JP2008145630A - Lens drive device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens drive device capable of holding the position of a lens holder by means of solenoids even if an impact is applied. <P>SOLUTION: The lens drive device includes: the lens holder 4 holding a lens 12; a moving mechanism 5 for moving the lens holder 4 in the direction of the optical axis of the lens 12; and the solenoids 6 for driving the moving mechanism 5. The moving mechanism 5 has movable pieces 30 disposed so as to link with the lens holder 4. The solenoids 6 to which a drive current has been applied attract the movable pieces 30, thereby moving the lens holder 4. After the movable pieces 30 are attracted and the lens holder 4 is thereby moved to a prescribed position, a holding current smaller than the drive current and required to hold the lens holder 4 in a prescribed position and a maintaining current equal to the drive current in magnitude are alternately applied to each of the solenoids 6 at prescribed time intervals. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a lens driving device that can move a lens holder holding a lens in the optical axis direction of the lens, and more particularly to a lens driving device that moves a lens holder using a solenoid.

  A camera module built in an electronic device such as a cellular phone includes a lens holder that holds a lens, and an image sensor that receives light from the lens and converts it into an electrical signal. Here, in order to change the focal length of the lens, a mechanism for moving the position of the lens holder may be provided. As a mechanism for moving the lens holder, a mechanism using a motor is conceivable. However, since the size and cost are increased, a simpler mechanism is required.

For this reason, a mechanism using a solenoid has been conventionally used. By using a solenoid, it can be configured more simply than using a motor, and downsizing can also be achieved. However, when a solenoid is used, power is always consumed while the lens holder is moved and held by the solenoid, so that it has been required to reduce the power consumption of the solenoid. On the other hand, as shown in Patent Document 1, for example, after the solenoid is energized and driven, the energization is stopped during the time zone in which the residual magnetic flux exists, and then the residual magnetic flux is periodically present. There is one that reduces power consumption during holding by energization.
Japanese Patent Laid-Open No. 9-162033

  However, when the control method of the prior art is performed, the magnetizing force rapidly decreases while the energization to the solenoid is stopped, so that the holding by the solenoid is released when an impact force is applied. was there. Further, once the holding by the solenoid is released, the holding state cannot be maintained because the magnetic flux for driving again is not generated.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a lens driving device that can hold the position of the lens holder with a solenoid even when an impact force is applied.

In order to solve the above problems, a lens driving device according to the present invention includes a lens holder that holds a lens, a moving mechanism that moves the lens holder in the optical axis direction of the lens, and a solenoid that drives the moving mechanism. In the provided lens driving device,
The moving mechanism has a movable piece provided so as to be linked with the lens holder, and the solenoid is applied with a drive current to the movable piece to move the lens holder,
When the movable piece is attracted to the solenoid and the lens holder is moved to a predetermined position, the solenoid has a holding current that is smaller than the driving current and is required to hold the lens holder at the predetermined position, and is equal to the driving current. A large amount of sustaining current is alternately applied at a predetermined period.

  In the lens driving device according to the present invention, the holding current is applied to the solenoid over a first predetermined time, and the sustaining current is applied over a second predetermined time shorter than the first predetermined time. It is configured as a feature.

  Furthermore, in the lens driving device according to the present invention, the first solenoid and the second solenoid are disposed opposite to each other with the lens holder interposed therebetween, and the sustain current is applied to the first solenoid and the second solenoid. It is configured to be added with a time shift.

  According to the lens driving device of the present invention, when the movable piece is sucked into the solenoid and the lens holder is moved to a predetermined position, the solenoid has a holding current that is smaller than the driving current and is required to hold the lens holder at the predetermined position. The sustaining current having the same magnitude as the driving current is alternately applied in a predetermined cycle, so that the original magnetized state is restored within a predetermined time even if the magnetized state of the movable piece on the solenoid is canceled due to an impact or the like. Since the lens holder can be restored, the holding state of the lens holder can be reliably maintained while saving power.

  According to the lens driving device of the present invention, the holding current is applied to the solenoid for the first predetermined time, and the maintenance current is applied for the second predetermined time shorter than the first predetermined time. Further power saving can be achieved while securing the magnetic attachment of the movable piece by the solenoid.

  Furthermore, according to the lens driving device of the present invention, the solenoid is arranged such that the first solenoid and the second solenoid are opposed to each other with the lens holder interposed therebetween, and the sustaining current is in time with respect to the first solenoid and the second solenoid. Since it is not necessary to flow a large current at the same time, the configuration for power supply can be simplified.

  Embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view of the lens driving device according to the present embodiment, FIG. 2 is an exploded perspective view of the lens driving device, and FIG. 3 is a plan view of the lens driving device with the top cover removed. ing. As shown in each of these drawings, the lens driving device in the present embodiment is provided with a base 2 and a box-shaped housing 3 on a rectangular substrate 1, and a lens holder 4 holding a lens 12 in the housing 3; A moving mechanism 5 for moving the lens holder 4 in the optical axis direction of the lens 12 and a solenoid 6 for driving the moving mechanism 5 are housed, and an upper surface cover 8 is provided on the upper surface of the housing 3 so that the lens 12 is exposed. It will be.

  As shown in FIG. 2, the lens holder 4 includes a cylindrical lens barrel 4a that holds the lens 12, and a ring-shaped lens barrel holding member 4b that is attached to and integrated with the lower portion of the lens barrel 4a. ing. The lens barrel 4 a and the lens barrel holding member 4 b include a position adjusting mechanism 20 that can adjust the position of each lens in the optical axis direction of the lens 12. The position adjusting mechanism 20 includes a protruding portion 21 formed on the outer peripheral surface of the lens barrel 4a and a mounting portion 22 formed on the inner peripheral surface of the lens barrel holding member 4b. The detailed configuration will be described later.

On the peripheral surface of the lens barrel holding member 4b, there are provided cylindrical spring holding portions 23 protruding upward at two locations facing each other. An urging spring 7 is attached to the spring holding portion 23 to urge the lens holder 4 downward. Thereby, the lens holder 4 can be automatically returned to the original position from the state where the lens holder 4 is pushed upward.
A through hole is provided on one side of the spring holding portion 23, and a guide pin 9 is attached to the through hole. The guide pins 9 prevent the lens holder 4 from being inclined with respect to the optical axis direction of the lens 12 when the lens holder 4 moves in the vertical direction.

  The lens 12 held by the lens holder 4 condenses the light from the imaging target on the imaging device 10 disposed on the substrate 1, and the imaging device 10 converts it into an electrical signal and outputs it. Here, the lens holder 4 can be moved by the moving mechanism 5 to three different positions in the optical axis direction of the lens 12 in addition to the position in the initial state. Since the distance between the lens 12 and the image sensor 10 is different for each position, the focal length of the lens 12 can be set in four ways.

  In the base 2, a filter 11 is disposed on the optical axis of the lens 12. The filter 11 has a function of blocking infrared rays in the light from the lens 12. Further, the lower surface of the housing 3 is engaged and fixed to the upper surface of the base portion 2. The housing 3 is formed to have a substantially rectangular outer surface, and a holder accommodating portion 30 formed on the inner surface so as to substantially match the outer peripheral surface of the lens holder 4, and substantially compatible with the outer peripheral surface of the solenoid 6. The solenoid accommodating part 31 formed so as to be formed is formed.

  The solenoid 6 includes a first solenoid 40 and a second solenoid 41. As shown in the plan view of FIG. 3, they are arranged in the housing 3 so as to face each other with the lens holder 4 interposed therebetween. Each of the first solenoid 40 and the second solenoid 41 includes a first coil 42 and a second coil 43 arranged in parallel.

  The configuration of the solenoid 6 will be described in more detail. FIG. 4 is an exploded perspective view of the solenoid 6, and FIG. 5 is a perspective view showing the positional relationship between the solenoid 6 and the movable piece 30. As shown in FIG. 4, in the solenoid 6, a first coil 42 and a second coil 43 that are driving members are juxtaposed in the lateral direction, and an iron core 44 is provided on each of them, and one end portion of the iron core 44. A yoke 45 extending toward the other end is attached so as to cover the coils 42 and 43.

  As shown in FIG. 5, the movable piece 30 is disposed so as to face the other end portion on the opposite side to the one end portion of the iron core 44 to which the yoke 45 is attached. FIG. 5 shows a state in which the first coil 42 and the second coil 43 are not energized. In this state, the movable piece 30 is separated from the other end of the iron core 44, and It is arranged in an inclined shape. When the first coil 42 and the second coil 43 are energized, the movable piece 30 is attracted to the other end of the iron core 44 and magnetically attached thereto, and swings accordingly.

  In this way, two coils 42 and 43 are arranged side by side for the solenoid 6, and the first solenoid 40 and the second solenoid 41 are arranged to face each other with the lens holder 4 interposed therebetween, whereby the coil 42. Even if the height of the lens holder 43 is reduced, the driving force can be sufficiently secured, and the lens holder 4 can be moved so as not to tilt.

  As shown in FIG. 2, the moving mechanism 5 is oscillated by the two movable pieces 30 provided for the first solenoid 40 and the second solenoid 41, respectively, and presses the lens holder 4. The swing member 31 is moved in the optical axis direction of the lens 12. The movable piece 30 is disposed below each solenoid 6, and the swing member 31 is disposed below the movable piece 30 and the lens holder 4, so that either or both movable pieces 30 are attracted by the solenoid 6. Accordingly, the lens holder 4 that is tilted from the initial state and abuts is moved. That is, the movable piece 30 is linked to the lens holder 4 via the swing member 31, and can move the lens holder 4 in the optical axis direction of the lens 12 in accordance with the operation. Details of the operation will be described later.

  Next, the configuration of the lens holder 4 will be described in detail. FIG. 6 shows an exploded perspective view of the lens barrel 4a and the lens barrel holding member 4b constituting the lens holder 4. As shown in FIG. As described above, the protruding portion 21 is formed on the outer peripheral surface of the lens barrel 4a, while the mounting portion 22 is formed on the inner peripheral surface of the lens barrel holding member 4b.

  A step is formed at an intermediate position in the vertical direction of the protruding portion 21 of the lens barrel 4a, whereby an inclined surface 21a facing downward is formed. In addition, a hook-shaped engaging portion 21 b is formed at the lower portion of the protruding portion 21.

  A stepped portion protruding inward is formed at an intermediate position in the vertical direction of the mounting portion 22 of the lens barrel holding member 4b, and an upper surface thereof is formed as an inclined surface 22a. The inclined surface 22a of the mounting portion 22 is formed with the inclined direction and angle suitable for the inclined surface 21a of the protruding portion 21 mounted thereon. Accordingly, when the lens holder 4 is rotated and the projecting portion 21 slides on the mounting portion 22, the lens barrel 4a changes its position in the vertical direction (the optical axis direction of the lens 12) with respect to the lens barrel holding member 4b. Can be made.

  Further, the engaging portion 21 b formed at the lower portion of the protruding portion 21 is engaged with the lower portion of the placement portion 22. FIG. 7 shows a cross-sectional view of the lens holder 4. As shown in this figure, the engaging portion 21b of the projecting portion 21 is located with respect to the lower portion of the mounting portion 22 in a state where the inclined surface 21a of the projecting portion 21 is mounted on the inclined surface 22a of the mounting portion 22. It is engaged so as to have play in the vertical direction. Accordingly, the vertical position of the lens barrel 4a with respect to the lens barrel holding member 4b can be changed within a predetermined range while the lens barrel 4a is temporarily stopped so as not to come off the lens barrel holding member 4b.

  FIG. 8 shows a plan view of the lens holder 4. As shown in this figure, the protruding portion 21 of the lens barrel 4a is formed shorter in the circumferential direction than the mounting portion 22 of the lens barrel holding member 4b. Therefore, the protruding portion 21 can be slid within a predetermined range in the circumferential direction within the mounting portion 22, and the lens barrel 4 a is moved up and down by the configuration of the inclined surface 21 a of the protruding portion 21 and the inclined surface 22 a of the mounting portion 22. Can be moved in the direction.

  In this manner, the inclined surface 21a of the protruding portion 21 is placed on the inclined surface 22a of the placing portion 22, and the lens barrel 4a can be moved in a predetermined range in the vertical direction and the circumferential direction with respect to the lens barrel holding member 4b. With this configuration, the vertical position of the lens barrel holding member 4b can be adjusted by rotating the lens barrel 4a, and the position of the lens 12 can be easily adjusted. Further, since the lens barrel 4a has the engaging portion 21b, the position of the lens 12 can be determined by rotating the lens barrel 4a in a state where the lens barrel 4a is temporarily fixed so as not to come off from the lens barrel holding member 4b. Since adjustment can be performed, position adjustment can be performed with simple manufacturing equipment without using a special jig. In addition, after performing this position adjustment, the lens barrel 4a and the lens barrel holding member 4b are integrated by pouring an adhesive into the protruding portion 21 and the mounting portion 22 and fixing them.

  Next, the movement of the lens holder 4 by the moving mechanism 5 will be described. FIG. 9 is a side view of the lens driving device excluding the housing 3, the urging spring 7, and the upper surface cover 8, and shows each state associated with the operation of the solenoid 6. FIG. 9A shows an initial state in which neither the first solenoid 40 nor the second solenoid 41 is energized.

  As shown in FIG. 9A, a first contact portion 31 a and a second contact portion 31 b that are in contact with the upper surface of the base portion 2 are formed on the lower surface of the swing member 31. The first contact portion 31a is formed at the end portion on the first solenoid 40 side in the left-right direction shown in FIG. 9, while the second contact portion 31b is the first contact portion 31a in the left-right direction shown in FIG. 2 on the solenoid 41 side, and is formed at an intermediate position between the center position and the end portion.

  A projection 24 is formed on the bottom surface of the lens holder 4, and the tip of the lens holder 4 is in contact with the top surface of the swing member 31 at the center position. Therefore, when the swinging member 31 swings to the left or right, or when the entire swinging member 31 is pulled upward, the lens holder 4 that is in contact with the swinging member 31 by the protrusion 24 is in the state shown in FIG. Move upwards.

  In the state of FIG. 9A, since neither the first solenoid 40 nor the second solenoid 41 is energized, the movable piece 30 is in a state of being inclined and spaced apart from the iron core 44. ing. On the other hand, as shown in FIG. 9B, when only the first solenoid 40 is energized, the movable piece 30 on the first solenoid 40 side is attracted to the iron core 44 and magnetized. It becomes. Accordingly, one end of the swing member 31 on the first solenoid 40 side is pulled up, whereby the first contact portion 31a is separated from the upper surface of the base portion 2, and the one side with the second contact portion 31b as a fulcrum. It will be in a state leaning to.

  When the oscillating member 31 is tilted by energizing the first solenoid 40, the lens holder 4 that is in contact with the oscillating member 31 by the protrusion 24 is pushed upward, whereby the lens holder 4 is moved as shown in FIG. Compared to the state of (a), the lens 12 moves in the optical axis direction by a predetermined distance a.

  On the other hand, as shown in FIG. 9C, when only the second solenoid 41 is energized, the movable piece 30 on the second solenoid 41 side is attracted to the iron core 44 and is magnetically attached. Accordingly, one end of the swinging member 31 on the second solenoid 41 side is pulled up, whereby the second contact portion 31b is separated from the upper surface of the base portion 2, and one side with the first contact portion 31a as a fulcrum. It will be in a state inclined to.

  When the swing member 31 is tilted by energization of the second solenoid 41, the lens holder 4 that is in contact with the swing member 31 by the protrusion 24 is pushed upward. Compared to the state of (a), the lens 12 moves in the optical axis direction by a predetermined distance b.

  Here, the distance from the first contact portion 31a serving as a fulcrum to the central portion of the swing member 31 with which the projection 24 of the lens holder 4 contacts is the center of the swing member 31 from the second contact portion 31b. Since the distance that the movable piece 30 is moved upward by the second solenoid 41 is the same as the distance that the movable piece 30 is moved upward by the first solenoid 40, the lens holder 4 is moved. The predetermined distance b is larger than the predetermined distance a in FIG.

  As shown in FIG. 9D, when both the first solenoid 40 and the second solenoid 41 are energized, both the movable pieces 30 are attracted to the iron cores 44 and are magnetically attached. Become. Accordingly, the entire swinging member 31 is pulled up, and the first contact portion 31 a and the second contact portion 31 b are both separated from the upper surface of the base portion 2.

  When the entire swinging member 31 is lifted by energizing the first solenoid 40 and the second solenoid 41, the lens holder 4 that is in contact with the swinging member 31 by the protrusion 24 is pushed upward. As a result, the lens holder 4 moves by a predetermined distance c in the optical axis direction of the lens 12 as compared with the state of FIG. The predetermined distance c in this case is larger than the predetermined distance a and the predetermined distance b due to the swinging member 31 tilting and the lens holder 4 being lifted. Thus, by energizing one or both of the first solenoid 40 and the second solenoid 41, the lens holder 4 can be positioned at any one of the four positions.

  Next, energization of the solenoids 40 and 41 will be described. In FIG. 10, the chart of the electric power supply with respect to the coils 42 and 43 of each solenoid 40 and 41 is shown. This figure shows a case where both the first solenoid 40 and the second solenoid 41 are energized. First, energization is started at time t0, and a driving current Ia necessary for attracting the movable piece 30 to the first solenoid 40 is supplied. Then, the movable piece 30 is magnetically attached to the iron core 44 of the first solenoid 40 until the time t1 elapses. Thereafter, the holding current Ib smaller than the driving current Ia is supplied to the first solenoid 40. The holding current Ib is a current that can hold the position of the lens holder 4 by the magnetic attachment of the movable piece 30 and can be, for example, about half the driving current.

  At the same time as the supply of the holding current Ib to the first solenoid 40 is started, the supply of the drive current Ia to the second solenoid 41 is started. In addition, after the time t1 has elapsed from the start of supply of the drive current Ia, the holding current Ib smaller than the drive current Ia is supplied. Both the first solenoid 40 and the second solenoid 41 are supplied with the holding current Ib for the time t2, and then supplied again with the sustaining current having the magnitude of Ia for the time t1. Even if the sustaining current has the same magnitude as the driving current and the impact is applied to the lens holder 4 and the magnetized state of the movable piece 30 is released while the holding current is being supplied, The size of the movable piece 30 can be sucked again.

  Thereafter, the holding current Ib and the sustaining current Ia are periodically and alternately supplied to both the first solenoid 40 and the second solenoid 41. Since the start of supply of drive current to the first solenoid 40 and the start of supply of drive current to the second solenoid 41 are shifted by time t1, the timing at which the sustain current is supplied is also shifted by time t1, The sustain current is not supplied to both the first solenoid 40 and the second solenoid 41 at the same time.

  Further, the time t2 during which the holding current is supplied is set longer than the time t1 during which the driving current and the sustain current are supplied. Specifically, for example, as described above, 50 msec is set as the time required for the movable piece 30 to be magnetically attached to the solenoid 6 at time t1, and 450 msec longer than that is set as time t2. As a result, the sustaining current is supplied at a cycle of 500 msec, so that even if the magnetized state of the movable piece 30 is released due to an impact or the like, it can be restored within 0.5 seconds.

  As described above, after the drive current is supplied to the solenoids 40 and 41 for a predetermined time, the holding current smaller than the drive current and the maintenance current having the same magnitude as the drive current are alternately supplied in a predetermined cycle. Therefore, current consumption can be reduced compared with the case where the drive current is continuously supplied, and even if the magnetized state of the movable piece 30 is once released by an impact or the like, it returns to the magnetized state within a predetermined time. Thus, the position of the lens holder 4 can be held.

  The embodiment of the present invention has been described above, but the application of the present invention is not limited to this embodiment, and can be applied in various ways within the scope of the technical idea. For example, in the present embodiment, the current supply timing is shifted between the first solenoid 40 and the second solenoid 41, but the present invention is not limited to this, and the current may be supplied at the same timing. In addition, the cycle for switching between the sustain current and the hold current can be set as appropriate. Furthermore, even if the lens holder is driven by one solenoid, the present invention can be applied.

It is a perspective view of the lens drive device in this embodiment. It is a disassembled perspective view of a lens drive device. It is a top view of a lens drive device in the state where an upper surface cover was removed. It is a disassembled perspective view of a solenoid. It is a perspective view showing arrangement relation of a solenoid and a movable piece. It is a disassembled perspective view of the lens barrel and the lens barrel holding member constituting the lens holder. It is sectional drawing of a lens holder. It is a top view of a lens holder. FIG. 6 is a side view of the lens driving device excluding a housing, an urging spring, and an upper surface cover, and showing each state associated with the operation of the solenoid. It is a chart figure of the electric power supply with respect to the coil of a solenoid.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Board | substrate 2 Base 3 Housing 4 Lens holder 4a Lens barrel 4b Lens barrel holding member 5 Movement mechanism 6 Solenoid 20 Position adjustment mechanism 21 Protrusion part 21a Inclined surface 21b Engagement part 22 Mounting part 22a Inclined surface 24 Projection part 30 Movable piece 31 Oscillating member 40 First solenoid 41 Second solenoid 42 First coil 43 Second coil

Claims (3)

In a lens driving device comprising a lens holder for holding a lens, a moving mechanism for moving the lens holder in the optical axis direction of the lens, and a solenoid for driving the moving mechanism,
The moving mechanism has a movable piece provided so as to be linked with the lens holder, and the solenoid is applied with a drive current to the movable piece to move the lens holder,
When the movable piece is attracted to the solenoid and the lens holder is moved to a predetermined position, the solenoid has a holding current that is smaller than the driving current and is required to hold the lens holder at the predetermined position, and is equal to the driving current. A lens driving device characterized in that a large amount of sustaining current is alternately applied in a predetermined cycle.   2. The lens driving device according to claim 1, wherein the holding current is applied to the solenoid over a first predetermined time, and the sustaining current is applied over a second predetermined time shorter than the first predetermined time. apparatus.   The solenoid is characterized in that a first solenoid and a second solenoid are arranged opposite to each other with the lens holder interposed therebetween, and the sustaining current is applied to the first solenoid and the second solenoid with a time lag. The lens driving device according to claim 1 or 2.

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