1. Field of the Invention
The present invention relates to a blur compensation device, a lens barrel, and a camera device.
2. Description of the Related Art
In recent years, there is a request such as downsizing of a blur compensation device. From this, as shown in Patent document 1, the blur compensation device has an asymmetrical shape of a movable member with respect to a center of a lens thereof. In regard to such a shape of the movable member, the center of the lens and a gravity center of the movable member hardly correspond to each other.
In conventional ways, as shown in Patent document 1, a voice coil motor (VCM) was placed so that a drive axis of the voice coil motor which drives a movable member was directed to a center of a lens. Therefore, in conventional arts, there was a problem that a rotary torque was worked around a gravity center of the movable member when the movable member was to move, so that control performances of the blur compensation device such as controlling stability or convergence properties of the movable member for a target position were adversely acted on during the blur compensation. In addition, there was a problem that a mass of the movable member increased and drive performances deteriorated in the case of using an adjusting member of the gravity center.
[Patent Document 1]
Japanese Unexamined Patent Publication No. 2009-169359
The object of the present invention is to provide a blur compensation device with excellent control performances, a lens barrel, and a camera device comprising the blur compensation device.
To achieve the above object, the blur compensation device (100) of the present invention comprises;
a movable member (130) provided with a blur compensation member, which is relatively movable to a fixed member (140) on a predetermined drive face, for compensating an image blur formed by an optical system and having a gravity center located different from a center of the blur compensation member (L3);
a first drive member (132, 142) which moves the movable member (130) along a first axis (X′) on the drive face; and
a second drive member (134, 144) which moves the movable member (130) along a second axis (Y′) crossing the first axis (X′) on the drive face, wherein
at least a part of the first drive member (132, 142) is provided on the movable member (130) and moves with the movable member (130) along the first axis (X′);
at least a part of the second drive member (134, 144) is provided on the movable member (130) and moves with the movable member (130) along the second axis (Y′); and
an intersection point (M) of the first axis (X′) with the second axis (Y′) is located nearer to the gravity center (G) of the movable member (130) than the center (O) of the blur compensation member (L3) on the drive face.
Note that, in order to easily explain the present invention, the numerals of the Figures shown in the embodiments are used. However, the present invention is not to be limited thereto. The constitution of the embodiments as stated below may be modified suitably, and at least some parts may be substituted by other constitution as well. Further, the constitutional element having no any particular limitation of its position is not limited to the position disclosed in the embodiments and the position can be changed as long as the function can be achieved.
The First Embodiment
As shown in
The lens barrel 2 comprises an imaging optical system constituted by arranging a first lens group L1, a second lens group L2, and a third lens group (a blur compensation lens group) L3 in order from a subject side. Further, the camera 1 of the present embodiment comprises an image sensor 3 represented by CCD or CMOS at the back of the third lens group (image surface side).
The first lens group L1 is provided at the nearest to the subject side in the imaging optical system. The first lens group L1 is movably driven by a drive mechanism 6 in the direction along the optical axis L and can ensure zooming. The second lens group L2 is movably driven by a drive mechanism 8 in the direction along the optical axis L and can ensure focusing.
The third lens group (the blur compensation lens group) L3 comprises a part of a blur compensation device 100. With the blur compensation device 100 which received a signal from a CPU 14, the blur compensation lens group L3 moves within a face crossing the optical axis L and decreases image blurs caused by the camera motion.
A diaphragm mechanism 4 is driven by a drive mechanism 10 so that camera exposure is controlled. The image sensor 3 generates an electrical image output signal based on light of the subject image formed by the imaging optical mechanism on the imaging face. The image output signal is inputted to the CPU 14 after A/D conversion or noise processing with a signal processing circuit 16.
An angle velocity sensor 12 such as gyro sensors is built in with the lens barrel 2. The angle velocity sensor 12 detects an angle velocity caused by hands movement etc. occurring to the camera 1 and outputs it to the CPU 14. A detecting signal from a AF sensor 18 is also outputted to the CPU 14. Based on the detecting signal, the drive mechanism 8 is controlled and an auto focus (AF) function is realized.
A storage medium 20, a nonvolatile memory 22, and some kind of operation button 24 etc. are connected to the CPU 14. The storage medium 20 is a memory such as an attachable card type memory which stores camera images and is read out by receiving an output signal from the CPU 14. There are several types of the attachable card type memory such as Compact Flash (a registered trademark) cards or SD cards, but it is not particularly limited.
The nonvolatile memory 22 stores information of adjusted values such as gain values of gyro sensors and is comprised of a semiconductor memory which is built in with inside of the camera with the CPU 14. For example, a release switch is exemplified as some kind of operation button 24 and a signal thereof is inputted to the CPU 14 by depressing the release switch half or completely.
The constitution of the blur compensation device 100 shown in
As shown in
The position detection part 120 comprises a first hall effect element 122 and a second hall effect element 124 and detects a position of the movable part 130. The first hall effect element 122 has a detection axis on X-axis vertical to the optical axis L and the second hall effect element 124 has a detection axis on Y-axis vertical to the optical axis L.
The first hall effect element 122 and the second hall effect element 124 detect magnetic fields of a first magnet 132 and a second magnet 134 which are provided on the movable part 130 and detect the position of the movable part 130.
The movable part 130 comprises the first magnet 132, the second magnet 134, and the blur compensation lens group L3. In the following description, in order to easily understand the present embodiment, the blur compensation lens group L3 will be described as one slide of the blur compensation lens L3.
The movable part 130 is attached to the fixed part 140 at the three points by three pulling coil springs 145. The pulling coil springs 145 are attached to between a spring installation part at the side of the fixed part 146 shown in
The movable part 130 moves on a face crossing the optical axis L by the driving force generated by the interaction between the first magnet 132 (the second magnet 134) provided on the movable part 130 and the first drive coil 142 (the second drive coil 144) provided on the fixed part 140. The first magnet 132 and the first drive coil 142 comprise a first VCM 152, and the second magnet 134 and the second drive coil 144 comprise a second VCM 154. VCM is an abbreviation of voice coil motors.
An example of a blur compensation motion by the blur compensation device 100 shown in
An angle velocity sensor 12 is included in the camera 1 shown in
The target position command generating part 162 generates signals regarding movable part target position xt and yt (mm) by converting the angle velocity signals ωp and ωy to blur angles θp and θy (rad) by integrating them and by projecting blur angles θp and θy on a face crossing the optical axis. The signals regarding movable part target position xt and yt are signals regarding a target position of the movable part 130 for cancelling a blur due to the angle velocity signals ωp and ωy.
By utilizing the movable part target position xt and yt and movable part position coordinates x and y (mm) from the hall effect elements 122 and 124, coil drive electric currents Ix and Iy (A) for driving coils 142 and 144 are generated.
Specifically, the signals regarding the movable part target position xt and yt are inputted to the adder 170 through the feedforward controller 166. Further, the signals regarding the movable part target position xt and yt and signals regarding movable parts position coordinates x and y are inputted to the adder 170 through the subtracter 164 and the feedback controller 168. By utilizing these inputted signals, the adder 170 generates the coil drive electric currents Ix and Iy and outputs them to the first VCM 152 (the first drive coil 142) and the second VCM 154 (the second drive coil 144).
When the coil drive electric currents Ix and Iy are inputted to the first VCM 152 and the second VCM 154, as shown in
The hall effect elements 122 and 124 shown in
Next, with
As shown in
The first hall effect element 122 detects a X-axis directional position of the first magnet 132 attached to the movable part 130 shown in
In the present embodiment, as shown in
The movable part 130 is provided with the first magnet 132 and the second magnet 134. By the interaction between the first drive coil 142 and the second drive coil 144 shown in
By the electromagnetic driving forces Fx′ and Fy′, the movable part 130 moves relatively to the fixed part 140 along X′-axis and Y′-axis. When the movable part 130 locates at the drive axis origin M which is a driving center thereof, the center O of the lens passes the optical axis L. The first magnet 132 is placed so that the center thereof passes X′-axis and the second magnet 134 is placed so that the center thereof passes Y′-axis.
As shown in
Further, the second drive coil 144 is placed on the fixed part 140 so that Y′-axis which is the drive axis of the second VCM 154 comprised of the second drive coil 144 and the second magnet 134 passes nearer to the gravity center G of the movable part than the center O of the lens. That is, the second drive coil 144 is placed so that the VCM drive axis Y′ is inclined toward the hall effect element detection axis Y at the drive axis inclined angle θ (deg). Note that, the inclined angle of X′-axis toward X-axis and the inclined angle of Y′-axis toward Y-axis may be different. Further, by changing a placement position of coils 142 and 144 on the fixed portion 140, the placement position may be adjusted so that X′-axis and Y′-axis pass nearer to the gravity center G of the movable part than the center O of the lens.
In the present embodiment, since the first drive coil 142 and the second drive coil 144 are placed as the above, the drive axis origin M which is an intersection point of the drive axis X′ with the drive axis Y′ exists nearer to the gravity center G of the movable part than the center O of the lens along A2-axis. The drive axis origin M preferably corresponds to the gravity center G of the movable part. In this case, the drive axis X′ and the drive axis Y′ cross at an angle of θ0 which is not perpendicular and the angle of θ0 is an obtuse angle (e.g. an angle of 91-degrees to 120-degrees) in the present embodiment.
As the above, in the present embodiment, as shown in
In this case, the driving force Fx′y is canceled by acting a driving force Fy′ on Y′-axis with the second VCM 154. That is, the driving force Fx′y is canceled by a driving force Fy′y of Y-axis directional component of the driving force Fy′. In this case, the following relation is held between the driving force Fx′y and the driving force Fy′y.
[Numerical Formula 1]
Fx′y−Fy′y=0 (numerical formula 1)
Note that, since a driving force Fy′x is also acted on in accordance with action of the driving force Fy′, a driving force to the target position xt of the movable part is eventually Fx′x−Fy′x. The following relations are held when the directions of the VCM drive axes X′ and Y′ shown in
[Numerical Formula 2]
Fx′x=fx′ cos θ·i, x′y=fx′ sin θ·j (numerical formula 2)
[Numerical Formula 3]
Fy′x=fy′ sin θ·i, Fy′y=fy′ cos θ·j (numerical formula 3)
Here, in the numerical formula 2 and the numerical formula 3, i and j are unit vectors in the directions of X-axis and Y-axis, respectively. When the numerical formula 2 and the numerical formula 3 are substituted in the numerical formula 1, the following numerical formula 4 is to be obtained.
[Numerical Formula 4]
fx′ sin θ=fy′ cos θ∴fy′=fx′ tan θ (numerical formula 4)
From the above, the target driving force Fx of X-axis direction to the target position xt of the movable part is represented by the numerical formula 5.
Here, the following numerical formula 6 is obtained when the X and Y axial directions of the hall effect element detection axes shown in
When the numerical formula 6 is substituted in the numerical formula 4, the numerical formula 7 is obtained.
Further, as shown in
By composing the numerical formula 6 and numerical formula 8, the driving force Fx′ of the first VCM 152 on X′-axis is represented by the following numerical formula 9-1 by means of the driving forces Fx and Fy in the X and Y direction of the hall effect element detection axis.
The numerical formula 9-1 is represented by the following numerical formula 9-2 by means of Fx′, Fx, and Fy.
In the same way, the driving force Fy′ of the VCM on Y′-axis is represented by the following numerical formula 10-1.
The numerical formula 10-1 is represented by the following numerical formula 10-2 by means of Fy′, Fx, and Fy.
By driving the VCM with vector conversions of the numerical formula 9-1 and the numerical formula 10-1, the consistency between the detection axes of the hall effect element and the drive axes of the VCM is preserved.
Next, the blur compensation device 100 of the present embodiment is dynamically modeled and control performances of the blur compensation device will be described. Hereinafter, in order to easily understand the present embodiment, control in the X-axis direction will only be described. Since control in the Y-axis direction is the same as control in the X-axis direction, control in the Y-axis direction will be omitted.
In
When each of physical quantity is set as the above, a motion of the movable part 130 along x-axial direction is represented by an equation of motion as shown in the following numerical formula 11 and numerical formula 12. An equation of motion regarding translation of the position of the gravity center of the movable part 130 is represented by the numerical formula 11 and an equation of motion regarding rotation of the position of the gravity center of the movable part 130 is represented by the numerical formula 12.
[Numerical Formula 11]
m{umlaut over (x)}+cx{dot over (x)}+kxx=fx (numerical formula 11)
[Numerical Formula 12]
JGz{umlaut over (θ)}Gz+cxl{dot over (θ)}Gz+kxl2θGz=fxδ (numerical formula 12)
When the above equations of motion shown by the numerical formula 11 and the numerical formula 12 are Laplace transformed, the following numerical formula 13 and numerical formula 14 are obtained.
A displacement XSensor (s) (mm) in the X-axial direction which the hall effect element detects is represented by a numerical formula 15 from the above numerical formula 13 and numerical formula 14.
Here, when an acceleration in the X-axial direction which acts on the movable part is ax (mm/s2), fs(s) is represented by a numerical formula 16.
[Numerical Formula 16]
fx(s)=max(s) (numerical formula 16)
When the numerical formula 16 is substituted in the numerical formula 15, the following transfer function, wherein input is the acceleration ax in the X-axial direction and output is the displacement XSensor in the X-axial direction detected by the hall effect element, is obtained.
Here, ωm and ωj represent natural angular frequencies (rad/s) in the translation direction (X-axial direction) and the rotation direction (rotation around the Z-axial direction passing the gravity center G of the movable part), respectively. ζm and ζJ represent damping ratios (−) (dimensionless numbers) of the translation direction and the rotation direction, respectively.
In the transfer function shown by the numerical formula 17, the first paragraph represents a transfer function in the translation direction and the second paragraph represents a transfer function in the rotation direction. In the control block diagram of
In the numerical formula 17, “mδB/JGZ” is an important parameter in discussing the control performances of the blur compensation device according to the present invention. This is defined as KK factor and represented by a numerical formula 18.
Here, to easily understand the control performances of the blur compensation device, it is hypothetically set that the resonance frequencies and damping ratios in the translation direction and rotation direction are equal as shown in the numerical formula 19, and a transfer function represented by a numerical formula 20 is obtained from the transfer function represented by the numerical formula 17.
As is evidenced by the numerical formula 20, when a value of KK factor is −1 or less, the transfer function represented by the numerical formula 20 is negative over the entire frequency band. Therefore, this case is out of control because feedback is a positive feedback.
When a value of KK factor is larger than −1 and less than 0, the transfer function represented by the numerical formula 20 is positive. However, in the transfer function represented by the numerical formula 17 in which a translation element and a rotation element are divided, the rotation element is negative. Therefore, in this case, it is understood that behavior of the rotation element is unstable.
When a value of KK factor is 0 or larger, the transfer function represented by the numerical formula 20 is positive and the rotation element of the transfer function represented by the numerical formula 17 is positive. Therefore, behavior of the rotation element is stable.
As the above, control is stable when a value of KK factor is positive and conversely, control is unstable when a value of KK factor is negative. Therefore, polarity of KK factor is closely related to control performances.
As shown by the numerical formula 18, polarity of KK factor is determined by a relation between the direction of the gap δ between the gravity center and the driving force Fx and the direction of the gap B between the gravity center and the hall effect element position. That is, in
In the present embodiment, as the above, the first VCM 152 and the second VCM 154 are placed so that the drive axis origin M shown in
In the present embodiment, as the above, in
The distance δ is 0 when the drive axis inclined angle θ is θ1. At this time, in
Further, KK factor is 0 or larger when the drive axis inclined angle θ is θ1 or less and KK factor is 0.2 or less when the drive axis inclined angle θ is θ4 or larger. That is, KK factor is 0 or larger and 0.2 or less in the range R2 (θ4≦θ≦θ1). By adjusting the drive axis inclined angle θ so that KK factor is 0 or larger and 0.2 or less, a stable control can be performed in the movement of the movable part.
In the present embodiment, the drive axis inclined angle θ is preferably adjusted in the range R3 (θ3≦θ≦θ1) which satisfies the condition of the range R1 and the condition of the range R2. This is because, by adjusting the drive axis inclined angle θ in the range R3, a rotation component can be suppressed and a stable control can be performed in the movement of the movable part.
Note that, more preferably, the drive axis inclined angle θ is adjusted to θ1 so that the distance δ between the drive axis origin M and the gravity center G of the movable part is close to 0 and KK factor is positive (in this case, as is evidenced by the numerical formula 18, the value of KK factor is also close to 0) in the above-mentioned range R3. In this way, by adjusting the drive axis inclined angle θ, a rotation component can be suppressed and a stable control can be performed more preferably.
In the present embodiment, as shown in
The control performances of the blur compensation part 100 according to the present embodiment is shown in
As shown in
On the other hand, in the present embodiment, as the above, since the drive axis of the VCM is directed to a position which is near to the gravity center of the movable part, the rotation torque around the gravity center of the movable part is remarkably small. Therefore, in the present embodiment, as shown
Further, in the present embodiment, as shown in
In the present embodiment, as shown in
In the present embodiment, as shown in
In the present embodiment, since the movable part 130 is moved by converting the target position coordinates along the detection axes X and Y of the first hall effect element 122 and the second hall effect element 124 into the target movement along the drive axes X′ and Y′ of the movable part 130, the blur compensation device can be preferably controlled.
The Second Embodiment
The second embodiment of the present invention is the same as the first embodiment except that the arrangement of the blur compensation device 100 toward the gravity direction is different from that of the first embodiment. In the following description, some part overlapped by the above embodiment will be omitted.
In
When the simultaneous equation of the numerical formula 21 and the numerical formula 22 is solved, the following numerical formula 23 and numerical formula 24 are obtained.
Here, when drive electric currents of the VCMs are Ix and Iy (A) and thrust constants of the VCM are kx and ky (N/A, kx=ky=k in the present embodiment), the following relation is obtained.
[Numerical Formula 25]
fx′=k·Ix′, fy′=k·Ix′ (numerical formula 25)
From the above, the following relation is realized regarding the drive electric currents of the VCMs.
Here, when resistant elements of the VCMs are Rx′ and Ry′ (Ω, Rx′=Ry′=R in the present embodiment), the electric power consumption P (W) in driving the first VCM 152 and the second VCM 154 is represented by the following numerical formula 28.
From the numerical formula 28, the inclined angle β of the gravity and the electric power consumption P have a relation shown in
In the present embodiment, as shown in
Note that, the present invention is not limited to the above embodiments.
The above embodiments describe a blur compensation device of an optical-system moving type which drives the blur compensation lens L3 shown in
In the above embodiments, the two VCMs are employed as a means of driving the movable part, but the present invention is not limited to this. For example, two or more VCMs may be employed. Other actuators such as piezoelectric actuators may be also used.
In the above embodiment, the two hall effect elements are employed as a means of detecting a position of the movable part, but the present invention is not limited to this. Two or more hall effect elements may be employed. Further, other position detection measures such as PSD sensors may be used as well.
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Number | Date | Country | |
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20140313583 A1 | Oct 2014 | US |
Number | Date | Country | |
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Parent | PCT/JP2012/084128 | Dec 2012 | US |
Child | 14323555 | US |