Motion compensation detection device for an optical system

A motion compensation device which detects vibration of an optical system and can discriminate between undesired movement or vibration of photographic equipment and intentional movement of the photographic equipment and compensate for the undesired movement while not compensating for the intentional movement. The motion compensation device contains a decision unit which calculates a variance value based on an angular velocity signal supplied by am angular velocity sensor. The decision unit then compares this variance value with a predetermined decision level value and determines if a large movement has occurred due to a photographic composition change, panning photography or the operator following of a randomly moving subject. A target value calculation unit, based on the decision result of the decision unit, calculates a target value of vibration motion compensation control to be executed. The target value calculation unit then varies the target value of vibration motion compensation control when large movements are detected by the angular velocity sensor. This motion compensation device may be contained within a lens barrel or camera body.

CROSS-REFERENCE TO RELATED APPLICATIONS
 This application is based upon and claims priority of a Japanese Patent
 Application No. 09-064386 filed Mar. 18, 1997, the contents of which are
 incorporated herein by reference.
 BACKGROUND OF THE INVENTION
 1. Field of the Invention
 The present invention relates to a motion compensation device which detects
 vibration of an optical system caused by hand tremors and other sources of
 undesired vibration. In particular, the present invention relates to a
 device which can discriminate between undesired movement or vibration of
 photographic equipment and intentional movement of the photographic
 equipment and compensate for the undesired movement while not compensating
 for the desired movement.
 2. Description of the Related Art
 Optical systems project an image onto an image plane. Conventional image
 blur suppression device suppress, or reduce, blurring of the image. A
 motion compensation device is a type of image blur suppression device, and
 compensates for motion incident upon the optical system. Motion is
 typically imparted to the optical system by vibrations in the optical
 system, or in a surrounding holding member. In general, conventional
 motion compensation devices cause a compensation lens to shift counter to
 the motion of the optical system so as to shift the image projected by the
 optical system relative to the optical system. Conventional cameras use a
 motion compensation device to suppress image blur resulting from motion of
 the camera. Such motion is typically caused by hand tremors of the
 photographer.
 A motion compensation in the prior art has a structure as disclosed in
 Japanese Laid-Open Patent Publication JP-A-4-76525 In FIG. 3 of
 JP-A-4-76525, the overall structure of a prior art optical system which
 performs motion compensation is shown. A camera having the motion
 compensation capability of JP-A-4-76525 is equipped with a blurring motion
 compensation lens which is capable of parallel motion in a plane at right
 angles to the optical axis. A drive actuator is used to drive the blurring
 motion compensation lens in up and down, and left and right directions.
 This drive actuator includes: a lens frame member which supports the
 blurring motion compensation lens; a plate member which supports this lens
 frame member; four wires mounted on the plate member; a body which
 supports these wires; a wound coil; a yoke; and a permanent magnet. A
 position detection device is included in the drive actuator and detects
 the position of the blurring motion compensation lens. This position
 detection device includes a light generating element and a light receiving
 element.
 The operation of the prior art motion compensation devices will be
 described below with reference to FIG. 8.
 FIG. 8 is a block diagram of a prior art blurring motion compensation
 device.
 In FIG. 8 an angular velocity sensor 10 would include a piezoelectric
 vibration type of angular velocity sensor used to detect a Coriolis force,
 and is a sensor to monitor the vibration of the camera. The output signal
 of the angular velocity sensor 10 is input to an integration unit 40 which
 integrates this output signal over time. After the integration unit 40 has
 converted the output signal of the angular velocity sensor 10 into a
 blurring motion angle of the camera, this angle is converted into target
 drive information for the blurring motion detection lens. A servo circuit
 100 is used to drive the blurring motion compensation lens according to
 the target drive position information. The servo circuit 100 calculates
 the difference in the target drive position information and the position
 information of the blurring motion compensation lens, and outputs a signal
 to an actuator 110. The actuator 110, based on this signal, drives the
 blurring motion compensation lens within a plane at right angles to the
 optical axis. A position detection device 120 monitors the movement of the
 blurring motion compensation lens and feeds it back to the servo circuit
 100.
 In the prior art of motion compensation devices, once the integration unit
 40 integrates the output signal of the angular velocity sensor 10, the
 information is converted into angular displacement information. As a
 result of this conversion, when the integration unit integrates the output
 signal of the angular velocity sensor 10 over time, it is necessary to set
 a constant of integration (referred to as a "standard value" hereinafter)
 including the target value of control. The output signal (referred to as
 "omega zero" hereinafter) of the angular velocity sensor, when the camera
 is stationary, is generally used as this standard value. This method of
 calculating the standard value is shown in FIG. 17 and FIG. 18 of Japanese
 Laid-Open Patent Publication JP-A-4-211230.
 The blurring motion sensor of the motion compensation device disclosed in
 JP-A-4-211230 is equipped with an angular velocity sensor which detects
 Coriolis force. A drift component detection unit which includes a central
 processing unit ("CPU") and a memory, calculates the average value of the
 output signal of the angular velocity sensor sampled in an interval from
 the present time to a predetermined earlier time. By subtracting the
 average value of the output signal of the angular velocity sensor the
 drift component detection unit eliminates the drift portion of the motion
 detected and outputs this subtraction value.
 Output signals of the angular velocity sensor are input every 10 ms into
 the drift component detection unit. Thereby fifty output signals are input
 every 0.5 second (10 ms.times.50). The calculated average value (referred
 to as "average 1" hereinafter) of these fifty output signals is stored in
 the memory of the drift component detection unit. After ten seconds (0.5
 seconds.times.20) has elapsed, the average 1 of a further 20 samples is
 input. Accordingly, after ten seconds have elapsed from the start, the
 average can be calculated of 1,000 (50.times.20) output signals of the
 angular velocity sensor.
 In the motion compensation devices of the prior art a problem is
 encountered when a large and usually intentional movement is detected.
 These large movements are usually a result of the camera operator changing
 the composition of the photograph by panning the camera to follow a moving
 subject or to focus on another subject (referred to as "field of view
 angle changes" hereafter). As far as the motion compensation device is
 concerned, these field of view angle changes are random and cannot be
 distinguished easily from other sources of vibration. The motion
 compensation device driving the blurring motion compensation lens in an
 attempt to compensate for these field of view angle changes runs into the
 movement limits (referred to as "drive limits" hereafter) of the blurring
 motion compensation lens which distorts the photograph taken and possibly
 damages the motion compensation device.
 FIG. 9A and FIG. 9B are diagrams depicting examples of the output signal of
 an angular velocity sensor and the resulting drive amount of the blurring
 motion compensation lens over a period of time when photographic
 composition changes occur.
 Referring to FIG. 9A, when the camera is completely stationary the angular
 velocity detected is 0 deg/s. As shown in FIG. 9A, the output signal
 suddenly rises when there is a change in the picture composition. Prior to
 this sudden change in photographic composition, the camera is
 approximately stationary in position. The camera is not completely
 stationary due to the addition of undesired motion such as hand tremors
 which must be accounted for in this example. For the sake of simplicity,
 these operator hand tremors are drawn as a sine wave.
 FIG. 9B shows the drive amount of the blurring motion compensation lens
 resulting from the angular velocity sensor of FIG. 9A integrating the
 output signal as the target value equal to 0. The blurring motion
 compensation lens, as shown in FIG. 9B, moves in unison with the output
 signal shown in FIG. 9A. However, as shown by the broken line in FIG. 9B,
 there exists a drive limitation for the blurring motion compensation lens.
 Due to this drive limitation, when a large movement of the camera occurs
 due to a photographic composition change and other causes, the blurring
 motion compensation lens reaches the drive (movement) limit, and cannot be
 driven beyond this point. As a result, a vibration motion cannot be
 compensated for using the blurring motion compensation lens.
 In addition, the time interval from t1 to t2 shown in FIG. 9B is the period
 of initiation of a photographic change, and because the blurring motion
 compensation lens is in a region within the drive limits, vibration motion
 can be compensated using the blurring motion compensation lens. However,
 from the point of view of the camera operator, a very disconcerting
 phenomena is seen through the viewfinder of the camera. When the camera
 operator starts panning the camera and causes a field of view change, the
 motion compensation device compensates for the movement and the image the
 operator sees does not move in spite of the operator's intentional
 movement of the camera. Then once the drive limit of the blurring motion
 compensation lens is reached the image seen by the operator and recorded
 by the camera suddenly jumps making for a very unnatural view and
 recording of images by the camera. Because of this phenomena, compensating
 for vibration motion while making field of view angle changes, it becomes
 necessary to be able to identify when large movements take place. Japanese
 Laid-Open Patent Publications JP-A-5-142614 and JP-A-7-261234, provide a
 method of detecting such large movements due to a field of view angle
 changes.
 FIG. 10A and FIG. 10B are diagrams showing an example of the movement
 amount of the blurring motion compensation lens and the output signal of
 the angular velocity sensor when panning. FIG. 10A is a diagram showing
 the output signal of the angular velocity sensor, and FIG. 10B is a
 diagram showing the movement amount of the blurring motion compensation
 lens. In the detection method described in JP-A-5-142614 and
 JP-A-7-261234, when the output of the detector for a predetermined time is
 in a fixed direction, it was determined that there is a field of view
 angle change. As a result, using this detection method as shown in FIG.
 10A, when the camera is panned in one direction for a given amount of
 time, it would be determined that the field of view angle changed.
 FIGS. 11A and 11B shows an example of the movement amount of the blurring
 motion compensation lens and the output signal of the angular velocity
 sensor when following a subject. FIG. 11A shows the output signal of the
 angular velocity sensor, and FIG. 11B shows the movement amount of the
 blurring motion compensation lens.
 FIG. 11A shows the output signal of the angular velocity sensor when
 following the movement of a subject, such as a soccer player, in which
 random movements occur frequently. As shown in FIG. 11A, the output signal
 of the angular velocity sensor, as shown in FIG. 10A, does not move in one
 direction only, but a large output signal is generated in both directions.
 As a result, using the detection method described in JP-A-5-142614, it
 cannot be determined that there w as a change in field of view angle.
 In this manner, in the prior art motion compensation devices, because there
 was no way of determining when the operator would intentionally move the
 camera, the problem arises that vibration motion compensation cannot be
 performed. In addition, in the prior art vibration motion compensation
 devices, the problem exists that the image seen in the viewfinder is
 unnatural. Also, as described in JP-A-5-142614, in the case that the
 output signal is in a fixed direction for a predetermined time, the
 vibration detection method would determine that a large movement in the
 camera is occurring and it could not handle movement of a randomly moving
 body.
 Therefore, it is recognized in the field of photography and optical imaging
 that a vibration motion detection device is needed which can compensate
 for undesired vibration with a high degree of precision and naturally
 track objects when large random movements due to field of view angle
 changes occur.
 SUMMARY OF THE INVENTION
 An object of the present invention is to provide a motion compensation
 device which can discriminate between undesired movement or vibration of
 photographic equipment and intentional movement of the photographic
 equipment and compensate for the undesired movement while not compensating
 for the desired movement.
 Objects and advantages of the present invention are achieved in accordance
 with embodiments by a vibration motion detection device that comprises a
 vibration motion detection unit to detect vibration motion and output a
 vibration motion detection signal, a variance value calculation unit to
 calculate a variance value based on the vibration motion detection signal,
 and a motion state decision unit to determine the motion state of the
 vibration motion detection unit based on the variance value.
 Further objects of the present invention are achieved by a vibration motion
 detection device which comprises a vibration motion detection unit to
 detect vibration motion and output a vibration motion detection signal,
 and a variance value calculation unit to calculate a variance value based
 on the vibration motion detection signal. A motion state decision unit is
 included in the device to determine the motion state of the vibration
 motion detection unit based on the variance value as well as a target
 value calculation unit to calculate a target value based on the vibration
 motion detection signal.
 Still further objects of the present invention are achieved by a camera
 which comprises a camera body having a power supply and a lens barrel
 connectable to the camera body. Within the lens barrel, devices are
 contained and receive power from the camera body including: a vibration
 motion detection unit to detect vibration motion and output a vibration
 motion detection signal; a variance value calculation unit to calculate a
 variance value based on the vibration motion detection signal; a motion
 state decision unit to determine the motion state of the vibration motion
 detection unit based on the variance value; and a target value calculation
 unit to calculate a target value based on the vibration motion detection
 signal.
 In accordance with embodiments of the present invention, the variance value
 calculation unit calculates the variance value based on an average value
 of a series of output values output from the vibration motion detection
 unit within a predetermined time period.
 In accordance with embodiments of the present invention, the variance value
 calculation unit calculates the variance value based on at least a portion
 of a series of output values output from the vibration motion detection
 unit within a predetermined time period and output after the passage of a
 predetermined time period.
 In accordance with embodiments of the present invention, the vibration
 motion detection unit is an acceleration detector to detect acceleration
 or a velocity detector to detect velocity.
 In accordance with embodiments of the present invention, the motion state
 decision unit determines that the vibration motion detection unit is in a
 motion state when the variance value exceeds a predetermined value.
 In accordance with embodiments of the present invention, the vibration
 motion detection device also includes a target value calculation unit to
 calculate a target value based on the vibration motion detection signal.
 In accordance with embodiments of the present invention, the target value
 calculation unit varies the target value of the vibration motion detection
 signal based on the variance value.
 In accordance with embodiments of the present invention, the vibration
 motion detection device also includes an amplifier to amplify the
 vibration motion detection signal, and the variance value calculation unit
 calculating the variance value based on the vibration motion detection
 signal amplified by the amplifier.
 In accordance with embodiments of the present invention, the vibration
 motion detection device also includes an amplifier to amplify the
 vibration motion detection signal, and the target value calculation unit
 calculating the target value based on the vibration motion detection
 signal amplified by the amplifier.

DESCRIPTION OF THE PREFERRED EMBODIMENTS
 Reference will now be made in detail to the preferred embodiments of the
 present invention, examples of which are illustrated in the accompanying
 drawings, wherein like reference numerals refer to like elements
 throughout.
 First Preferred Embodiment
 FIG. 1 is a cross sectional diagram schematically showing a single lens
 reflex camera containing a vibration motion detection device according to
 the first preferred embodiment of the present invention.
 An angular velocity sensor 10 detects vibrations of the camera, and acts as
 a sensor which outputs a voltage value proportional to the Coriolis force
 acting on the camera. The angular velocity sensor 10, in order to detect
 angular velocity in two axial directions, normally contains two sensors.
 These sensors include a pitch angular velocity sensor which detects
 angular velocity around the X axis, and a yaw angular velocity sensor
 which detects angular velocity around the Y axis. In FIG. 1, the angular
 velocity sensor of one axis is omitted from the drawing. The angular
 velocity sensor 10 operates while a half depression timer 90 is ON, and it
 is possible to detect angular velocity. The detected vibration motion
 detection signal is output to an amplifier 20.
 The amplifier 20 amplifies the output value of the angular velocity sensor
 10. The amplified output signal is input to a decision unit 30, to a
 target value calculation unit 35, and an integration unit 40.
 The decision unit 30 includes a variance value calculation unit which
 calculates a variance value of the vibration motion detection signal
 amplified by the amplifier 20, and decides whether there was a movement
 due to a field of view angle change by the camera in which the angular
 velocity sensor 10 is loaded. The decision unit 30 outputs to the target
 value calculation unit 35, a decision signal relating to whether there was
 a movement due to a field of view angle change.
 The target value calculation unit 35 takes the output value of the angular
 velocity sensor 10 as amplified by the amplifier 20 when it is stationary
 and calculates a target value (omega zero value) for vibration motion
 compensation control. In addition, the target value calculation unit 35,
 based on the decision signal output from the decision unit 30, changes the
 calculation format of this target value, and thereby varies the target
 value. The target value calculation unit 35 outputs the calculated target
 value to an integration unit 40.
 The integration unit 40 performs an integration calculation by subtracting
 the target value calculated by the target value calculation unit 35 from
 the vibration motion detection signal as amplified by the amplifier 20.
 The integration unit 40 converts the angular velocity signal into an
 angular displacement signal by using this integration calculation.
 The drive unit 50, based on the angular displacement signal from the
 integration unit 40, outputs a drive signal to drive a vibration or
 blurring motion compensation lens 60. The drive unit 50 is equipped with a
 servo circuit and an actuator which drives the blurring motion
 compensation lens 60. The drive unit 50 also includes a position detection
 device to detect the drive position of the blurring motion compensation
 lens 60.
 As shown in FIG. 1, the blurring motion compensation lens 60 compensates
 for vibration motion by being driven in a direction at right angles to the
 optical axis I. The blurring motion compensation lens 60 is built into the
 imaging optical system of the photographic device. The blurring motion
 compensation lens 60, based on the drive signal from the drive unit 50,
 compensates for blurring motion by moving the optical axis of the imaging
 optical system of the photographic device in the opposite direction of the
 vibration.
 A lens barrel 80 houses the photographic optical system which includes the
 blurring motion compensation lens 60. The lens barrel 80 is
 interchangeable and is mounted to be freely detachable from the camera
 body 70.
 An electrical power supply unit 130 supplies electric power to the angular
 velocity sensor 10 when a switch SW1 is ON. The electrical power supply
 130 while the half depression timer 90 is ON, continues the supply of
 electrical power to the angular velocity sensor 10, and stops the supply
 of electric power to the angular velocity sensor 10 when the half
 depression timer is OFF.
 The half depression timer 90 is a timer which is set ON when the half
 depression switch SW1 is ON. The half depression timer 90 remains ON while
 the half depression switch SW1 is pressed, and remains ON for a fixed time
 period when the half depression switch SW1 is turned OFF.
 The half depression switch SW1 is a switch used to commence a series of
 photographic preparation operations. The ON operation of the half
 depression switch SW1 is coupled to the half depression action of a
 release button (not shown in the drawing).
 A full depression switch SW2 is a switch in order to commence the exposure
 operation of the c amera and other photographic operations. The ON
 operation of the full depression switch SW2 is coupled to the full depress
 ion operation of the release button.
 The operation of the vibration motion detection device according to the
 first preferred embodiment of the present invent ion will be described,
 with special emphasis on the operation of the decision unit.
 FIG. 2 is a flow chart which describes the operation of a single lens
 reflex camera which uses the vibration motion detection device according
 to the first preferred embodiment of the present invention.
 A photographic operation is started by setting ON a power supply switch on
 the camera body (not shown in the drawing) Further, in the description
 provided below, except where otherwise stated, each step is performed in
 the decision unit 30.
 Referring to FIG. 2, in step (referred to as "S" hereinafter) 100, it is
 determined whether the half depression switch SW1 is set ON. When the half
 depression switch SW1 is set ON, the routine proceeds to S200. When the
 half depression switch SW1 is OFF, processing continues to repeat S100
 until the half depression switch SW1 is set ON.
 In S200, simultaneously with the half depression switch SW1 being set ON,
 the half depression timer 90 resets a time t of the timer to zero.
 In S300, the half depression switch SW1 is ON, the half depression timer 90
 time t was reset, and simultaneously the half depression timer 90 is set
 ON.
 In S400, the power supply unit 130, simultaneously with the turning ON of
 the half depression timer 90, supplies electric power to the angular
 velocity sensor 10, and the angular velocity sensor 10 begins to operate.
 The angular velocity sensor 10 detects vibration present in the camera
 body 70 and lens barrel 80, and outputs a vibration motion detection
 signal.
 In S500, the half depression timer 90 commences timing simultaneously with
 the half depression switch SW1 being set ON.
 In S600, the drive unit 50 outputs a drive signal, and the blurring motion
 compensation lens 60 is driven based on this drive signal.
 In S700, the decision unit 30 decides whether a field of view angle change
 is in progress. The decision unit 30 determines whether the camera is in
 an approximately stationary (referred to as "stationary stable state"
 hereinafter) or whether the camera is in the course of large movements due
 to field of view angle changes (referred to as "composition change state"
 hereinafter). When the camera is in a stationary stable state, the routine
 proceeds to S900. When composition change states are occurring, processing
 proceeds to S800. Further, a stationary stable state is not a state in
 which the camera is completely stationary, but in spite of the
 photographer's best efforts to make the camera stationary, is a state in
 which the camera vibrates due to the photographer's unintended hand tremor
 motions.
 In S800, the target value calculation unit 35 calculates, based on the
 vibration motion detection signal, the target value of vibration motion
 compensation control in the field of view angle change state by changing
 to the calculation format of the target value in a stationary stable
 state. The integration unit 40, subtracting the output value of the target
 value calculation unit 35 from the output value of the amplifier 20 and
 performing an integration calculation, converts the angular velocity
 signal to an angular displacement signal. The drive unit 50 outputs a
 drive signal based on the angular displacement signal from the integration
 unit 40 and, based on this drive signal, compensates for vibration motion
 by adjusting the optical axis of the imaging optical system of the
 photographic device.
 In S900, the target value calculation unit 35 calculates, based on the
 vibration motion detection signal, the target value of vibration motion
 compensation control in the stationary stable state. The integration unit
 40, based on this target value, converts the angular velocity signal to an
 angular displacement signal, and the drive unit 50 drives the blurring
 motion compensation lens 60 based on this angular displacement signal.
 In S1000, it is determined whether the half depression timer 90 is set ON.
 When the half depression timer 90 is set ON, the routine proceeds to
 S1100. When the half depression timer 90 is OFF, the routine proceeds to
 S1300.
 In S1000, it is determined whether the full depression switch SW2 is set
 ON. When the full depression switch SW2 is set ON, the routine proceeds to
 S1200. When the full depression switch SW2 is set OFF, the routine
 proceeds to S100, and it is determined whether the half depression switch
 SW1 is set ON.
 In S1200, the photographic operation is performed. This photographic
 operation includes: opening and closing the shutter using the shutter
 mechanism; winding the film by the film winding mechanism; and ending this
 sequence of operations.
 In S1300, the decision unit 30 stops the calculation of variance values by
 the variance value calculation unit, and the target value calculation unit
 35 stops the calculation of target values.
 In S1400, the angular velocity sensor 10 is turned OFF. In S1000, when it
 has been determined that the half depression timer 90 is OFF, the
 electrical power supply unit 130, simultaneously with the OFF operation of
 the half depression timer 90, stops the supply of electrical power to the
 angular velocity sensor 10.
 In S1500, the timing of the half depression timer 90 stops. The half
 depression timer 90 stops timing simultaneously with the OFF operation of
 the half depression switch 90, and the operation of the sequence ends.
 The processing flow of calculations of the decision unit in the vibration
 motion detection device according to the first mode of embodiment of the
 present invention will next be described.
 FIG. 3 is a flow chart which illustrates the processing flow of
 calculations of the decision unit in the vibration motion detection device
 according to the first preferred embodiment of the present invention.
 FIG. 3 gives a detailed description of S700 in FIG. 2 and the decision unit
 30 performs calculations as described below.
 Referring to FIG. 3, in S710, it is determined whether the clock time t is
 smaller than a decision level (decision value) t.sub.1. When the elapsed
 time t, from the clock start of the half depression timer 90, is below the
 time decision level t.sub.1, the routine proceeds to S720. When the
 elapsed time t, from the clock start of the half depression timer 90,
 exceeds the time decision level t.sub.1, the routine proceeds to S740.
 Further, in the execution of S720 to S740, the decision unit 30 performs
 calculations using the output data from the angular velocity sensor 10
 which were obtained up to a given time t.
 In S720, the decision unit 30 calculates the average value E(y).sub.N of
 the output value y of the angular velocity sensor 10 in the elapsed time
 t. The decision unit 30 finds the average value E(y).sub.N, based on all
 the blurring motion detection signals from the detection commencement
 (t=0) of the blurring motion detection signals to the time t by using the
 angular velocity sensor 10, from the following Equation 1, and proceeds to
 S730.
 ##EQU1##
 In Equation 1, N is the sample number and t is the time when N samples have
 been performed (N=t (sec)/sampling time (sec)).
 In S730, the decision unit 30, using the variance value calculation unit,
 calculates a variance value V(y).sub.N of elapsed time t. The decision
 unit 30 finds the variance V(y).sub.N of the angular velocity values based
 on all of the vibration motion detection signals from detection
 commencement (t=0) of the vibration motion detection signals using the
 angular velocity sensor 10, and proceeds to S760.
 ##EQU2##
 In S740, the decision unit 30 calculates the average value E'(y).sub.N of
 the output value y of the angular velocity sensor 10 in the calculation
 interval. The decision unit 30 calculates a moving average of only the
 data of the angular velocity sensor 10 in a range of some calculation
 interval K0 using Equation 3, and proceeds to S750.
 ##EQU3##
 In Equation 3, K0 is the amount of data (K0=calculation interval
 (s)/sampling time (s)) in some calculation interval length.
 In S750, the decision unit 30, using the variance value calculation unit,
 calculates a variance value V'(y).sub.N of the elapsed time t in the
 calculation interval. The decision unit 30 finds the variance V'(y).sub.N
 in only the data of the angular velocity sensor 10 in some range of
 calculation interval length K0, and proceeds to S760.
 ##EQU4##
 In S760, the decision unit 30 determines whether the calculated variance
 value V(y).sub.N or the variance value V'(y).sub.N is greater than a
 decision level V.sub.t. When the calculated variance value V(y).sub.N is
 greater than the decision level V.sub.t, execution proceeds to S770. When
 the calculated variance value V(y).sub.N is less than the decision level
 V.sub.t, the routine proceeds to S780.
 In S770, the decision unit 30 determines that there is a field of view
 angle change. The decision unit 30 determines that the camera is in the
 course of a large movement, due to photographic composition change,
 panning photography, following a randomly moving subject and other field
 of view angle changes, and proceeds to S800.
 In S780 the decision unit 30 decides that the camera is in a stationary
 stable state without large movements due to field of view angle changes,
 and proceeds to S900.
 A discussion will now be given of the decision results of the decision unit
 in the vibration motion detection device according to the first preferred
 embodiment of the present invention.
 FIGS. 4A, 4B and 4C are diagrams showing the output signal of the angular
 velocity sensor and its variance value when there is a field of view angle
 change. FIG. 4A is a diagram which shows the output signal of the angular
 velocity sensor, and its variance value, when there is a photographic
 composition change. FIG. 4B is a diagram which shows the output signal of
 the angular velocity sensor, and its variance value, when panning
 photography is in effect. FIG. 4C is a diagram which shows the output
 signal of the angular velocity sensor, and its variance value, when
 following a randomly moving subject.
 In FIGS. 4A, 4B and 4C, the broken line shows the output signal (angular
 velocity value) of the angular velocity sensor 10 due to hand tremor
 motions. The solid line indicates the variance value of the output signal
 (angular velocity value). In the vibration motion detection device of the
 first preferred embodiment of the present invention, the decision value
 V.sub.t can be fixed at an optional value. As shown in FIGS. 4A-4C, in a
 stationary stable state the variance value V(y).sub.N is less than
 V.sub.t0 equal to 1.5. Setting the decision value V.sub.t at as small as
 possible, it is possible to quickly detect a field of view angle change,
 but when the decision value is set too small, there is a possibility of
 reaching a decision that there was a field of view angle change even in a
 stationary stable state. However, when the decision value V.sub.t is set
 to too large, the decision that a field of view angle change has started
 takes too long. In the first preferred embodiment of the present
 invention, the decision value V.sub.t is set to 2.0, slightly larger than
 the variance value V(y).sub.N (V.sub.t0)=1.5 in the stationary stable
 state. As shown in FIGS. 4A-4C, in a photographic composition change, such
 as when taking panning photographs, or when following a moving subject,
 the variance V(y).sub.N provides a value larger than 1.5. Because of this,
 using the variance value V(y).sub.N calculated by the decision unit 30, it
 can be accurately determined that a large movement of the camera is taking
 place. In particular, in the vibration motion detection device according
 to the first preferred embodiment of the present invention, as shown in
 FIG. 4C, the variance V(y).sub.N also takes on a large value when
 following a randomly moving object. As a result, as shown in FIGS. 4A and
 4B, even when the output signal of the angular velocity sensor 10 is not
 in one direction, it is possible to accurately detect the movement state
 of the camera due to a field of view angle change.
 FIG. 5A is a diagram which shows the output signal of the angular velocity
 sensor, and the target value for controlling the blurring compensation
 lens 60 calculated using the target value calculation unit when a
 photographic composition change takes place. FIG. 5B is a diagram which
 shows the drive amount of the blurring motion compensation lens
 corresponding to the output signal of FIG. 5A.
 FIG. 6A is a diagram which shows the output signal of the angular velocity
 sensor, and the target value of control calculated using the target value
 calculation unit, when panning photography is taking place. FIG. 6B is a
 diagram which shows the drive amount of the blurring motion compensation
 lens corresponding to the output value of FIG. 6A.
 FIG. 7A is a diagram which shows the output signal of the angular velocity
 sensor, and the target value of control calculated by using the target
 value calculation unit when a randomly moving subject is followed. FIG. 7B
 is a diagram which shows the drive amount of the blurring motion
 compensation lens corresponding to the output signal of FIG. 7A.
 In FIGS. 5A, 6A and 7A, the broken lines show the output signal (angular
 velocity value) of the angular velocity sensor 10 due to hand tremor
 vibration motions. The solid lines, in these figures, are the target value
 which was calculated by using the target value calculation unit. Further,
 FIGS. 5B, 6B and 7B show the drive amount of the blurring motion
 compensation lens including integration of the angular velocity signal,
 based on the target value. In the first preferred embodiment of the
 present invention, the target value calculation unit 35 varies the target
 value of control based on the decision result of the decision unit 30. As
 a result, as shown in FIGS. 5B, 6B and 7B, the blurring motion
 compensation lens 60 can compensate for vibration motion without exceeding
 the drive limits.
 In the vibration motion detection device according to the first preferred
 embodiment of the present invention, a determination can be made of the
 stationary stable state and composition change state of the camera using
 the decision unit 30. As a result, when the camera moves due to a
 photographic composition change, the blurring motion compensation lens
 also moves but only to compensate for vibrations, and the unpleasant
 sensation that the image in the viewfinder is not moving while the camera
 is, can be reduced. In addition, in the case that a large movement was
 effected by the camera due to a field of view angle change, blurring
 motion can simultaneously be compensated for. Also, in the case of
 following a randomly moving subject, vibration motion can be compensated
 even when the camera oscillates in every possible direction.
 Referring to FIG. 3, in the first preferred embodiment of the present
 invention, the decision unit 30, after a decision level t.sub.1 in time
 has elapsed, calculation proceeds from S740 to S750. This flow from S740
 to S750 calculates similar statistical information to that from S720 to
 S730. However, in contrast to calculations of S720 to S730 which use all
 existing information data, S740 to S750 only uses information data of a
 limited interval length (K0). As a result, the calculation method from
 S740 to S750 is different from the calculation method from S720 to S730.
 In the first preferred embodiment of the present invention, the time from
 the ON operation of the angular velocity sensor 10 until its output is
 comparatively stable as the decision level t.sub.1, and can be accurately
 determined using only the information of the limited interval length after
 t.sub.1 has elapsed.
 Second Preferred Embodiment
 In the second preferred embodiment of the present invention, the
 calculation method of the decision unit 30 in the flow chart FIG. 3
 differs from the first preferred embodiment of the present invention.
 In S720, the decision unit 30 determines the average value E(y).sub.N of
 the output value y of the angular velocity sensor 10 in the elapsed time t
 using Equation 5.
 ##EQU5##
 In S730, the decision unit 30 finds the variance value V(y).sub.N of the
 elapsed time t using Equation 6.
 ##EQU6##
 In S740, the decision unit 30 determines the average value E'(y).sub.N of
 the output value y of the angular velocity sensor 10 in the elapsed time t
 in the calculation interval length, using Equation 7.
 ##EQU7##
 In S750, the decision unit 30, using the variance value calculation unit,
 determines the variance value V(y).sub.N of the elapsed time t in the
 calculation interval length according to Equation 8.
 ##EQU8##
 In the second preferred embodiment of the present invention, when
 calculating the variance values, the method uses the statistical values
 calculated in the previous time sampling period. For example, the angular
 velocity average value E(y).sub.N is calculated from the time the angular
 velocity sensor goes ON (t=0 s) to t=1 s. Here, E(y).sub.N is the average
 value of the angular velocity from t=0 to t=1. In the next sampling period
 at t=1.001 s, the average value E(y).sub.N+1 from E(y).sub.N, the oldest
 data (in this example, the angular velocity value at t=0) is taken out
 among the data used in the calculation of E(y).sub.N, and the data at
 t=1.001 s is added.
 Therefore, in comparison with the first preferred embodiment of the present
 invention which calculates using all data within the calculation interval,
 in the case of the second preferred embodiment of the present invention,
 the amount of calculation can be much smaller, and an increased
 calculation speed can be realized. In addition, because the amount of data
 retained for the calculation is reduced, an advantage is realized in a
 smaller memory size required by the calculation unit.
 Further Preferred Embodiments
 Without limitation to the above-described preferred embodiment, various
 modifications and alterations are possible, and these also fall within the
 scope of the invention.
 For example, in the vibration motion detection device according to the
 preferred embodiments of the present invention, the target value
 calculation unit 35 calculates the target values of control in the
 stationary stable state using Equation 9. When the field of view angle
 changes take place, Equation 10 can be used when K0' is &lt;K0.
 ##EQU9##
 ##EQU10##
 Equations 9 and 10 are moving averages with the calculation interval
 changed in the stationary stable state and the field of view angle change
 state.
 In the vibration motion detection device according to the preferred
 embodiments of the present invention, the blurring motion detection unit
 is not limited to an angular velocity sensor 10. The present invention can
 utilize a suitable acceleration sensor or other types of sensors. In
 addition, the decision unit 30 may be built into the target value
 calculation unit 35. The variance value calculation unit which calculates
 variance values and the decision unit may be completely separate units.
 Further, the integration unit 40 may be built into the decision unit 30.
 In the preferred embodiments of the present invention, a description was
 given mentioning examples of a vibration motion detection device included
 in a single lens reflex still camera. However, the present invention can
 be suitably applied to video cameras and like photographic devices, as
 well as binoculars, telescopes, and other like optical devices. In
 addition, the invention can be used in compact cameras in which exchange
 of the lens barrels is not possible. Also, the method of calculation of
 the target values in the cases of the stationary stable state and a field
 of view angle change state is not limited to the methods of the preferred
 embodiments of the present invention. The calculation method of the
 stationary stable state and the calculation method of the photographic
 composition change state may be varied, and methods resembling these may
 be used.
 Utilizing the preferred embodiments of the present invention, large
 movement changes which occur in the vibration motion detection unit due to
 photographic composition changes, panning photography, or the following of
 a randomly moving subject can be identified.
 Also, because the variance value calculation unit calculates the variance
 value based on average values of the output values which are output within
 a predetermined time by the vibration motion detection unit, the
 calculation of variance values can be accomplished with high degree of
 accuracy.
 Further, since the variance calculation unit can use only output values
 output after a predetermined time had elapsed and at least a portion of
 the output values which were output by the vibration motion detection unit
 within a predetermined time, it can accurately obtain variance values and
 reduce the amount of calculation necessary, thereby shortening the
 calculation time.
 The vibration motion detection unit of the present invention can use either
 an acceleration detector or a velocity detector to calculate the variance
 values based on the output signal from either of these devices.
 Also, the vibration motion detection unit of the present invention, when
 the variance value exceeds a predetermined value, can determine that the
 optical device is moving due to field of view angle change based on using
 this predetermined value as a target.
 Still further, the target value calculation unit of the present invention,
 based on the variance values, can vary the target values of the blurring
 motion detection signal, even if there is a photographic composition
 change state, or when panning or following a randomly moving subject,
 vibration motion can be accurately compensated for.
 The above embodiments of the present invention are also described as
 relating to a camera. However, embodiments of the present invention are
 not intended to be limited to a camera. For example, the present invention
 can be used in devices including, but not limited to, camcorders, motion
 picture camera, telescopes, binoculars, microscopes, range finding
 equipment, lasers, fiber optic communications systems, various optical
 projection systems and CD mastering systems.
 Although a few preferred embodiments of the present invention have been
 shown and described, it will be appreciated by those skilled in the art
 that changes may be made in these embodiments without departing from the
 principles and spirit of the invention, the scope of which is defined in
 the claims and their equivalents.