving means so as to have a quantity;
A lens driving device comprising:   2. The lens driving device according to claim 1, wherein the driving control means controls the lens driving means so as to perform at least one reciprocal half-reciprocation before the lens group moving operation.   3. The lens driving device according to claim 1, wherein the lens driving means is a voice coil motor. 3. The lens driving device according to claim 1, wherein the lens driving means is a linear drive mechanism capable of converting the rotation of the DC motor into a linear motion.

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