JP3548285B2 - Camera image stabilizer - Google Patents

Description

[0001]
[Industrial applications]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera image blur prevention device that works to prevent image blur caused by camera shake or the like in a camera, an optical device, or the like.
[0002]
[Prior art]
Conventionally, as a vibration isolator of this type, as shown in FIG. 9, rotational shake around two vertical axes parallel to the film surface of the camera shown in FIG. Sensors 301 and 302 for detecting are arranged, and based on the outputs from these sensors, the correction optical system is driven via predetermined driving means 303 and 304, so that the image blur (that is, shooting) (Caused by camera shake of the user) is reduced.
[0003]
[Problems to be solved by the invention]
Normally, the camera shake frequency band of the photographer is at most about 20 Hz, and such a frequency is a range that can be sufficiently followed by a current sensor (for example, a vibration gyro) and a correction optical system (for example, a shift optical system described later). .
[0004]
However, in a camera or the like having a focal plane type shutter, each of the front curtain and the rear curtain travels at about 100 Hz (this frequency is determined by the traveling speed of the shutter curtain. That is, the period of the shake is determined by the start of travel and the completion of travel. ), The current sensor and correction system cannot sufficiently follow this frequency.
[0005]
FIG. 10 shows the state of the shake waveform during the shutter running. At the timing of the start of the front curtain running shown in (a), the original shake waveform shown in (c) rapidly decreases in the downward direction. This waveform rapidly rises upward at the timing of the completion of the front curtain running.
[0006]
On the other hand, since the actual motion output of the sensor and the correction system is delayed with respect to the original shake as shown in (d), the resulting shake on the actual image plane is shown in (e). In this way, it becomes very large until a predetermined time elapses from the start of traveling of the front curtain. Also, in the case of the trailing curtain running, a shake is generated in synchronization with the start and trailing end of the trailing curtain shown in (b), and a shake occurs on the image plane. Because the timing is close to, the influence is less than that of the front curtain driving.
[0007]
The effect of such shutter shake is eliminated when the shutter speed is low, since the proportion of the time during which the effect occurs is reduced compared to the entire exposure time. In the case of a high-speed shutter, the exposure time itself is short. There is no problem in this case. Therefore, there is a serious problem with a medium-speed shutter having a shutter speed of about 1/30 to 1/250 second.
[0008]
The present invention has been made in view of the above-described circumstances, and when a shake that cannot be properly detected and corrected by a normal sensor or a correction system, for example, a high-frequency shake as described above occurs. However, an object of the present invention is to provide an image blur prevention device for a camera which enables appropriate image blur prevention.
[0009]
[Means for Solving the Problems]
SUMMARY OF THE INVENTION In order to achieve the above object, the present invention generates a signal at a predetermined timing in a camera image stabilization device that corrects image shake based on an output of a camera shake detection unit that detects image shake of a camera. A signal generating unit, an arithmetic unit for combining an output of the shake detecting unit with a signal generated by the signal generating unit in accordance with an exposure start timing of a camera, and a shake correction based on a calculation result by the arithmetic unit The signal generated by the signal generation means monotonically increases or decreases until the output of the shake detection means reaches a maximum, and thereafter increases or decreases after the maximum. Is a signal waveform that stops and becomes constant .
[0010]
【Example】
(First embodiment)
FIG. 1 is a block diagram showing an outline of an overall configuration of a camera according to a first embodiment of the present invention, and this configuration will be described below. The appearance and the arrangement of each component are the same as those shown in FIG.
[0011]
Reference numeral 1 denotes a shake sensor for detecting the shake of the entire camera. Generally, a vibration gyro is used as an angular velocity sensor using Coriolis.
[0012]
The output of the shake sensor 1 is input to an integration circuit 3 after unnecessary signal components are removed and amplified through a filter circuit 2, where the angular velocity is converted into each displacement.
[0013]
The output of the integration circuit 3 and the output of an arbitrary timing generation circuit 4 for generating an arbitrary waveform at a predetermined timing from the sequence control circuit 16 are added in an addition circuit 5, and the output from the addition circuit 5 is a lens. After being converted into a correction system drive amount necessary for shake correction by the drive conversion circuit 6, it is input to the subtraction circuit 7.
[0014]
The other input of the subtraction circuit 7 is connected to the output from the correction optical system position detection means 8. Here, the specific configuration of the actual correction optical system 9, correction optical system drive means 10, and drive coil 11 will be described. Will be described with reference to FIG.
[0015]
FIG. 2 shows details of the correction optical system 9 of FIG. 1 and a configuration for driving the same. The correction optical system shown in the figure shows the configuration of a shift optical system that drives the optical path incident on the photographing optical system of the camera eccentrically by shifting the lens in parallel in the xy directions perpendicular to the optical axis. Numerals 30 and 31 denote yoke portions constituting a magnetic circuit unit serving as an actual drive source in the x and y axes directions, and 32 and 33 denote coils forming a pair with the yokes. Accordingly, when the necessary power is supplied from the correction optical system driving means 10 shown in FIG. 1 to this coil portion, the correction lens 34 forming a part of the photographing lens is eccentrically driven in the x and y axis directions.
[0016]
Reference numeral 35 denotes a support frame and a support arm for fixing the lens 34. The actual movement of the shift lens is performed by the iREDs 36 and 37 that move integrally with the lens and the lens barrel 40 that holds the entire shift lens. Non-contact is detected by a combination with the attached PSDs 42 and 43.
[0017]
Alternatively, 38 is a mechanical lock mechanism for holding the lens substantially at the center of the optical axis when power supply to this shift system is stopped, 39 is a charge pin, and 41 is a tilt for regulating the falling direction of the shift system. Each of the supporting spheres serves as a stop.
[0018]
As described above, the movement of the correction optical system driven for image blur correction is input to the subtraction circuit 7 through the correction optical system position detection means 8, where the subtraction from the signal input from the sensor is performed. Then, the result becomes a drive signal to the correction optical system 9 through the correction optical system drive means 10, and as a result, the correction optical system 9 is driven so as to be equal to the sensor output. Therefore, the image formed on the film surface 20 through the correction optical system 9 and the photographing optical system 12 is always substantially at the same position without being affected by camera shake by the photographer. Here, lens position information relating to a photographing magnification such as zoom / focus of the photographing lens 12 is taken into the sequence control 16 via the lens position detecting means 13.
[0019]
On the other hand, the photometric information from the photometric unit 17 accompanying the ON operation of the switch unit 18 in conjunction with the operation of the SW1 of the camera (the half-press operation of the release button) is taken into the sequence control circuit and converted into predetermined shutter speed information. Further, the running operation of the shutter 14 is performed through the shutter control unit 15 in accordance with the start of the actual exposure operation in response to the ON operation of the switch unit 19 interlocked with the operation of the SW2 of the camera (the full press operation of the release button). I have. Further, all of the portion A surrounded by the dotted line can be constituted by one CPU.
[0020]
Next, the actual control operation will be described with reference to the flowchart of FIG. 3 showing the control operation of the control circuit 16 and the timing chart of FIG.
[0021]
First, in step 100 of FIG. 3, it is determined whether or not the switch means 18 of FIG. 1 is ON, that is, whether or not the SW1 (half-press of the release button) of the camera is ON. If it is ON, the process proceeds to step 101, where the driving of the correction optical system 9 is started according to the output of the shake sensor 1 as shown in FIG. Therefore, at this point, image blur correction due to normal camera shake is performed.
[0022]
Next, in step 102, the actual aperture and shutter speed for realizing the optimal exposure are calculated and determined based on the subject luminance information from the photometry means 17 shown in FIG.
[0023]
Subsequently, at step 103, it is determined whether or not the switch means 19 of FIG. 1 is ON, that is, whether or not the SW2 (release button fully pressed) of the camera is ON. Then, the process proceeds to step 104, where the state of the SW1 of the camera is determined again as in step 100.
[0024]
If SW1 is ON in step 104, the process returns to step 103 again, but if it is OFF, the process proceeds to step 105 to stop driving of the correction optical system 9 (normally, the mechanical lock shown in FIG. 2). Since the lens is mechanically fixed by the mechanism 38), the image blur correction operation due to camera shake is stopped at this point.
[0025]
On the other hand, when it is determined in step 103 that the SW2 of the camera is ON, first, in step 106, a timer in the sequence control circuit 16 is reset, and an initial setting operation of each timing described later is performed. Next, at step 107, the driving of the front curtain of the shutter 14 via the shutter control means 15 is started.
[0026]
Here, the state of the shake, the shake signal, and the like at the time of driving the front curtain will be described with reference to the timing chart of FIG.
[0027]
The timing chart of FIG. 4 shows the fluctuation of the actual shake state, the shake sensor output, and the like accompanying the driving of the shutter first curtain and the rear curtain. In this figure, (a) shows the driving state of the shutter front curtain, (b) shows the driving state of the shutter rear curtain, (c) shows the actual camera shake state, (d) the output of the shake sensor and the displacement of the correction system, e) is the correction data to be described later, (f) is the result of adding the shake sensor output and the correction data, and the displacement of the correction system that operates accordingly, and (g) is the correction system as shown in (f). The respective image plane remaining amounts on the image plane when operating are shown.
[0028]
As shown in FIG. 4 (c), when the front curtain is driven and running, the camera body has a downward shake which is much faster than the camera shake. Swing occurs.
[0029]
This is due to the fact that the camera body is moving due to the reaction of the front curtain running and stopping.
[0030]
On the other hand, in the actual shake sensor output, as shown by the solid line in (d), the occurrence timing of the shake and the peak timing (the delay t ₁ from the original shake peak to the sensor output peak) are respectively delayed. This is due to the deterioration of the high frequency performance of the shake sensor itself. Further, drive displacement when the correction optical system is driven based on the output of the shake sensor The output of the correction optical system position detecting means 8 in FIG. 1 is as shown by a dotted line in FIG. The waveform has a further delay compared to the output of the shake sensor, but this is due to the deterioration of the high frequency performance of the correction system itself.
[0031]
In step 108, a determination is made whether T ₀ has elapsed after the front curtain traveling start, if not reached T _0, the waveform output of an arbitrary timing waveform generation circuit 4 at step 109 is cleared And the data added to the sensor output remains at 0.
[0032]
On the other hand, if it is determined in step 108 that the timer value exceeds T ₀ , the process proceeds to step 110 to determine whether the timer value has exceeded T ₁ (≧ T ₀ ). Done. Further, when not passed the T _1, the output of any timing waveform generation circuit 4 where the program proceeds to step 111 occurs as shown in FIG. 4 (e), the shake sensor output via the adder circuit 5 Is added to. Here, arbitrary waveform that monotonously increases with a constant slope in than after T ₀ hours elapsed occurs.
[0033]
Further, if the value of the timer is determined to be beyond the T ₁ in step 110, the increase of the output of any timing waveform generation circuit is stopped in step 112, so that the value in the subsequent exposure period is held . FIG. 4 (f) shows the result obtained by adding an arbitrary waveform which maintains the level after such a predetermined monotonic increase to the output of the shake sensor, and is apparent from comparison with FIG. 4 (d). Thus, in the period of Δt from the completion of the front curtain, the original waveform shown in (c) is corrected in the opposite direction in (d), whereas the original waveform shown in (c) is corrected in (f). Although it does not completely follow, it can be seen that the correction is made in the same direction as the actual shake of (c). The final shake amount on the image plane obtained by such a correction operation is shown in FIG. 4 (g). When this is compared with FIG. 10 (e), on the other hand, at the timing before the shutter is fully opened, Although the remaining amount of correction is large, the ratio contributing to the actual exposure during this period is slightly smaller than that in the fully open state, and after the shutter is fully opened, the amount of remaining image blur correction is much smaller than that in FIG. This makes it possible to reduce the shake in actual exposure.
[0034]
The above-described set times T ₀ and T ₁ are set in consideration of the shake characteristics of the camera and the response delay characteristics of the shake sensor caused by the running of the shutter curtain as shown in FIG. For example, in the case of the present embodiment, T ₀ is set to be the time from the start of running of the shutter front curtain to the time when the influence of the running of the shutter front curtain starts to appear as camera shake, and T ₁ is the time of the shutter front curtain. the output of the shake sensor from running start is set to be the time until the time to peak (the time when the vibration caused by the shutter front curtain is delayed by t ₁ in FIG. 4 from the time to peak).
[0035]
Again At a flow chart of FIG. 3, the value of the timer at step 113 is made whether the determination has reached the shutter control time T ₂ which is determined from photometric level, if not passed back to step 108 again However, if it is determined that the time has elapsed, the routine proceeds to step 114, where the rear curtain running start operation is performed.
[0036]
In the case of rear-curtain travel, a shake waveform as shown in FIG. 4C is generated as in the case of front-curtain travel. However, since the shutter curtain is closing, the effect on actual exposure is smaller than that of the front curtain. It will be small. In the present embodiment, therefore, the correction operation is not performed in the rear curtain, but it is needless to say that further improvement is expected when the shake sensor output correction similar to that in the front curtain is performed.
[0037]
The value of step 115 a timer is made is determined whether or not reached T _3, reached if it is determined that the front curtain here proceeds to step 116, the energization to the actuator performing the driving of the rear curtain The shutter is stopped under the control of the shutter control means 15.
[0038]
Subsequently, in step 117, the above-mentioned arbitrary timing generation circuit is cleared and its output becomes 0, and the addition of the correction data to the addition circuit 5 is stopped. When the above operation is completed, the film is fed by a feeding circuit (not shown) in step 118, and the process returns to step 103 again when the feeding is completed.
[0039]
FIG. 5 shows a modification of the correction data shown in FIG. 4 (e). FIG. 5 (a) shows a case where the inclination of the straight line changes by two steps (or two or more steps). The inclination prevents the original shake and the movement of the correction system from being opposite to each other, and the gentle inclination in the latter half prevents overcorrection when the original shake and the movement of the correction system are in the same direction.
[0040]
Further, if a curved waveform that increases exponentially as shown in FIG. 3B is used, the same effect as described above can be expected.
[0041]
(Second embodiment)
Next, a second embodiment of the present invention will be described. FIG. 6 is a timing chart showing the actual shake state and the fluctuation of the shake sensor output and the like accompanying the shutter drive, wherein (a) to (e) are the same as (a) to (e) in FIG. Is shown.
[0042]
FIG. 6 shows a case where the shutter speed is faster than that of the first embodiment shown in FIG. 4, and in this case, the traveling of the front curtain and the traveling of the rear curtain are timing-dependent. Because of the overlap, the deflection waveform in (c) is larger than that in FIG. In such a case, the output of the shake sensor and the remaining image plane correction due to the delay of the driving of the correction system corresponding to the output of the shake sensor tend to increase.
[0043]
In other words, since the shake characteristic, the shake sensor output, and the delay characteristic of the correction optical system drive generated by the shutter drive change depending on the shutter speed, it is naturally necessary to change the correction data according to the shutter speed used together.
[0044]
FIGS. 7 and 8 are flowcharts showing a control method when the method of the correction timing is changed according to the shutter speed. Steps 200 to 205 are exactly the same as steps 100 to 105 in FIG. Is omitted.
[0045]
In step 206, information corresponding to the shutter speed determined by the photometric calculation in step 202, for example, when the shutter speed changes by one step from 1/250 to 1/125, the value of n increases by one. Then, a predetermined integer value is determined.
[0046]
Next, in steps 207 to 209, the parameter value of each correction data whose integer value corresponds to n is derived from the correction data table. First, in step 207, the value of the table data f (n) is described in the first embodiment. as the value of T _0, then the value _{T 1} of the step 208 similarly table data g (n), an amount corresponding to the maximum amplitude D of the correction data as shown in FIG. 6, step 209 h (n) Is transferred to the register L inside the CPU.
[0047]
Further, in step 210, the value of the register L is transferred to the arbitrary timing waveform generating circuit 4 in FIG. 1, and the amount of correction data to be generated at the time of actual shutter control is determined. Next, the operations during the actual exposure are shown in steps 211 to 223. However, since this operation is completely the same as steps 106 to 118 in FIG. 3, the description is omitted here.
[0048]
If you change the data to be corrected in accordance with the shutter speed in this manner, as shown in FIG. 6 (e), the timing T ₀ the waveform _rises, the timing T ₁ increases in waveform, reduction is stopped _and, The maximum amplitude D of the waveform changes, and optimal correction data corresponding to the original shake can be set.
[0049]
In this embodiment, the correction data is changed only in accordance with the shutter speed to be used. However, according to the zoom and focus information detected by the lens position detecting means 13 shown in FIG. Changing the correction data is also effective. This is to prevent the effect of the shutter shake on the image plane from increasing as the focal length of the zoom becomes longer. In this case, it is necessary to use correction data closer to the shake waveform shown in FIG. is there.
[0050]
Also, when controlling the diameter of the aperture disposed in the lens via the aperture control means 21 shown in FIG. 1 in addition to the shutter speed, the fluctuation waveform varies due to the different aperture drive time according to the aperture value. Therefore, it is also effective to have different correction data depending on the set aperture.
[0051]
In each of the above-described embodiments, the stop of the shutter curtain is predicted by time. However, the actual movement of the shutter curtain is directly detected, and a signal for correcting the shake sensor output is detected based on the detection result. May be controlled or the state change may be controlled.
[0052]
In each of the above-described embodiments, an example has been described in which a shake caused by the influence of the driving of the focal plane shutter is dealt with. However, a configuration that causes other shakes, for example, another type of shutter or a quick return mirror of a single-lens reflex camera. Alternatively, the configuration may be such that the influence of driving of a film feeding mechanism or the like is dealt with. Also in this case, the method of coping is changed in accordance with the driving condition of the configuration causing the shake (the waveform of the shake sensor output correction data and the generation timing are changed as in the above-described second embodiments). Is also good.
[0053]
In the present invention, any type of shake detecting means may be used as long as it can detect an angular accelerometer, an accelerometer, an angular velocity meter, a speedometer, an angular displacement meter, a displacement meter, and a shake.
[0054]
The present invention provides, in addition to a shift optical system that moves an optical member in a plane perpendicular to the optical axis as shake correction means, other light beam changing means such as a variable apex prism, and a plane perpendicular to the optical axis. Any object may be used as long as it can prevent shake, such as a device that moves a shooting surface, a device that corrects shake by image processing, and the like.
[0055]
The present invention is not limited to the means for directly correcting the shake as the shake correction means, but warns the user that the shake is occurring or may occur by light, sound, etc. By paying attention to this, the shake may not be generated indirectly.
[0056]
INDUSTRIAL APPLICABILITY The present invention can be applied to a single-lens reflex camera, a lens shutter camera, a video camera, an optical device other than a camera, another device, and a constituent unit.
[0057]
In the present invention, each component or a part of the components of the claims or the embodiments may be provided in a separate device. For example, the shake detection means camera body, may be kicked set in the lens barrel stabilization means is mounted on the camera.
[0058]
【The invention's effect】
As described above, according to the present invention, the output of the shake detecting means according to the exposure start timing of the camera, monotonically increases or decreases until the output of the shake detecting means becomes maximum, Is calculated by synthesizing a signal whose increase or decrease stops and becomes constant, and shake correction is performed based on the calculation result. Therefore, when it is not possible to properly prevent image shake only by the output of the shake detection means, for example, Appropriate image blur prevention can be achieved even in the case where a shake of a frequency higher than the frequency that can be appropriately detected by the detection means occurs.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating an outline of an overall configuration of a camera according to a first embodiment of the present invention.
FIG. 2 is a perspective view showing details of a configuration relating to image blur correction of the camera according to the first embodiment of the present invention.
FIG. 3 is a flowchart showing an operation of the camera according to the first embodiment of the present invention.
FIG. 4 is a timing chart for explaining the operation of the camera according to the first embodiment of the present invention.
FIG. 5 is a timing chart for explaining the operation of the camera according to the first embodiment of the present invention.
FIG. 6 is a timing chart for explaining the operation of the camera according to the second embodiment of the present invention.
FIG. 7 is a flowchart illustrating an operation of the camera according to the second embodiment of the present invention.
FIG. 8 is a flowchart showing the operation of the camera according to the second embodiment of the present invention.
FIG. 9 is a perspective view schematically showing a conventional camera with an image blur prevention function.
FIG. 10 is a timing chart for explaining a problem of a conventional camera with an image blur prevention function.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 shake sensor 4 arbitrary timing waveform generation circuit 5 addition circuit 9 correction optical system 10 correction optical system driving means 16 sequence control circuit

Claims (2)

In an image blur prevention device for a camera that corrects image blur based on an output of a shake detector that detects image blur of the camera, a signal generator that generates a signal at a predetermined timing; and Calculating means for synthesizing the output of the shake detecting means and the signal generated by the signal generating means; and shake correcting means for correcting the shake based on the calculation result by the calculating means. The generated signal is a signal waveform that monotonically increases or decreases until the output of the shake detection unit reaches a maximum, and after the maximum, the increase or decrease stops and becomes constant. Camera shake prevention device. 2. The image of the camera according to claim 1, wherein the signal waveform monotonically increases or decreases after a lapse of time from an exposure start timing of the camera until an influence of shutter travel starts to appear as camera shake. Anti-shake device.

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