JP3614617B2 - Image motion correction device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image motion correction apparatus used for camera shake correction or the like of an imaging apparatus, and more particularly to a technique for improving its performance.
[0002]
[Prior art]
In recent years, consumer video cameras (hereinafter referred to as “video movies”) have become smaller, lighter, and optical zooms have become higher in magnification. -Is one of the ordinary home appliances.
[0003]
However, on the other hand, downsizing, weight reduction, high zooming of optical zoom, and the spread of video movies to consumers who are not proficient in shooting are the instability of the screen due to camera shake during shooting. There is also a problem. In order to solve this problem, video movies equipped with an image motion correction device have been developed and commercialized.
[0004]
For example, the following technologies (1) to (3) have been proposed as conventional image motion correction devices.
[0005]
(1) An image pickup unit including an image pickup optical system and a solid-state image pickup device is supported by a gimbal mechanism, and this is driven and controlled based on movement information of the image pickup apparatus itself obtained from an angular velocity sensor, thereby correcting the image movement. (For example, refer to “Development of image blur prevention technology for video camera” Television Society Technical Report Vol. 11, No. 28, pp 19-24 (1987)).
[0006]
Specifically, it is rotatably supported by a gimbal mechanism at the center of gravity of the imaging unit described above, and is composed of a coil and a magnet based on movement information in the two directions of pitching and yawing obtained from the angular velocity sensor. The captured image is stabilized by controlling the posture of the image pickup unit by the actuator.
[0007]
(2) There is a method of correcting the movement of an image by providing a variable apex prism in the front part of the imaging optical system and controlling the drive according to the information from the angular velocity sensor (for example, “optical image stabilization system”). Television Society Technical Report Vol. 17, No. 5, pp 15-20 (1993)).
[0008]
Specifically, two glass plates are connected with something like a bellows made of a special film, and a variable apex prism filled with a liquid with a high refractive index is provided in the front stage of the solid-state imaging device, By tilting the two glass plates of the variable apex prism in the horizontal and vertical directions based on the information on the movement of the imaging device in the pitching and yawing directions obtained from the angular velocity sensor, the optical axis of the incident light is adjusted. Bending and stabilizing the movement of the photographed image.
[0009]
(3) A method for correcting a motion of an image by moving a frame by changing a driving timing of the solid-state image sensor by providing a frame for reading only a part of the image on the solid-state image sensor as an output image. There is.
[0010]
Specifically, using a solid-state image sensor having a larger number of pixels than a standard solid-state image sensor conforming to the broadcasting system, information on the movement of the imaging device in the pitching and yawing two directions obtained from the angular velocity sensor is obtained. The amount of movement of the image on the solid-state image sensor is converted based on the focal length, the drive timing of the solid-state image sensor is controlled based on the conversion result, and the position of reading the image from the solid-state image sensor (frame) according to the movement of the captured image ) To stabilize the movement of the captured image.
[0011]
[Problems to be solved by the invention]
However, the conventional image motion correction apparatuses (1) to (3) have the following problems.
[0012]
In other words, when an external sensor such as an angular velocity sensor is used for motion detection, it takes a certain amount of time for the output of the angular velocity sensor to stabilize, particularly when power is turned on or when the power is reset (specifically, drift Therefore, it is difficult to accurately detect movement immediately after energization is started or immediately after power is reset. For this reason, an appropriate motion correction operation cannot be performed, and on the contrary, there is a possibility that a malfunction may be caused from inaccurate motion information and the captured image may be difficult to see.
[0013]
In addition, the longer the focal length of the imaging optical system, the greater the effect of the motion correction malfunction is reflected on the shooting screen. Therefore, the more unstable the imaging device having the imaging optical system with the longer focal length, the more unstable the output of the angular velocity sensor. It can be said that there is a big problem.
[0014]
[Means for Solving the Problems]
An image motion correction device according to the present invention includes a motion detection unit that detects a motion of the imaging device itself, a motion correction unit that corrects a motion of a captured image caused by the motion of the imaging device itself, and the motion detection unit. Control signal generating means for generating a control signal for controlling the motion correcting means based on the output.
[0015]
As a result, the motion correction performance is limited by changing the response characteristics of the control signal generation means within a predetermined period immediately after the start of energization of the imaging device or immediately after power reset and within other operation periods, The photographed image will not be unsightly.
[0016]
The image motion correction apparatus according to the present invention includes a motion detection unit that detects a motion of the imaging apparatus itself, an imaging optical system that includes a plurality of lens groups and has a variable focal length, and a focal length of the imaging optical system. Generating a focal length detecting means, a motion correcting means for correcting the motion of the captured image caused by the motion of the imaging device itself, and a signal for controlling the motion correcting means based on the output of the motion detecting means Control signal generating means.
[0017]
Thereby, the response characteristic of the control signal generating means is detected by the focal length detecting means within a predetermined period immediately after the start of energization of the imaging apparatus or immediately after resetting the power supply and within another operation period. By changing according to the focal length, particularly when the focal length of the imaging optical system is long, the motion correction performance is further limited, and the captured image is not made difficult to see due to the malfunction.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Claim1The described inventionAngular velocity detection means for detecting the angular velocity of the movement of the imaging device itself, motion correction means for correcting the movement of the captured image caused by the movement of the imaging device itself, and the motion correction means based on the output of the angular velocity detection means Control signal generating means for generating a control signal for controllingThe control signal generating means is generated insideSaidFor controlling the motion compensation meansAboveClip means to limit the signal width of the control signalComprisingBy limiting the signal width within a predetermined period immediately after the start of energization to the angular velocity detecting means or within a predetermined period immediately after power reset, the control signal generating means is limited to be smaller than the signal width within other periods. The response characteristic is changed.
[0027]
As a result, the motion correction performance by the motion correction means is limited within a predetermined period immediately after the start of energization of the angular velocity detection means or within a predetermined period immediately after power reset, and accurate motion detection is difficult. It has the effect of reducing the malfunctions that occur.
[0028]
Claim2The described invention includes an angular velocity detection unit that detects an angular velocity of a movement of the imaging apparatus itself, an imaging optical system that includes a plurality of lens groups and has a variable focal length, and a focal length detection that detects a focal length of the imaging optical system. A control signal generator for generating a signal for controlling the motion correction means based on an output of the angular velocity detection means; A response characteristic of the control signal generating means in a predetermined period immediately after the start of energization of the angular velocity detecting means or in a predetermined period immediately after power reset and in other periods, This is changed according to the focal length of the imaging optical system detected by the detecting means.
[0029]
This has the effect of reducing malfunctions that occur because it is difficult to accurately detect motion within a predetermined period immediately after the start of energization of the angular velocity detection means or within a predetermined period immediately after power reset.
[0030]
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0031]
(Embodiment 1)
FIG. 1 is a block diagram of an image motion correction apparatus according to Embodiment 1 of the present invention.
[0032]
In the figure, an optical shake correction system 1 is a means for optically correcting the movement of an image caused by shaking of an image pickup apparatus, and here, as an example, a variable apex angle prism (hereinafter abbreviated as VAP). ) 1 applies.
[0033]
The optical shake correction system drive control means 2 is a means for driving and controlling the VAP 1 based on a detection output of an angular velocity sensor 10 described later, specifically, orthogonal to the optical axis of the imaging optical system 4 described later. The parallel plane plate of VAP1 is rotationally driven about two axes orthogonal to each other in the plane.
[0034]
The angle detection means 3 detects the actual rotation angle of the plane parallel plate of the VAP 1 and outputs a detection signal. The angle detection means 3 and the optical shake correction system drive control means 2 together with the optical shake correction system drive control means 2 control the feedback control. -Forming a loop.
[0035]
The imaging optical system 4 includes a lens system that can perform an optical zoom operation and a focusing operation, and the imaging optical system drive control means 5 drives and controls the imaging optical system 4 to perform an optical zoom operation. Or a focusing operation.
[0036]
The solid-state imaging device 6 converts an image incident via the VAP 1 and the imaging optical system 4 into an electrical signal, and is driven and controlled by the solid-state imaging device drive control means 16.
[0037]
The analog signal processing means 7 performs analog signal processing such as gamma processing on the image signal obtained by the solid-state imaging device 6. The A / D conversion means 8 converts an analog signal into a digital signal. The image signal converted into the digital signal by the A / D conversion means 8 is a digital signal for noise removal, contour enhancement, etc. The processing is performed by the digital signal processing means 9 at the next stage.
[0038]
The angular velocity sensor 10 detects the angular velocity of the movement of the imaging apparatus itself, and outputs signals in both positive and negative directions depending on the direction of movement of the imaging apparatus with reference to the output when the imaging apparatus is stationary. . Two angular velocity sensors 10 are originally required to detect movement in two directions of yawing and pitching, but FIG. 1 shows only one direction.
[0039]
The filter 11 is for removing an unnecessary band component included in the output of the angular velocity sensor 10, for example, a resonance frequency component of the sensor. The amplifier 12 adjusts the signal level of the output of the angular velocity sensor 10, and the A / D conversion means 13 converts the output of the angular velocity sensor 10 into a digital signal.
[0040]
A microcomputer (hereinafter abbreviated as “microcomputer”) 14 performs filtering, integration processing, gain adjustment on the output of the angular velocity sensor 10 taken in via the A / D conversion means 13, that is, the angular velocity of the movement of the imaging device. Clip processing or the like is performed to obtain a drive control amount (hereinafter referred to as a control signal) of the VAP 1 necessary for motion correction, and this is supplied to the optical shake correction system drive control means 2 via the D / A conversion means 15. To send. Then, the optical shake correction system drive control means 2 drives the VAP 1 based on the control signal from the microcomputer 14 to correct the motion of the image.
[0041]
Next, the operation of the image motion correction apparatus according to the first embodiment configured as described above will be described in accordance with a processing program stored in the microcomputer 14. Although a series of operations such as angular velocity detection by the angular velocity sensor 10 and drive control of the VAP 1 are actually performed in both the horizontal and vertical directions, the control contents are the same in both the horizontal and vertical directions. In order to simplify the description, the horizontal and vertical directions are not distinguished, and only one direction is described.
[0042]
FIG. 2 is an example of a flowchart of a processing program stored in the microcomputer 14.
[0043]
When power is turned on to the imaging apparatus main body, first, a counter for measuring the time after the power is turned on to the angular velocity sensor 10 is reset (step 101).
[0044]
Next, the state of a motion correction switch (not shown) for instructing whether or not to perform motion correction (hereinafter referred to as SW) is determined (step 102), and the SW is turned on to instruct the photographer to execute motion correction. When the angular velocity sensor 10 is powered on, the process proceeds to the next step 104. If the SW is OFF, the process waits in this state.
[0045]
In step 104, the counter is incremented and held every processing cycle in order to measure the time after the angular velocity sensor 10 is turned on.
[0046]
Next, according to the count value of the counter, a cut-off frequency for performing band limitation using a high-pass filter (hereinafter referred to as HPF) is applied to the signal from the angular velocity sensor 10 taken into the microcomputer 14. Determine (step 105).
[0047]
As a method for determining the cut-off frequency, for example, a function for calculating the cut-off frequency from the count value or a table for defining the relationship between the count value and the cut-off frequency is provided in the microcomputer 14. Alternatively, a cutoff frequency corresponding to the count value is determined using a table. The reason for changing the cut-off frequency according to the count value is as follows.TheWill be described in detail later.
[0048]
Subsequently, band limitation is performed on the signal from the angular velocity sensor 10 taken into the microcomputer 14 by HPF (step 106). That is, the HPF has a transfer function of (1-Z^-1) / (1-a · Z^-1The filter passband (cutoff frequency) is changed by changing the coefficient a.
[0049]
Subsequently, the signal from the angular velocity sensor 10 that has passed through the HPF is integrated to obtain an angle from the angular velocity (step 107). Then, after adjusting the gain of the signal of this angle (step 108), the correction amount that the control signal sent from the microcomputer 14 to the optical shake correction system drive control means 2 exceeds the correction range of the optical shake correction system 1 Is clipped (step 109) and output to the D / A conversion means 15.
[0050]
FIG. 3 is an example of a cut-off frequency determination method in step 105 of FIG.
[0051]
In the example shown in the figure, the time t determined in advance based on the characteristics of the angular velocity sensor 10 from when the angular velocity sensor 10 is turned on (t = 0).₁Until, the cutoff frequency of the HPF is set to fcon and the time t₁Thereafter, fc (<fcon) is set. In other words, a certain period of time immediately after the power is turned on (here, 0 to t₁The cut-off frequency of the HPF is temporarily set high as fcon (> fc) only during the period of (1). As a result, even if a low-frequency fluctuation such as a drift that occurs in the output of the angular velocity sensor 10 occurs immediately after the power is turned on, the influence can be removed, and it is difficult to accurately detect the movement immediately after the power is turned on. Therefore, malfunctions that occur can be reduced.
[0052]
Note that if the cutoff frequency fcon of the HPF is set high in step 106, the motion correction performance when the imaging apparatus moves at a low frequency will deteriorate.₁It is desirable to set as short as possible. In this way, since the user is not aware of the deterioration of the correction performance due to the temporarily set high cutoff frequency of the HPF, there is no particular problem in actual use.
[0053]
FIG. 4 is another example of the method for determining the cut-off frequency in step 105 of FIG.
[0054]
In the method for determining the cut-off frequency shown in FIG. 3, since the cut-off frequency can be switched only in two stages, fcon and fc, there is a possibility that the motion correction performance will change drastically at the time of switching, resulting in a sense of incongruity.
[0055]
Therefore, in FIG. 4, the period from fcon to fc is continuously changed. In this way, since the cut-off frequency is gradually switched, the sense of incongruity at the time of switching is greatly relieved.
[0056]
In FIG. 4, the cut-off frequency is linearly changed. However, the present invention is not limited to this. For example, as shown in FIG. 5, it may be changed non-linearly. 4 and 5, the time t₂After that, the cutoff frequency starts to decrease, but t₂= 0, that is, the cut-off frequency may be gradually decreased immediately after the angular velocity sensor 10 is turned on.
[0057]
In addition to the example in which the cutoff frequency continuously changes as shown in FIGS. 4 and 5, it is needless to say that the cutoff frequency may be changed in multiple stages.
[0058]
As described above, in the first embodiment, the microcomputer 14 has a high-pass filter that removes a low-frequency component included in the output of the angular velocity sensor 10, and within a predetermined period immediately after the energization of the angular velocity sensor 10 is started. Alternatively, the motion correction performance of the optical shake correction system 1 is limited by setting the cutoff frequency of the high-pass filter temporarily higher than in other periods within a predetermined period immediately after the power reset. For this reason, it is possible to reduce malfunctions that have conventionally occurred because it is difficult to detect accurate movement immediately after the start of energization or immediately after power reset.
[0059]
(Embodiment 2)
The basic configuration of the image motion correction apparatus according to the second embodiment of the present invention is the same as that of the first embodiment, and only the contents of the processing program in the microcomputer 14 are different.
[0060]
Therefore, the description of the configuration of the image motion correction apparatus according to the second embodiment is omitted, and the operation of the apparatus will be described below according to the processing program stored in the microcomputer 14. In the second embodiment as well, a series of operations such as angular velocity detection by the angular velocity sensor 10 and drive control of the VAP 1 is not distinguished between horizontal and vertical directions, and only one direction will be described.
[0061]
FIG. 6 is an example of a flowchart of the processing program stored in the microcomputer 14.
[0062]
When power is turned on to the imaging apparatus main body, first, a counter for measuring the time after power is turned on to the angular velocity sensor is reset (step 201).
[0063]
Next, the state of a motion correction switch (not shown) for instructing whether or not to execute motion correction (hereinafter referred to as SW) is determined (step 202), and the SW is turned on to instruct the photographer to execute motion correction. When the angular velocity sensor 10 is turned on, the process proceeds to the next step 204. If the SW is OFF, the process waits in this state.
[0064]
In step 204, the signal from the angular velocity sensor 10 taken into the microcomputer 14 is band-limited using a high-pass filter (HPF). That is, the HPF has a transfer function of (1-Z^-1) / (1-b · Z^-1) And the influence of low frequency fluctuations such as temperature drift included in the output of the angular velocity sensor 10 is removed.
[0065]
In the next step 205, in order to measure the time after the angular velocity sensor 10 is turned on, the counter is incremented and held every processing cycle.
[0066]
Next, the microcomputer 14 determines a coefficient K (where 0 <K <1) that defines the frequency characteristics of the integration process (integration filter) for obtaining the angle from the signal (angular velocity information) from the acquired angular velocity sensor 10. (Step 206).
[0067]
As a method of determining the coefficient K, for example, a function for calculating the coefficient K from the count value or a table for defining the relationship between the count value and the coefficient K is provided in advance in the microcomputer 14, and this function or Determine the coefficient K corresponding to the count value using the bull. The reason why the coefficient K is changed in accordance with the count value will be described in detail later.
[0068]
Subsequently, an integration process is performed on the signal from the angular velocity sensor 10 taken into the microcomputer 14 to obtain an angle from the angular velocity (step 207). That is, the integration filter in this case has, for example, a transfer function of 1 / (1-K · Z^-1) Filter characteristics.
[0069]
The coefficient K is determined in the previous step 206. The smaller the coefficient K, the smaller the gain for the low frequency component of the integration process (integration filter). For example, when K = 0.9, the filter gain for the DC component is 1 / 0.1 = 10, but when K = 0.8, the filter gain for the DC component is 1/0. It is clear from 2 = 5.
[0070]
Thus, after adjusting the gain of the angle signal obtained from the integration result in step 207 (step 208), the control signal sent from the microcomputer 14 to the optical shake correction system drive control means 2 is transmitted to the optical shake correction system. Clip processing is performed so that a correction amount exceeding the correction range of 1 is not instructed (step 209), and the result is output to the D / A conversion means 15.
[0071]
FIG. 7 is an example of a method for determining the coefficient K in step 206 of FIG.
[0072]
In the example shown in the figure, the time t determined in advance based on the characteristics of the angular velocity sensor 10 from when the angular velocity sensor 10 is turned on (t = 0).₁Until the integration coefficient K is set to Kon and time t₁Thereafter, Ks (> Kon) is set. That is, a certain time immediately after the power is turned on (here, 0 to t₁The coefficient K is temporarily set small as Kon (<Ks) only during the period of (1).
[0073]
As described above, the smaller the coefficient K, the smaller the gain for the low frequency component of the integration process (integration filter). Therefore, even if a low frequency fluctuation such as a drift occurring in the angular velocity sensor output occurs immediately after the power is turned on, It can be made less susceptible to this, and it is possible to reduce malfunctions that occur because it is difficult to detect accurate movements immediately after power-on.
[0074]
Note that when the coefficient K is set to be small in step 206, the motion correction performance when the image pickup apparatus moves at a low frequency is deteriorated.₁It is desirable to set as short as possible. In this way, since the user is not aware of the deterioration of the correction performance due to the low-frequency gain of the integration process (integration filter) being set low, there is no particular problem in actual use.
[0075]
In the method for determining the coefficient K shown in FIG. 7, since the coefficient K can be switched only in two stages, Kon and Ks, the motion correction performance may change suddenly at the time of switching, which may cause a sense of discomfort. In order to solve this problem, as in the first embodiment, a method of changing the coefficient K continuously or a method of changing in multiple steps can be employed.
[0076]
As described above, in the second embodiment, the microcomputer 14 has an integration unit that integrates the output of the angular velocity sensor 10 and converts the angular velocity into an angle, and within a predetermined period immediately after the start of energization of the angular velocity sensor 10, Alternatively, the motion correction performance of the optical shake correction system 1 is limited by temporarily setting the low-frequency gain of the integrating means within a predetermined period immediately after the power reset to a lower value than during other periods. For this reason, it is possible to reduce malfunctions that have conventionally occurred because it is difficult to detect accurate movement immediately after the start of energization or immediately after power reset.
[0077]
(Embodiment 3)
The basic configuration of the image motion correction apparatus according to the third embodiment of the present invention is the same as that of the first embodiment, and only the contents of the processing program in the microcomputer 14 are different.
[0078]
Therefore, the description of the configuration of the image motion correction apparatus according to the third embodiment is omitted, and the operation of the apparatus will be described below according to the processing program stored in the microcomputer 14. In the third embodiment as well, a series of operations such as angular velocity detection by the angular velocity sensor 10 and drive control of the VAP 1 are not distinguished between horizontal and vertical directions, and only one direction will be described.
[0079]
FIG. 8 is an example of a flowchart of a processing program stored in the microcomputer 14.
[0080]
When power is turned on to the imaging apparatus main body, first, a counter for measuring the time after the power is turned on to the angular velocity sensor 10 is reset (step 301).
[0081]
Next, the state of a motion correction switch (not shown) that indicates whether or not motion correction is to be executed (hereinafter referred to as SW) is determined (step 302), and the SW is turned on to instruct the photographer to execute motion correction. When the angular velocity sensor 10 is powered on, the process proceeds to the next step 304. If the SW is OFF, the process waits in this state.
[0082]
In step 304, the signal from the angular velocity sensor 10 taken into the microcomputer 14 is band-limited using a high-pass filter (HPF). That is, the HPF has a transfer function of (1-Z^-1) / (1-b · Z^-1) And the influence of low frequency fluctuations such as temperature drift included in the output of the angular velocity sensor 10 is removed.
[0083]
In the next step 305, the angular velocity of the movement of the imaging device detected by the angular velocity sensor 10 is converted into an angle by integration processing.
[0084]
In step 306, the counter is incremented and held every processing cycle in order to measure the time after the angular velocity sensor is turned on.
[0085]
Next, the microcomputer 14 determines a gain G for performing gain adjustment with respect to the angle information of the movement of the imaging apparatus obtained in step 305 (step 307). As a method of determining the gain G, a function for calculating the gain G from the count value or a table for defining the relationship between the counter value and the gain G is provided in advance in the microcomputer 14, and this function or table Is used to determine the gain G corresponding to the count value. The reason why the gain G is changed according to the count value will be described in detail later.
[0086]
Subsequently, the gain G determined in step 307 is multiplied by the output (angle information) of step 305 (step 308).
[0087]
Thus, clip processing is performed so that the control signal sent from the microcomputer 14 to the optical shake correction system drive control means 2 does not indicate a correction amount exceeding the correction range of the optical shake correction system 1 (step 309). It is output to the D / A conversion means 15.
[0088]
FIG. 9 is an example of a method for determining the gain G in step 307 shown in FIG.
[0089]
In the example shown in the figure, the time t determined in advance based on the characteristics of the angular velocity sensor 10 from when the angular velocity sensor 10 is turned on (t = 0).₁Until the gain G is set to Gon and the time t₁Thereafter, it is set to Gs (> Gon). That is, a certain time immediately after power-on (here, 0 to t₁The gain G is temporarily set to a small value such as Gon (<Gs) only during this period. Thus, when the gain G is set to a small value, the control signal itself sent from the microcomputer 14 to the optical shake correction system drive control means 2 also becomes small. Even if the fluctuation occurs, it can be made less susceptible to the influence. As a result, it is possible to reduce malfunctions that occur because it is difficult to accurately detect movement immediately after power is turned on.
[0090]
Note that when the gain G is set to a small value in step 307, the motion correction performance of the image pickup apparatus deteriorates in all frequency bands.₁It is desirable to set as short as possible. In this way, since the user is not aware of the correction performance deterioration caused by setting the gain G of the control signal low, there is no particular problem in actual use.
[0091]
In the method for determining the gain G shown in FIG. 9, since the gain G can be switched only in two stages, Gon and Gs, the motion correction performance may change drastically at the time of switching, which may cause a sense of incongruity. In order to solve this problem, a method of changing the gain G continuously or a method of changing the gain G in multiple stages can be adopted as in the first embodiment.
[0092]
As described above, in the third embodiment, the microcomputer 14 has the gain adjustment means for adjusting the gain of the control signal for controlling the optical shake correction system 1 and immediately after the start of energization of the angular velocity sensor 10. By setting this gain temporarily lower in a predetermined period or in a predetermined period immediately after power reset, the motion correction performance by the optical shake correction system 1 is limited. For this reason, it is possible to reduce malfunctions that have conventionally occurred because it is difficult to detect accurate movement immediately after the start of energization or immediately after power reset.
[0093]
(Embodiment 4)
The basic configuration of the image motion correction apparatus according to the fourth embodiment of the present invention is the same as that of the first embodiment, and only the processing content in the microcomputer 14 is different.
[0094]
Therefore, the description of the configuration of the image motion correction apparatus according to the fourth embodiment will be omitted, and the operation of the apparatus will be described below according to the processing program stored in the microcomputer 14. In the fourth embodiment as well, a series of operations such as angular velocity detection by the angular velocity sensor 10 and drive control of the VAP 1 is not distinguished between horizontal and vertical directions, and only one direction will be described.
[0095]
FIG. 10 is an example of a flowchart of a processing program stored in the microcomputer 14.
[0096]
When power is turned on to the imaging apparatus main body, first, a counter for measuring the time after the power is turned on to the angular velocity sensor 10 is reset (step 401).
[0097]
Next, the state of a motion correction switch (not shown) that indicates whether or not motion correction is executed (hereinafter referred to as SW) is determined (step 402), and the SW is turned on to instruct the photographer to execute motion correction. When the angular velocity sensor is turned on, the process proceeds to the next step 402. If the SW is OFF, the process waits in this state.
[0098]
In step 404, band limitation is performed on the signal from the angular velocity sensor 10 taken into the microcomputer 14 using a high-pass filter (HPF). That is, the HPF has a transfer function of (1-Z^-1) / (1-b · Z^-1) And the influence of low frequency fluctuations such as temperature drift included in the output of the angular velocity sensor 10 is removed.
[0099]
Next, the angular velocity of the movement of the imaging device detected by the angular velocity sensor 10 is converted into an angle by integration processing (step 405), and then gain adjustment is performed on the output of step 405 (step 406).
[0100]
In the next step 407, in order to measure the time after the angular velocity sensor 10 is turned on, the counter is incremented and held every processing cycle.
[0101]
Subsequently, a clip value for performing clip processing so that the control signal sent from the microcomputer 14 to the optical shake correction system drive control means 2 does not indicate a correction amount exceeding the correction range of the optical shake correction system 1. C is determined (step 408).
[0102]
As a method of determining the clip value C, for example, a function for calculating the clip value C from the count value or a table for defining the relationship between the count value and the clip value C is provided in the microcomputer 14. Alternatively, the clip value C corresponding to the count value is determined using a table.
[0103]
In step 409, the control signal is clipped based on the clip value C determined in step 408 and output to the D / A converter 15.
[0104]
FIG. 11 is an example of a method for determining the clip value C in step 408 of FIG.
[0105]
In the example shown in the figure, the time t determined in advance based on the characteristics of the angular velocity sensor 10 from when the angular velocity sensor 10 is turned on (t = 0).₁Until the clip value C is set to Con and the time t₁Thereafter, Cs (> Con) is set. That is, a certain time immediately after power-on (here, 0 to t₁The clip value C is set as small as Con (<Cs) only during the period of (1). As a result, even if a low-frequency fluctuation such as a drift occurring in the output of the angular velocity sensor 10 occurs immediately after the power is turned on, the signal width of the control signal sent from the microcomputer 14 to the optical shake correction system drive control means 2 is limited to be small. The For this reason, it is possible to reduce malfunctions that occur because it is difficult to detect accurate movements immediately after the power is turned on.
[0106]
Note that when the clip value C is set to be small in step 408, the correction range for motion correction becomes narrow and the motion correction performance deteriorates.₁It is desirable to set as short as possible. In this way, since the user is not aware of the correction performance deterioration caused by setting the clip value of the control signal to be small, there is no particular problem in actual use.
[0107]
In FIG. 11, only the determination method of the clip value in one direction centering on the center value (zero) is shown, but the clip value in the opposite direction is inverted as the clip value shown in the figure as -Con, -Cs. Use it.
[0108]
In the method of determining the clip value C shown in FIG. 11, since the clip value C can be switched only in two stages, Con and Cs, the motion correction performance may change drastically at the time of switching, and there is a possibility that an uncomfortable feeling may occur. In order to solve this problem, as in the first embodiment, a method of changing the clip value C continuously or a method of changing in multiple stages can be employed.
[0109]
As described above, in the fourth embodiment, the microcomputer 14 has clip means for limiting the maximum value and the minimum value of the control signal for controlling the optical shake correction system 1, that is, limiting the control signal width. By setting the control signal width temporarily within a predetermined period immediately after the start of energization of the angular velocity sensor 10 or within a predetermined period immediately after resetting the power supply, the optical shake correction system 1 can be used. Motion compensation performance is limited. For this reason, it is possible to reduce malfunctions that have conventionally occurred because it is difficult to detect accurate movement immediately after the start of energization or immediately after power reset.
[0110]
(Embodiment 5)
FIG. 12 shows a block diagram of an image motion correction apparatus according to Embodiment 5 of the present invention. Components corresponding to those in Embodiment 1 shown in FIG.
[0111]
The fifth embodiment is characterized in that the imaging optical system drive control means 5 drives and controls the imaging optical system 4 to perform an optical zoom operation and a focusing operation, and the focal length of the imaging optical system 4 is set to A. The data is sent to the microcomputer 14 via the / D conversion means 22, while the microcomputer (hereinafter referred to as a microcomputer).23Is based on the output of the angular velocity sensor 10 taken in via the A / D conversion means 13 and the focal length information of the imaging optical system 4 taken in via the A / D conversion means 22, and the VAP 1 necessary for motion correction. This is configured so as to obtain a drive control amount (hereinafter referred to as a control signal).
[0112]
Since the other configuration is the same as that of the first embodiment shown in FIG. 1, detailed description is omitted here.
[0113]
Next, the operation of the image motion correction apparatus according to the fifth embodiment configured as described above will be described in accordance with a processing program stored in the microcomputer 14. Although a series of operations such as angular velocity detection by the angular velocity sensor 10 and drive control of the VAP 1 are actually performed in both the horizontal and vertical directions, the control contents are the same in both the horizontal and vertical directions. In order to simplify the description, the horizontal and vertical directions are not distinguished, and only one direction is described.
[0114]
FIG. 13 is an example of a flowchart of a processing program stored in the microcomputer 14.
[0115]
Steps 501 to 505 and steps 509 to 511 in FIG. 13 correspond to steps 101 to 105 and steps 107 to 109 in the first embodiment shown in FIG. Description is omitted. In step 506, the microcomputer 14 determines a numerical value D (≧ 1) corresponding to this focal length based on the focal length information of the imaging optical system 4 captured via the A / D conversion means 22.
[0116]
As a method of determining the numerical value D corresponding to the focal length, for example, a function for calculating the numerical value D from the focal length or a table for defining the relationship between the focal length and the number D is provided in the microcomputer 14. The numerical value D corresponding to the focal length is determined using this function or table. However, in this case, when the cutoff frequency of the HPF obtained in step 505 is set to the cutoff frequency during the normal correction operation in which the output of the angular velocity sensor means 10 is stable, D = Set to 1. The reason for changing the numerical value D in accordance with the focal length will be described in detail later.
[0117]
Multiplication of the numerical value D obtained in step 506 and the cutoff frequency of HPF obtained in step 505 is performed to finally determine the cutoff frequency of HPF (step 507).
[0118]
FIG. 14 is an example of a method for determining the numerical value D in step 506 of FIG.
[0119]
In the example shown in the figure, the value of D is determined in accordance with the focal length of the imaging optical system 4, and for example, if the focal length of the imaging optical system 4 is the minimum value, D = 1 is set. The numerical value D is set not to increase as the value of becomes longer.
[0120]
Thus, the reason why the numerical value D is changed according to the focal length is as follows.
[0121]
Immediately after the power is turned on, when the output of the angular velocity sensor 10 undergoes a relatively slow fluctuation in output such as a drift, the output of the angular velocity sensor 10 is particularly increased as the imaging optical system 4 is set to the telephoto side. The motion of the image based on is increased.
[0122]
Therefore, in the fifth embodiment, D (≧ 1) is obtained according to the focal length, the cutoff frequency of HPF obtained in step 505 is multiplied by D, and when the focal length is long, the cutoff of HPF. By setting the frequency high, it is possible to further reduce the influence of low frequency fluctuations such as drift that occurs in the output of the angular velocity sensor 10 immediately after the power is turned on.
[0123]
In FIG. 14, the numerical value D changes linearly according to the focal length. However, the present invention is not limited to this. For example, the numerical value D may change nonlinearly as shown in FIG. . In addition to the example in which the numerical value D changes continuously as shown in FIGS. 14 and 15, the numerical value D may change in multiple stages.
[0124]
As described above, in the fifth embodiment, the microcomputer 14 has a high-pass filter that removes a low-frequency component included in the output of the angular velocity sensor 10, and a predetermined period immediately after the start of energization of the angular velocity sensor 10 or The cut-off frequency of the high-pass filter is temporarily set higher than that in other periods within a predetermined period immediately after the power reset, and the cut-off frequency in that case is changed according to the focal length. As a result, the motion correction performance of the optical shake correction system 1 is limited, and it is possible to reduce malfunctions that occur because it is difficult to detect accurate motion immediately after the start of energization or immediately after power reset.
[0125]
It should be noted that the processing in step 506 and step 507 described in the fifth embodiment can be incorporated into the processing in the second to fourth embodiments.
[0126]
In this case, as an example, a numerical value D (≦ 1) is determined in step 506 by the method shown in FIGS. 16 and 17 (however, D = 1 is output during normal correction operation). As in the fifth embodiment, the coefficient K and the numerical value D are multiplied by 2, the gain G and the numerical value D are multiplied in the third embodiment, and the clip value C and the numerical value D are multiplied in the fourth embodiment, respectively. The correction performance can be limited to the above-described effects, and effects greater than those shown in the second to fourth embodiments can be realized.
[0127]
In addition to those shown in FIGS. 16 and 17, for example, the numerical value D can be determined linearly between the minimum value and the maximum value of the focal distance, or the numerical value D can be determined in multiple stages.
[0128]
In each of the first to fifth embodiments, the optical shake correction system 1 has been described as a variable apex angle prism. However, the present invention is not limited to this and is driven relatively to the imaging optical system 4. Means for realizing optical axis correction, for example, means for moving the optical axis by shifting a part or all of the lenses in a direction perpendicular to the optical axis (for example, Japanese Patent Application No. Sho 63- (See Japanese Patent Publication No. 2016622), the optical shake correction system 1 can be used.
[0129]
In each of the first to fifth embodiments, as the optical shake correction system 1, the imaging optical system 4, the solid-state imaging device 6 and the like are supported and driven so as to be rotatable with respect to the housing of the imaging apparatus. A configuration for correcting the motion (for example, see “Development of Video Camera Image Stabilization Technology” Television Society Technical Report Vol. 11, No. 28, pp 19-24 (1987)) is also conceivable.
[0130]
Further, in each of the first to fifth embodiments, the description has been given by taking, as an example, the one that optically corrects the shake as the means for correcting the motion of the image. However, the present invention is not limited to this. Even when the motion is corrected by driving control of the image memory, the effect of the present invention can be realized when an external sensor such as an angular velocity sensor is used for motion detection.
[0131]
In each of the first to fifth embodiments described above, the example of the program processing by the microcomputer has been described. However, the present invention is not limited to this, and the program processing by the microcomputer can be realized by hardware such as an electronic circuit. Needless to say.
[0132]
In each of the first to fifth embodiments, the number of solid-state imaging elements of the imaging device is not particularly mentioned. However, in any imaging device of a single-plate imaging device, a two-plate imaging device, and a three-plate imaging device. However, it is clear that the present invention is effective. Further, it is apparent that the present invention is also effective in an image pickup apparatus using an image pickup tube instead of a solid-state image pickup element.
[0133]
【The invention's effect】
The present invention has the following effects.
[0134]
(1) In the present invention, the motion correction performance is improved by changing the response characteristics of the control signal generating means within a predetermined period immediately after the start of energization of the motion detecting means or immediately after power resetting, and within other periods. Since the restriction is made, it is possible to reduce malfunctions that occur because it is difficult to detect an accurate movement immediately after starting energization or immediately after resetting the power supply.
[0135]
(2) Further, in the present invention, the response characteristic of the control signal generation means is determined as the focal length detection means within a predetermined period immediately after the start of energization of the motion detection means or immediately after power reset, and within other periods. Since the motion compensation performance is further limited especially when the focal length of the imaging optical system is long, the power correction is performed immediately after the start of energization or power reset. It is possible to further reduce the malfunction that occurs because it is difficult to detect an accurate motion immediately after that.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an image motion correction apparatus according to a first embodiment of the present invention.
FIG. 2 is a flowchart for explaining processing contents performed by the microcomputer 14 according to the first embodiment of the present invention;
FIG. 3 is a graph showing an example of a cutoff frequency determination method according to Embodiment 1 of the present invention.
FIG. 4 is a graph showing an example of a cutoff frequency determination method according to Embodiment 1 of the present invention.
FIG. 5 is a graph showing an example of a cutoff frequency determination method according to Embodiment 1 of the present invention.
FIG. 6 is a flowchart for explaining the processing contents by the microcomputer 14 according to the second embodiment of the present invention;
FIG. 7 is a graph showing an example of a method for determining a coefficient K according to the second embodiment of the present invention.
FIG. 8 is a flowchart for explaining processing contents performed by the microcomputer 14 according to the third embodiment of the present invention;
FIG. 9 is a graph showing an example of a method for determining gain G according to the third embodiment of the present invention.
FIG. 10 is a flowchart for explaining the processing contents by the microcomputer 14 according to the fourth embodiment of the present invention;
FIG. 11 is a graph showing an example of a clip value C determination method according to Embodiment 4 of the present invention;
FIG. 12 is a block diagram showing an image motion correction apparatus according to a fifth embodiment of the present invention.
FIG. 13 is a flowchart for explaining the processing contents by the microcomputer 23 according to the fifth embodiment of the present invention;
FIG. 14 is a graph showing an example of a method for determining a numerical value D according to the fifth embodiment of the present invention.
FIG. 15 is a graph showing an example of a method for determining a numerical value D according to the fifth embodiment of the present invention.
FIG. 16 is a graph showing an example of a method for determining a numerical value D according to the fifth embodiment of the present invention.
FIG. 17 is a graph showing an example of a method for determining a numerical value D according to the fifth embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Optical shake correction system, 2 ... Optical shake correction system drive control means, 3 ... Angle detection means, 4 ... Imaging optical system, 5 ... Imaging optical system drive control means, 6 ... Solid-state image sensor, 7 ... Analog signal Processing means, 8 ... A / D conversion means, 9 ... Digital signal processing means, 10 ... Angular velocity sensor, 11 ... Filter, 12 ... Amplifier, 13 ... A / D conversion means, 14 ... Microcomputer, 15 ... D / A conversion Means, 16 ... Solid-state image sensor drive control means

Claims (14)

Angular velocity detection means for detecting the angular velocity of movement of the imaging device itself;
Motion correction means for correcting the movement of the captured image caused by the movement of the imaging device itself;
Control signal generating means for generating a control signal for controlling the motion correcting means based on the output of the angular velocity detecting means,
It said control signal generating means includes a clip means for limiting the signal width of the control signal for controlling the motion compensation means for generating therein,
The control signal generation is performed by limiting the signal width within a predetermined period immediately after the start of energization to the angular velocity detection unit or within a predetermined period immediately after power resetting to be smaller than the signal width in other periods. An image motion correction apparatus characterized by changing a response characteristic of the means . Angular velocity detection means for detecting the angular velocity of movement of the imaging device itself;
An imaging optical system composed of a plurality of lens groups and having a variable focal length;
A focal length detection means for detecting a focal length of the imaging optical system;
Motion correction means for correcting the movement of a captured image caused by the movement of the imaging device itself;
Control signal generating means for generating a signal for controlling the motion correcting means based on the output of the angular velocity detecting means,
The imaging in which the response characteristic of the control signal generating means is detected by the focal length detecting means within a predetermined period immediately after the start of energization of the angular velocity detecting means or within a predetermined period immediately after resetting the power supply and in other periods. An image motion correction device, wherein the image motion correction device is changed according to a focal length of an optical system. The control signal generating means has a high-pass filter that removes a low-frequency component contained in the output of the angular velocity detecting means,
The cut-off frequency of the high-pass filter is compared with the cut-off frequency of the high-pass filter in other periods within a predetermined period immediately after the start of energization of the angular velocity detecting means or within a predetermined period immediately after power reset. The response characteristic of the control signal generating means is changed by setting the cutoff frequency of the high-pass filter higher as the focal length of the imaging optical system is longer. The image motion correction apparatus according to claim 2 . The control signal generating means has integrating means for integrating the output of the angular velocity detecting means and converting the angular velocity into an angle,
The integration means has a transfer function represented by 1 / (1−K · Z ⁻¹ ) (where 0 <K <1), and within a predetermined period immediately after the start of energization of the angular velocity detection means or power reset The value of K in a predetermined period immediately after is set smaller than the value of K in other periods, and the value of K is set smaller as the focal length of the imaging optical system is longer. The image motion correction apparatus according to claim 2 , wherein the response characteristic of the control signal generating means is changed. The control signal generation means has a gain adjustment means for adjusting the gain of the control signal for controlling the motion correction means generated therein,
The gain of the control signal within a predetermined period immediately after the start of energization of the angular velocity detecting means or within a predetermined period immediately after the power reset is set smaller than the gain of the control signal within the other period, and the imaging optical 3. The image motion correcting apparatus according to claim 2 , wherein the response characteristic of the control signal generating means is changed by setting the gain of the control signal to be smaller as the focal length of the system is longer. The control signal generation means has clip means for limiting the signal width of the control signal for controlling the motion correction means generated inside,
The signal width in a predetermined period immediately after the start of energization to the angular velocity detection means or in a predetermined period immediately after power reset is limited to be smaller than the signal width in other periods, and the focal length of the imaging optical system 3. The image motion correction apparatus according to claim 2 , wherein the response characteristic of the control signal generating means is changed by limiting the signal width to be smaller as the length is longer. Response characteristic of the control signal generating means includes a right after energization start immediately or power reset to the angular velocity detecting means, between the other periods, claims 1, characterized in that is changed stepwise within a predetermined time The image motion correction apparatus according to claim 6 . Response characteristic of the control signal generating means includes a right after or power reset immediately after energization start to the angular velocity detecting means, between the other periods, claims 1, characterized in continuously changing within a predetermined time The image motion correction apparatus according to claim 6 . 3. The image motion correction apparatus according to claim 1 , wherein the motion correction means is a variable apex angle prism. The image motion correction apparatus according to claim 1 , wherein the motion correction unit is driven relative to the imaging optical system to decenter the optical axis of the imaging optical system. Motion compensation means according to claim 1 or claim 2, wherein the consisting of one or more lenses to decenter the optical axis of the imaging optical system by being driven individually in a direction perpendicular to the optical axis Image motion correction device. 3. The image motion correction apparatus according to claim 1 , wherein the motion correction unit is configured to rotationally drive the imaging optical system about two axes orthogonal to the optical axis. The image motion correction apparatus according to claim 1 , wherein the motion correction unit reads out only a part of an image photographed by the solid-state image sensor by drivingly controlling the solid-state image sensor. 3. The image motion correction apparatus according to claim 1 , wherein the motion correction means reads out only a part of the image recorded on the image memory by driving and controlling the image memory.

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