JPH05100279A - Image blurring preventing camera - Google Patents

Abstract

PURPOSE:To accurately correct image blurring by utilizing sufficiently correction stroke owned by a camera. CONSTITUTION:Vmax being the maximum value and Vmin being the minimum value of an image blurring speed in a specified period before a release signal is generated are detected by using a blurring sensor 1 and a camera CPU 5. When the Vmax and the Vmin are different marks, the initializing position of a blurring correction optical system 2 is set as a point for interiorly dividing the correction stroke at the ratio of ¦Vmax¦ :¦Vmin¦, and when the Vmax and the Vmin are the same marks, the initializing position of the system 2 is set in the vicinity of the limit position of the correction stroke.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image blur prevention camera having a correction means for correcting image blur such as camera shake.

[0002]

2. Description of the Related Art Conventionally, as an image blur correction method, Japanese Patent Application Laid-Open No.
The one disclosed in Japanese Unexamined Patent Publication No. 100019 is known. This image blur correction method predicts the lens drive amount and direction required for image blur prevention during shooting, based on the camera shake velocity immediately before the shutter is released (immediately before the start of exposure) (hereinafter simply referred to as “blurring velocity”). However, the lens is preliminarily shifted to a position where it can be covered immediately before the shutter is opened, and this is set as the initial position of the image blur prevention operation, so that the movable range (correction stroke) of the lens is effectively utilized. Is. The lens shift amount is desired to be half the product of the shutter open time and the camera shake speed.

[0003]

However, in the above-described conventional image blur correction method, the camera shake speed immediately before the start of exposure is used as information for predicting the lens drive amount and the direction necessary for preventing image blur during photographing. However, this is not enough as information on camera shake that occurs continuously.
For example, when the shutter release button happens to be pressed at a time when the blurring speed is low, such as near the peak position of the blurring waveform, there is a possibility that the blurring may start immediately after the exposure starts, even though the blurring is hardly observed immediately before the shutter is released. .. In this case, the correction stroke of the camera cannot be fully utilized, and accurate image blur correction cannot be performed.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and to provide an anti-shake camera which drives a correction means so that the correction stroke can always be effectively utilized.

[0005]

In order to solve the above-mentioned problems, an anti-shake camera according to the present invention has an image shake having a correction means for shifting a shake correction optical system by a predetermined correction stroke contrary to the shake caused by camera shake or the like. In the prevention camera, Vmax, which is the maximum value, and Vmin, which is the minimum value, of the image blurring speed in a predetermined period before the release signal is generated.
Image blur velocity detecting means (1) for detecting
And / or initial setting position determining means (CPU 5, S150, S155) for determining an initial setting position during the correction stroke of the correcting means at the start of exposure by the release signal generation based on Vmin. In the present invention, Vmin does not mean the minimum absolute value. Therefore, the case of negative sign is also included.

In this case, when the Vmax and the Vmin have different signs, the initial setting position determining means sets the ratio of the initial setting position of the correcting stroke range of the correcting means to | Vmax |: | Vmin | Can be internally divided into points (S150).
Note that when Vmax and Vmin have different signs, Vmax>
0, Vmin <0. Therefore, considering this, the internal division point is Vmax (or | Vmax
|):-Vmin (or | Vmin |). The internal division of the ratio of | Vmax |: | Vmin | in the present invention includes these cases.

Further, when the Vmax and the Vmin have the same sign, the initial setting position determining means sets the initial setting position near the limit position of the correction stroke range of the correcting means (S155). Can be

Further, when the exposure time is t and the correction stroke width of the correction means is B, B / t is C1, and when Vmax and Vmin have different signs, | V
When max-Vmin |> C1 (S141), a warning means (7) for issuing a warning can be provided.

Furthermore, when the exposure time is t and the correction stroke width of the correction means is B, B / t is C1, and when Vmax and Vmin have the same sign, | Vmax | or | Vmin It can be characterized by having a warning means (7) for issuing a warning when any one of the larger | is larger than C1 (S146).

[0010]

In the present invention, Vmax and Vmin are determined from the measurement result of the blur during the predetermined half-press period before the release signal is generated. Therefore, the reliability of the correction is higher than that of the conventional method of determining the image blur speed from the measurement result immediately before the shutter is opened.

The shake vibration when Vmax and Vmin have different signs is continuously generated across a stationary state (neutral state), and there is a possibility of shaking from the stationary state in either direction. This situation generally does not change until the end of the shoot, as the shooter is trying to maintain the neutral point. In a normal position, vertical blur often applies. The expected value of the blur amount during the exposure time is opposite to the direction of the blur, and the absolute amount ratio is | Vmax |: | Vmin |. Therefore, in order to make the most effective use of the blur correction stroke (to enable the longest exposure time), in the present invention, the position where the correction stroke range is internally divided into the ratio | Vmax |: | Vmin | The initial setting position of. In this way, the correction strokes in both directions can be maximized without waste.

When Vmax and Vmin have the same sign, the blurring directions are biased. Always 1 without holding the stationary state
Directional blur is applied. It is a normal posture, and it is a feature that has a lot of lateral blurring. For example, it corresponds to blurring that occurs when shooting from an automobile running at a constant speed. The expected values of the blur amount during exposure are in the same direction. Therefore, Vm
By providing the initial setting position of the correction means in the vicinity of the correction stroke limit in the ax and Vmin directions, the blurring can occur in only one direction, so that the entire correction stroke range can be utilized for correction.

[0013]

EXAMPLES The present invention will be described below based on examples.
FIG. 1 is a block diagram showing an embodiment of a blur prevention camera according to the present invention. The blur sensor 1 is for detecting blur, and can use the output difference of a known angular displacement sensor, a vibration type angular velocity sensor, an angular acceleration sensor, or two pairs of acceleration sensors. The blur correction optical system 2 is an optical system that corrects image blur by shifting the imaging lens. The correction driving unit 3 includes the shake correction optical system 2
Is a part for driving the shift.

The correction optical system position sensor 4 is a sensor for detecting and outputting the shift position of the shake correction optical system 2, and for example, a known linear encoder can be used. The camera CPU 5 calculates the image blur amount based on the blur output from the blur sensor 1, calculates the shift amount of the blur correction optical system 2 corresponding thereto, and monitors the output of the correction optical system position sensor 4. The correction drive unit 3 is controlled to shift the shake correction optical system 2 by an appropriate amount. In addition, the camera CPU 5 also performs general sequence control of the camera, AF, AE calculation, and the like. The warning sound generation unit 7 is a unit that generates a warning sound in response to a signal from the camera CPU 5. In addition, 6 is a film and 8 is a camera body.

FIG. 6 is a diagram showing an example of image blur (displacement) data due to a normal camera shake. In FIG. 6, X is an image blur (displacement) amount, and V is an image blur (displacement) speed. The horizontal axis is the time axis (t). When the camera is held by hand, it often vibrates continuously in the vertical direction with a neutral point sandwiched in the vertical direction, as shown in FIG. Further, the vertical movement speed may be deviated due to the habit of the photographer.

FIG. 7 is a diagram for explaining another example of image blur (displacement) data due to camera shake. Each symbol is the same as in FIG. The hand-held image blur in the horizontal direction may continuously vibrate with one-way fine vibration as shown in FIG. For example, such vibration often occurs when photographing from an automobile running at a constant speed. The moving direction and speed vary depending on the habit of the photographer.

2 and 3 are flowcharts showing the algorithm of the operation sequence of the camera according to the present embodiment described in FIG. Unless otherwise specified, the process is performed by the camera CPU 5. In this algorithm, the warning sound generator 7 does not operate. Step (hereinafter abbreviated as S) 10
At 0, the camera power is turned on by half-pressing the release switch (not shown), and the routine starts.

In step S105, the shake signal output by the shake of the shake sensor 1 is input. Here, the blur signal output varies depending on the type of the blur sensor 1. For example, in the case of an angular velocity sensor, a signal (often a voltage) proportional to the angular velocity is output. A signal proportional to the amount of change in angle is output if the sensor is an angular displacement sensor, and a signal proportional to angular acceleration is output if the sensor is an angular acceleration sensor.

In step S110, the output of the blur sensor 1 is processed into the image blur velocity of the camera, and the image blur velocity signal is obtained. If the blur sensor 1 is an angular velocity sensor, the image blur velocity can be calculated by the following formula. V = K × ω (1) where V is the image blur velocity (μm / s) and ω is the angular velocity (r
ad / s) and K are conversion coefficients (μm / rad). Although only the image blur caused by the change of the angle of the optical axis can be expressed by this formula, the image blur amount caused by the parallel movement of the photographing optical axis which is another image blur element is described in JP-A-3-48229. As described above, during normal shooting (except for shooting with a super-telephoto lens and close-up at a close range), the size is negligibly small compared to the former, so it need not be considered. In the case of a sensor other than the angular velocity sensor, that is, if it is an angular acceleration sensor, integration is performed, and if it is an angular displacement sensor, differentiation is performed on the output signal, and after conversion into an angular velocity amount, the above (1 The image blur velocity signal may be obtained by the equation).

In S120, the image blur velocity signal V for a predetermined time is stored. When the storage capacity is a predetermined amount or when the storage capacity is full, the old order is updated to the new one. Here, the predetermined amount is the exposure time equivalent amount already calculated by the camera CPU 5 from the shutter speed selection means (not shown) or the output of the photometric means (not shown), or 1
The longer one of the amounts corresponding to / 2 seconds may be set. Of course, the limit value is the storage capacity limit. The reason for this is that, in general, the frequency for taking measures against camera shake when holding the camera by hand is about 2 Hz or higher (see Japanese Patent Laid-Open No. 63-53531). It is desirable to spend such a time for detecting the characteristics of camera shake. However, when the exposure time is longer, it is desirable to set the time equivalent to the exposure time as the time for predicting blurring that may occur within the exposure time.

In S125, it is determined whether or not a release signal is generated by fully pressing a release switch (not shown).
If no release signal is generated, the process returns to S105 and repeats a series of routines. If a release signal is generated, S1
Proceed to 30.

In S130, the camera CPU 5 always selects the maximum value (= Vmax) and the minimum value (= Vmin) of the blurring speed from the stored image blurring speed signal. Here, the minimum value does not mean the minimum absolute value, but also includes the case where the maximum value has an opposite sign (minus sign).

Next, in S140 of FIG. 3, the above Vm
The signs of ax and Vmin are determined. If different sign, S1
If 50 and the same sign, the process proceeds to S155. FIG. 6 described above.
When the blur shown in FIG. 7 occurs, the signs of Vmax and Vmin are different signs, and when the blur shown in FIG. 7 occurs,
The signs of Vmax and Vmin are the same.

In S150, the image blur correction stroke range due to the shift of the blur correction optical system 2 is internally divided into the ratio of | Vmax |: | Vmin | along the Vmax direction. This internally dividing point becomes the initial setting position for image blur correction drive, and the blur correction optical system 2 is quickly shifted to this position.

When the process proceeds to S155, the start position of the image blur correction drive in which the blur correction optical system 2 is set near the correction stroke limit position in the Vmax and Vmin directions is set as the initial setting position.

Next, in S160, while the output of the correction optical system position sensor 4 is being monitored, a control signal is output to the correction drive unit 3 so that the shake correction optical system 2 is determined in S150 or S155 which will be described later. After moving to the shift position (= initial setting position of image blur correction drive), the process proceeds to S165, and waits for the generation of the correction drive start signal before a predetermined time before the exposure is started by releasing the shutter.

In this embodiment, the blur correction optical system 2
The image blur correction is performed by canceling out the image blur (displacement) caused by the camera shake caused by the image shift caused by the shift of. Image blur correction is achieved by driving the blur correction optical system 2 so that the image moving speed due to the shift of the blur correction optical system 2 becomes −V. Here, the predetermined time for the exposure start and the generation of the correction drive start signal is a speed (the speed at which the image shake correction drive speed of the shake correction optical system 2 is sufficient to cancel the image shake speed (V) by driving the correction drive unit 3 ( It is the time estimated for the transient time to reach −V). Note that this amount of time can be preset when the camera is manufactured.

In S165, the correction drive start signal related to the operation of the shutter member (not shown) is the camera CPU 5
If it is input to, the process proceeds to S170 and the blur sensor 1
Sensor output from the sensor is processed in real time, a control signal is output to the correction driving unit 3 while monitoring the output of the correction optical system position sensor 4, and the shift correction optical system 2 starts shift driving so as not to cause image blur. ..

As described above, the shake correction optical system 2 is provided during the predetermined time between the generation of the correction drive start signal and the start of exposure.
The image blur correction driving speed reaches the image blur canceling speed, and good image blur correction becomes possible.

If an exposure end signal is input from the shutter member to the camera CPU 5 in S175, S180
Proceed to. If there is no input, the process returns to S170 to continue the image blur correction driving.

In S180, the correction optical system position sensor 4
While monitoring the output of, the control signal is output to the correction drive unit 3, the blur correction optical system 2 is moved to the standby position (correction stroke center position; neutral position) when not operating, and the operation relating to blur correction is performed in S190. finish.

In S180, the shake correction optical system 2 is in a standby position when it is inoperative (correction stroke center position; neutral position).
The reason for moving to is for the following reasons. That is, it is uncertain which position the initial setting position of the image blur correction drive of the next shooting operation will be, but it is because the movement efficiency is good if it is waited at the correction stroke center position (neutral position). In addition, if the blur correction optical system 2 cannot be driven after some reason, the optical axis does not tilt and the correction stroke center position (neutral position) is the best in lens performance.
This is because it is better to have a correction optical system in.

In the algorithms shown in FIGS. 2 and 3, the characteristics of camera shake are detected in a predetermined time immediately before the release,
It is possible to set the initial position of the correction optical system to a position where the stroke of the blur correction considering the maximum value and the minimum value of the blur speed is used most effectively.

FIG. 8 shows an example of initial setting positions when Vmax and Vmin have different signs, and LU and L in the figure are shown.
L is the upper limit position and the lower limit position of the correction stroke, respectively. Vmax and Vmin are the maximum values of the image blurring speed,
And the minimum value. S is an initial setting position of the correction optical system. As described above, in the case of FIG. 8, the expected value of the blur amount during the exposure time is opposite in direction to the blur, and the absolute amount ratio is | Vmax |: | Vmin |. For the position of S in the figure, the corrected stroke range (between LU and LL) is | Vmax.
It is a position that is internally divided into the ratio of |: | Vmin |, and is a position where the correction strokes in both directions can be secured to the maximum without waste. In other words, if the correction optical system is driven at -Vmax or -Vmin that can correct the image blurring speed Vmax or Vmin from the position S, LU to LL
The initial setting position that can be accommodated for the longest time is the corrected stroke range (between LU and LL) | Vmax |: | V
It is the position of S that is internally divided to the ratio of min |.

FIG. 9 shows an example of the initial setting position when Vmax and Vmin have different signs, and the initial setting position S is
It is on the LU which is the corrected stroke limit position in the Vmax and Vmin directions.

4 and 5 are flow charts showing an algorithm showing another operation sequence of the camera of the present invention shown in FIG. The same parts as those in FIGS. 2 and 3 are designated by the same reference numerals, and the description will be simplified or omitted. This flow chart is an example of issuing a warning sound of excessive blurring amount.

The procedure from S100 to S120 is the same as in FIG. Next, S125 is removed and S130
~ Go to S140. In S140, the signs of Vmax and Vmin are determined. If the sign is different, the process proceeds to S141. If the codes are the same, the process proceeds to S146.

At S141, | Vmax-Vmin
The value of | is compared with a predetermined numerical value C1. Where C1
Is the corrected stroke width (=
It is a maximum image blur compensable speed when the correction stroke width is effectively used up, which is obtained by the equation (2) by a value obtained by dividing B) by the set exposure time (= t). C1 (μm / s) = B (μm) / t (sec) (2)

At S141, | Vmax-Vmin
If |> C1, the expected image blur amount exceeds the range of the correction stroke, so the process proceeds to S142, where a warning signal is issued to the warning sound generating unit 7, and a warning sound is issued from the warning sound generating unit 7. Warn the photographer. Then, the process proceeds to S150.

At S141, | Vmax-Vmin
If not |> C1, the process proceeds to S150. When the process proceeds to S146 by the determination in S140, in S146,
The larger of | Vmax | and | Vmin | (= M
ax (denoted as | Vmax |, | Vmin |) and C1 are compared. Max (| Vmax |, | Vmin |)> C1
If so, since the expected image blur amount exceeds the range of the correction stroke, the process proceeds to S147, where a warning signal is issued to the warning sound generating unit 7 and a warning sound is issued from the warning sound generating unit 7 to warn the photographer. give. Then, the process proceeds to S155.

At S146, Max (│Vmax
If |, | Vmin |)> C1, the process proceeds to S155. S150 and S155 are S150 and S of FIG.
The same process as 155 is performed.

After S150 and S155, the process proceeds to S125. The processing content is the same as S125 in FIG. S125
At, it is determined whether or not a release signal is generated by fully pressing a release switch (not shown). If no release signal is generated, the process returns to S105 and repeats a series of routines. When the release signal is generated, the process proceeds to S160 in FIG. In S160 and the subsequent steps, the same processing as in S160 and the subsequent steps in FIG. 3 is performed. In this embodiment, S is input before the release signal is input.
Since the image blurring speed is evaluated in 141 or S146, and the warning is issued in S142 or S147 according to the result, the photographer can be informed in advance of the uncorrectable case.

Although two examples have been described above, the present invention is not limited to the above embodiments. For example, FIG. 1 shows the case where the angular velocity detection and image blur correction directions are in the vertical direction of the camera optical axis, but it is clear that the same configuration may be set in the horizontal direction. Further, a combination of both vertical and horizontal directions may be used.

As soon as the image stabilization optical system 2 arrives at the initial setting position of the image blur correction drive, instead of waiting for the generation of the correction drive start signal a predetermined time before the exposure start by the shutter release in S165 of FIGS. 3 and 5. Immediately, the correction drive unit 3 may be driven to start the image shake correction drive of the shake correction optical system 2. In this case, after a time (this amount of time is also set in advance at the time of manufacturing the camera) for estimating a transition time for the image blur correction driving speed of the blur correction optical system 2 to catch up with the image blur speed, a shutter unit (not shown) is placed. An exposure start signal may be output from the camera CPU 5.

The signal from the blur sensor 1 and the compensation optical system position sensor 4 is monitored for a transitional state in which the image blur compensation driving speed of the blur compensation optical system 2 catches up with the image blur velocity, and the image blur of the blur compensation optical system 2 is monitored. When the correction drive speed catches up with the image blur speed and it is sensed that the transient state has ended, an exposure start signal is sent to the camera C by a shutter unit (not shown).
You may output from PU5.

In the flow chart of FIG. 4, while the warning signal is being generated in S142 or S147, the camera CPU
It is also possible to refrain from outputting the exposure start signal from 5 to the shutter unit (not shown).

When Vmax or Vmin that is suddenly large in absolute value is input, while Vmax or Vmin remains in the storage capacity of the image blur speed described above, an excessive Vmax or Vmin. There is also a case where the correction drive is strongly affected by the value of, and the initial position of the correction drive is deviated for a long period of time or a warning signal is continuously generated. Therefore, when the absolute value of Vmax or Vmin exceeds a predetermined value, the stored value is replaced by the numerical value of C1 described in FIG. 4 (if Vmax is replaced, C1, Vm
If in is replaced, -C1) may be stored. Specifically, in both the flowcharts of FIGS. 2 and 4, S110 and S120.
This step may be performed by providing a step between the steps.

Even if the image blur velocity in the storage capacity of the image blur velocity described above is divided into several groups in time series and the initial setting position is corrected in consideration of the variation of the average value of each group. Good. Specifically, the stored image blur velocity data is divided into two groups, the first half and the second half, and a value obtained by subtracting 1/2 of the difference between the average values (first half average value-second half average value) from the second half average value is shown in FIG. , Vma selected in S130 in FIG.
The following steps can be performed in addition to the values of x and Vmin. Further, extrapolation may be performed by performing high-level interpolation (secondary interpolation or the like).

[0049]

As described above, according to the present invention, the characteristic of the camera shake of the photographer is detected in a predetermined time immediately before the release, and the blur correction stroke considering the maximum and minimum values of the blur speed is most effective. It is possible to set the position of the correction optical system to the position used for. Therefore, it is possible to perform image blur correction even when the exposure time is longer than that in the conventional example, without using up the correction stroke.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of an anti-shake camera according to the present invention.

FIG. 2 is a flowchart showing an operation sequence of the anti-shake camera according to the embodiment.

FIG. 3 is a flowchart showing an operation sequence of the blur prevention camera according to the embodiment.

FIG. 4 is a flowchart showing another operation sequence of the blur prevention camera according to the embodiment.

FIG. 5 is a flowchart showing another operation sequence of the blur prevention camera according to the embodiment.

FIG. 6 is a diagram illustrating image blur (displacement) data.

FIG. 7 is a diagram illustrating image blur (displacement) data.

FIG. 8 is a diagram showing an example of an initial setting position of the blur prevention camera according to the embodiment.

FIG. 9 is a diagram showing another example of the initial setting position of the blur prevention camera according to the embodiment.

[Explanation of symbols]

 1 shake sensor 2 shake correction optical system 3 correction drive unit 4 correction optical system position sensor 5 camera CPU 7 warning sound generator

Claims (5)

[Claims] 1. An image blur prevention camera having a correction means for shifting a blur correction optical system by a predetermined correction stroke, which is opposite to a blur caused by camera shake, and is a maximum value of an image blur speed in a predetermined period before a release signal is generated. Image blur velocity detecting means for detecting Vmax and Vmin which is a minimum value, and based on the Vmax and / or the Vmin,
An image blur prevention camera, comprising: an initial setting position determining unit that determines an initial setting position in a correction stroke of the correction unit at the start of exposure by generating a release signal. 2. The initial setting position determining means is the Vm
When ax and Vmin have different signs, the correction stroke range of the correction means is set to | Vmax for the initial setting position.
The image blur prevention camera according to claim 1, wherein the point is internally divided into a ratio of |: | Vmin |. 3. The initialization position determining means is configured to control the Vm.
The image blur prevention camera according to claim 1, wherein when the ax and the Vmin have the same sign, the initial setting position is set near a limit position of a correction stroke range of the correction means. 4. When the exposure time is t and the correction stroke width of the correction means is B, B / t is C1, and the V
when max and the Vmin have different signs, and | Vma
4. The image blur prevention camera according to claim 1, further comprising warning means for issuing a warning when x-Vmin |> C1. 5. When the exposure time is t and the correction stroke width of the correction means is B, B / t is C1, and the V
When max and the Vmin have the same sign, and | Vma
4. The image blur prevention camera according to claim 1, further comprising a warning unit that issues a warning when either x | or | Vmin |, whichever is larger, is larger than C1.