WO2018128098A1

WO2018128098A1 - Imaging device and focus adjusting method

Info

Publication number: WO2018128098A1
Application number: PCT/JP2017/046203
Authority: WO
Inventors: 円嘉堀内
Original assignee: オリンパス株式会社
Priority date: 2017-01-07
Filing date: 2017-12-22
Publication date: 2018-07-12
Also published as: JP6739357B2; JP2018112592A

Abstract

Provided are an imaging device and a focus adjusting method which enable focus to be adjusted with good precision. The imaging device comprises: an optical system 2 including a focus lens for changing the focus state of a subject imaged; an optical system driving unit 3 for moving the focus lens in an optical axis direction; an imaging element 7 for exposing a subject image, and converting the exposed subject image to an image signal; a distance measuring pixel control unit 16 for detecting a subject distance by means of a distance measuring pixel included in an imaging element; and a system control CPU 10 for controlling how much the focus lens is moved by the optical system driving unit 3, on the basis of the detected subject distance and a focal point position of the focus lens. The system control CPU 10 controls the focus lens such that the focus lens is moved by the optical system driving unit 3 in a direction in which the subject distance and focal point position are made to coincide on the basis of a deviation amount between the focal point position of the focus lens and the subject distance detected by a distance measuring data detecting unit 11 while the imaging device 7 exposes the subject image by using the image signal as a means for recording.

Description

Imaging apparatus and focus adjustment method

The present invention is an imaging device having a focus adjustment function. In particular, the present invention relates to an imaging apparatus and a focus adjustment method capable of performing focus adjustment during an exposure operation for image recording.

Conventionally, an imaging apparatus equipped with an automatic focus adjustment device that automatically adjusts the focus lens is commercially available. However, the conventional imaging apparatus cannot detect the focus lens focus state when performing an exposure operation for image recording. That is, in the conventional imaging device, when the subject distance is close, the subject distance fluctuates due to camera shake while the subject is being photographed. However, it is impossible to correct out-of-focus (out-of-focus state shifts from the in-focus state) that occurs during still image exposure. Therefore, a displacement sensor, such as an acceleration sensor, that detects the amount of camera displacement that occurs during the exposure operation to correct out-of-focus in the shooting state, is detected by the displacement sensor. There has been proposed a camera with an automatic focusing function having a function of sequentially correcting the focus lens focus shift based on the amount (see Patent Document 1).

Japanese Patent Laid-Open No. 10-312006

The camera with an automatic focusing function disclosed in Patent Document 1 described above performs focus adjustment using a displacement sensor such as an acceleration sensor. Conventionally, it has been known that when a displacement sensor is used for a long time, an error of the displacement amount such as an offset deviation is generated from the gradually detected displacement amount. For this reason, an error in the amount of displacement adversely affects the accuracy of focus adjustment.

The present invention has been made in view of circumstances in the background art. That is, it is an object of the present invention to provide an imaging apparatus and a focus adjustment method that can perform focus adjustment with high accuracy while photographing.

An imaging apparatus according to a first aspect of the present invention includes an optical lens including a focus lens that changes a focus state of a subject to be imaged, a focus driving unit that moves the focus lens in an optical axis direction, and the optical lens. An image sensor that exposes a formed subject image and converts it into a video signal; a distance measuring unit that detects a subject distance between the imaging device and the subject; a subject distance detected by the distance measuring unit; and the focus A focus control unit that controls a movement amount of the focus lens by the focus driving unit based on a focus position of the lens, and the focus control unit is configured to record the video signal by the imaging element for recording the video signal. Based on the amount of deviation between the subject distance detected by the distance measuring unit and the focus position of the focus lens while exposing the subject image, In a direction to match the serial object distance and the focus position, and performs control to move the focus focusing by the focus drive unit.

In the focus adjustment method according to the second aspect of the present invention, when detecting an image signal of an object image formed by an optical lens including a focus lens by an image sensor and detecting the image signal for recording, Based on the detection of the subject distance between the imaging device and the subject and the amount of deviation between the detected subject distance and the focus position of the focus lens, the subject distance and the focus position are set to coincide with each other. , Calculating a movement amount relative to the focus lens, and moving the focus lens based on the calculated movement amount.

According to the present invention, it is possible to provide an imaging apparatus and a focus adjustment method capable of performing focus adjustment with high accuracy while photographing.

It is a block diagram which shows mainly an electrical structure of the camera which concerns on 1st Embodiment of this invention. It is a block diagram which mainly shows the electric constitution of the camera which concerns on the modification of 1st Embodiment of this invention. FIG. 3 is a block diagram illustrating functions of a focus correction amount calculation unit 12 in the first embodiment of the present invention. 6 is a flowchart illustrating an operation for correcting out-of-focus blur during still image exposure of the camera according to the first embodiment of the present invention. It is a timing chart which shows operation | movement of the camera which concerns on 1st Embodiment of this invention. It is a block diagram which mainly shows the electrical structure of the camera which concerns on 2nd Embodiment of this invention. It is a block diagram which mainly shows the electric constitution of the camera which concerns on the modification of 2nd Embodiment of this invention. FIG. 10 is a block diagram illustrating the function of a focus correction amount calculation unit 18 in the second embodiment of the present invention. It is a timing chart which shows the operation | movement of a focus blur correction during still image exposure of the camera which concerns on 2nd Embodiment of this invention. It is a flowchart which shows operation | movement of the camera which concerns on 2nd Embodiment of this invention. It is a block diagram which mainly shows the electrical structure of the camera which concerns on 3rd Embodiment of this invention. It is a block diagram which shows mainly an electrical structure of the camera which concerns on the modification of 3rd Embodiment of this invention. FIG. 10 is a block diagram illustrating functions of a focus correction amount calculation unit 20 in the third embodiment of the present invention. It is a timing chart which shows operation | movement of the camera which concerns on 3rd Embodiment of this invention. It is a flowchart which shows the operation | movement of a focus blur correction during the still image exposure of the camera which concerns on 3rd Embodiment of this invention. It is a flowchart which shows the operation | movement of a focus blur correction during the still image exposure of the camera which concerns on 3rd Embodiment of this invention.

Hereinafter, an example applied to a digital camera (hereinafter referred to as “camera”) as a preferred embodiment of the present invention will be described. This camera includes an imaging unit that converts a subject image into image data, and a display unit that is disposed on the back of the main body. This display unit displays a subject image in a live view based on the image data converted by the imaging unit. The user observes the live view display and determines the composition of the image for shooting and the time point (shutter timing) for starting shooting. At the time of the release operation, still image data acquired by photographing is recorded on a recording medium. The image data recorded on the recording medium can be reproduced and displayed on the display unit when the reproduction mode is selected.

Further, in the present embodiment, an AF sensor 5 (an image sensor 7 in which a ranging pixel is provided in a part of the pixels in the modification of the present embodiment) is provided in addition to the image sensor 7. When the user fully presses the release button, the defocus amount of the focus lens is calculated by so-called phase difference AF at predetermined time intervals during exposure for acquiring still image data. The focus lens is subjected to focus adjustment based on the calculation result so as to maintain the in-focus state.

FIG. 1 is a block diagram mainly showing an electrical configuration in the present embodiment. This camera includes a camera body 1, an optical system 2, an optical system drive unit 3, a half mirror 3, an AF sensor 5, a shutter 6, an image sensor 7, and a system control CPU 10.

The optical system 2 includes a focus lens and forms a subject image on the image sensor 6. The focus lens can move in the optical axis direction. The optical system drive unit 3 moves the focus lens to the in-focus position. The optical system 2 functions as an optical lens including a focus lens that can change the focus state of a subject to be imaged.

Half mirror 4 is a translucent mirror such as a pellicle mirror. The half mirror 4 is on the optical axis of the optical system 2 and is fixed by being inclined 45 degrees with respect to the optical axis. The half mirror 4 transmits a part of the subject light beam transmitted through the optical system 2 and reflects the remaining light beam to the AF sensor 5. In the present embodiment, the half mirror 4 is fixed. However, the half mirror 4 is not limited to a fixed one. For example, the half mirror 4 may be configured to move so as to move on the optical axis of the optical system 2 when the release button is fully pressed. The half mirror 4 has an action of causing a part of the subject image incident by the optical system to enter the imaging surface of the image sensor, an action of dividing a different part of the subject image in a direction different from the incident direction of the imaging surface, It functions as a spectroscopic unit (optical path splitter) having an effect of guiding a part of the subject image to the distance measuring unit (ranging sensor). The distance measuring unit detects the subject distance by a distance measuring sensor different from the image sensor.

The AF sensor 5 is a detection element that receives a subject light beam split from the half mirror 4 and outputs an electrical signal for generating distance measurement data. As an example, the AF sensor 5 may employ a phase difference detection method having a polarizing element and two detection units. In the phase difference detection method, the light split from the half mirror 4 is further separated into two light beams having different polarization directions by a polarizing element. The focus detection method detects a defocus amount (a defocus amount) from a positional relationship where each separated light beam forms an image.

The shutter 6 is disposed between the optical system 2 and the image sensor 7 and on the optical axis of the optical system 2. The shutter 6 performs an opening / closing operation based on an instruction from the shutter control unit 13. When the shutter 6 is in an open state, a subject image is formed on the image sensor 7 and is in an exposed state. Further, when the shutter 6 is closed, a subject image is not formed on the image sensor 7 and a light shielding state is established. That is, the exposure time of the image sensor 7 at the time of still image shooting is controlled by controlling the time when the shutter 6 is opened.

The imaging element 7 has a plurality of pixels arranged on the imaging surface, and each pixel converts a subject image formed on the imaging surface into an electrical signal (pixel signal). A pixel signal is read out from each of these pixels by the imaging pixel control unit 14. Further, video data is formed from these pixel signals. The image sensor 7 functions as an image sensor that exposes a subject image formed by an optical lens and converts it into a video signal.

The system control CPU 10 is a controller having a CPU (Central Processing Unit), its peripheral circuits, and volatile and nonvolatile memory, and controls each part in the camera body 1 according to a program stored in the nonvolatile memory. To control the entire camera. In the system control CPU 10, a distance measurement data detection unit 11, a focus correction amount calculation unit 12, a shutter control unit 13, an imaging pixel control unit 14, and a focus lens drive amount calculation unit 15 are provided. These parts are realized by executing a peripheral circuit in the system control CPU 10 and a control program. The system control CPU 10 has various functions. However, in this specification, the focus adjustment control during still image exposure will be mainly described, and description of other functions will be omitted.

The system control CPU 10 functions as a focus control unit that controls the amount of movement of the focus lens by the focus driving unit based on the subject distance detected by the distance measuring unit and the focus position of the focus lens (for example, FIG. S11 to S17 in FIG. 4, S35 to S43 in FIG. 10, S51 to S59 in FIG. 15A, and S61 to S71 in FIG. 15B). The focus control unit detects the amount of deviation between the subject distance detected by the distance measuring unit and the focus lens focus position while the image sensor exposes the subject image when shooting a still image for recording. Based on the above, a drive signal is given to the focus drive unit in a direction to match the subject distance and the focus position, and the focus lens is moved.

The shutter control unit 13 includes a shutter control circuit, calculates subject luminance based on the pixel signal from the image sensor 14, and obtains a shutter speed value to obtain appropriate exposure (exposure amount) based on the subject luminance. calculate. When the user fully presses the release button, the shutter 6 is opened and closed based on the calculated shutter speed value (or the shutter speed value manually set by the user) to control the exposure time.

The imaging pixel control unit 14 includes an imaging control circuit for reading out pixel signals from each imaging pixel provided in the imaging element 7. The imaging pixel control unit 14 reads pixel signals for live view display until the release button is fully pressed. Further, when the release button is fully pressed and the opening / closing operation of the shutter 6 is completed, still image data for recording is read out.

The ranging data detection unit 11 may have a ranging data detection circuit, and detects the ranging data based on the electrical signal acquired from the AF sensor 5. The focus correction amount calculation unit 12 may include a focus correction amount calculation circuit, and based on the distance measurement data detected by the distance measurement data detection unit 11, the amount of deviation (defocus) from the focus position of the focus lens. Amount), that is, a focus correction amount in the optical axis direction is calculated. The distance measurement data detection unit 11 functions as a distance measurement unit that detects a subject distance between the imaging apparatus and the subject. In addition, the distance measuring unit operates to detect the subject distance in parallel with the exposure operation while the image sensor exposes the subject image (see, for example, FIGS. 5, 9, and 14). ). In the present embodiment, the distance measuring unit detects the defocus amount of the optical system 2 as the subject distance. However, the present invention is not limited to this. For example, the distance from the camera body 1 to the subject may be directly detected using the subject light flux that has passed through the optical system other than the optical system 2, and the subject distance may be used.

The focus lens drive amount calculation unit 15 may have a focus lens drive amount calculation circuit, performs unit conversion from the focus correction amount calculated by the focus correction amount calculation unit 12 to focus lens drive, and drives the drive position or drive. Calculate the amount.

The system control CPU 10 realizes the functions of the distance measurement data detection unit 11, the focus correction amount calculation unit 12, the shutter control unit 13, the imaging pixel control unit 14, and the focus lens drive amount calculation unit 15 by software using a program. Alternatively, it may be realized by a peripheral circuit, or may be realized by a combination of a program and a peripheral circuit.

The optical system drive unit 3 includes a drive actuator (for example, a stepping motor) and a drive circuit, and moves the focus lens of the optical system 2 in the optical axis direction. The optical system drive unit 3 performs focus control of the focus lens of the optical system 2 based on the drive position or drive amount obtained from the focus lens drive amount calculation unit 15. The optical system drive unit 3 functions as a focus drive unit that moves the focus lens in the optical axis direction.

FIG. 2 is a block diagram showing a modification of the first embodiment. Since most of the blocks in FIG. 2 are the same as those in FIG. 1, differences will be mainly described.

The distance measuring unit (ranging sensor) in the modification of the first embodiment has the function of the AF sensor 5 in FIG. The image pickup device 7 has a plurality of pixels on the image pickup surface, like the image pickup device 7 shown in FIG. In FIG. 1, the image sensor 7 has only image pixels. On the other hand, in FIG. 2, the image sensor 7 includes an image plane phase difference AF pixel (ranging pixel) in addition to the image pickup pixel.

1 has only a function of converting a subject image into an electrical signal. However, the image sensor 7 in FIG. 2 also has a function of converting it into an electrical signal for obtaining distance measurement data corresponding to the distance to the subject. That is, the image sensor 7 includes distance measuring pixels on the imaging plane and image pickup pixels (non-range pixels) that output image signals from the subject image. Of the electrical signals obtained by the imaging device 7, the pixel signal from the imaging pixel is output to the imaging pixel control unit 14, while the electrical signal from the ranging pixel is output to the ranging pixel control unit 16. Accordingly, the subject image information is processed by the imaging pixel control unit 14, and the distance information to the subject is processed by the ranging pixel control unit 16.

The image pickup pixel and the distance measurement pixel are independently operated to start and end the exposure for each pixel, and a pixel output circuit for independently reading the pixel signal for each pixel is formed. The imaging pixel control unit 14 and the ranging pixel control unit 16 can operate in parallel during exposure to read out the output of the imaging pixel and the output of the ranging pixel. That is, it is a configuration that can obtain the output of the ranging pixel during exposure.

The ranging pixel control unit 16 may include a readout control circuit that performs readout control of readout of the ranging pixel, and based on the electrical signal obtained from the ranging pixel of the image sensor 7, the ranging data up to the subject To produce. Further, since the distance measurement information can be acquired from the distance measurement pixels of the image sensor 7, the AF sensor 5 is not required, and the half mirror 4 is not required. For this reason, the light beam that has passed through the optical system 2 is directly imaged on the image sensor 7 without being dispersed. The distance measuring unit can independently read out pixel signals output from the distance measuring pixels while the non-range pixels are performing the exposure operation, detect the subject distance, and acquire the result. In the modification of the first embodiment, the distance measuring unit includes a distance measuring pixel of the image sensor 7 and a distance measuring pixel control unit 16.

The difference between FIG. 1 and FIG. 2 is a method for acquiring distance measurement data up to the subject. The distance measurement data detection unit 11 and the distance measurement pixel control unit 16 of the system control CPU 10 output the same type of distance measurement data. It becomes. In the modification shown in FIG. 2, the half mirror 4 and the AF sensor 5 can be omitted by providing a distance measuring pixel in the image sensor 7.

FIG. 3 is a block diagram showing details of the function of the focus correction amount calculation unit 12, and is composed of distance measurement data 121 and a defocus amount calculation unit 122. Each block may be realized by software by the CPU of the system control CPU 10 according to a program, may be realized by a peripheral circuit, or may be realized by a combination of a program and a peripheral circuit.

In the first embodiment shown in FIG. 1, the distance measurement data 121 is output from the distance measurement data detection unit 11 that processes an electrical signal output from the AF sensor 5. In the modification shown in FIG. 2, the distance measurement data 121 corresponds to data output from the distance measurement pixel control unit 16 that processes an electrical signal from the distance measurement pixel of the image sensor 7.

The defocus amount calculation unit 122 calculates the defocus amount based on the distance measurement data 121 during still image exposure.

The focus lens driving amount calculation unit 15 performs unit conversion for driving the focus lens based on the calculated defocus amount, and calculates the driving position or driving amount of the focus lens. The lens-side optical system drive unit 3 can use the calculated drive position / drive amount to drive the focus lens of the optical system 2 and perform focus correction in the optical axis direction during still image exposure.

Next, the process of correcting the out-of-focus blur during still image exposure in the present embodiment will be described using the flowchart shown in FIG. This control flow is realized by the system control CPU 10 controlling each part in the camera body 1 according to a program stored in the nonvolatile memory.

4. When the flow shown in FIG. 4 starts, it is first determined whether or not 1R (1st. Release) is pressed (S1). Here, it is determined whether or not the user has pressed the release button halfway. If 1R depression is not detected, a standby state is entered.

If the result of determination in step S1 is that 1R has been depressed, an autofocus operation (AF operation) is started, and distance measurement data is first acquired (S3). Here, the ranging data detection unit 11 or the ranging pixel control unit 16 acquires the ranging data. While the 1R depression is detected, the distance measurement data is continuously acquired at regular intervals. The operation of continuously acquiring the distance measurement data at regular intervals while detecting the 1R depression is an example of the operation. The operation procedure is not limited to this, and during live view shooting, the distance measurement data may be continuously acquired at regular intervals regardless of whether or not the 1R is depressed.

When the ranging data is acquired, the defocus amount is calculated (S5). Here, the focus correction amount calculation unit 12 calculates the defocus amount using the distance measurement data acquired in step S3.

After calculating the defocus amount, the focus lens is driven (S7). Here, the focus lens drive amount calculation unit 15 calculates the drive position or drive amount of the focus lens, and the optical system drive unit 3 moves the focus lens to the focus position.

When the focus lens is driven, it is next determined whether or not 2R (2nd. Release) is depressed (S9). When the user intends to shoot a still image, the user fully presses the release button. In this step, it is determined whether or not the release button has been fully pressed. As a result of the determination, if there is no 2R depression, the process returns to step S3, the above operation is repeated, and the focus lens is maintained at the in-focus position.

If the result of determination in step S9 is that 2R has been pressed, the operation moves to still image shooting. That is, exposure control is performed with the aperture value and shutter speed value for proper exposure based on the subject brightness before 2R is pressed, and the pixel signal of the imaging pixel is read out from the imaging device 7 after the exposure time has elapsed, for still image recording. After the image processing is performed, image data is recorded on the recording medium. In parallel with this still image shooting operation, during the exposure operation of the image sensor 7, a focus lens focus adjustment operation (focus blur correction operation) is performed in steps S11 to S17. Therefore, during the still image shooting operation, that is, from the 2R depression (S9 Yes) to the end of the still image exposure (S17 Yes), the imaging pixels of the imaging device 7 photoelectrically convert the subject luminous flux and continue the charge accumulation. On the other hand, during the still image shooting operation, the AF pixels 5 or the ranging pixels of the image sensor 7 output ranging data at predetermined time intervals.

First, ranging data is acquired (S11). Here, as in step S3, distance measurement data is continuously acquired at regular intervals. When the distance measurement data is acquired, the defocus amount is calculated (S13). Here, as in step S5, the focus correction amount calculation unit 12 periodically calculates the defocus amount. Subsequently, focus lens driving is performed (S15). Here, as in step S7, the focus lens is periodically moved to the in-focus position by the focus lens drive amount calculation unit 15 and the optical system drive unit 3.

Once the focus lens is driven, it is next determined whether or not the still image exposure is completed (S17). When the exposure time elapses and the shutter 6 is closed, the still image exposure is completed. If the result of this determination is that the still image exposure has not been completed, the process returns to step S11, and steps S11 to S15 are repeated at predetermined time intervals to maintain the focus lens at the in-focus position. When the still image exposure is finished, this flow is finished.

In the flow shown in FIG. 4, steps S3 to S7 and steps S11 to S15 are the same process. However, in the present embodiment, as shown in FIGS. 1 and 2, distance measurement data can be acquired using the distance measurement pixels of the AF sensor 5 or the image sensor 7 even during still image exposure. For this reason, it is possible to perform out-of-focus correction even during still image exposure.

Next, using the timing chart shown in FIG. 5, the operation of defocus correction during the still image exposure shown in FIG. 4 will be described. In FIG. 5, the horizontal axis indicates the passage of time, and the vertical axis indicates the operation content of the camera, the output of the image sensor 7 or the AF sensor 5, the processing content of the system control CPU 10, and the operation content of the focus lens, respectively. Show.

In FIG. 5, the time point “1R” indicates a time point when the release button is half-pressed, and corresponds to a time point when it is determined that the 1R button is pressed in step S1 of FIG. When it is determined that 1R is depressed, the system control CPU 10 periodically calculates the defocus amount by using the distance measurement data from the AF sensor 5 or the imaging sensor 7. Then, the focus lens is periodically driven. The downward arrow from the distance measurement data to the defocus amount calculation shown in FIG. 5 indicates the time point at which the defocus amount is calculated periodically using the distance measurement data.

In FIG. 5, “2R” indicates a time point when the release button is fully pressed, and corresponds to a time point when it is determined that 2R is pressed in step S9 of FIG. If 2R depression is determined, an exposure operation is performed for still image shooting, and distance measurement data is periodically acquired in parallel with this. Then, the focus lens is driven using the defocus amount calculated from the distance measurement data. The downward arrow from the distance measurement data to the defocus amount calculation shown in FIG. 5 indicates the timing at which the defocus amount is periodically calculated using the distance measurement data even after the start of still image shooting. While the image sensor exposes the subject image, this exposure operation is independently performed in parallel to detect distance measurement data.

As described above, in the present embodiment and the modification thereof, the defocus detection unit (for example, the AF sensor 5, the distance measurement data detection unit 11, the image sensor 7 and the distance measurement which can detect the defocus amount during exposure). A focus control unit (for example, focus lens drive) that performs defocus detection during exposure and correction drive of the focus lens position at predetermined time intervals based on the detection result. A quantity calculating unit 15 and an optical system driving unit 3).

Specifically, the above-described defocus detection unit includes an image separation unit (half mirror 4) and a focus sensor (ranging pixel (phase difference sensor) of the image sensor 7). As another example of the defocus detection unit, an imaging element having imaging pixels and ranging pixels (pupil eccentricity, pupil division, etc.) on the imaging surface is configured. In addition, it has a pixel readout circuit for reading out pixel signals from the image sensor, and this pixel readout circuit has a readout circuit for imaging pixels and a readout circuit for pixels for distance measurement, each of which is provided with an independent readout circuit. ing. A pixel output is obtained independently by each readout control. This makes it possible to detect a change in the defocus state (defocus amount and defocus method) with time during still image shooting exposure.

As described above, in the present embodiment and the modification thereof, the positional relationship between the subject before exposure and the camera is maintained, so that the focus shift due to the shake during the exposure is corrected and the focus accuracy is improved. Furthermore, since it is possible to follow not only camera shake fluctuation in the optical axis direction but also subject fluctuation, the out-of-focus in still image shooting is further reduced.

Next, a second embodiment of the present invention and its modification will be described with reference to FIGS. In this embodiment and the modification, in addition to the detection result by the distance measurement sensor (AF sensor 5 or the distance measurement pixel of the image sensor 7), the detection result by the acceleration sensor is used for the focus adjustment of the focus lens.

FIG. 6 is a block diagram mainly showing an electrical configuration of the second embodiment. Compared to the block diagram in the first embodiment shown in FIG. 1, an acceleration sensor 8 and an acceleration data detection unit 17 are added in the second embodiment. Furthermore, the difference is that the focus correction amount calculation unit 12 in the first embodiment is replaced with a focus correction amount calculation unit 18.

The acceleration sensor 8 detects the translational motion applied to the camera as acceleration and outputs it to the system control CPU 10. The acceleration information includes X-axis information in the horizontal direction of the camera, Y-axis information in the vertical direction, and Z-axis information in the optical axis direction. In the present embodiment, only the Z axis (optical axis) is described, and thus the description of the X axis and the Y axis is omitted.

The acceleration data detection unit 17 may have an acceleration data detection circuit, and outputs acceleration information in the optical axis direction based on an electrical signal obtained from the acceleration sensor 8. When the acceleration information is integrated once with time, it becomes speed information, and when the speed information is integrated with time once, it becomes distance information. That is, the time change of the distance between the camera and the subject can be detected by integrating the acceleration information twice. In the present embodiment, the function of the acceleration data detection unit 17 is realized by the system control CPU 10 mainly based on a program. However, an acceleration data detection circuit is provided as a peripheral circuit of the system control CPU 10 (controller). It may be realized.

The acceleration data detection unit 17 functions as a movement amount detection unit that detects the movement amount of the focus lens in the optical axis direction. The system control CPU 10 functions as a focus control unit. Then, the focus control unit calculates the movement amount with respect to the focus driving unit based on the subject distance detected by the distance measurement unit, the movement amount of the focus lens in the optical axis direction detected by the movement amount detection unit, and the focus lens focus position. Output (for example, see S35 to S43 in FIG. 10). The movement amount detection unit described above calculates a correction value based on the acceleration sensor 8 that detects the movement acceleration in the optical axis direction and the acceleration output of the acceleration sensor based on the subject distance detected by the distance measurement unit, and uses the correction value as an acceleration. An acceleration correction unit that calculates by adding or subtracting to the output is included (see, for example, S27 and S37 in FIG. 10).

The focus correction amount calculation unit 18 calculates the focus correction amount in the optical axis direction based on the acceleration information in the optical axis direction detected by the acceleration data detection unit 17. As described above, the focus correction amount is calculated by integrating the acceleration information twice over time. Specifically, the focus correction amount is calculated using the distance measurement data to calculate the absolute speed at the start of exposure and the absolute acceleration (reference point correction), respectively, and use it to calculate the focus correction amount. is doing. The calculation of the focus correction amount will be described later with reference to FIGS.

FIG. 7 is a block diagram showing a modification of the second embodiment. Many of the blocks shown in FIG. 7 are the same as the block diagram shown in FIG. The only difference is that the acceleration sensor 8 and the acceleration data detection unit 17 are added and replaced with a focus correction amount calculation unit 18. Since this difference is the same as the configuration shown in FIG. 6, detailed description thereof is omitted.

Next, the details of the function of the focus correction amount calculation unit 18 will be described with reference to FIG. FIG. 8 is a block diagram showing details of the function of the focus correction amount calculation unit 18, and includes acceleration data 181, distance measurement data 182, speed conversion unit 183, acceleration conversion unit 184, acceleration data (after reference point correction) 185, And a defocus amount calculation unit 186. In the present embodiment, each block is realized by software according to the CPU of the system control CPU 10 according to a program, but is not limited thereto, and may be realized by a peripheral circuit, or by a combination of a program and a peripheral circuit. May be.

The acceleration data 181 is acceleration information in the optical axis direction of the optical system 2 and is obtained from the acceleration sensor 8 shown in FIGS.

In the second embodiment shown in FIG. 6, the distance measurement data 181 corresponds to data output from the distance measurement data detection unit 11 that processes an electrical signal output from the AF sensor 5. In the modification shown in FIG. 7, the distance measurement data 181 corresponds to data output from the distance measurement pixel control unit 16 that processes an electric signal from the distance measurement pixel of the image sensor 7.

The speed conversion unit 183 can receive the distance measurement data 182 and convert it into speed data by differentiating it at a certain time. For example, if a difference between a certain time and distance measurement data at a time after a predetermined time is divided by a predetermined time, it can be converted into speed data.

The acceleration conversion unit 184 can convert the converted velocity data 183 into acceleration data 184 by differentiating the converted velocity data 183 over a certain period. For example, if a difference between speed data at a certain time and speed data at a subsequent time is divided by a predetermined time, it can be converted into acceleration data before reference point correction.

The acceleration data calculation unit 185 is generated from the acceleration data 181 generated from the acceleration sensor 8 and the ranging pixels of the AF sensor 5 or the image sensor 7 and further converted by the acceleration conversion unit 184 before the reference point correction. The acceleration data after the reference point correction is calculated using the two acceleration data.

The defocus amount calculation unit 186 uses the acceleration data after the reference point correction calculated by the acceleration data calculation unit 185 and the absolute speed at the time immediately before the exposure time converted by the speed conversion unit 183. Calculate the defocus amount.

Next, using the timing chart shown in FIG. 9, the method for calculating the acceleration data after the reference point correction calculated by the acceleration data calculation unit 185 shown in FIG. 8 and the defocus amount of the defocus amount calculation unit 186 are calculated. A calculation method will be described.

First, calculation of the reference sensor error and absolute velocity of the acceleration sensor using the acceleration data 181 and the distance measurement data 182 before still image exposure will be described. The distance measurement data acquired at a certain distance measurement interval T is defined as X1, X2, and X3 (see A in FIG. 9). From these values, speed data V1 and V2 are calculated by (Expression 1) and (Expression 2).
V1 = (X2-X1) / T (Equation 1)
V2 = (X3-X2) / T (Equation 2)

According to (Expression 2), V2 is calculated as the speed data immediately before the still image exposure. The speed data V2 is used as an absolute speed at the start of exposure. Further, the acceleration data A_ave is calculated from (Equation 3) using the speed data V1 and V2.
A_ave = (V2-V1) / T (Equation 3)

Next, an acceleration average value a_ave before the still image exposure is obtained using the acceleration data 181 (see B in FIG. 9). The acceleration average value a_ave is an average value of the acceleration data a1 to a13 during the data acquisition period of X1 to X3 used in the distance measurement data (Formula 4). In the example shown in FIG. 9, 13 pieces of acceleration data up to a13 are used. In FIG. 9B, an (n is 1 to 20) represents acceleration data before reference point correction.
a_ave = Σ (an) / n (Formula 4)

Using A_ave and a_ave calculated in

Equations

3 and 4, the reference point error can be calculated from (Equation 5). This reference point error is the difference between the acceleration calculated from the distance measurement data and the acceleration calculated from the acceleration data. Originally, it is preferable that both coincide. However, since an offset is superimposed on the output of the acceleration sensor 8, there is a difference (difference) between the acceleration values. In calculating the defocus amount based on the acceleration data, the offset deviation is corrected using the reference point error.
Reference point error = a_ave-A_ave (5)

Acceleration data (an ′) after the start of still image exposure can be calculated from the following (formula 6). That is, a value obtained by subtracting the reference point error calculated by (Equation 5) from the acceleration data 181 (an in FIG. 9) is set as acceleration data after reference point correction. That is, the reference point correction of the acceleration sensor is performed on the acceleration data a1 to a13 using the reference point error.
an '= an-reference point error ... (Formula 6)
Note that in B in FIG. 9, an ′ (n is 13 to 20) represents acceleration data after reference point correction.

Note that by obtaining the acceleration data after the reference point correction, the defocus amount calculation unit 186 uses the acceleration data after the reference point correction and the absolute velocity V2 immediately before the exposure obtained in (Expression 2), 7), a highly accurate defocus amount can be calculated.
Defocus amount = ∫ (V2 + ∫an ') (Equation 7)

In Expression 7, after the defocus amount is calculated, the focus lens drive amount calculation unit 15 converts the calculated defocus amount into an amount necessary for driving the focus lens, and performs drive conversion. Calculate the position or drive amount.

Next, the processing for correcting the out-of-focus blur during still image exposure according to the present embodiment will be described with reference to the flowchart shown in FIG. As in the case of the first embodiment, this control flow indicates that the system control CPU 10 controls each part in the camera body 1 according to a program stored in the nonvolatile memory.

When the flow shown in FIG. 10 is started, first, similarly to step S1, it is determined whether or not 1R is depressed (S21). Here, it is determined whether or not the user has pressed the release button halfway. If 1R depression is not detected, a standby state is entered.

If the result of determination in step S1 is that 1R has been depressed, an autofocus operation (AF operation) is started, and acceleration data (an) is first acquired (S23). Here, the acceleration data detection unit 17 acquires acceleration data (an) from the acceleration sensor 8 at regular intervals (every distance measurement interval T).

Subsequently, ranging data (Xn) is acquired (S25). Here, the ranging data detection unit 11 or the ranging pixel control unit 16 acquires the ranging data. While the 1R button is pressed, distance measurement data is continuously acquired at regular intervals. As can be seen from FIGS. 9A and 9B, the timing for obtaining the distance measurement data and the acceleration data is different. Both acquire data appropriately according to a preset period.

When the acceleration data (an) and distance measurement data (Xn) are acquired, a reference point error is calculated (S27). Here, the reference point error is calculated using Equation 5 as described with reference to FIG. The reference point error is sequentially updated using the most recently acquired data.

Subsequently, the defocus amount is calculated (S29). Here, the focus correction amount calculation unit 21 calculates the defocus amount using the distance measurement data (Xn) acquired in step S25.

Once the defocus amount is calculated, the focus lens is driven (S31). Here, the focus lens drive amount calculation unit 15 calculates the drive position or drive amount of the focus lens, and the optical system drive unit 3 moves the focus lens to the focus position.

Once the focus lens is driven, it is next determined whether or not the 2R has been depressed (S33), as in step S9. When the user intends to shoot a still image, the user fully presses the release button. In this step, it is determined whether or not the release button has been fully pressed. If the result of determination in step S33 is that there has been no 2R depression, processing returns to step S23 and the above operation is repeated to maintain the focus lens in the in-focus position. Note that, as in the first embodiment, while the 1R button is pressed, the operation of continuously acquiring acceleration data and distance measurement data at regular intervals is an example. Without being limited to this operation procedure, during live view shooting, it may be an operation of continuously acquiring acceleration data and distance measurement data at regular intervals regardless of whether or not the 1R button is pressed.

If the result of determination in step S33 is that there has been 2R depression, the operation proceeds to a still image shooting operation, as in the first embodiment. In parallel with the still image shooting operation, during the exposure operation of the image sensor 7, a focus lens focus adjustment operation (focus blur correction operation) is performed in steps S35 to S41. Immediately after the 2R button is pressed, the latest reference point error (immediately before the still image exposure) calculated in S27 and the absolute velocity V2 (calculated by Expression 2) are held while the 1R button is pressed. This is for use in calculating the defocus amount during still image exposure.

Acceleration data (an) is acquired (S35). During the still image exposure period after the 2R button is pressed, acceleration data (an) is continuously acquired at regular intervals. Further, acceleration data (an ') is calculated (S37). Here, using the reference point error, acceleration data (an ′) after the reference point correction is calculated using Equation 6.

Next, the defocus amount is calculated (S39). Here, the focus correction amount calculation unit 18 periodically calculates the defocus amount using the acceleration data (an ′) acquired in step S35 and the absolute velocity V2 calculated in step S37 according to Equation 7.

When the defocus amount is calculated, the focus lens is then driven (S41). Here, the focus lens drive amount calculation unit 15 and the optical system drive unit 3 regularly drive the focus lens of the optical system 2 using the defocus amount obtained in step S39.

When the focus lens is driven, it is next determined whether or not the still image exposure is completed (S43). In this determination, when the exposure time has elapsed and the shutter 6 is closed, it is determined that the still image exposure has been completed. If the result of this determination is that the still image exposure has not been completed, the process returns to step S35, and steps S35 to S41 are repeated at predetermined time intervals to maintain the focus lens at the in-focus position even during still image exposure. To do. When the still image exposure is completed as a result of the determination in step S43, this flow is terminated.

As described above, in the second embodiment and the modification thereof, the reference point correction of the acceleration data is performed by using the distance measurement data for the focus correction in the optical axis direction, thereby improving the reference point accuracy of the acceleration sensor. Realizes highly accurate focus correction. The problem that the position accuracy of the acceleration sensor in the prior art is low can be solved.

In the present embodiment and its modifications, the acceleration sensor 8 is used in addition to the distance measuring function (sensor) as the defocus detection unit, and a correction unit that corrects (calibrates) the detection value in a complementary manner is provided. Yes. Defocus amount detection during exposure is mainly calculated from the output of the acceleration sensor, but the offset from the acceleration sensor output due to time changes occurs, so information from the distance measurement sensor obtained in the same detection period Is used to calibrate the offset deviation of the acceleration sensor output.

In the second embodiment, detection of a defocus amount based on an acceleration sensor output is used as a main detection unit, and detection unit is used as a sub-defocus amount of a distance measuring sensor. Such proper use is from the following viewpoints (i) and (ii).

(I) When using a distance measuring sensor, the exposure amount is low (exposure time is short (Tv value indicated by APEX value is short), subject luminance B is low (Bv value indicated by APEX value is small)), etc. In the state of the photographing condition, the sensor signal output of the distance measuring sensor becomes low, and it becomes difficult to detect the defocus amount. For this reason, it is necessary to increase the sampling time (accumulation time).

(Ii) When an acceleration sensor is used, a change in posture (defocus amount) can be detected regardless of shooting conditions. However, when the detection time of the acceleration sensor becomes long, the detection accuracy shifts due to the offset shift of the acceleration sensor.

For this reason, in the second embodiment, the defocus amount is mainly detected by the output of the acceleration sensor, and the offset deviation that occurs during long-time use is calibrated using the output of the distance measuring sensor.

Next, a third embodiment of the present invention and its modification will be described with reference to FIGS. 11 to 15B. In the present embodiment and the modification, the output of either the distance measurement sensor or the acceleration sensor is selected and detected as a defocus amount detection unit according to the subject brightness and the exposure time.

FIG. 11 is a block diagram mainly showing an electrical configuration of the third embodiment. Compared to the block diagram in the second embodiment shown in FIG. 6, in the third embodiment, a photometric sensor 9 and an exposure control unit 19 are added, and the focus correction amount calculation unit 18 is replaced with a focus correction amount calculation unit 20. Is different.

The photometric sensor 9 is a sensor that acquires the luminance of the subject, and outputs the acquired luminance information to the exposure control unit 19. In addition, as an output of the photometric sensor 9, a pixel signal from an imaging pixel in the imaging device 7 may be used. In this case, luminance information of the subject can be acquired based on the pixel signal, Further, the photometric sensor 9 can be omitted. The photometric sensor 9 functions as a photometric unit that detects subject luminance.

The exposure control unit 19 calculates a shutter speed value, an aperture value, and an ISO sensitivity value during still image shooting based on the luminance information of the subject input from the photometric sensor 9, and controls the shutter 6 and the like based on these values. To do. The role of the exposure control unit 19 in this embodiment is that the focus correction unit uses the focus correction amount obtained from the acceleration sensor 8 based on the shutter speed value at the time of still image shooting, or the AF sensor 5 (described later). In the modification of the third embodiment, it is determined whether to use the focus correction amount obtained from the distance measuring element in the image sensor 7. This determination processing is performed by the focus correction amount calculation unit 20, and details will be described later with reference to FIGS. In the present embodiment, the function of the exposure control unit 19 is realized by the system control CPU 10 mainly based on a program. However, an acceleration data detection circuit is provided as a peripheral circuit of the system control CPU 10 (controller), and is realized by this circuit. May be.

The system control CPU 10 functioning as a focus control unit selects whether to select one or both of the detection values of the distance measurement unit and the movement amount detection unit for detection of the subject distance according to the subject luminance. It further has a selection part (for example, refer to S51 of Drawing 15A). Further, the system control CPU 10 functioning as a focus control unit performs control for moving the focus focus drive unit in a direction in which the subject distance and the focus position are matched based on the subject distance detected after being selected by the selection unit. (For example, see S53 to S59 in FIG. 15A and S63 to S71 in FIG. 15B).

FIG. 12 is a block diagram showing a modification of the third embodiment. Most of the blocks in FIG. 12 are the same as those in FIG. 7, and the only difference is that a photometric sensor 9 and an exposure control unit 19 are added and replaced with a focus correction amount calculation unit 20. Since this difference is the same as the configuration shown in FIG. 11, detailed description thereof is omitted.

Next, details of the function of the focus correction amount calculation unit 20 will be described with reference to FIG. FIG. 13 is a block diagram illustrating details of the function of the focus correction amount calculation unit 20. The focus correction amount calculation unit 20 includes distance measurement data 201, a speed conversion unit 202, an acceleration conversion unit 203, acceleration data 204, and acceleration data. A calculation unit (after reference point correction) 205, a defocus amount calculation unit (distance measurement) 206, a defocus amount calculation unit (acceleration) 207, and a focus correction unit switching unit 208 are included.

The block diagram shown in FIG. 13 combines FIG. 3 of the first embodiment and FIG. 8 of the second embodiment, and adds a focus correction unit switching unit 208 to this. That is, the distance measurement data 121 and the defocus amount calculation unit 122 in FIG. 3 correspond to the distance measurement data 201 and the defocus amount calculation unit 206 in FIG. In addition, the acceleration data 181, distance measurement data 182, speed conversion unit 183, acceleration conversion unit 184, acceleration data calculation unit 185, and defocus amount calculation unit 186 in FIG. , The speed conversion unit 202, the acceleration conversion unit 203, the acceleration data calculation unit 205, and the defocus amount calculation unit 207. Therefore, only the added focus correction unit switching unit 208 will be described with reference to FIG.

The focus correction unit switching unit 208 outputs the defocus amount obtained from the distance measurement data or the defocus amount obtained from the acceleration data based on the shutter speed information acquired from the exposure control unit 19 during still image shooting. Switch whether to do. In some cases, neither of the two is performed and focus correction is not performed. Details of this determination will be described later with reference to FIG.

The defocus amount selected and output by the focus correction unit switching unit 208 is converted into a unit for driving the focus lens by the focus lens driving amount calculation unit 15 to calculate a driving position or a driving amount. The lens-side optical system drive unit 3 uses the calculated drive position and drive amount to drive the focus of the optical system 2 to correct the focus in the optical axis direction during still image exposure.

Next, selection of the defocus amount calculated by the acceleration data calculation unit (ranging) 206 and the defocus amount calculation unit (acceleration) 207 shown in FIG. 13 will be described using the timing chart shown in FIG. . The defocus amount calculation method in the third embodiment is a combination of the defocus amount calculation methods in the first embodiment and the second embodiment. For this reason, the block diagram shown in FIG. 14 differs from the block diagram shown in FIG. 9 of the second embodiment in that the distance measurement data is acquired even during still image exposure. Therefore, the defocus amount calculation part during still image exposure will be described.

In FIG. 14, immediately after the 2R button is pressed (immediately after the start of still image exposure), the focus correction unit switching unit 208 outputs the defocus amount (Xn) obtained from the distance measurement data 201 or the defocus obtained from the acceleration data 204. Switching between output of the quantity (xn) is performed (see the shaded portion in FIG. 14). Details of this determination processing will be described later with reference to FIG.

The focus lens driving amount calculation unit 15 performs unit conversion for driving the focus lens based on the defocus amount calculated from the distance measurement data 201 or the acceleration data 204, and calculates a driving position or a driving amount.

Next, the process of correcting the out-of-focus blur during still image exposure in the present embodiment will be described using the flowcharts shown in FIGS. 15A and 15B. Similar to the first and second embodiments, this control flow is realized by the system control CPU 10 controlling each part in the camera body 1 in accordance with a program stored in the nonvolatile memory.

When the flow shown in FIG. 15A is started, the process is the same as steps S21 to S33 in the flow shown in FIG. 10 until it is determined whether or not 1R is pressed and whether or not 2R is pressed. Steps for performing the same processing are given the same step numbers, and detailed description is omitted.

Immediately after it is determined in step S33 that 2R has been pressed, the latest reference point error (just before the still image exposure) calculated in step S27 and absolute velocity V2 (see Equation 2) are held during 1R pressing. Keep it.

Subsequently, it is determined whether or not the subject has a brightness higher than a predetermined brightness (S51). Here, the determination is made based on the subject brightness calculated by the exposure control unit 19 based on the detection result of the photometric sensor 9. The predetermined luminance may be a luminance that allows the distance measurement data to be acquired by the AF sensor 5 or the image sensor 7 in a relatively short time. In other words, since the lower the luminance, the more easily affected by the noise component, the predetermined luminance is a subject luminance value that enables the distance measurement data obtained in a relatively short time to be sufficiently distinguished from the noise component. . In the present embodiment, the determination is made based on the brightness. However, the present invention is not limited to this, and the determination may be made based on the exposure amount Ev, or may be made based on other exposure control values.

If the result of determination in step S51 is that the subject has high brightness, distance measurement data (Xn) is acquired (S53). Here, distance measurement data is adopted from the AF sensor 5 (in the modification of the present embodiment, the distance measurement pixel of the image sensor 7). During still image exposure, distance measurement data is continuously acquired at regular intervals.

When the ranging data (Xn) is acquired, the defocus amount is calculated next, similarly to step S13 (see FIG. 4) (S55). Here, the focus correction amount calculation unit 20 periodically calculates the defocus amount using the distance measurement data (Xn) acquired in step S53.

Once the defocus amount has been calculated, the focus lens is then driven in the same manner as in step S15 (see FIG. 4) (S57). Here, the focus lens drive amount calculation unit 15 and the optical system drive unit 3 periodically move the focus lens to the in-focus position.

Once the focus lens is driven, it is next determined in step S17 (see FIG. 4) whether or not still image exposure has been completed (S51). When the exposure time elapses and the shutter 6 is closed, the still image exposure is completed. If the result of this determination is that the still image exposure has not ended, the process returns to step S53, and steps S53 to S59 are repeated at predetermined time intervals to maintain the focus lens at the in-focus position. When the still image exposure is finished, this flow is finished.

Returning to step S51, if the result of determination in this step is that the subject is not bright, it is determined whether or not the exposure time is shorter than a predetermined time (S61). Here, the determination is made based on the shutter speed value calculated by the exposure control unit 19 based on the detection result of the photometric sensor 9. The predetermined time may be a time that can maintain the reliability of the acceleration data by correcting the reference point. If the result of this determination is that the exposure time is not shorter than the predetermined time, the flow of out-of-focus during still image exposure is terminated without driving the defocus amount calculation and focusing lens.

If the result of determination in step S61 is that the exposure time is shorter than the predetermined time, acceleration data (an) is acquired as in step S35 (see FIG. 10) (S63). Here, the acceleration data (an) is continuously acquired from the acceleration sensor 8 and the acceleration data detection unit 17 at regular intervals during still image exposure.

Once the acceleration data (an) is acquired, next, acceleration data (an ') after the reference point correction is calculated (S65) as in step S37 (see FIG. 10). Here, the acceleration data (an ′) after the reference point correction is calculated according to Equation 6 using the reference point error stored immediately before 2R is pressed.

Subsequently, as in step S39 (see FIG. 10), the defocus amount is calculated (S67). Here, the focus correction amount calculation unit 20 periodically calculates the defocus amount according to Equation 7 using the acceleration data (an ′) and the absolute velocity V2.

Once the defocus amount has been calculated, the focus lens is then driven in the same manner as in step S41 (see FIG. 10) (S69). Here, the focus lens drive amount calculation unit 15 and the optical system drive unit 3 periodically drive the focus lens of the optical system 2 using the defocus amount calculated in step S65.

When the focus lens is driven, it is next determined whether or not the still image exposure is completed (S71). When the exposure time elapses and the shutter 6 is closed, the still image exposure is completed. If the result of this determination is that still image exposure has not ended, the process returns to step S63, and steps S63 to S71 are repeated at predetermined time intervals to maintain the focus lens in the in-focus position even during still image exposure. To do. When the still image exposure is finished, this flow is finished.

As described above, in the flow shown in FIGS. 15A and 15B, when the subject has high brightness (Yes in S51), focus adjustment control of the focus lens is performed using the distance measurement data (see S53 to S59). On the other hand, when the subject is not bright and the exposure time for still image shooting is short (S51 No → S61 Yes), focus adjustment control of the focus lens is performed using the acceleration data (see S63 to S71). If neither is found, neither the distance measurement data nor the acceleration data is used, and the subsequent processing is not performed.

The reason for determining whether or not the distance measurement data can be adopted based on the luminance of the subject is that if the subject has a low luminance, it is necessary to lengthen the distance sampling time in order to obtain the required accuracy of the distance measurement data. For this reason, the sampling time of the distance measurement cannot obtain the sampling time necessary for detecting the subject distance change due to the camera shake, and the accuracy of the distance measurement data is remarkably lowered. The reason for determining whether or not to adopt acceleration data based on the exposure time is that if the exposure time is long, the time-dependent change of the reference point of the acceleration sensor greatly affects the reliability of the acceleration data and the accuracy of focus correction This is because of the decrease.

As described above, in the third embodiment and the modification thereof, when the subject has low luminance and the distance sampling time becomes long, the acceleration sensor data is used for the exposure, even under dark conditions. Focus correction is possible.

Further, in the third embodiment and its modification, a detection unit (for example, see photometric sensor 9) that detects subject brightness, an exposure condition calculation (exposure time calculation) unit (for example, see exposure control unit 19), and A change unit (for example, a focus correction amount calculation unit 20; see S61 in FIG. 15B) that changes the calculation of the defocus amount based on the output of the acceleration sensor according to the exposure time is provided. By configuring in this way, based on the subject luminance detected by the detection unit, for example, even when setting an arbitrary exposure time in the program exposure mode, either the output of the acceleration sensor or the distance measurement data, By calculating the defocus amount by selecting the one that provides the optimum defocus amount, it is possible to perform focus correction during exposure without depending on the exposure conditions.

It is difficult to detect the defocus amount of the distance measuring sensor (AF sensor 5 and the distance measuring pixel of the image sensor 7) with a low exposure amount (a short exposure time and a low subject luminance). For this reason, it is necessary to extend the detection time (integration time). On the other hand, the acceleration sensor 8 can detect a posture change (defocus amount) regardless of the exposure amount. However, when the exposure time becomes longer, the acceleration sensor has a deviation in accuracy for detecting a change in posture due to an offset deviation in output. In this embodiment, the advantages and disadvantages of the two defocus detection units can be switched according to the conditions of subject brightness and exposure time.

If it is determined in step S61 (see FIG. 15B) that the exposure time is longer than the predetermined time, the defocus amount is not corrected by the acceleration data in step S63 and subsequent steps. However, it is not limited to this. As an example, the defocus amount is corrected in step S63 and subsequent steps until a predetermined time elapses after the exposure is started. Then, when a predetermined time has elapsed after the start of exposure, the defocus amount correction in step S63 and subsequent steps may not be performed.

As described above, in each embodiment and modification of the present invention, the defocus amount is exposed during the exposure period in the imaging apparatus having the focus driving unit (for example, the optical system driving unit 3) that drives the focus lens. A defocus detection unit (for example, a AF pixel 5 and a distance measuring pixel of the image sensor 7) that detects at a plurality of time points in a period, and a focus control unit that performs focus control using a defocus amount obtained during an exposure period (For example, the focus lens drive amount calculation unit 15). For this reason, it is possible to accurately detect the change of the focus state sequentially during the exposure and correct the focus shift sequentially and accurately. Even if the acceleration sensor 8 is not used, the focus shift can be corrected during exposure, and the in-focus state can be maintained even during shooting. In particular, in close-up shooting, in-focus shooting can be performed even in situations where the aperture value is small and the depth of field is shallow and the camera is susceptible to camera shake.

Further, in each embodiment or modification of the present invention, when a video signal is detected by an image sensor for a subject image formed by an optical lens including a focus lens, and the video signal is detected for recording (for example, 4 (see S9 Yes in FIG. 4), the subject distance between the imaging device and the subject is detected (see, for example, S11 in FIG. 4), and the subject distance obtained by detecting the subject distance and the focus lens focus position Based on the deviation amount, the movement amount with respect to the focus lens is calculated in the direction in which the subject distance and the focus position are matched (for example, S13 in FIG. 4), and the focus lens is moved based on the calculated movement amount. (For example, S15 in FIG. 4).

Further, in the second and third embodiments and modifications of the present invention, a movement amount detection unit (for example, acceleration data detection unit 17) for detecting the movement amount of the focus lens in the optical axis direction is provided, and this movement amount detection is performed. Output is corrected (for example, acceleration data calculation unit 185 in FIG. 8, S37 in FIG. 10). For this reason, when correcting the position of the focus lens based on the amount of movement of the focus lens in the optical axis direction, the focus adjustment is performed accurately even when the output of the movement amount detection unit is offset. Can do.

In each embodiment of the present invention, the subject light flux that has passed through the optical system 2 is guided to the AF sensor 5 using the half mirror 4. However, the present invention is not limited to this. For example, an optical system different from the optical system 2 may be provided to guide the subject light flux to the AF sensor 5. That is, a distance measuring optical system having an optical system different from the optical lens may be provided, and distance measurement may be performed based on subject light from a different path from the optical lens.

In the second and third embodiments and modifications of the present invention, the acceleration sensor 8 is provided to detect the movement amount of the focus lens in the optical axis direction. However, the present invention is not limited to this, and any sensor that can detect the amount of movement of the camera body 1 such as an angular velocity sensor or a gyro may be used.

In each embodiment and modification of the present invention, the system control CPU 10 as a controller realizes each part in the system control CPU 10 by a peripheral circuit, a CPU (Central Processing Unit), and a program code. However, the present invention is not limited to this, and the controller may be realized by a circuit executed by a program code such as DSP (Digital Signal Processor) or the like, and is generated based on a program language described by Verilog. A hardware configuration such as a gate circuit may be used. Of course, the controller may be executed by a hardware circuit. Further, a part of the function of the system control CPU 10 may be realized by a circuit executed by a program code such as a DSP, or hardware such as a gate circuit generated based on a program language described by Verilog. It may be configured, or may be realized by a hardware circuit.

In each embodiment and modification of the present invention, a digital camera is used as an apparatus for photographing. Examples of digital cameras may be digital single-lens reflex cameras, mirrorless cameras, compact digital cameras, video cameras such as video cameras and movie cameras, and mobile phones, smartphones, personal digital assistants, personal computers A computer (PC), a tablet computer, a camera built in a game machine, a medical camera, a camera for a scientific instrument such as a microscope, a car-mounted camera, or a monitoring camera may be used. In any case, the present invention can be applied to any device capable of photographing.

Of the techniques described in this specification, the control mainly described in the flowchart is often settable by a program and may be stored in a recording medium or a recording unit. The recording method for the recording medium and the recording unit may be recorded at the time of product shipment, may be a distributed recording medium, or may be downloaded via the Internet.

In addition, regarding the operation flow in the claims, the specification, and the drawings, even if it is described using words expressing the order such as “first”, “next”, etc. It does not mean that it is essential to implement in this order.

The present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, you may delete some components of all the components shown by embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

DESCRIPTION OF SYMBOLS 1 ... Camera body, 2 ... Optical system, 3 ... Optical system drive part, 4 ... Half mirror, 5 ... AF sensor, 6 ... Shutter, 7 ... Image sensor, DESCRIPTION OF SYMBOLS 8 ... Acceleration sensor, 9 ... Photometry sensor, 10 ... System control CPU, 11 ... Distance measurement data detection part, 12 ... Focus correction amount calculation part, 13 ... Shutter control part, 14 ... Image pickup pixel control unit, 15 ... Focus lens drive amount calculation unit, 16 ... Distance measuring pixel control unit, 17 ... Acceleration data detection unit, 18 ... Focus correction amount calculation unit, 19 ... Exposure control unit, 20 ... Focus correction amount calculation unit

Claims

An optical lens including a focus lens that changes a focus state of a subject to be imaged;
A focus drive unit for moving the focus lens in the optical axis direction;
An image sensor that exposes a subject image formed by the optical lens and converts it into a video signal;
A distance measuring unit for detecting a subject distance between the imaging device and the subject;
A focus control unit that controls the amount of movement of the focus lens by the focus driving unit based on the subject distance detected by the distance measuring unit and the focus position of the focus lens;
Have
The focus control unit is based on the amount of deviation between the subject distance detected by the distance measuring unit and the focus position of the focus lens while the image sensor exposes the subject image for recording the video signal. An image pickup apparatus, wherein the focus drive unit is controlled to move the focus focus in a direction in which the subject distance and the focus position are matched.
2. The imaging according to claim 1, wherein the distance measuring unit performs an operation of detecting a subject distance in parallel with the exposure operation while the imaging element exposes the subject image. apparatus.
The imaging element includes a ranging pixel on the imaging surface and a non-ranging pixel that outputs an image signal from the subject image.
A pixel output circuit that independently reads the detection signal from the ranging pixel and the detection signal to the non-ranging pixel;
The distance measuring unit can independently read out a pixel signal output from the distance measuring pixel while the non-range pixel is performing an exposure operation, detect a subject distance, and obtain a result. The imaging device according to claim 1 or 2.
A part of the subject image incident by the optical system is incident on the imaging surface of the image sensor, and a different part of the subject image is divided in a direction different from the incident direction of the imaging surface, A spectroscopic unit for guiding a part of the subject image;
The imaging apparatus according to claim 1, wherein the distance measuring unit detects a subject distance by a distance measuring sensor different from the image sensor.
The distance measuring unit further includes a distance measuring optical system having an optical system different from the optical lens,
The imaging apparatus according to claim 1, wherein the distance is measured based on subject light from a different path from the optical lens.
A movement amount detector for detecting the movement amount of the focus lens in the optical axis direction;
The focus control unit is configured to drive the focus based on the subject distance detected by the distance measuring unit, the movement amount of the focus lens in the optical axis direction detected by the movement amount detection unit, and the focus position of the focus lens. The imaging apparatus according to claim 1, wherein a movement amount with respect to the unit is output.
The movement amount detection unit is
An acceleration sensor for detecting movement acceleration in the optical axis direction;
An acceleration correction unit for calculating an acceleration output of the acceleration sensor based on a subject distance detected by the distance measuring unit, and calculating by adding or subtracting the correction value to or from the acceleration output;
The imaging apparatus according to claim 6, further comprising:
A metering unit for detecting the subject brightness;
Further comprising
The focus control unit is a selection unit that selects whether one or both of the detection values of the distance measurement unit and the movement amount detection unit are selected for the detection of the subject distance according to the subject luminance. And further
The focus control unit performs control to move the focus driving unit in a direction in which the subject distance matches the focus position based on a subject distance detected after being selected by the selection unit. The imaging apparatus according to claim 6 or 7.
A video signal is detected by the image sensor using the image sensor, which is formed by the optical lens including the focus lens.
When detecting the video signal for recording, the subject distance between the imaging device and the subject is detected,
Based on the detected subject distance and the shift amount between the focus position of the focus lens, the amount of movement with respect to the focus lens is calculated in a direction in which the subject distance and the focus position are matched,
Moving the focus lens based on the calculated amount of movement;
A focus adjustment method for an image pickup apparatus.
10. The focus adjustment method according to claim 9, wherein an operation for detecting a subject distance is performed in parallel with the exposure operation while the image pickup device exposes the subject image.
The imaging element includes a ranging pixel on the imaging surface and a non-ranging pixel that outputs an image signal from the subject image.
The detection signal from the ranging pixel and the detection signal to the non-ranging pixel are read out independently,
11. The pixel signal output from the ranging pixel is read independently while the non-ranging pixel is performing an exposure operation, the subject distance is detected, and the result is obtained. The focus adjustment method described in 1.
Detect the amount of movement of the focus lens in the optical axis direction,
The movement amount with respect to the focus driving unit is output based on the detected subject distance, the detected movement amount of the focus lens in the optical axis direction, and the focus position of the focus lens. The focus adjustment method described.
It has an acceleration sensor that detects movement acceleration in the optical axis direction,
13. The focus adjustment according to claim 12, wherein the acceleration output of the acceleration sensor is calculated by calculating a correction value based on the detected subject distance and adding or subtracting the correction value to or from the acceleration output. Method.
A metering unit for detecting the subject brightness;
According to the subject brightness, select whether to detect the subject distance based on one or both of the detection value of the video signal or the acceleration sensor,
The focus adjustment according to claim 13, wherein the focus lens is controlled to move in a direction in which the subject distance and the focus position coincide with each other based on the subject distance detected after the selection. Method.