JPH0833386A - Control device of voice-coil motor - Google Patents

Abstract

PURPOSE:To provide the control device, of a voice-coil motor, which can set a proper bias current to surely hold the position of a moving part when the operation of an apparatus is started. CONSTITUTION:A control device is provided with a position detection means 102 which detects the position of a linearly movable moving part, with a VCM drive circuit 104 which supplies a prescribed voltage in order to drive the moving part in a trial manner at an electrifying initial state and with a CPU 103 which has an arithmetic means to operate the movement amount, in a definite time, of the moving part by the trial driving operation at the electrifying initial stage on the basis of an output from the position detection means 102, in which a bias storage part 103a having stored in advance the relationship between the movement amount and a bias current suitable for driving the moving part is installed and which decides the bias current on the basis of information from the bias storage part 103a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voice coil motor control device, and more particularly to a voice coil motor control device in which the load of a movable portion of the voice coil motor changes depending on a posture or a position.

[0002]

2. Description of the Related Art Conventionally, in a lens frame of a video camera or the like, an electromagnetic drive type having a coil and a magnet has been widely used as an actuator for focus / zoom. As an example thereof, Japanese Patent Laid-Open No. 4-25811 discloses a lens drive unit using a voice coil motor. This technical means includes a lens movable frame suspended on a shaft, a coil is arranged on the outer periphery of the lens movable frame, and a magnet / yoke portion is arranged on a fixed frame so as to face the coil. The detection means is configured.

This technical means has an advantage over the prior art in that there is no protrusion and there is no moment inclining the optical axis.

[0004]

By the way, in general,
A feature of the voice coil motor is that it has advantages such as responsiveness and power consumption, but it does not have a position holding force.
That is, when a load is applied to the movable frame of the voice coil motor when the power is off, the movable frame loses the load and drifts. That is, when used in a video camera or the like, the posture of the camera changes depending on the shooting state, but the change in the posture places the center of gravity of the movable frame in the moving direction of the voice coil motor, increasing the load on the voice coil motor. However, in some cases, the movable frame may drift.

Generally, the movable frame requires wiring such as a voice coil motor coil, a speed sensor coil, etc., and a wiring such as a flexible printed circuit board is interposed between the movable frame and the fixed portion for the wiring connection. To do. In the case of a voice coil motor having such a configuration, it is possible that the movable frame may lose the load of the flexible printed circuit board and drift. In this case, the load of the flexible printed board can be reduced to some extent by the thickness and material of the flexible printed board, but it is difficult to reduce the number of pins of the flexible printed board.

As described above, in a voice coil motor used in a camera or the like, load fluctuation of the movable frame may occur due to posture and position (load on the flexible printed circuit board), and the movable frame may drift (cannot hold the position). is there.

In order to suppress this drift, it is possible to flow a bias current in the direction opposite to the load.
If the bias current is not appropriate, the movable frame will drift again.

On the other hand, when the main switch of the camera body is off, that is, when the voice coil motor is not energized, the position of the voice coil motor cannot be specified. If the main switch of the camera body is turned on in such a state, the shooting posture at this time is unspecified, so the load of the voice coil motor may increase or decrease depending on the case, and normal movement Will be different.
Therefore, it is difficult to obtain an appropriate bias current for the voice coil motor.

The present invention has been made in view of the above problems, and provides a control device for a voice coil motor capable of setting an appropriate bias current for reliably holding the position of the movable portion when the operation of the device is started. The purpose is to

[0010]

In order to achieve the above object, a first voice coil motor control device according to the present invention comprises a position detecting means for detecting the position of a movable portion which can move linearly, and an initial stage of energization. Drive current supply means for supplying a predetermined current for driving the movable portion on a trial basis, and movement amount of the movable portion for a certain period of time due to the trial drive at the initial stage of energization are calculated based on the output from the position detecting means. And a storage unit that stores in advance the relationship between the moving amount and the bias current suitable for driving the movable unit, the bias based on the output from the calculation unit, and the information from the storage unit. Bias current determining means for determining a current.

In order to achieve the above object, a second voice coil motor control device according to the present invention, in the first voice coil motor control device, drives the movable part on a trial basis at the initial stage of energization. The predetermined current of is a constant current.

In order to achieve the above object, a third voice coil motor control device according to the present invention is arranged such that, in the first voice coil motor control device, the movable part is driven on a trial basis at an initial stage of energization. The predetermined current of is a current that increases stepwise until the movable part moves.

[0013]

In the first voice coil motor controller according to the present invention, the position detecting means detects the position of the movable portion which is linearly movable. Further, the drive current supply means supplies a predetermined current for driving the movable portion on a trial basis at the initial stage of energization. Further, the calculating means calculates the amount of movement of the movable part in a fixed time by the test drive in the initial stage of energization based on the output from the position detecting means. On the other hand, the storage means stores in advance the relationship between the movement amount and the bias current suitable for driving the movable portion. Then, the bias current determining means determines the bias current based on the output from the calculating means and the information from the storing means.

A second voice coil motor control device according to the present invention is the same as the first voice coil motor control device, wherein a predetermined current for driving the movable portion on a trial basis at the initial stage of energization is constant. It is an electric current.

A third voice coil motor control apparatus according to the present invention is the same as the first voice coil motor control apparatus, wherein a predetermined current for driving the movable portion on a trial basis in the initial stage of energization is the movable current. It rises in stages until the department moves.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 4 are exploded perspective views of a lens barrel to which a voice coil motor controller according to a first embodiment of the present invention is applied. FIG. 5 is a vertical sectional view of the lens barrel.

The lens barrel to which the control device for the voice coil motor of this embodiment is applied is a zoom lens barrel having a four-group structure, and for zooming, the cam ring 3 is driven by a stepper (stepping motor) as a drive source. By rotating, each lens group holding frame is advanced and retracted. Focusing is performed by driving the CCD holder 14 itself, which holds the CCD that is the image pickup element, back and forth by the voice coil motor (VCM) 101 (see FIG. 12) that is an electromagnetic actuator.

The present lens barrel has the above-mentioned perspective view,
As shown in the cross-sectional view and the like, the outer fixed frame 1 fixed to the camera body mainly via each fixed frame described later, and the first group lens 41.
And holds the cam ring 3 through the three cam followers 22a.
The first group frame 2 which is one of the lens holding frames having a so-called three-piece suspension structure, which can be freely moved back and forth by the cam grooves 3a, and the cam grooves 3a, 3b, 3c, 3d for driving the respective holding frames are arranged. A rotatable cam ring 3, a corrugated washer 4 for urging the cam ring, and an inner fixed frame 5 fixed to the outer fixed frame 1 are provided.
And have.

Further, the lens barrel holds the guide shafts 7 and 8 for movably advancing and retracting each lens frame other than the first group frame 2 and the CCD holder 14, and the second group lens 42. 2 is a lens holding frame that is supported by 8 and can move back and forth.
Holding the group frame 9 and the third group lens 43, the guide shaft 7,
A third group frame 1 which is a lens holding frame which is supported by 8 and can freely move back and forth.
A fourth group frame 11 which is a lens holding frame which holds 0 and a fourth group lens 44 and is supported by the guide shafts 7 and 8
And the above-mentioned VC which is an electromagnetic actuator for driving a CCD
The yoke 12 that constitutes M101, the guide shaft 7,
8. The rear fixed frame 13 supporting the yoke 12 and the guide shafts 7, 8 slidably supported by the CCD 55 and the LP.
LE, which is a light emitting element for holding the F54 and detecting the forward / backward position
A VCM with a D61 attached and that drives itself forward and backward
C, around which the drive coil 14b that constitutes 101 is wound
CD holder 14, the LPF 54, the CCD 55
And a rear cover that restricts the guide shafts 7 and 8 in the axial direction.
15 and the stepper 5 for driving the rotation of the cam ring.
A cam ring driving unit having a driving source 1 and the CCD holder 1
4 is a position detecting means for detecting the advancing / retreating position, and has a PSD 62 which is supported on the rear fixed frame 13 side, receives light from the LED 61, and detects the position.

The outer fixed frame 1, the inner fixed frame 5, and the rear fixed frame 1
3 is integrally fixed with screws through the respective mounting holes 1a and 5a ', 5a and 13a in a state where the respective constituent members described below are incorporated. The relative positioning of the frames 1 and 13 in the rotational direction at the time of fixing is performed by fitting the positioning pins 1b and 13b into the positioning holes 5b of the inner fixed frame 5.

Then, the first group frame 2 is inserted into the outer fixed frame 1 so as to be able to move forward and backward in a state in which the rotation is restricted.
The rotation is restricted by inserting a boss 23 coaxially provided with the pin 22 of the first group frame 2 into the straight guide groove 1j arranged on the inner peripheral portion of the outer fixed frame 1 to restrict the rotation. To be done. Here, instead of the boss 23, a roller may be supported by the pin 22 and fitted into the straight guide groove 1j. The forward / backward drive of the first group frame 2 during zooming is performed by the rotation of a cam ring 3 described later.

Further, on the inner peripheral portion of the outer fixed frame 1, convex portions 1d and 1e which are linear reference guide portions are formed downward along the advancing / retreating direction.
However, linear projections 1f and 1g are provided on the upper side. Further, a leaf spring 21, which is a biasing member, is screwed to the mounting portion 1h in the opening 1i at the upper center. Even if the above-mentioned first group frame 2 is fitted in the convex portions 1d, 1e, 1f, 1g in a state where there is a fitting backlash required for mechanical or component precision, the first group frame 2 is downward. And the outer periphery thereof is in contact with the convex portions 1d and 1e. During the zooming operation, the first group frame 2 moves forward and backward in this state, and in the normal photographing state, this contact state is always maintained, and the first group lens 41 does not tilt with respect to the lens barrel optical axis O. become. In addition, when an upward external force is applied to the first-group frame 2, the outer circumference of the first-group frame 2 has convex portions 1f, 1
It only moves slightly until it contacts g.

The cam ring 3 is rotatably fitted in the inner peripheral portion of the first group frame 2, and further, the inner fixed frame 5 is fitted in the inner peripheral portion of the cam ring 3. However, a corrugated washer 4 is inserted on the outer periphery of the inner fixed frame 5, and the corrugated washer 4 has a flange portion 3h of the cam ring 3 and a flange portion 1c of the outer fixed frame 1.
Press so as to abut. Due to this pressing force, the above 1
The group frame 2 is positioned with respect to the inner and outer fixed frames 5 and 1 in the optical axis direction. Further, since the corrugated washer 4 is inserted with the groove 4a provided on the inner periphery thereof fitted in the convex portion 5e of the inner fixed frame 5, its rotation is restricted.

A gear portion 3i is provided along the outer circumference of the flange portion of the cam ring 3, and a drive gear 34a of a cam ring driving portion, which will be described later, is meshed with the gear portion 3i through a groove 1m of the fixed frame 1. And the cam ring 3 is driven by the drive unit.
Is rotated from the wide position to the tele position.

The wide position is detected by a PI (photo interrupter) 53 in which the shielding leaf portion 3j provided on the flange portion is arranged at a rotation position corresponding to the wide position on the rotation locus. It Positioning of each zooming position is performed on the basis of the wide position. A protruding stopper 3k arranged on the flange portion of the cam ring 3.
Is a groove portion 1k arranged in the flange portion 1c of the outer fixed frame 1.
Is inserted into the cam ring 3 and functions as a rotation stopper at the wide end or the tele end of the cam ring 3.

There are three first-group-frame cam grooves 3a provided on the outer periphery of the cam ring 3, and the cam followers 22a of the first-group frame 2 are slidably fitted therein. The first group frame 2
Is restricted in its rotation, and when the cam ring 3 rotates, it moves back and forth in the optical axis O direction.

Further, cam grooves 3b, 3c and 3d for the second, third and fourth group frames are provided on the inner peripheral portion of the cam ring 3, and the second, third and fourth group frames 9, 10, 11 are respectively provided. The cam followers 9c, 10c, 11c fixed to the above are slidably fitted. When the cam ring 3 rotates, the holding frames move to the optical axis O.
It will move back and forth in the direction.

The cam ring drive section uses the stepper 51 as a drive source, and the rotation of the output gear thereof is transmitted to the drive gear 34a via the gear train and further transmitted to the gear section 3i of the cam ring 3. To be done.

The support structure for the guide shafts 7 and 8 is as follows.
In front of the guide shafts 7 and 8 on the inner fixed frame 5 (subject side)
Support holes 5f and 5g for supporting the end of the
The ends of the guide shafts 7 and 8 are inserted therein, the radial direction is positioned, and further, the subject side direction is restricted in the optical axis direction.

The approximately middle portion of the guide shafts 7 and 8 is supported by the axial holes 13f and 13g of the rear fixing frame 13 in a state of being positioned in the radial direction. The positions of the shaft hole 13f and the shaft hole 13g in the optical axis direction are shifted so as to be convenient because of the support structure of the lens holding frame and the CCD holder, as will be described later. Forward,
That is, it is located on the subject side. After the CCD holder 14 is inserted, the rear (CCD side) end portions of the guide shafts 7 and 8 are attached to the rear fixing frame 13 by the bottomed holes 15f and 15g of the rear cover 15 and the optical axes. The direction is regulated and held down.

The guide shafts 7 and 8 slidably support the second group frame 9, the third group frame 10 and the fourth group frame 11 between the inner fixed frame 5 and the rear fixed frame 13. That is, the guide shaft 7 has a forked portion 9f of the second group frame 9, a third group frame 10, and a shaft hole portion 10 of the fourth group frame 11.
f and 11f are fitted. The guide shaft 8 has a shaft hole portion 9g of the second group frame 9, a third group frame 10, and a forked portion 10g, 11 of the fourth group frame 11.
g is fitted, and the frames 9, 10 and 11 are slidably supported in a state of being housed inside the inner fixed frame 5.

Then, as described above, the cam followers 9c, 1 fixed to the second, third, fourth group frames 9, 10, 11 are attached.
0c and 11c are openings 5c and 5d, which will be described later, of the inner fixed frame 5.
To be slidably fitted into the cam grooves 3b, 3c, 3d of the cam ring 3. The escape of the followers 9c, 10c, 11c, and the guide shafts 7, 8 and the frames 2, 3, 4 group 9,
The inner fixing frame 5 is provided with the openings 5c and 5d along the optical axis O in order to allow the shaft holes 10 and 11 to escape, and the CCD holder 14 is rear-fixed. Shaft hole 13 of frame 13
The guide shafts 7 and 8 supported by f and 13g are slidably inserted by being inserted from the side opposite to the subject side, that is, the CCD side. In the fitted state, the drive coil 14b is inserted forward through the opening 13h and is located in a portion surrounded by the inner peripheral portion 12b of the yoke 12 and the magnet 16. After that, the rear cover 15 is attached to the rear of the rear fixed frame 13, and the guide shafts 7 and 8 are in a state in which the position of the guide shafts 7 and 8 is regulated in the optical axis direction.

On the other hand, as described above, the above-mentioned fourth group frame 11 is mounted on the subject side of the rear fixed frame 13, that is, on the front side, and the length of the fourth group frame 11 in the optical axis direction is on the guide shaft 7 side. Has a relatively long shaft hole 11f, and a bifurcated portion 11g having a relatively short length in the optical axis direction of the fourth group frame 11 is fitted on the guide shaft 8 side. In addition, the shaft hole 13f of the rear fixing frame 13,
As for the disposition position of 13g, as described above, the shaft hole 1f into which the guide shaft 7 is inserted is closer to the shaft hole 13f into which the guide shaft 8 is inserted.
It is located rearward of 3 g along the optical axis direction.

When the CCD holder 14 is attached to the guide shafts 7 and 8, the length of the holder 14 in the optical axis direction may be relatively short in terms of holding accuracy.
On the side of the guide shaft 7 supported by f, a shaft hole 14g that needs to have a relatively long length in the optical axis direction in terms of holding accuracy is formed in the shaft hole 1
They are inserted through the guide shaft 8 side supported by 3 g.

The yoke 12 constituting the VCM 101
Is made of a magnetic material, and is attached to the subject side of the rear fixing frame 13 through the attachment holes 12a.
It is fixed at 3d.

FIG. 6 is a sectional view around the yoke portion,
(A) is a sectional view orthogonal to the optical axis, and (B) is its C-C.
It is sectional drawing. As shown in the figure, the yoke 12 has a yoke inner peripheral portion 12b, and four magnets 16 are mounted on the top, bottom, left and right so as to face the inner peripheral portion 12b. Those magnets 1
The width of 6 is set to about 3/5 of one side of the yoke inner peripheral portion 12b, but not limited to this size, an appropriate size may be adopted so as to satisfy various conditions.

The magnets 16 disposed above and below the magnet 16 are attached along the horizontal scanning direction of the CCD 55,
Further, the magnets 16 disposed on the left and right are CCDs.
It is attached along the vertical scanning direction 55. Further, the magnet 16 arranged in the horizontal direction is attached to the right side of the optical axis O, and the magnet 16 arranged in the vertical direction is attached to the lower side of the optical axis O. Further, in the present embodiment, the four magnets 16 are the inner peripheral portion 1 of the yoke 12.
They are arranged symmetrically with respect to a substantially diagonal line Lc passing through the optical axis O of 2b. The arrangement state of the magnet 16 is determined in relation to the positions of the shaft hole 14g portion and the bifurcated portion 14f portion of the holder 14 as described later. Therefore, the four magnets 16
The arrangement of is not necessarily limited to the above arrangement.

As shown in FIG. 5 and the like, an LPF (low pass filter) 54 and a CCD 55 are mounted on the CCD holder 14 from the rear side, that is, from the CCD side. Furthermore, the C
The drive coil 14b is provided on the outer periphery of the cylindrical portion outside the LPF54 mounting portion of the CD holder 14 so as to surround the LPF54.
It is wound around the bobbin of the CD holder 14.

In the sectional view around the yoke portion shown in FIG. 6A, the relative arrangement positional relationship between the yoke 12 and the guide shafts 8 and 7 as seen from the CCD side is shown. As shown in this figure, the guide shaft 8 insertion shaft hole 14g portion of the holder 14 and the guide shaft 7 supporting bifurcated portion 14f portion are located in a gap between the magnet 16 installation positions and the yoke 12 portion. There are a lower right position and an upper left position on a substantially diagonal line Lc passing through the optical axis O. Therefore, the center line connecting the guide shafts 8 and 7 and the diagonal line Lc on the inner circumference of the yoke substantially coincide with each other.

The LED 61 of the light emitting element and the PS of the light receiving element which constitute the advancing / retreating position detecting portion (position detecting means) of the CCD 55.
As shown in FIGS. 7 and 8, the arrangement state of the D (light position detecting element) 62 is arranged on the side of the center line Lc connecting the guide shafts 7 and 8.

The CCD holder 14 and the CCD 55 are also provided.
As for the relative position of the CCD holder 14 in the optical axis direction, as shown in the operation diagram of the CCD holder in the tilted state of FIG. 10 and the optical axis direction sectional view around the CCD holder of FIG. On the vertical line passing through the center point 14i of the sleeve 14h length of the 14g portion, the image plane 55 of the CCD 55
It is arranged so that a is located.

Further, as shown in the sectional view of FIG. 11, the FPC 56 for electric signal connection, one end of which is fixed to the CCD 55, is mounted by being folded back in a U shape and extended from the rear cover 15 and fixed. Has been done.

Among the lens barrel to which the present embodiment having the above-mentioned structure is applied, particularly the optical element driving device section, the structure and the operation thereof will be described in detail.

First, the state in which the thrust acts on the CCD holder 14 will be described. Since the CCD holder 14 is supported by the guide shafts 7 and 8 so as to be able to move forward and backward as described above, the drive constituting the VCM 101 is constituted. The thrust F in the optical axis direction is applied to the CCD holder 14 by the current flowing through the coil 14b.
(See FIG. 6B) occurs. Due to the thrust F,
The CCD holder 14 and hence the CCD 55 can be driven back and forth.

Next, in this embodiment, the light emitting element 61 which constitutes the advancing / retreating position detecting portion (position detecting means) of the CCD 55.
The arrangement state and operation of the PSD 62 will be described in detail.

FIG. 7 is a perspective view showing an arrangement state of the CCD holder 14 and the advance / retreat position detecting portion, and FIG. 8 is the CCD.
It is the figure which looked at holder 14 and the circumference of an advance / retreat position detection part from the CCD side.

As shown in the figure, in the PSD 62, the light receiving surface 62a thereof is positioned on a line orthogonal to the line Lc passing through the optical axis O and connecting the centers of the guide shafts 7 and 8, and the rear fixing frame 13 is positioned. Supported by. The CCD holder 14 does not necessarily need to be integrally formed, but in the present embodiment, an integrally formed slit 14i is provided at a position facing the PSD 62, and the slit 14i is further provided.
At the end of i, an LED 61 is disposed so as to be supported by the CCD holder 14.

By disposing the position detector as in the above-mentioned embodiment, when the CCD holder 14 moves forward and backward along the optical axis O by the thrust F, the CCD holder 14 is
As shown in FIG. 9, even if the optical disc is tilted in the optical axis direction along the center line Lc by the gap of the guide shaft hole 14g, the movement amount D0 of the CCD 55 in the optical axis center due to the tilt is PS.
The same movement amount is detected by D62. Therefore,
The forward / backward movement amount itself of the optical axis center including the movement amount due to the tilt of the CCD holder 14 can be accurately detected by the PSD 62.

A driving operation of the present lens barrel incorporating the optical element driving device as described above will be described.

First, when a power switch (not shown) is turned on, the stepper 51 is driven and the cam ring 3 is rotated to the wide end position which is the reset position, and 1, 2, 3, 4
The group frames 2, 9, 10, and 11 are moved to the wide end positions, respectively. When performing zooming, the stepper 51 is driven from the above state, the cam ring 3 is rotated, and 1, 2, 3, 4
The group frames 2, 9, 10, and 11 are moved in accordance with zooming. And VCM which is an electromagnetic actuator
By controlling the current of the drive coil 14b of 101, the CCD 55 supported by the CCD holder 14 is moved to follow the zoom tracking position which is the focus position corresponding to the zooming position. That is, the CCD 55 moves hourly according to the zooming operation in order to maintain the in-focus state. Also, when performing focusing, VCM1
The CCD holder 14 is driven back and forth by 01, and the CCD 55
Move to the in-focus position.

Next, the configuration of the control device for the voice coil motor of this embodiment will be described in more detail.

FIG. 12 is a block diagram showing the configuration of a voice coil motor controller according to the first embodiment of the present invention.

The VCM 101 is a CCD 5 which is an image pickup device.
5, a yoke 12, which is an electromagnetic actuator for driving, a rear fixed frame 13 that supports the yoke 12, and slidably supported by the guide shafts 7 and 8, and the CCD 55 and the LPF.
LE, which is a light emitting element for detecting the forward / backward position,
The CCD holder 14 to which the D61 is attached and the drive coil 14b is wound, the LPF 54, the CCD 55, and the rear cover 15 that restricts the guide shafts 7 and 8 in the axial direction. Is configured.

As described above, the above-mentioned C which is an optical moving member.
The CD holder 14 is provided with an LED 61, which is a light emitting element for detecting the advancing / retreating position. Further, a PSD 62, which is a light receiving element for position detection, is attached to the rear fixed frame 13 side facing the LED 61. And VC
When the LED 61 moves in the optical axis direction by driving M101, the light emission center of the LED 61 shifts relatively to the PSD 62, so that the output of the PSD 62 changes. The output of the PSD 62 is sent to the CPU 103 described later via the position detection circuit 102a. In addition,
The LED 61, the PSD 62, and the position detection circuit 102a constitute the position detection means 102. Also, although not shown,
The position detecting means 102 is provided with a speed detecting portion arranged on the CCD holder 14.

Inside the CPU 103, a bias storage unit 103a as a storage unit and a target position / wobbling calculation processing unit 103b are provided.
The numeral 3 serves as an arithmetic means for receiving a signal from the position detecting means 102 and performing later-described arithmetic / processing, and sends a VCM control command to the VCM drive circuit 104. Further, the bias storage unit 103a provided in the CPU 103 stores in advance a bias current corresponding to a movement amount within a fixed time at a fixed bias current. Then, the CPU 103, which functions as a bias current determining unit, uses the information from the position detecting unit 102 and the bias storage unit 10.
A new bias current is determined from the stored value from 3a.

The VCM drive circuit 104 is the CPU 1
Drive control of the VCM 101 is performed based on a command from 03. That is, at the initial stage of energization of the VCM 101, it serves as a drive current supply means for supplying a predetermined current for driving the movable portion (CCD holder 14) on a trial basis, and also supplies a drive current in a normal state. Also plays a role.

The wobbling is to vibrate a predetermined optical element near the focal point.

Next, the operation of the bias storage section 103a in this embodiment will be described with reference to the flow chart shown in FIG. 13 and the diagram shown in FIG.

In a camera to which the control device for the voice coil motor of this embodiment is applied, generally, a photographing posture as shown in FIG. 15 can be considered. In the figure, the above VCM
The inclination and the movement amount of 101 are θ and L, respectively, and the friction coefficient at this time is μ as shown in FIG. In this embodiment, the bias storage unit 103a stores the V
The bias current with respect to the movement amount within a constant time at a constant bias current when the inclination θ of the CM 101 is changed is stored.

Here, referring to FIG. 14, the VCM 101
The description will be made separately for the case where the slope of + is + θ and the case where it is −θ. When the inclination is + θ, μ> tan | −θ |
It also includes −θ that satisfies the condition. Further, the bias current A is θ =
The value should be able to hold 90 °.

Now, if a bias current A is applied,
When θ = −5, 5, 10 ° and the amount of movement L of each posture for a certain time ΔT, the amount of movement L is different,
On the other hand, the movement amount L is inversely proportional. Then, the bias current for θ is obtained by actual measurement. As a result, the bias current for the movement amount L when the constant bias current A is determined. In other words, the bias current for θ is determined. Similarly, in the case of −θ (−θ also includes θ that satisfies μ> tan θ), the bias current is −A. As a result, the bias current for the movement amount L when the constant bias is −A is determined.

The bias current corresponding to the movement amount L is stored in the bias storage unit 103a.

Next, the actual operation will be described with reference to the flowchart shown in FIG.

When the power is turned on (step S1), the photographing postures shown in FIG. 15 can be considered. As described above, the bias current A depends on the posture angles of + θ and −θ.
Have different polarities. First, where is the position of the drive,
That is, the position detection means 102 determines whether + θ or −θ.
Based on the information from the CPU 103 (step S
2). Specifically, when + θ, the movable part (CCD
It is considered that the holder 14) has a position as shown in FIG. 17 when the friction coefficient μ between the support mechanism and the CCD holder 14 is μ <tan θ, and an arbitrary position when μ ≧ tan θ. When −θ, the friction coefficient μ
Is μ <tan | −θ |, the CCD holder 14 is at the position shown in FIG. 18, and μ ≧ tan | −θ |
When, it is considered to be an arbitrary position.

When the CCD holder 14 is in the vicinity shown in FIG. 17, it is + θ, and when it is in the vicinity shown in FIG. 18, it is −θ. Other than that, consider + θ. The information can be obtained from the position detecting means 102.

In step S2, the posture of the VCM 101 when the power is turned on is in the state shown in FIG. 17, that is, at + θ near the end of the rear fixed frame 13 based on the information from the position detecting means 102. When determining that there is, the CPU 103 causes the VCM drive circuit 104
On the other hand, the VCM 101 is instructed to apply a constant bias current A to move it to the lens side (step S4). As a result, the constant bias current A is applied to the VCM coil 14b of the VCM 101 for a time ΔT, and the CCD holder 1
4 starts to move.

After this, within the time ΔT, the CCD holder 14
The amount L of movement of the CCD holder 14 is detected by the position detecting means 102 (step S6), and when the change of the CCD holder 14 is in the bias direction, the CPU 103 causes the change of the CCD holder 14, that is, the movement. A bias current value corresponding to the amount L is read from the bias storage unit 103a, and the VCM drive circuit 104 is instructed to apply the bias current to the VCM coil 14b (step S7). In step S6, the CCD
When there is no change in the holder 14, the CPU 10
3 instructs the VCM drive circuit 104 to increase the bias current in the same direction (step S8).

Further, in step S2, the attitude of the VCM 101 when the power is turned on is in the state shown in FIG. 18, that is, near the lens side end by -θ, based on the information from the position detecting means 102. When determining that there is, the CPU 103 instructs the VCM drive circuit 104 to apply a constant bias current A to the VCM 101 and move it to the fixed frame 13 side (step S).
3). As a result, the VCM coil 14 of the VCM 101 is
The constant bias current A is applied to b for time ΔT, and the CCD
The holder 14 starts to move.

Similarly, the position detecting means 102 detects the amount of movement L of the CCD holder 14 within the time ΔT (step S6), and when the change of the CCD holder 14 is in the bias direction. , The CPU 103 uses the C
The degree of change of the CD holder 14, that is, the bias current value corresponding to the movement amount L is read from the bias storage unit 103a, and the VCM drive circuit 104 is instructed to apply the bias current to the VCM coil 14b (step). S7). Further, in step S6,
When there is no change in the CCD holder 14, the above CP
U103 uses VC to increase the bias current in the same direction.
The M drive circuit 104 is instructed (step S8).

On the other hand, in step S2, when the posture of the VCM 101 when the power is turned on is not in any of the states shown in FIGS. 17 and 18 according to the information from the position detecting means 102, that is, μ> ≧ tan | θ
If it is |, the same processing as in step S4 and thereafter is performed.

In this embodiment, the position detecting element of the CCD holder 14 may be a magnetoresistive element.

Further, the movable part includes a part to which an optical element such as an image pickup device element or a lens is fixed.

Further, in this embodiment, the VCM
The drive circuit 104 serves both as a circuit for supplying a predetermined current for experimentally driving the movable part in the initial stage of energization and as a drive current supply circuit for normal operation, but these two actions are different. It goes without saying that the circuit may be used.

According to this embodiment having such a configuration,
It is possible to set an appropriate bias current for surely maintaining the movement of the movable part (CCD holder), and even if it is moved in either direction next time, the load will be uniform and there will be no drift during wobbling. Play.

Further, since the proper bias current can be set when the power is turned on, the responsiveness of the movable part becomes good.

Next, a second embodiment of the present invention will be described.

The controller of the voice coil motor according to the second embodiment has the same structure as that of the first embodiment and is different only in that the bias current is applied stepwise. Then, I will explain only the differences,
Descriptions of other parts are omitted.

In the voice coil motor controller of the first embodiment, as shown in FIG.
1, the bias current was linearly applied during ΔT from time T1 to T2, but in the second embodiment, this Δ
The feature is that the bias current is applied stepwise during T.

The other operations are the same as those of the first embodiment, and the second embodiment having such a structure also has the same effects as the first embodiment.

[Appendix] According to the embodiments of the present invention as described in detail above, the following configurations can be obtained. That is, (1) a movable part that moves linearly by the supporting means and a light emitting element for position detection are provided on the movable part, and a light receiving part for position detection is provided at a position facing the light emitting element on the fixed part. A voice coil motor control device including a voice coil motor having the same, a position detection circuit for converting the output of the light receiving unit into position information, and a drive circuit unit for driving the voice coil motor. A bias current storage unit that stores the correlation of the bias current with respect to is provided, and a constant bias current is applied at the beginning of energization to read the bias current value from the bias current storage unit based on the position change of the position detection circuit, and this value is biased. Control device for voice coil motor that uses electric current.

(2) The voice coil motor control device according to (1), wherein the constant bias current is divided into a plurality of parts.

According to the control device for the voice coil motor described in (1) and (2) above, since an appropriate bias current can be obtained before the operation, there is an effect that there is no focus delay and zoom tracking delay. .

[0084]

As described above, according to the present invention, it is possible to provide a voice coil motor control device capable of setting an appropriate bias current for surely holding the position of the movable portion when the operation of the device is started.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a main part showing a part of a lens barrel having a built-in controller of a voice coil motor according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view showing a part of the lens barrel shown in FIG.

FIG. 3 is an exploded perspective view showing a part of the lens barrel shown in FIG.

FIG. 4 is an exploded perspective view showing a part of the lens barrel shown in FIG.

5 is a vertical cross-sectional view taken along the optical axis of the lens barrel shown in FIG.

6 is a cross-sectional view of the yoke of the voice coil motor of the optical element driving device for the lens barrel shown in FIG. 1, in which (A) is a cross-sectional view of a plane orthogonal to the optical axis and (B).
FIG. 4 is a sectional view taken along the optical axis.

FIG. 7 is a perspective view of a position detection unit in the control device for the voice coil motor according to the present embodiment.

FIG. 8 is a view of the position detection unit in the control device for the voice coil motor according to the present embodiment as viewed from the CCD side.

FIG. 9 is a diagram showing a CCD displacement and a PSD position detection state when the CCD holder in the control device for the voice coil motor according to the present embodiment is tilted by a certain amount.

FIG. 10 is a diagram showing the displacement of the image plane of the CCD when the CCD holder is tilted in the control device for the voice coil motor of this embodiment.

FIG. 11 is a cross-sectional view around a CCD holder in the control device for the voice coil motor of this embodiment.

FIG. 12 is a block diagram showing a configuration of a voice coil motor control device of the present embodiment.

FIG. 13 is a flowchart illustrating the operation of the voice coil motor control device according to the present embodiment.

FIG. 14 is a diagram illustrating an operation of the control device for the voice coil motor according to the present embodiment.

FIG. 15 is a diagram showing an example of a shooting posture by a camera to which the control device for the voice coil motor according to the present embodiment is applied.

FIG. 16 is a diagram showing the relationship between the inclination θ of the voice coil motor and the friction coefficient μ in the control device for the voice coil motor of this embodiment.

FIG. 17 is a cross-sectional view showing an example of the position of the CCD holder in the control device for the voice coil motor of this embodiment.

FIG. 18 is a cross-sectional view showing another example of the position of the CCD holder in the control device for the voice coil motor of this embodiment.

[Explanation of symbols]

 101 ... VCM (voice coil motor) 102 ... Position detecting means 61 ... Light emitting element (LED) 62 ... Light receiving element (PSD) 102a ... Position detecting circuit 103 ... CPU 103a ... Bias storage section 103b ... Target position / wobbling calculation processing section 104 VCM drive circuit 13 Rear fixed frame 14 CCD holder 55 CCD

Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location H02K 33/18 B (72) Inventor Ryota Ozumi 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Industry Within the corporation

Claims (3)

[Claims] 1. A position detecting means for detecting the position of a movable part which can move linearly, a drive current supplying means for supplying a predetermined current for driving the movable part on a trial basis at the initial stage of energization, and an initial stage of energization. The relation between the calculation means for calculating the movement amount of the movable portion in a certain time by the trial drive based on the output from the position detection means, the movement amount, and the bias current suitable for driving the movable portion is previously described. A voice coil motor control device comprising: a stored memory means, a bias current determining means for determining a bias current based on an output from the arithmetic means, and information from the memory means. 2. The voice coil motor control device according to claim 1, wherein the predetermined current for driving the movable portion on a trial basis in the initial stage of energization is a constant current. 3. The predetermined current for tentatively driving the movable part at the initial stage of energization is a current that gradually increases until the movable part moves. Voice coil motor controller.