Abstract:
A motion compensation device comprising, a detector to detect a vibration of an imaging device which takes an image, a controller to control a compensation amount of an influence of said vibration based on an output of said detector, said controller increasing said compensation amount according to lapse of shooting time of said imaging device.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a motion compensation device to operate compensation of image blurring and an optical device. 
         [0003]    2. Description of the Related Art 
         [0004]    In recent years, it has been known that technologies not only compensating blurring motion by hand, but also compensating blurring which occurs when attached with a tripod. As a method for compensating a blurring occurred when attached with a tripod shooting, a technology shown in JP Patent Publication No. 2000-330152 is exemplified. 
         [0005]    At the time of shooting with a tripod, a vibration which is different from hand blurring is occurred. In a technology shown in JP Patent Publication No. 2000-330152, memorizing a signal corresponding to blurring which occurs at the time of activating mechanism in a camera, a method for image blurring compensation on the basis of the memorized signal thereof is shown. 
         [0006]    For example, although a main component of blurring frequency occurred at the time of tripod shooting is about 10 Hz and so, a high frequency component higher than 50 Hz is included in addition to the main component. There will be a risk for delayed response of lens against the high frequency component. 
         [0007]    The present invention has been made due to considering these circumstances, a purpose of the invention is to provide a motion compensation device and an optical device available to compensate an image blurring effectively. 
       SUMMARY OF THE INVENTION 
       [0008]    In order to achieve the above purpose, a motion compensation device of the present invention comprises; 
         [0009]    a detector to detect a vibration of an imaging device which takes an image, 
         [0010]    a controller to control a compensation amount of an influence of said vibration based on an output of said detector, 
         [0011]    said controller increasing said compensation amount according to lapse of shooting time of said imaging device. 
         [0012]    Another aspect of the motion compensation device of the present invention comprises; 
         [0013]    a motion compensator to compensate said influence of said vibration by relatively moving an image formed with an optical system and an image pick-up face of said imaging device based on the output of said detector, wherein; 
         [0014]    said controller may comprises; 
         [0015]    a target position calculator which calculates a target position so as to move said motion compensator; 
         [0016]    an amplifier which amplifies and outputs an image signal from said target position calculator; and 
         [0017]    an altering portion which increases amplification ratio of said amplifier according to lapse of shooting time of said imaging device. 
         [0018]    Further aspect of the motion compensation devise of the present invention comprises; 
         [0019]    a motion compensator to compensate said influence of said vibration by relatively moving an image formed with an said optical system and an image pick-up face of said imaging device based on the output of said detector, wherein; 
         [0020]    said controller may comprises; 
         [0021]    a target position calculator which calculates a target position so as to move said motion compensator; and 
         [0022]    an altering portion which changes said target position so as to increase a moving amount of said motion compensator according to lapse of shooting time of said imaging device. 
         [0023]    Said controller may increase said compensation amount according to lapse of shooting time of said imaging device after decreasing said compensation amount in response to timing of shooting of said imaging device. 
         [0024]    Said imaging device comprises a first output portion to output a first signal when the imaging device is in an image shooting mode where said imaging device is supported on a support base, wherein; 
         [0025]    said controller may increase said compensation amount according to lapse of shooting time of said imaging device when said first signal is output from said first output portion. 
         [0026]    Although a said support base is not particularly limited, said support base is a unipod or a tripod, for example. 
         [0027]    Said imaging device comprises a determining portion to determine as to whether said imaging device is supported on said support base or not, based on the output of said detector, wherein; 
         [0028]    said first output portion may outputs said first signal when said detector determines that said imaging device is supported on said support base. 
         [0029]    Further aspect of the motion compensation device according to the present invention comprises an optical system holder to hold at least one portion of said optical system, wherein; 
         [0030]    said optical system holder may relatively moves with respect to an image pick-up face of said imaging device in response to said compensation amount controlled by said controller. 
         [0031]    Further aspect of the motion compensation device comprises an image pick-up element holder for holding an image pick-up element to pick-up an image by said optical system, wherein; 
         [0032]    said image pick-up element holder may relatively moves with respect to at least one portion of said optical system in response to said compensation amount controlled by said controller. 
         [0033]    A photographic device according to the present invention comprises; 
         [0034]    a detector to detect a blurring of the device, 
         [0035]    a driving portion to be driven at least mechanically in response to shooting action, and 
         [0036]    a controller connected with said detector and said driving portion, the controller cooperating with said driving portion to control a compensation amount for blurring motion of said image so as to increase the compensation amount according to lapse of time after said driving portion driven. 
         [0037]    Said controller may increase said compensation amount according to lapse of shooting time of said imaging device in response to shooting action. 
         [0038]    Said driving portion is not particularly limited, and for example, is a shutter to cut off a photographic light or a mirror which retracts so as not to prevent the photographic light in response to shooting action. 
         [0039]    Said controller may increase said compensation amount according to lapse of shooting time of said imaging device after reducing said compensation amount before said driving portion operates in response to shooting action. 
         [0040]    Another aspect of the photographic device according to the present invention comprise a first output portion to output a signal to said controller, the signal showing that the device is supported on a support, wherein; 
         [0041]    said controller may increase said compensation amount according to lapse of time after operating said driving portion in response to the output from said first output portion showing that the device is supported on the support base. 
         [0042]    A motion compensation method according to the present invention comprises steps of; 
         [0043]    detecting a blurring of a imaging device taking an image from an optical system with using a detector; and 
         [0044]    controlling a compensation amount for correcting said image on the basis of the detected blurring of said imaging device, wherein; 
         [0045]    said compensation amount increases according to lapse of shooting time of said imaging device. 
         [0046]    Said compensation amount may increase according to lapse of shooting time of said imaging device after decreasing said compensation amount in response to timing of shooting of said imaging device. 
         [0047]    Said compensation amount may increase according to lapse of shooting time of said imaging device when a signal is output, showing a shooting mode where the imaging device is supported on a support base. 
         [0048]    A method for manufacturing a motion compensation device according to the present invention comprises; 
         [0049]    providing a detector to detect blurring of an imaging device which takes an image from an optical system; 
         [0050]    connecting a controller with said detector to control a compensation amount for correcting said image blurring based on an output of said detector; and 
         [0051]    setting said controller to increase the compensation amount according to lapse of shooting time of said imaging device. 
         [0052]    Said controller may be set to increase the compensation amount according to lapse of shooting time of said imaging device after decreasing said compensation amount in response to timing of shooting of said imaging device. 
         [0053]    Said controller may be set to increase said compensation amount according to lapse of shooting time of said imaging device when a first signal is output at an image shooting mode that said imaging device is supported on a support base. 
         [0054]    A method for manufacturing a motion compensation device according to the present invention comprises; 
         [0055]    providing a detector which detects blurring of an imaging device which takes an image from an optical system; 
         [0056]    connecting a controller with said detector to control a compensation amount for correcting said image blurring based on an output of said detector; 
         [0057]    connecting said controller with a driving portion driven mechanically in response to shooting action of said imaging device; 
         [0058]    setting said controller to increase said compensation amount according to lapse of time after driving said driving portion in response to shooting action of said imaging device. 
         [0059]    Said controller may be set to increase said compensation amount according to lapse of shooting time of said imaging device after said compensation amount is decreased prior to driving said driving portion in response to shooting action of said imaging device. 
         [0060]    Said controller may be set to increase said compensation amount according to lapse of shooting time of said imaging device, when a signal is provided to show that said imaging device is supported on the support base. 
         [0061]    A photographic device according to the present invention comprises the above mentioned motion compensation device. In the present invention, a photographic device is not particularly limited, and includes a compact camera, a single lens reflex camera, a still/video camera, a lens barrel, a camera body, a cellular phone and the like. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0062]      FIG. 1  is a schematic block view of a camera according to one embodiment of the present invention. 
           [0063]      FIG. 2  is a flow chart showing one example for controlling the camera shown in  FIG. 1 . 
           [0064]      FIG. 3  is a time chart of controlling shown in  FIG. 2 . 
           [0065]      FIG. 4A  is a graph showing a frequency characteristic of an angular velocity sensor, and  FIG. 4B  is a graph showing relation of a blurring frequency and a blurring degree. 
           [0066]      FIG. 5A  and  FIG. 5B  are respective time charts showing a control method according to other embodiments of the present invention. 
           [0067]      FIG. 6  is a time chart showing further embodiment of control method according to the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0068]    As shown in  FIG. 1 , a camera  2  according to one embodiment of the present invention comprises a camera body  4  and a lens barrel  6  detachably equipped to the camera body  4 . A blurring motion compensation lens  14  and a lens group which is not shown are equipped inside of the lens barrel  6 . Several lenses of the lens group are movably arranged along with an optical axis L 1  for performing zooming operation and auto focusing operation. 
         [0069]    An image pick-up element  8  and, in front of the element a shutter  10  are provided in the camera body  4 . Also, a mirror  12  is arranged anteriorward of the optical axis L 1  direction movably between a cut-off position of the optical axis L 1  and an evacuating position where the optical axis L 1  is not cut-off. 
         [0070]    The camera body  4  comprises a body CPU  20 , and the lens barrel  6  comprises a lens CPU  30 . It is possible to communicate between the CPU  20  and CPU  30  in a status that the lens barrel  6  is equipped at the camera body  4 . The CPU  20  and CPU  30  are a portion to operate, for example, for predetermined controlling or calculation. 
         [0071]    The body CPU is included in the camera body  4  to perform a sequence controlling by a sequence control portion  24  with receiving an input signal from a release switch  22  and to conduct an image procession of a data taken by an image pick-up element B at an image taking portion  26 . Also, the body CPU conducts a communication with the lens CPU  30 . 
         [0072]    The lens CPU  30  is included in the lens barrel  6  to control a motor for an auto focusing (AF) at AF controlling portion  31  and to conduct a communication with the body CPU  20 . Also, the lens CPU  30  reads information from a zooming encoder  32  and a distance encoder  34  in a lens. 
         [0073]    An angular velocity sensor  36  composed by a gyro sensor and the like is equipped in the camera body  4  or the lens barrel  6  and detects an angular velocity applied to a camera. A detected output of the angular velocity sensor is through a LPF (low pass filter)+an amplifier  38  in which unnecessary high frequent noise is removed, and the output is amplified until a certain level which is suitable to A/D of the body CPU  20 . An output of the LPF+the amplifier  38  is input to a blurring information processing portion  40  at the lens CPU  40 . In the blurring information processing portion  40 , a blurring information to be corrected is extracted on the basis of information of the angular velocity sensor  36 . 
         [0074]    In the present embodiment, the lens CPU  30  contains a target driving position calculating portion  42 . The target driving position calculating portion operates calculation for a target driving position of a plane direction X which is vertical to the optical axis L 1  in the blurring motion compensation lens  14  based on information from the zooming encoder  32  and the distance encoder  42 , and an output of the blurring information processing portion. Generation of a target driving position of pre-exposure centering motion mentioned below and target driving position gain altering operation during exposure based on a control signal from a target position gain changing portion  44  are operated in the target driving position calculating portion  42 . 
         [0075]    An output from the target driving position calculating unit  42  is input to a follow-up controlling calculating unit  46 . In the follow-up controlling calculating unit  46 , follow-up controlling calculation of the blurring lens is operated based on target driving position information. 
         [0076]    An output signal from the follow-up controlling calculating unit  46  is input to a VCM driver  48 . In the driver  48 , power supplying operation to a voice coil motor (VCM)  16  is made according to a signal from the follow-up controlling calculating unit  46 . 
         [0077]    The VCM  16 , which is an electromagnetic actuator, is composed of a coil and a magnet, and generates a driving force by applying an electric current to the coil. By this VCM  16 , the blurring motion compensation lens  14  is driven to the plane direction X vertical to the optical axis L 1  to operate motion compensation controlling. Note that a driving portion is not limited to the VCM  16 , and may be PZT type actuators such as SIDM and the like, or STM and the like. 
         [0078]    A position detecting portion  18  is equipped on a frame which supports the blurring motion compensation lens  14 . The position detecting portion  18  detect a position of the blurring motion compensation lens  14 . A sensor using PSD is general as the position detection  18 . A detected position of the blurring motion compensation lens  14  detected by the position detecting portion  18  is feed back to the target driving portion calculating portion  42  via the follow-up controlling calculating unit  46 . Note that a position sensor which detects alteration of magnetic flux density using a magnet and hall element may be used as the position detecting portion  18  which is not limited to the above mentioned PSD. 
         [0079]    A hand blurring compensation switch  50  and a mode switch  52  are mounted on the camera body  4  or the lens barrel  6 . The hand blurring compensation switch  50  is a switch for selecting on/off of the hand blurring compensation by a camera operator. When the hand blurring switch  50  is ON, according to the output of the angular velocity sensor  36 , the compensation lens  14  is controlled to move to the plane direction X which is vertical to the optical axis L 1  so as to overcome the blurring. Also, when the hand blurring compensation switch  50  is OFF, the compensation lens  14  is fixed by a locking mechanism not shown at a position where the optical axis L 1  and a center of the compensation lens  14  are coincided. 
         [0080]    The mode switch  52  operates to select a sort of compensation operating motion. In the present embodiment, there are two modes which are Normal mode and Tripod mode. When the Normal mode is selected, compensation for an ordinal hand blurring as a target is operated, and when the Tripod mode is selected, compensation for a blurring occurred at the time of tripod shooting as target is operated. Note that it is possible to control with using a tripod determining algorithm which determines the tripod shooting condition automatically, based on the output of the angular velocity sensor  36 , without using the mode switch  52 . 
         [0081]    Difference of a normal hand blurring and a blurring of a tripod shooting will be specified.  FIG. 4B  shows an image drawing of frequency characteristics and amplitudes for the respective blurring. A frequency of a blurring of a camera of the tripod shooting is higher and a blurring amount is smaller. 
         [0082]    In the follow-up controlling calculation unit  46  shown in  FIG. 1 , a conventionally known PID control is used. Frequency range by the PID control is, for example, 80 Hz or so, and it is hard to increase the range because of a sampling time relation. The angular velocity sensor  36  also includes LPF internally thereof for removing noise, and generally there is 15 to 20 deg or so of a delay at 40 Hz as shown in  FIG. 4 . 
         [0083]    Namely, according to frequency characteristics of the angular velocity sensor  36  and the follow-up controlling unit  46  shown in  FIG. 1 , as a frequency characteristic of a whole system of the motion compensation system, a blurring amount increases at an accelerated pace after 30 Hz, and there is no compensation effect, on the contrary, there is a risk for deterioration. 
         [0084]    Next, in a status that a camera is fixed on a unipod or a tripod (hereinafter, specified as tripod fixing) behavior of blurring of a camera and an operation example of the compensation lens in case of the camera shooting, are specified based on  FIG. 1  to  FIG. 3 . 
         [0085]    According to compensation motion during a half-pressing of the release switch  22  shown in  FIG. 1 , the blurring motion compensation lens  14  away from a center of the optical axis L 1  receives an exposure starting signal sent from the body CPU  20  and performs centering operation to a center of the optical axis once, while the mirror  12  of the body  4  rises upwardly. According to this centering operation, an operating range of the compensation lens can be maintained and also, an exposure can be started at neighborhood of the optical axis where the deterioration of optical performance is less. 
         [0086]    When controlling is started at a step S 1  shown in  FIG. 2 , the exposure starting signal is sent to the lens CPU  30  from the body CPU  20 , by using the release switch  22  shown in  FIG. 1  as a trigger. In accordance with the exposure starting signal, the compensation lens  14  re-starts compensation operation which is based on an output of the angular velocity sensor  36  again. 
         [0087]    At a side of the camera body  4 , the mirror  12  rises upwardly to open the shutter  10 , and an exposure sequence is commenced. A tripod blurring occurs by the mirror  12  rising operation and an opening operation of the shutter. As previously mentioned, the base frequency of 10 Hz or so and the high frequency of the 50 Hz or so are mixed in the tripod blurring, and both frequencies appear in the target position information of the compensation lens  14 . The compensation lens  14  can follow-up to a low frequency without problems, but delays to a high frequency. There is a risk to deteriorate the shooting result, in spite of the compensation operation. 
         [0088]    As a result of this, conventionally, in case that a shutter speed is slow, compensation effect can be obtained, but in case that the shatter speed is fast, there is a risk to reverse the compensation effect. 
         [0089]    Thus, in the present embodiment, due to a small blurring amount at the high frequency side and difficulty in rising compensation band, after starting shooting operation (for example, after starting the exposure), the target position gain is set as zero once, and then, the gain is raised according to lapse of time. 
         [0090]    Namely, at a step S 2  shown in  FIG. 2 , in case that the lens CPU  30  shown in  FIG. 1  receives the exposure starting signal, the lens CPU  30  measures a time from an exposure starting signal receiving time t 0  shown in  FIG. 3 , at a step of S 3  shown in  FIG. 2 . When the time from the exposure starting signal receiving time t 0  exceeds a predetermined time T 1  at a time point t 1 , the target driving position calculating portion  42  shown in  FIG. 1  receives a control signal from the target position gain altering unit  44  at a step S 4  shown in  FIG. 2 , and changes setting of a target position gain G 1  from 1 to 0 as shown in  FIG. 3 . 
         [0091]    Note that the target position gain G 1  is a control coefficient at the time of obtaining a compensation lens target position lc 2  after the gain calculation shown in a following formula. 
         [0000]        lc 2 =G 1×( lc 1 −LC _center) 
         [0092]    Here, lc 1  is a target position of the compensation lens before the gain calculation, and LC_center is an optical axis center position (centering position) which is individually adjusted and written at the time of shipment from the factory. 
         [0093]    In the present embodiment, after decreasing the target position gain G 1  to 0 at a step  4  shown in  FIG. 2 , a time from a time point t 1  shown in  FIG. 3  at a step S 5  is measured to determine whether the time is more than a predetermined time (T 2 +T 3 ). A predetermined time T 2  from the time point t 1  shown in  FIG. 3  is time from decreasing target position G 1  to 0 to a time point t 2  wherein an exposure is actually started. Also, a predetermined time T 3 , which is from a time point of shooting start, namely, the exposure time point t 2 , is time to a time point t 3  where the target position gain G 1  returns the original target position gain G 1 =1. 
         [0094]    Namely, at a step S 5  shown in  FIG. 2 , in case that a time from the time point t 1  shown in  FIG. 3  becomes more than a predetermined time (T 2 +T 3 ), the target position gain G 1  is set as G 1 =1 as a normal gain at a step S 7  shown in  FIG. 2 , and in the target driving position calculating portion  42 , calculation at the time of a normal hand blurring compensation is performed. When the exposure is finished, the control is finished at a step S 8  shown in  FIG. 2 . 
         [0095]    Also, at a step S 5  shown in  FIG. 2 , in case that a time passage from the time point t 1  shown in  FIG. 3  does not fulfill the predetermined time (T 2 +T 3 ), at a step S 6  shown in  FIG. 2 , the target position gain G 1  is raised gradually from 0 as shown in  FIG. 3 , based on a signal from the target position gain altering unit  44  shown in  FIG. 1 . 
         [0096]    In the present embodiment, the predetermined time T 1  differs depending on, for example, a release time-lag of the body, it is set by a time-lag information sent from the body, the predetermined time T 2  is 5 to 15 msec, the predetermined time T 3  is 30 to 50 msec. 
         [0097]    As shown in  FIG. 3 , in the present embodiment, immediately after the exposure start, by the target position gain G 1  of the compensation lens is set 0 once and gradually returns the gain G 1 , it is possible to prevent excessive response of the compensation lens to the blurring of high frequency component arise from a tripod blurring and the like. As a result in the present embodiment, the reverse phenomenon has been conventionally occurred at high shutter speed can be prevented. 
         [0098]    For example, as shown by a dotted line of  FIG. 3 , in a conventional motion compensation device, the compensation lens has excessively been responded to the blurring the high frequency component arise from a tripod blurring and the like around the exposure starting time point t 2 . Against this, the motion compensation device of the present invention, by the compensation lens target position lc 2  is calculated close to the gain G 1 =0 around the exposure starting time point t 2 , the blurring of an actual position of the compensation lens (dashed line V 2 ) becomes smaller. 
         [0099]    Namely, in the present embodiment, according to decreasing the gain G 1  at the exposure starting time, the compensation lens does not move to follow the high frequency component uselessly, it becomes possible to minimize the deterioration of the compensation effects at the high shutter speed. 
         [0100]    Note that the present invention is not limited to the above explained embodiment and can be modified within a scope of the present invention. 
         [0101]    For example, as shown by a dashed line of  FIG. 5A , after decreasing a gain G 1  to ½ degree without decreasing the gain G 1  to 0 at the time point t 1  after passing a predetermined time T 1  from a receiving time point t 0  of an exposure starting signal, then after, the gain G 1  may be returned gradually at a predetermined time (T 2 +T 3 ). Alternatively, as shown by a solid line of  FIG. 5A , after decreasing a gain G 1  to near 0 degree at the time point t 1  after passing a predetermined time T 1  from a receiving time point t 0  of an exposure starting signal, the gain G 1  may be returned in a stepwise fashion at a predetermined time (T 2 +T 3 ). 
         [0102]    Also, in the present embodiment, a method for multiplying a gain to the target position of the compensation lens is shown, however, similar effects can be obtained by multiplying a gain to a target speed of the compensation lens. 
         [0103]    Further, as the other embodiment of the present invention, as shown in  FIG. 5B , the gain G 1  is set as 0 before a receiving time point t 0  of the exposure starting signal, the gain G 1  may be returned gradually to a normal gain starting from a time point t 1  after lapse of the predetermined time T 1  during a predetermined time (T 2 +T 3 ). Such control can be used, for example, in case that a controlling mode that motion compensation is operated when the release switch  22  is fully pushed only, the motion compensation is not operated when the release switch is half-pushed. 
         [0104]    Further, as the other embodiment of the present invention, as shown in  FIG. 6 , the gain G 1  is set as 0 before a receiving time point t 0  of the exposure starting signal, the gain G 1  may be returned rapidly to a normal gain starting from a time point t 3  after lapse of the predetermined time (T 1 +T 2 +T 3 ) from a time point t 0 . Alternatively, in  FIG. 6 , the gain G 1  may be returned to a normal gain during time from any time point between the time points t 2  and t 3  to the time point t 3 . 
         [0105]    Further, although an optical system moving type motion compensation device drive the compensation lens  14  shown in  FIG. 1  is specified in the above mentioned embodiment, the present invention may be applied to an image-pick element moving type motion compensation device in which an image-pick up element  8  moves shown in  FIG. 1 . Namely, the motion compensation device in the present embodiment comprises an image pick-up element supporting portion which supports the image pick-up element taking an image from an optical system, the image pick-up element supporting portion moves to at least one portion of the optical system in response to a calculated compensation amount which is calculated by the calculating portion  42  shown in  FIG. 1 . Also, the present invention may be applied to an electronic type hand blurring (VR). 
         [0106]    Further, in the present invention, the target driving position calculating portion  42  may comprise a first calculating portion of a target driving position at a first predetermined time (T 2 +T 3 ) on before and after exposure stating and a second calculating portion of a target driving position at a second predetermined time (T 3 ) after exposure starting. In that case, a first gain for calculating a target driving position at the first calculating portion is preferably lower than a second gain for calculating a target driving portion at the second calculating portion. 
         [0107]    Furthermore, it is preferable that the first calculating portion and the second calculating portion are physically identical arithmetic circuit in which an arithmetic expression for calculating the target driving position is commonly used, and numerical values of the gain included in the arithmetic expression can be switched. 
         [0108]    Alternatively, the first calculating portion and the second calculating portion are physically different arithmetic circuit, and after lapse of the second predetermined time (T 3 ) after exposure starting time, it may be switched from the first calculating portion to the second calculating portion. 
         [0109]    In the first calculating portion, the numerical value of the gain is an altering value gradually rises according to lapse of time, in the second calculating portion, the numerical value of the gain is a constant value according to lapse of time, which are preferable. 
         [0110]    Also, in the present invention, as a support output portion which outputs a first signal when an imaging device such as a camera and the like are supported on a fixed base is not limited to the mode switch  52  shown in  FIG. 1 , a slide operation switch, a push down type (tact switch) and a tripod automatic determining circuit may be used.