Image stabilizing apparatus and image pickup apparatus

The image stabilizing apparatus includes a base member, a first member shiftable with respect to the base member in a direction orthogonal to an optical axis direction, a first actuator shifting the first member with respect to the base member, an image-pickup element constituted by a photoelectrical conversion element, a second member holding the image-pickup element. The second member is shiftable together with the first member in the direction orthogonal to the optical axis direction and rotatable with respect to the first member in a plane orthogonal to the optical axis direction. The apparatus further includes a second actuator rotating the second member with respect to the first member.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image stabilizing apparatus reducing image blur caused by hand shake or the like, and particularly to a sensor moving image stabilizing apparatus shifting and rotating an image sensor (image-pickup element) to reduce the image blur.

2. Description of the Related Art

Image stabilizing apparatuses (or image blur correction apparatuses) detect shaking of image pickup apparatuses caused by user's hand shake or the like by using an angular velocity sensor or an acceleration sensor, and shift an image-pickup element in a direction orthogonal to an optical axis direction or rotate the image-pickup element in a plane orthogonal to the optical axis to reduce image blur. Voice coil motors each being constituted by a coil and a magnet are often used as actuators to shift and rotate (roll) the image-pickup element.

Japanese Patent Laid-Open Nos. 2007-025616 and 2006-094199 have disclosed image stabilizing apparatuses each of which shifts and rolls an image-pickup element by using plural actuators, and detects movement amounts of coils constituting the plural actuators by using hall elements to control a shift position and a roll position of the image pickup element.

However, in the image stabilizing apparatuses disclosed in Japanese Patent Laid-Open Nos. 2007-025616 and 2006-094199, the shift of the image-pickup element influences the detection of the roll position (roll amount) of the image-pickup element, which makes it difficult to accurately control the roll position of the image-pickup element.

SUMMARY OF THE INVENTION

The present invention provides an image stabilizing apparatus capable of reducing an influence of one of a shift operation and a rotation (roll) operation of an image-pickup element on control of the other thereof to accurately control a shift position and a rotation (roll) position of the image-pickup element, and provides an image-pickup apparatus with the same.

The present invention provides as an aspect thereof an image stabilizing apparatus including a base member, a first member configured to be shiftable with respect to the base member in a direction orthogonal to an optical axis direction, a first actuator configured to shift the first member with respect to the base member, an image-pickup element constituted by a photoelectrical conversion element, a second member configured to hold the image-pickup element, and configured to be shiftable together with the first member in the direction orthogonal to the optical axis direction and rotatable with respect to the first member in a plane orthogonal to the optical axis direction, and a second actuator configured to rotate the second member with respect to the first member.

The present invention provides as another aspect thereof an image pickup apparatus includes the above-described image stabilizing apparatus and an image generating part configured to generate image data using an output from the image-pickup element.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Exemplary embodiments of the present invention will hereinafter be described with reference to the accompanying drawings.

FIG. 1shows a configuration of a single-lens reflex digital camera (image-pickup apparatus) equipped with an image stabilizing unit (image stabilizing apparatus) that is an embodiment of the present invention.FIGS. 2,3,4,5and6show a detail configuration of the image stabilizing unit.

Reference numeral100denotes the single-lens reflex digital camera (hereinafter simply referred to as the “camera”), and reference numeral102denotes a lens apparatus (interchangeable lens) detachably attached to a mount portion101of the camera100. The camera100and the lens apparatus102constitute a lens-interchangeable single-lens reflex digital camera system.

The lens apparatus102is provided with an image-pickup optical system103including a zoom lens unit (not shown), a focus lens unit (not shown) and an aperture stop (shown inFIG. 7with reference numeral104).

The camera100includes a focal-plane shutter having plural shutter blades, and an image-pickup element15that is constituted by a photoelectrical conversion element such as a CCD sensor or a CMOS sensor and whose exposure amount is controlled by the focal-plane shutter20. In an optical path L1from the image-pickup optical system103to the image-pickup element15(that is, on an optical axis of the image-pickup optical system103), an optical filter11is disposed which is formed by laminating optical elements such as an infrared cutting filter and a phase plate.

The image-pickup element15photoelectrically converts an object image formed by the image-pickup optical system103to output an image-pickup signal. Predetermined processing is performed on the image-pickup signal, and thereby an image data signal (image data) is generated. The image data is displayed on a display unit107provided on a back of the camera100. A user can determine an image-pickup composition by observing the image data displayed as an electronic viewfinder image on the display unit107. Moreover, the image data is recorded in a recording medium (not shown) such as a semiconductor memory as still image data or moving image data in response to an image-pickup starting operation of a release switch120.

Reference numeral111denotes a main mirror constituted by a half mirror, which reflects a part of a light flux from the image-pickup optical system103and transmits another part thereof. Reference numeral105denotes a focusing screen on which an object image is formed by the light flux reflected by the main mirror111. Reference numeral112denotes a pentaprism. Reference numerals109-1,109-2and109-3denote viewfinder lenses to make it possible for a user to observe the object image formed on the focusing screen105through the pentaprism112. The focusing screen105, the pentaprism112and the viewfinder lenses109-1to109-3constitute a viewfinder optical system.

Reference numeral163denotes an eyepiece shutter that prevents light inversely entering through the viewfinder optical system from reaching the image-pickup element15to generate ghost or flare in self-timer image-pickup.

A sub-mirror122is provided at a back (image plane side) of the main mirror111. The sub-mirror122reflects the light flux transmitted through the main mirror111to introduce it to a focus detection unit121. The main mirror111and the sub-mirror122are arranged in the optical path L1as shown in the figure when an object is observed through the viewfinder optical system, and is retracted to a position out of the optical path L1shown by dotted lines111′ and122′in the figure when the object is observed by the electronic viewfinder image and image-pickup is performed.

In the focus detection unit121, an image reforming lens166provided in the focus detection unit121divides the light flux entering from the sub-mirror122through a condenser lens164and a reflective mirror165. An area sensor167photoelectrically converts paired object images formed by the split light from the image reforming lens166to generate paired image signals. Calculating a phase difference between the paired image signals enables detection of a focus state of the image-pickup optical system103by a phase difference detection method.

Reference numeral114denotes a pop-up flash unit that is movable between a retracted position at which the flash unit114is retracted in the camera100and a pop-up position (light-emitting position) at which the flash unit114is protruded from the camera100.

Reference numeral119denotes a main switch to turn the power of the camera100on and off. A half-press operation (image-pickup preparing operation) of the release switch120starts image-pickup preparation processing including photometry and autofocus (AF), and a full-press operation (image-pickup starting operation) of the release switch120starts image-pickup processing for capturing the object image and recording the image data in the recording medium.

Reference numeral123denotes an image stabilizing switch that is operated by the user to select whether or not to cause the image stabilizing unit to operate. Reference numeral180denotes an optical viewfinder information display unit that displays predetermined information on the focusing screen105.

Reference numeral190denotes a shake sensor that detects shaking of the camera100in a pitch direction or/and a yaw direction. The shake sensor190is constituted by an angular velocity sensor in this embodiment, but it may be constituted by other sensors such as an acceleration sensor. The shake sensor190detects pitch shaking190pthat is angular shaking in a plane parallel to a paper plane ofFIG. 1and yaw shaking190ythat is angular shaking in a plane vertical to the paper plane ofFIG. 1. Reference numeral190ris a rolling shake sensor that is constituted by an angular velocity sensor or an acceleration sensor, and detects rotational (rolling) shaking190cin a plane orthogonal to a direction of the optical axis (hereinafter referred to as the “optical axis direction”) of the image-pickup optical system103.

InFIG. 2, the focal-plane shutter20includes a front curtain21constituted by plural shutter blades21ato21d, a rear curtain22constituted by plural shutter blades, and an intermediate plate23that separates running spaces of the front curtain21and the rear curtain22. Moreover, the focal-plane shutter20includes a retainer plate24and a cover plate25that respectively serve as retainer plates for the rear curtain22and the front curtain21. The retainer plate24and the cover plate25are respectively provided with an aperture24aand an aperture25afor exposure of the image-pickup element15.

InFIGS. 2 to 5, an image-pickup part10includes the optical filter11, a filter holder12that holds the optical filter11, a mask member13having an aperture13athrough which effective entering light passes and blocking unnecessary entering light, the image-pickup element15, and a cover member15athat protects the image-pickup element15. A sealing member is provided between the cover member15aand the optical filter11for sealing a gap therebetween. Connecting terminals15cof the image-pickup element15are connected to a substrate17on which a drive circuit that drives the image-pickup element15is formed. The image-pickup part10thus configured is held by a roll base30that is a second member.

A pin (boss) portion30bthat is a protruding portion extending in the optical axis direction is formed in a central part of a back face of the roll base30. The pin portion30bis rotatably inserted into a hole portion40bformed in a shift base40that is a first member. Concave portions30aare formed at circumferential three places of the back face of the roll base30as shown inFIG. 4, and balls55aare respectively disposed in the concave portions30a. Each ball55ais sandwiched in the optical axis direction between the concave portion30a(roll base30) and a ball receiving face35aprovided in the shift base40and formed of metal such as copper foil.

Concave portions40aare formed at circumferential three places in a marginal part of a back face of the shift base40, and balls55bare respectively disposed in the concave portions40a. Each ball55bis sandwiched in the optical axis direction between the concave portion40a(shift base40) and a ball receiving face35bprovided in a base plate50that is a base member of the entire image stabilizing unit70, the ball receiving face35bbeing formed of metal such as copper foil.

Plural compression coil springs53are disposed in a charged state between a chassis100bof the camera100and the roll base30to bias the roll base30and the shift base40toward the base plate50. Biasing forces of the compression coil springs53press the roll base30against the shift base40via the balls55a, and thereby the shift base40is pressed against the base plate50via the balls55b.

With this configuration, the image-pickup part10(image-pickup element15) is held rotatably (rollably) in the plane orthogonal to the optical axis direction together with the roll base30(that is, integrally with the roll base30) with respect to the shift base40. Further, the image-pickup part10and the roll base30are held movable (shiftable) in the pitch direction and the yaw direction that are orthogonal to the optical axis direction together with the shift base40(that is, integrally with the shift base40) with respect to the base plate50. Thus, the image-pickup part10and the roll base30are configured to be shiftable in the pitch and yaw directions and rollable in the plane orthogonal to the optical axis direction with respect to the base plate50.

The term “shift” in this embodiment means that the image-pickup part10and the roll base30moves in the pitch and yaw directions orthogonal to the optical axis direction with respect to the base plate50, and the term “roll” in this embodiment means that the image-pickup part10and the roll base30rotate in the plane orthogonal to the optical axis direction with respect to the base plate50.

A yoke57r1is attached to the roll base30. A permanent magnet58ris attracted by the yoke57r1to be fixed thereto. Moreover, yokes57pand57yare attached to the shift base40. Permanent magnets58pand58yare respectively attracted by the yokes57pand57yto be fixed thereto.

A yoke57r2and a coil59rare fixed to the shift base40at positions facing the permanent magnet58rattached on the roll base30. The coil59r, the permanent magnet58rand the yokes57r1and57r2constitute a rolling actuator (rotating actuator) corresponding to a second actuator. Energization of the coil59rgenerates a thrust force between the coil59rand the permanent magnet58r, and the thrust force rolls the roll base30in a direction shown by an arrow132rin the plane orthogonal to the optical axis direction with respect to the shift base40.

A roll position detector (rotation detector)56rconstituted by a hall element is fixed to the shift base40. The roll position detector56routputs an electrical signal corresponding to a change of a magnetic field caused by the roll of the permanent magnet58rfacing the roll position detector56rtogether with the roll base30. Using the electrical signal output from the roll position detector56renables detection of a roll amount (rotation amount) of the roll base30.

Moreover, as shown inFIG. 3, the base plate50is provided with three pins61to which one ends of three tension springs54are hooked, and other ends of the three tension springs54are hooked to circumferential three places of the shift base40. Spring forces of the tension springs54hold the shift base40such that its center coincides with a position of the optical axis in a neutral state where the shift base40is not shifted by pitch and yaw shift actuators which will be described later.

Between an outer circumferential part50aof the base plate50and the chassis100bof the camera100, adjusting members51such as washers are disposed so as to enable position adjustment of the image-pickup element15in the optical axis direction and tilt adjustment thereof with respect to the optical axis.

A concave portion50bis formed at a central part (that is, a part intersecting with the optical axis) of the base plate50. The pin portion30bformed on the roll base30is inserted into the concave portion50b. In the concave portion50b, a damper material52such as silicone gel is disposed. The damper material52has a function of attenuating shift and roll of the axis part30b(that is, of the roll base30) with respect to the concave portion50b(that is, with respect to the base plate50). The axis part30bincludes projecting portions30cat its tip, the projecting portions30cprojecting in a radial direction of the axis part30bas shown inFIG. 4. The projecting portions30chave a larger contact area contacting the damper material52than that of the axis part30b, which increases the attenuating effect of the damper material52attenuating the shift and roll of the roll base30. Thus, the concave portion50b, the axis part30bincluding the projecting portions30cand the damper material52can constitute a compact damper mechanism having a highly attenuating effect to attenuate the shift and roll of the roll base30.

Yokes57pand57yand coils59pand59yare fixed to the base plate50at positions facing the permanent magnets58pand58yattached on the shift base40. The coil59p, the permanent magnet58pand the yokes57p1and57p2constitute a pitch shift actuator. The coil59y, the permanent magnet58yand the yokes57y1and57y2constitute a yaw shift actuator. Each of the pitch and yaw shift actuators corresponds to a first actuator.

Energization of the coil59pgenerates a thrust force between the coil59pand the permanent magnet58p, and the thrust force shifts the shift base (together with the roll base30and the image-pickup part10) in the pitch direction shown by an arrow132pinFIG. 3. Energization of the coil59ygenerates a thrust force between the coil59yand the permanent magnet58y, and the thrust force shifts the shift base (and the roll base30and the image-pickup part10) in the yaw direction shown by an arrow132yinFIG. 3.

A pitch shift position detector56pand a yaw shift position detector56yeach of which is constituted by a hall element are fixed to the base plate50. These shift position detectors56pand56youtput electrical signals corresponding to changes of magnetic fields caused by the shift of the permanent magnets58pand58yfacing the shift position detectors56pand56ytogether with the shift base40. Using the electrical signals output from the shift position detectors56pand56yenables detection of shift amounts of the shift base40in the pitch and yaw directions.

Description will be made of an electrical configuration of the camera system of this embodiment with reference toFIG. 7. The camera system includes an image-pickup system, an image processing system, a recording/replaying system and a controlling system.

The image-pickup system is constituted by the image-pickup optical system103and the image-pickup element15. The image processing system includes an A/D converter130that performs A/D conversion of the image-pickup signal output from the image-pickup element15, an RGB image processing circuit131that performs various image processing on a digital image-pickup signal from the A/D converter130to generate a color image signal (image data), and a YC processing circuit132.

The recording/replaying system is constituted by a record processing circuit133that records the image data to a recording medium, and a replay processing circuit134that replays the image data recorded in the recording medium to display it on the display unit107. The controlling system is constituted by a camera system controlling circuit135as a controller that governs control of the entire camera100, an operation detection circuit136that detects various user's operations, and an image-pickup element driving circuit137that drives the image-pickup element15.

Reference numeral138denotes a connection terminal to which an external apparatus such as a personal computer is connected. The camera100sends the image data to the external apparatus through the record processing circuit133and the connection terminal138.

The camera system controlling circuit135controls a stop actuator143through a lens system controlling circuit141provided in the lens apparatus102to drive the aperture stop104included in the image-pickup optical system103. The camera system controlling circuit135also controls drive of the focal-plane shutter20through a shutter controlling circuit145to control an exposure amount of the image-pickup element15. The camera system controlling circuit135further controls a charge accumulating operation of the image-pickup element15and an image-pickup signal reading operation therefrom through the image-pickup element driving circuit137.

Reference numeral140denotes an AF controlling circuit that receives the paired image signals from the focus detection unit121(area sensor167) to calculate the phase difference of the paired image signals. The AF controlling circuit140calculates a defocus amount of the image-pickup optical system103from the phase difference, and then calculates on the basis of the defocus amount a movement amount of the focus lens (not shown) included in the image-pickup optical system103for obtaining an in-focus state. The AF controlling circuit140sends information on the movement amount of the focus lens to the lens system controlling circuit141through the camera system controlling circuit135. The lens system controlling circuit141drives an AF motor147on the basis of the information on the movement amount to move the focus lens, thereby obtaining the in-focus state.

Further, the camera system controlling circuit135controls drive of the optical viewfinder information display unit180through an information display circuit142to cause the optical viewfinder information display unit180to display various information in the viewfinder optical system.

Reference numeral126denotes a lens attachment sensor provided in the mount portion101of the camera100. The camera system controlling circuit135detects that the lens apparatus102is attached to the mount portion101through the lens attachment sensor126.

Reference numerals101aand102adenote mount contacts that are electrical contacts respectively provided in the mount portion101of the camera100and a mount portion of the lens apparatus102. The camera system controlling circuit135communicates with the lens system controlling circuit141through the mutually connected mount contacts101aand102a.

The camera system controlling circuit135is connected to the shake sensors190and190r, the shift position detectors56pand56yand the roll position detector56r. The camera system controlling circuit135performs integration calculation on each of output signals (angular velocity signals) from the shake sensors190and190r, and then converts the integrated signals into shake signals showing angular displacements in the pitch, yaw and roll directions. Then, the camera system controlling circuit135calculates target shift positions of the shift base40in the pitch and yaw directions and a target roll position of the roll base30(image-pickup element15) such that displacements of the object image on the image-pickup element15due to the angular displacements in the pitch, yaw and roll directions are canceled.

Further, the camera system controlling circuit135energizes the coils59pand59yaccording to the calculated target shift positions to shift the shift base40in the pitch and yaw directions, and energizes the coil59raccording to the calculated target roll position to roll the roll base30.

The camera system controlling circuit135compares the shift positions of the shift base40in the pitch and yaw directions detected by the shift position detectors56pand56ywith the target shift positions to control the energization of the coils59pand59ysuch that the detected shift positions coincide with the target shift positions. Further, the camera system controlling circuit135compares the roll position of the roll base30detected by the roll position detector56rwith the target roll position to control the energization of the coil59rsuch that the detected roll position coincides with the target roll position. Such feedback control can shift and roll the image-pickup element15held by the shift base40and the roll base30accurately to the target shift positions in the pitch and yaw directions and the target roll position, thereby performing a highly accurate image blur correction (reduction) operation.

Moreover, when the shift base40and the roll base30are respectively driven to the target shift positions and the target roll position, vibrations generated due to the drive of the shift base40and the roll base30are suppressed (attenuated) by the damper material52. Therefore, the shift base40and the roll base30hardly vibrate at the respective target positions, which achieves further improvement of the accuracy of the image blur correction.

As described above, the image stabilizing unit70of this embodiment performs the feedback control of the shift amount of the shift base40and the feedback control of the roll amount of the roll base30independently of each other. Therefore, the image blur correction operation in the roll direction does not influence the shift amount of the shift base40and the image blur correction operation in the shift direction does not influence the roll amount of the roll base30, which enables improvement of the image blur correction accuracy in each of the shift direction and the roll direction.

Moreover, the shift base40and the roll base are arranged on the base plate50, which makes it possible to dispose the damper material52at the central part intersecting with the optical axis in the base plate50. This enables simultaneous vibration suppression of the roll base30and the shift base40, and enables further improvement of the image blur correction accuracy at the target shift and roll positions, as compared with a case where the damper material52is disposed at a position other than the central part in the base plate50.

If the roll base30and the shift base40are driven to the target roll and shift positions while their vibrations are suppressed by the damper material52, the roll base30and the shift base40minutely vibrate until becoming completely still. This minute vibration is attenuated by the damper material52. However, if the damper material52is disposed at the position other than the central part of the base plate50, before the minute vibration is attenuated, the minute vibration and elasticity of the tension springs54cause the roll base30or the shift base40to roll or shift around the position other than the central part of the base plate50, which deteriorates the image.

In contrast thereto, when the damper material52is disposed at the central part of the base plate50as described in this embodiment, even if the minute vibration causes the roll base30and the shift base40to roll or shift until they becomes still, the roll base30and the shift base40are rolled or shifted around the central part, and therefore the deterioration of the image is hardly caused. Accordingly, the image blur correction accuracy can be improved as mentioned above.

Although the above embodiment has described the image stabilizing unit equipped in the single-lens reflex digital camera as one of image-pickup apparatuses, alternative embodiments of the present invention include image stabilizing apparatuses equipped to other image-pickup apparatuses such as lens-integrated digital cameras, video cameras, monitoring cameras, web cameras and cameras for cellular phones.

This application claims the benefit of Japanese Patent Application No. 2009-199250, filed on Aug. 31, 2009, which is hereby incorporated by reference herein in its entirety.