JP7014255B2 - Focus detector and image pickup device - Google Patents

Description

The present invention relates to a focus detection device and an image pickup device.

In the general focus detection process of the mountain climbing contrast method, the high frequency component of the image captured by the image sensor is sharply replaced while performing the so-called wobbling operation in which the optical system for focus adjustment is moved back and forth in small steps during the mountain climbing operation. The focus evaluation value is acquired sequentially. Then, the drive direction and the in-focus position of the optical system for focus adjustment are determined from the change in the focus evaluation value.

The interchangeable lens of a digital single-lens reflex camera has a large weight of the focus lens, which is the optical system for adjusting the focus. Therefore, there are problems that the wobbling operation cannot be performed at high speed when the wobbling operation is performed using the focus lens, and that the driving sound and vibration of the focus lens are generated during the mountain climbing operation. The driving sound and vibration of the focus lens are particularly noticeable when the focus lens is accelerated or decelerated.

Regarding the problem of wobbling operation speed, Patent Document 1 discloses a method of performing high-speed wobbling operation by minutely driving an optical system or an image pickup element having a mass smaller than that of a focus lens in the optical axis direction. ..

Patent No. 4437244

With conventional technology, the focus lens may stop past the in-focus position.

The focus detection device according to the first aspect of the present invention is based on an image pickup element that captures an image by an optical system having a first lens and a second lens and outputs a signal, and a signal output from the image pickup element. The evaluation value calculation unit that calculates the evaluation value of the generated image, the instruction unit that instructs the focusing operation for focusing the image of the optical system on the image pickup element, and the instruction unit indicate the focusing operation. The control unit includes a control unit that calculates the evaluation value a plurality of times while moving the first lens in one direction, and the control unit stops the first lens after the evaluation value starts to decrease. The first control of moving the second lens so that the evaluation value is increased, and the first control of moving the first lens in one direction while moving the second lens in the first direction and in the direction opposite to the first direction. The second control of repeatedly moving the lens in two directions is performed.
The focus detection device according to the second aspect of the present invention is based on an image pickup element that captures an image by an optical system having a first lens and a second lens and outputs a signal, and a signal output from the image pickup element. The evaluation value calculation unit that calculates the evaluation value of the generated image, the instruction unit that instructs the focusing operation for focusing the image of the optical system on the image pickup element, and the instruction unit indicate the focusing operation. And a control unit that calculates the evaluation value a plurality of times while moving the first lens in one direction, and the control unit stops the first lens when the evaluation value starts to decrease. The first control to move the second lens after stopping the first lens, and the second lens in the direction opposite to the first direction and the first direction while moving the first lens in one direction. The second control of repeatedly moving the lens in the second direction is performed, and the control unit performs the movement amount of the image of the optical system per unit movement amount of the first lens and the second control in the first control. The second lens is moved based on the amount of movement of the image of the optical system per unit movement amount of the lens, and the control unit moves the optical system by moving the second lens in the first control. The second lens is driven so that the direction in which the image moves is opposite to the direction in which the image of the optical system moves due to the movement of the first lens .

The image pickup device according to the third aspect of the present invention has a focus detection device according to any one of the first and second aspects.

According to the present invention, it is possible to focus appropriately.

It is a block block diagram of the digital camera by 1st Embodiment of this invention. It is a figure explaining the drive of a focus lens and a wobbling lens. It is a flowchart of the focus detection process in 1st Embodiment of this invention. It is a figure for demonstrating the peak detection of a focus evaluation value. It is a figure explaining the operation of each optical system in the focal point detection process in 1st Embodiment of this invention. It is a modification of the flowchart of the focus detection process in the 1st Embodiment of this invention. It is a figure explaining the operation of each optical system in the focal point detection process in the 2nd Embodiment of this invention. It is a flowchart of the focus detection process in the 2nd Embodiment of this invention. It is a modification of the flowchart of the focus detection process in the 2nd Embodiment of this invention. It is a figure explaining the operation of each optical system in the focal point detection process in the 3rd Embodiment of this invention. It is a flowchart of the focus detection process in 3rd Embodiment of this invention. It is a block block diagram of the digital camera by 4th Embodiment of this invention. It is a figure explaining the drive of a focus lens and an image pickup element. It is a flowchart of the focus detection process in 4th Embodiment of this invention. It is a figure explaining the operation of each optical system in the focal point detection process in 4th Embodiment of this invention. It is a modification of the flowchart of the focus detection process in the 4th Embodiment of this invention.

(First Embodiment)
FIG. 1 is a block diagram of an interchangeable lens digital camera equipped with a focus adjustment device according to the first embodiment of the present invention. The interchangeable lens digital camera of FIG. 1 includes a camera body 100 and a photographing lens 200. The photographing lens 200 is detachably attached to the camera body 100.

The photographing lens 200 has a focus lens 210 for adjusting the focus, a focus lens drive unit 211 composed of a motor and a drive circuit for driving the focus lens 210, and a position for detecting the position of the focus lens 210 in the optical axis direction. It has a detection unit 212. Further, the photographing lens 200 detects the position of the wobbling lens 220 for performing the wobbling operation, the wobbling lens driving unit 221 including the motor and the driving circuit for driving the wobbling lens 220, and the wobbling lens 220 in the optical axis direction. It has a position detection unit 222 and a position detection unit 222. The positive / negative of the power of the focus lens 210 (whether the focus lens 210 is a convex lens or a concave lens) and the positive / negative of the power of the wobbling lens 220 (whether the wobbling lens 220 is a convex lens or a concave lens) match. And.

Further, the photographing lens 200 has a lens controller 250. The lens controller 250 calculates the target position or drive speed of the focus lens 210 and the wobbling lens 220 in the photographing lens 200 according to the instruction from the camera body 100, and outputs the lens from the position detection units 212 and 222 of each lens. Positioning control of the focus lens 210 and the wobbling lens 220 is executed while feeding back the position information.

The lens controller 250 adjusts the focus by driving the focus lens 210 with the focus lens driving unit 211 or driving the wobbling lens 220 with the wobbling lens driving unit 221.

The camera body 100 includes an image pickup element 101, an analog signal processing unit 102, an A / D converter 103, a digital signal processing unit 111, a buffer memory 112, an Enc / Dec processing unit 113, an external storage medium 115, a VRAM 120, and an LCD monitor 121. It has a body controller 150 and an operation unit 180.

The image pickup element 101 is composed of a CCD image pickup element, a MOS type image pickup element, and the like. The subject image imaged by the photographing lens 200 is projected onto the image pickup surface of the image pickup element 101. The image pickup element 101 outputs an electric signal (imaging signal) corresponding to the light intensity of the subject image formed on the image pickup surface to the analog signal processing unit 102.

The analog signal processing unit 102 includes a CDS circuit, an AGC circuit, a color separation circuit, and the like, and performs various analog signal processing on the image pickup signal output from the image pickup element 101. The image pickup signal processed by the analog signal processing unit 102 is output to the A / D converter 103. The A / D converter 103 converts the image pickup signal processed by the analog signal processing unit 102 from an analog signal to a digital signal. The image pickup signal A / D converted by the A / D converter 103 is input to the digital signal processing unit 111 and the body controller 150.

The digital signal processing unit 111 includes a signal processing circuit such as a gain control circuit, a luminance signal generation circuit, and a color difference signal generation circuit. The digital signal processing unit 111 performs various image processing such as contour enhancement, gamma correction, and white balance adjustment on the image pickup signal A / D converted by the A / D converter 103.

The buffer memory 112 is a frame memory capable of storing data for a plurality of frames captured by the image pickup device 101. The digital signal processing unit 111 uses the buffer memory 112 as a working area when performing various image processing such as contour enhancement, gamma correction, and white balance adjustment. The image pickup signal input to the digital signal processing unit 111 is stored in the buffer memory 112. The image pickup signal stored in the buffer memory 112 is read out each time various image processes such as contour enhancement, gamma correction, and white balance adjustment are performed, and the processed image pickup signal is stored in the buffer memory 112. The image pickup signal that has been subjected to a series of processing by the digital signal processing unit 111 and stored in the buffer memory 112 is output to the Enc / Dec processing unit 113.

The Enc / Dec processing unit 113 performs a series of processing by the digital signal processing unit 111, data-encodes the image pickup signal stored in the buffer memory 112 into a predetermined data format, and performs data encoding processing on the external image data such as a memory card. Record on the storage medium 115. The data format encoded by the Enc / Dec processing unit 113 is, for example, a JPEG format for still images and a format such as MPEG2 or H264 / AVC for moving images. Further, the Enc / Dec processing unit 113 performs data decoding processing when reading the image data having been encoded from the external storage medium 115. The Enc / Dec processing unit 113 also includes an interface for performing data communication with the external storage medium 115.

The image pickup signal captured by the image pickup element 101 at predetermined time intervals is signal-processed by the analog signal processing circuit 102, the A / D converter 103, and the digital signal processing circuit 111, and then transferred to the VRAM 120. The transferred image data is stored in the VRAM 120. The LCD monitor 121 functions as an EVF (Electronic Viewfinder) at the time of shooting, and the image data stored in the VRAM 120 is displayed as an image called a through image. Further, the LCD monitor 121 can display the image data stored in the external storage medium 115 as an image. In the LCD monitor 121, the image data read from the external storage medium 115 is transferred to the VRAM 120 and reproduced and displayed on the LCD monitor 121.

The body controller 150 includes a focus evaluation calculation unit 151, an AE calculation unit 152, an AWB calculation unit 153, and other calculation units, and controls the entire camera. The body controller 150 can give a drive instruction to the focus lens 210 and the wobbling lens 220 via the lens controller 250.

The focus evaluation value calculation unit 151 extracts a predetermined high frequency component from the spatial frequency of the image data of the AF area preset on the imaging screen, and integrates the absolute value of the extracted high frequency component to obtain the focus evaluation value. Is calculated. When a plurality of AF areas of a predetermined size are arranged at a predetermined position on the image pickup screen, the integrated value of these multiple AF areas is the focus evaluation value, and the AF area or the specific subject area set as the AF area. It shows the contrast of the image in.

The AE calculation unit 152 performs an automatic exposure calculation for shooting a subject with an appropriate exposure based on an image pickup signal from the A / D converter 103. The AWB calculation unit 153 sets the white balance adjustment gain based on the image signals (R, G, B signals) from the A / D converter 103.

The operation unit 180 is an operation member for performing operation instructions and various settings by the user, and is, for example, a release button, a moving image recording start / stop button, a setting button for performing various settings, and the like.

FIG. 2 is a diagram for explaining driving of the focus lens 210 and the wobbling lens 220 in the first embodiment. FIG. 2A shows a drive range 21 of the focus lens 210 and a drive range 22 of the wobbling lens 220. The drive range 21 has an infinity side end 21b on the subject side and a close end 21a on the image pickup element side. The drive range 22 has an infinity side end 22b on the subject side and a close end 22a on the image pickup element side.

When the focus lens 210 is driven toward the image sensor 101 along the optical axis 20, it focuses on the subject on the closest side, and conversely, when it is driven toward the subject along the optical axis 20, it focuses on the subject on the infinity side. And. It is assumed that the focusing position of the photographing lens 200 is simply moved by driving the focus lens 210. Similarly, when the wobbling lens 220 is driven toward the image sensor 101 along the optical axis 20, it focuses on the subject on the nearest side, and when it is driven toward the subject along the optical axis 20, it focuses on the subject on the infinity side. And. Hereinafter, the direction in which the focus lens 210 and the wobbling lens 220 are driven toward the image pickup device 101 along the optical axis 20 is referred to as a close-up direction. Further, the direction in which the focus lens 210 and the wobbling lens 220 are driven toward the subject along the optical axis 20 is referred to as an infinity direction.

In FIG. 2A, the wobbling lens 220 is positioned at the center position of the drive range 22 of the wobbling lens 220. Hereinafter, the central position of the drive range 22 of the wobbling lens 220 will be referred to as a reference position 23 of the wobbling lens 220. The optical characteristics (aberration characteristics, etc.) of the photographing lens 200 are designed to be optimum when the wobbling lens 220 is at the reference position 23.

The wobbling lens 220 is offset from the reference position 23 when the focusing lens 210 starts driving. As shown in FIG. 2B, when the focusing lens 210 starts driving toward the image sensor side (closest direction), the wobbling lens 220 is driven in the closest direction by a predetermined offset amount D _OFS from the reference position 23. Therefore, it is positioned at the focusing operation detection position 24a. As shown in FIG. 2C, when the focusing lens 210 starts driving toward the subject side (infinity direction), the wobbling lens 220 is driven in the infinity direction by a predetermined offset amount D _OFS from the reference position 23. Then, it is positioned at the focusing operation position 24b.

The focus detection process of the interchangeable lens digital camera according to the first embodiment will be described with reference to FIG. FIG. 3 is a flowchart of the focus detection process of the mountain climbing contrast method. The process of FIG. 3 is started when the user performs an operation corresponding to the focus detection operation such as pressing the release button halfway. In step S101, the body controller 150 determines the driving direction of the focus lens 210. In step S101, the driving direction of the focus lens 210 is determined to be, for example, "not driven", "infinity direction", or "closest direction".

The drive direction of the focus lens 210 in step S101 can be determined by, for example, the following method. First, the body controller 150 positions the wobbling lens 220 at the reference position 23 via the lens controller 250. Next, the body controller 150 acquires the focus evaluation value from the focus evaluation value calculation unit 151 while reciprocating the wobbling lens 220 (wobbling operation). The body controller 150 compares the focus evaluation value when the wobbling lens 220 is closer to the subject than the reference position 23 with the focus evaluation value when the wobbling lens 220 is closer to the image sensor side than the reference position 23. When the focus evaluation value does not change due to the reciprocating drive of the wobbling lens 220, the body controller 150 determines that the drive direction of the focus lens 210 is "not driven". When the focus evaluation value when the wobbling lens 220 is closer to the subject than the image sensor side is larger, the body controller 150 determines the drive direction of the focus lens 210 to be "infinity direction". When the focus evaluation value when the wobbling lens 220 is closer to the image sensor side than the subject side is larger, the body controller 150 determines the drive direction of the focus lens 210 to be the "closest direction".

In step S102, the body controller 150 determines whether the drive direction of the focus lens 210 determined in step S101 is "not driven", "infinity direction", or "closest direction". If the body controller 150 decides not to drive the focus lens 210 in step S101, the focus detection process of FIG. 3 proceeds from step S101 to step S110. When the drive direction of the focus lens 210 is determined to be the "infinity direction", the body controller 150 advances the focus detection process of FIG. 3 from step S101 to step S103b. When the drive direction of the focus lens 210 is determined to be the "closest direction", the body controller 150 advances the focus detection process of FIG. 3 from step S101 to step S103a.

In step S103a, the body controller 150 calculates the offset amount D _{OFS according to the following equation (1), and adds the calculated offset amount D OFS to} the reference position 23 to calculate the position of the focusing operation position 24a. L _OVS in the equation (1) is an estimated value of the amount of overshoot (overrun) of the peak position by the focus lens 210 when the peak of the focus evaluation value is detected by the mountain climbing operation of the focus detection process. It can be calculated by the formula (2). α is the image plane movement coefficient of the focus lens 210, and is the ratio of the movement amount of the focus lens 210 to the movement amount of the image plane position as represented by the following equation (3). β is the image plane movement coefficient of the wobbling lens 220, and is the ratio of the movement amount of the wobbling lens 220 to the movement amount of the image plane position as represented by the following equation (4). In the following equation (1), the offset amount D _OFS converts the estimated value of the overshoot amount of the focus lens 210 into the amount of movement by the wobbling lens 220. The _TS of the equation (2) is a sampling period in which the body controller 150 acquires the focus evaluation value from the focus evaluation value calculation unit 151. n is the number of subsequent samples sampled to determine whether the focus evaluation value is a peak. V _FOCUS is the driving speed of the focus lens 210 when the peak of the focus evaluation value is detected, and is predetermined. L ₀ is an estimated distance at which the focus lens 210 is driven until the lens controller 250 decelerates and stops the focus lens 210 having a drive speed V _FOCUS when the peak of the focus evaluation value is detected.
D _OFS = L _OVS / α × β ・ ・ ・ (1)
L _OVS = ( _TS × n × V _FOCUS + L ₀ ) ・ ・ ・ (2)
α = amount of movement of the focus lens / amount of movement of the image plane position due to the movement of the focus lens ... (3)
β = amount of movement of the wobbling lens / amount of movement of the image plane position due to the movement of the wobbling lens ... (4)

In step S103b, the body controller 150 calculates the offset amount D _{OFS according to the above equation (1), and calculates the position of the focusing operation position 24b by subtracting the calculated offset amount D OFS from} the reference position 23.

In step S104, the body controller 150 drives the position of the wobbling lens 220 to the focusing operation position via the lens controller 250. The body controller 150 is driven to the position of the focusing operation position 24a calculated in step S103a when the driving direction of the focus lens 210 is in the closest direction, and is calculated in step S103b when the driving direction of the focus lens 210 is in the infinity direction. It is driven to the position of the focused operation position 24b.

In step S105, the body controller 150 starts driving the focus lens 210 in the driving direction determined in step S101 via the lens controller 250. The focus lens 210, which has started driving in step S105, is set to a driving speed faster than _VFOCUS at the peak time. The body controller 150, which has started driving the focus lens 210, proceeds to step S106 and acquires a focus evaluation value from the focus evaluation value calculation unit 151. The acquisition of the focus evaluation value in step S106 is performed in the sampling period _TS of the above equation (2). The focus lens 210 is driven in step S105, and the focus evaluation value is acquired in step S106, whereby the peak detection operation of the mountain climbing contrast method is started.

The peak detection operation executed by the body controller 150 will be described with reference to FIG. FIG. 4 is a diagram illustrating the time change of the focus evaluation value. The horizontal axis of FIG. 4 is time, and the vertical axis is the focus evaluation value. FIG. 4 illustrates the focus evaluation values X _p-1 to X _{p + 4} acquired from the focus evaluation value calculation unit 151. Focus evaluation values X _p-1 to X _{p + 4} are acquired for each sampling period _TS . In FIG. 4, X _p is the focal evaluation value of the peak. The body controller 150 focuses when n focus evaluation values X _{p + 1} to X _{p + n} acquired after the focus evaluation value X _p (n is the number of subsequent samples in the equation (2)) are smaller than the focus evaluation value X _p . The evaluation value _Xp is detected as the peak value of the focus evaluation value. Assuming that n = 1 in the example of FIG. 4, the focus evaluation value X _p-1 is compared with the focus evaluation value X _p , and since X _p-1 <X _p , the focus evaluation value X _p-1 is detected as a peak. However, the focus evaluation value X _p is compared with the focus evaluation value X _{p + 1} , and is detected as a peak because X _p > X _{p + 1} . The number of subsequent samples n may be set to n> 1 in consideration of the influence of noise. For example, when the number of subsequent samples n = 4, the focus evaluation value X _p is detected as a peak when it is larger than the subsequent four focus evaluation values X _{p + 1} to X _{p + 4} .

FIG. 5 is a diagram for explaining the operation of the focus lens 210 and the wobbling lens 220 during the peak detection operation. FIG. 5A is a graph showing an example of time change of the focus evaluation value in the peak detection operation. FIG. 5B shows an example of a time change in the drive speed of the focus lens 210 in the peak detection operation. FIG. 5C shows an example of time change of the position of the focus lens 210 in the peak detection operation. FIG. 5D shows an example of time change of the position of the wobbling lens in the peak detection operation. 5 (a) to 5 (d) show an example of peak detection operation when it is determined in step S101 that the focus lens 210 is driven in the close direction.

The time T0 is the time when the drive of the focus lens 210 is started in step S105. The drive speed of the focus lens 210 is gradually accelerated from time T0 as shown in FIG. 5 (b). Then, as shown in FIG. 5C, the position of the focus lens is gradually driven in the closest direction from the time T0. As shown in FIG. 5D, the position of the wobbling lens 220 is already positioned at the focusing operation position 24a driven in the closest direction by the offset amount D _OFS from the reference position 23 at the time T0.

The time T1 is the time when the focal evaluation value peaks. The time T2 is the time when the focal evaluation value of the peak is detected as the peak value. By the time it is detected that the focal evaluation value of the peak is actually the peak value, the focal evaluation values of n subsequent samples are acquired in the sampling period _TS . That is, the difference between the time T1 and the time T2 is a value based on the number of subsequent samples n and the sampling period _TS . The focus lens 210 is speed-controlled so as to reach a predetermined speed V _FOCUS at a time when the focus evaluation value peaks, such as time T1. As shown in FIG. 5B, the focus lens 210 starts decelerating when a peak value is detected at time T2, and stops at time T3.

In the graph of FIG. 5B, the range from the peak value of the focus evaluation value at time T1 to the stop of the focus lens 210 at time T3 is shaded. When the shaded portions shown in FIG. 5B are integrated, the overshoot amount L1 actually _overshooted by the focus lens 210 is obtained.

The time T4 is a time for starting deceleration of the drive speed of the focus lens 210 toward a predetermined drive speed _VFOCUS at the time of peak detection. At time T4, the focus lens 210 is at position P4. The position P4 is located at a position separated by a predetermined amount from the position P1 at which the focus lens 210 peaks on the side opposite to the drive direction of the focus lens 210. In the example of FIG. 5C, since the driving direction of the focus lens 210 is the closest direction, the position P4 is closer to the subject than the position P1.

In step S107 of FIG. 3, the body controller 150 determines whether or not the drive speed of the focus lens 210 is reduced to a predetermined drive speed V _FOCUS . That is, it is determined whether or not the position of the focus lens 210 has reached the position P4 in FIG. 5 (c). The body controller 150 comprehensively estimates the position P4 from the focus evaluation value repeatedly acquired from the time T0 in the sampling period _TS and the amount of change (differential value) thereof. For example, the position where the amount of change in the focal evaluation value starts to decrease is estimated as the position P4.

If it is determined in step S107 that the body controller 150 decelerates the drive speed of the focus lens 210, the process proceeds to step S108, and if it is determined that the drive speed of the focus lens 210 is not decelerated, the process proceeds to step S106 to obtain the next focus evaluation value. get. In step S108, the body controller 150 reduces the drive speed of the focus lens 210 to the drive speed V _FOCUS via the lens controller 250. After that, the drive speed of the focus lens 210 is maintained at the drive speed V _FOCUS until the peak value of the focus evaluation value is detected at time T2.

In step S109, the body controller 150 determines whether or not the peak value of the focus evaluation value has been detected. That is, as in the focus evaluation value X _p in FIG. 4, it is determined whether or not the subsequent n focus evaluation values X _{p + 1} to X _{p + n} are smaller than the focus evaluation value X _p . If the body controller 150 determines in step S109 that the peak value of the focus evaluation value is detected, the process proceeds to step S110, and if it is determined that the peak value of the focus evaluation value is not detected, the process proceeds to step S106 to perform the next focus evaluation. Get the value.

In step S110, the body controller 150 stops the focus lens 210 via the lens controller 250 (from time T2 to time T3 in FIG. 5B). At this time, the focus lens 210 is speed-controlled by the lens controller 250 with high accuracy to decelerate, and finally stop.

In step S111, the body controller 150 drives the wobbling lens 220 via the lens controller 250 to drive the wobbling lens 220 to the reference position 23 (from time T2 to time T5 in FIG. 5D).

In step S112, the body controller 150 confirms that the focus lens 210 and the wobbling lens 220 are stopped via the lens controller 250. The stop of the focus lens 210 is confirmed based on the change in the position of the focus lens 210 acquired by the lens controller 250 from the focus lens position detection unit 212. The stop of the wobbling lens 220 is confirmed based on the change in the position of the wobbling lens 220 acquired by the lens controller 250 from the wobbling lens position detection unit 222.

In step S113, the body controller 150 performs a wobbling operation by the wobbling lens 220 via the lens controller 250, and finely adjusts the in-focus position. Then, when the fine adjustment of the focusing position is completed, the process of FIG. 3 is completed.

In the focus detection process of FIG. 3, the focus lens 210 is stopped in _a state of overshooting by the overshoot amount L1 at time T3. The focus shift caused by the overshoot is corrected by driving the wobbling lens 220 in step S111. When the focus lens 210 moves by the overshoot amount L ₁ , the image plane position moves by L ₁ / α. When the wobbling lens 220 is driven by the offset amount D _OFS in the direction opposite to the driving direction of the focus lens 210 as in step S111, the image plane position moves by D _OFS / β = L _OVS / α. If the deviation of the image plane position due to the overshoot of the focus lens 210 and the deviation of the image plane position due to the driving of the wobbling lens 220 in step S111 substantially match, it can be said that the focus shift is corrected.

The period from the time T1 to the time T3 in which the focus lens 210 is overshooting is divided into a period from the time T1 to the time T2 and a period from the time T2 to the time T3. In step S108, the drive speed of the focus lens 210 between the time T1 and the time T2 is maintained at a predetermined drive speed _VFOCUS . Therefore, the distance actually overshooted by the focus lens 210 between the time T1 and the time T2 is a predetermined drive speed V in the time until the focus evaluation values of n subsequent samples are acquired in the sampling cycle _TS . Since it is the distance driven by the focus lens 210 in _FOCUS , it is estimated accurately by _TS × n × V _FOCUS in the above equation (2).

During the time T2 to the time T3, the focus lens 210 is decelerated by the lens controller 250 until it stops (the drive speed is zero) from the predetermined drive speed _VFOCUS . When the focus lens 210 can be speed-controlled so that the lens controller 250 always decelerates at a constant speed transition, the overshoot amount between the time T2 and the time T3 can be measured at the design stage of the photographing lens 200. If the above-mentioned estimated distance L ₀ is set as such a measured value, the overshoot amount of the focus lens 210 from the time T2 to the time T3 can be estimated accurately.

Therefore, the overshoot amount L1 actually overshooted by the focus lens 210 during the period from the time T1 to the time T3 is accurately estimated by the estimated value L _OVS of the overshoot amount calculated by the above equation ( ₂ ). (L _OVS = L ₁ ). Therefore, the magnitude of the movement amount D _OFS / β that the image plane position moves by driving the wobbling lens 220 from the in-focus detection operation position to the reference position 23 and the image plane position that moves due to the actual overshoot of the focus lens 210. It is consistent with the magnitude of the movement amount L ₁ / α of (D _OFS / β = L _OVS / α = L ₁ / α).

Therefore, by driving the wobbling lens 220 in the direction opposite to the driving direction of the focus lens 210 by a predetermined offset amount D _OFS in step S111, it is possible to correct the focus shift caused by the overshoot of the focus lens 210. ..

According to the first embodiment described above, the following effects are exhibited.
The camera of FIG. 1 includes a photographing lens 200 having a focus lens 210 and a wobbling lens 220 having a mass smaller than that of the focus lens 210. In the camera body 100, the body controller 150 controls the focus lens driving unit 211 via the lens controller 250 of the photographing lens 200 to drive the focus lens 210. Further, in the camera body 100, the body controller 150 controls the wobbling lens driving unit 221 via the lens controller 250 to drive the wobbling lens 220. The body controller 150 determines the driving direction of the focus lens 210 in step S101 of FIG. The camera body 100 includes an image pickup device 101 that receives an image of a subject imaged by a photographing lens 200 and outputs an image signal. Further, the camera body 100 includes a focus evaluation value calculation unit 151 that detects a focus evaluation value representing a focus adjustment state of the photographing lens 200 based on an image signal output from the image sensor 101. The body controller 150 stops the wobbling lens 220 at the focusing operation detection position (step S104 in FIG. 3), then drives the focus lens 210 in the driving direction (step S105 in FIG. 3), and the focus evaluation value peaks. When the value is reached (time T1), the focus lens 210 is stopped at a position separated by a predetermined amount (L ₁ ) from the position of the focus lens 210 (step S110 in FIG. 3). After that, the body controller 150 drives the wobbling lens 220 in the direction opposite to the driving direction to the reference position 23 with the focus lens 210 stopped (step S111 in FIG. 3). According to the present invention, after the peak of the focus evaluation value is detected, the focus lens 210 is not driven, but the wobbling lens 220, which has a smaller mass than the focus lens 210, is driven to correct the focus shift. The occurrence can be suppressed.

The first embodiment described above can be modified and implemented as follows.
(Modification 1-1) In the explanation using the flowchart of FIG. 3, the wobbling lens 220 is driven to the in-focus detection operation position in step S104, the mountain climbing operation by the focus lens 210 is started in step S105, and the mountain climbing operation is started in step S111. The wobbling lens 220 was returned to the reference position 32. However, if the wobbling lens 220 is driven by a predetermined offset amount D _OFS in the direction opposite to the driving direction of the focus lens 210 from the position when the peak value of the focus evaluation value is detected, the mountain climbing operation is performed. The position of the wobbling lens 220 at the time of starting may remain the reference position.

FIG. 6 is a modified example of the focus detection process of the mountain climbing contrast method shown in FIG. In the example of FIG. 6, when the mountain climbing operation by the focus lens 210 is started (step S105), the wobbling lens 220 is in the position of the reference position 23. Of the flows of FIG. 6, the same flow as that of FIG. 3 will be omitted.

In step S121 of FIG. 6, the body controller 150 determines whether or not it is necessary to drive the focus lens 210 by the wobbling operation of the wobbling lens 220. That is, it is determined whether or not the subject is already in focus. In step S121, if the drive direction of the focus lens 210 is determined to be "not driven" in step S101, it is assumed that the focus lens 210 does not need to be driven, and the process proceeds to step S110 of FIG. On the other hand, if the drive direction of the focus lens 210 is determined to be "infinity direction" or "closest direction" in step S101, the focus lens 210 needs to be driven, and the process proceeds to step S105 of FIG. 6 to start the mountain climbing process. do. In step S122 of FIG. 6, the body controller 150 drives the wobbling lens 220 by a predetermined offset amount D _OFS in the direction opposite to the driving direction of the focus lens 210 determined in step S101 via the lens controller 250. do.

When the focus detection process of the mountain climbing contrast method is performed according to the flowchart of FIG. 6, the optical characteristics (aberration) of the photographing lens 200 are obtained even if the wobbling lens 220 is deviated from the reference position 23 by a predetermined offset amount D _OFS . It is desirable to design so that the characteristics, etc.) are good.

(Second embodiment)
A second embodiment of the present invention will be described. In the focus adjusting device according to the second embodiment of the present invention, the focus detection process of the mountain climbing contrast method is different from that of the first embodiment. The focus detection process according to the second embodiment of the present invention can be carried out by using the interchangeable lens digital camera of FIG.

In the focus detection process according to the second embodiment of the present invention, the position of the focus lens 210 in the optical axis direction is detected from the focus lens position detection unit 212, and the distance actually overshooted by the focus lens 210, that is, overshoot. The quantity L ₁ is detected. Then, the detected overshoot amount L1 is substituted into the following equation ( ₅ ) to calculate the focusing position correction amount D _AR that drives the wobbling lens 220 for focusing deviation correction. Then, after the focus lens 210 is stopped, the wobbling lens 220 is driven in the direction opposite to the drive direction of the focus lens 210 by the focus position correction amount D _AR . When the wobbling lens 220 is driven from the focusing detection operation position by the focusing position correction amount D _AR , the image plane position moves by D _AR / β. This amount of movement coincides with the magnitude of the amount of movement L ₁ / α of the image plane position moved by the actual overshoot of the focus lens 210 (D _AR / β = (L ₁ / α × β) / β = L ₁ ). / Α). Therefore, by driving the wobbling lens 220, it is possible to correct the focus shift caused by the overshoot of the focus lens 210.
D _AR = L ₁ / α × β ・ ・ ・ (5)

FIG. 7 is a diagram for explaining the operation of the focus lens 210 and the wobbling lens 220 during the peak detection operation in the second embodiment. FIG. 7 (a) is a graph showing an example of the time change of the focus evaluation value in the peak detection operation, and shows the same example as in FIG. 5 (a). FIG. 7B shows an example of a time change in the driving speed of the focus lens 210 in the peak detection operation, and shows the same example as in FIG. 5B. FIG. 7 (c) shows an example of the time change of the position of the focus lens 210 in the peak detection operation, and shows the same example as in FIG. 5 (c). FIG. 7D shows an example of the time change of the position of the wobbling lens 220 in the peak detection operation. FIG. 7 (d) differs from FIG. 5 (d) only in that the wobbling lens 220 is driven not by the offset amount D _OFS but by the focusing position correction amount D _AR after the time T3.

FIG. 8 shows a flowchart of the focus detection process of the mountain climbing contrast method in the second embodiment. Of the flows of FIG. 8, the same steps as those of FIG. 3 will be omitted.

In step S201, the body controller 150 determines whether the drive direction of the focus lens 210 determined in step S101 is "not driven", "infinity direction", or "closest direction". If the body controller 150 decides not to drive the focus lens 210 in step S101, the focus detection process of FIG. 8 proceeds from step S101 to step S113. The body controller 150 advances the focus detection process of FIG. 8 from step S101 to step S103b when the drive direction of the focus lens 210 is "determined in the infinity direction. The body controller 150 drives the focus lens 210. When the direction is determined to be the "closest direction", the focus detection process of FIG. 8 proceeds from step S101 to step S103a.

In step S202, the body controller 150 acquires information regarding the position of the focus lens 210 detected by the focus lens position detection unit 212 via the lens controller 250.

In step S203, the body controller 150 calculates the in-focus position correction amount D _AR . First, the body controller 150 acquires information regarding the position of the focus lens 210 after the focus lens 210 is stopped in step S110 from the lens controller 250. Next, the body controller 150 overshoots based on the position of the focus lens 210 acquired in step S202 when the focus evaluation value peaks and the position of the focus lens 210 acquired after the focus lens 210 has stopped. _Acquire the shoot amount L1. Then, the body controller 150 calculates the in-focus position correction amount D _AR by the above equation (5). In step S204, the body controller 150 drives the wobbling lens 220 via the lens controller 250 by the in-focus position correction amount D _AR calculated in step S203.

According to the second embodiment described above, the following effects are obtained.
The camera provided with the focus adjusting device of the second embodiment includes a photographing lens 200 having a focus lens 210 and a wobbling lens 220 having a mass smaller than that of the focus lens 210. In the camera body 100, the body controller 150 controls the focus lens driving unit 211 via the lens controller 250 of the photographing lens 200 to drive the focus lens 210. Further, in the camera body 100, the body controller 150 controls the wobbling lens driving unit 221 via the lens controller 250 to drive the wobbling lens 220. The body controller 150 determines the driving direction of the focus lens 210 in step S101 of FIG. The camera body 100 includes an image pickup device 101 that receives an image of a subject imaged by a photographing lens 200 and outputs an image signal. Further, the camera body 100 includes a focus evaluation value calculation unit 151 that detects a focus evaluation value representing a focus adjustment state of the photographing lens 200 based on an image signal output from the image sensor 101. The body controller 150 stops the wobbling lens 220 at the focusing operation detection position (step S104 in FIG. 8), then drives the focus lens 210 in the driving direction (step S105 in FIG. 8), and the focus evaluation value peaks. When the value is reached (time T1), the focus lens 210 is stopped at a position separated by a predetermined amount (L1) from the position of the focus lens 210 (step S110 in FIG. 8). After that, the body controller 150 drives the wobbling lens 220 in the direction opposite to the driving direction by the focus position correction amount D _AR while the focus lens 210 is stopped (step S204 in FIG. 8). According to the present invention, after the peak of the focus evaluation value is detected, the focus lens 210 is not driven, but the wobbling lens 220, which has a smaller mass than the focus lens 210, is driven to correct the focus shift. The occurrence can be suppressed. Further, since the focus position correction amount D _AR is calculated based on the actually measured overshoot amount L ₁ , the focus shift due to the overshoot of the focus lens 210 can be more accurately performed than in the first embodiment. It can be corrected. The second embodiment can also be used when the lens controller 250 cannot accurately control the driving speed of the focus lens 210.

The second embodiment described above can be modified and implemented as follows.
(Modification 2-1) In the explanation using the flowchart of FIG. 8, after driving the wobbling lens 220 to the in-focus detection operation position in step S104, the mountain climbing operation by the focus lens 210 is started in step S105, and the mountain climbing operation by the focus lens 210 is started in step S110. After the focus lens 210 was stopped, the wobbling lens 220 was driven by the focus position correction amount D _AR in step S204. However, if the wobbling lens 220 is driven from the position when the peak value of the focus evaluation value is detected by the focus position correction amount _DAR in the direction opposite to the drive direction of the focus lens 210, it is possible to climb a mountain. The position of the wobbling lens 220 at the start of operation may remain the reference position.

FIG. 9 is a modified example of the focus detection process of the mountain climbing contrast method shown in FIG. In the example of FIG. 9, when the mountain climbing operation by the focus lens 210 is started (step S105), the wobbling lens 220 is in the position of the reference position 23. Since each flow of FIG. 9 is the same as the flow of FIGS. 6 and 8, the description thereof will be omitted.

(Third embodiment)
A third embodiment of the present invention will be described. In the focus adjusting device according to the third embodiment of the present invention, the focus detection process of the mountain climbing contrast method is different from that of the first embodiment. The focus detection process according to the third embodiment of the present invention can be carried out by using the interchangeable lens digital camera of FIG. In the third embodiment of the present invention, after starting the deceleration of the focus lens 210 to the drive speed _VFOCUS (> 0), wobbling is performed while driving the focus lens 210 until the peak value of the focus evaluation value is detected. The wobbling operation is performed by the lens 220.

FIG. 10 is a diagram for explaining the operation of the focus lens 210 and the wobbling lens 220 during the peak detection operation in the third embodiment. FIG. 10D shows an example of the time change of the position of the wobbling lens 220 in the peak detection operation. In FIG. 10D, the wobbling operation by the wobbling lens 220 is performed from the time T4 at which the deceleration of the focus lens 210 to the predetermined drive speed V _FOCUS (> 0) is started to the time T3 at which the focus lens 210 is stopped. It has been. FIG. 10A is a graph showing an example of time change of the focus evaluation value in the peak detection operation, and the portion from the time T4 to the time T3 during the wobbling operation of the wobbling lens 220 is shown in FIG. 5A. different.

FIG. 11 shows a flowchart of the focus detection process of the mountain climbing contrast method according to the third embodiment. Of the flows of FIG. 1, the same steps as those of FIGS. 3 and 8 will be omitted.

In step S301, if the wobbling operation by the wobbling lens 220 has not yet started, the body controller 150 instructs the lens controller 250 to start the wobbling operation.

In step S302, the body controller 150 determines whether or not the peak value of the focus evaluation value has been detected. If the peak value of the focus evaluation value is detected, the process proceeds to step S303, and if the peak value of the focus evaluation value is not detected, the process proceeds to step S106 to acquire the next focus evaluation value. In step S303, the body controller 150 instructs the lens controller 250 to stop the wobbling operation.

According to the third embodiment described above, the following effects are exhibited.
The camera provided with the focus adjusting device of the third embodiment includes a photographing lens 200 having a focus lens 210 and a wobbling lens 220 having a mass smaller than that of the focus lens 210. In the camera body 100, the body controller 150 controls the focus lens driving unit 211 via the lens controller 250 of the photographing lens 200 to drive the focus lens 210. Further, in the camera body 100, the body controller 150 controls the wobbling lens driving unit 221 via the lens controller 250 to drive the wobbling lens 220. The body controller 150 determines the driving direction of the focus lens 210 in step S101 of FIG. The camera body 100 includes an image pickup device 101 that receives an image of a subject imaged by a photographing lens 200 and outputs an image signal. Further, the camera body 100 includes a focus evaluation value calculation unit 151 that detects a focus evaluation value representing a focus adjustment state of the photographing lens 200 based on an image signal output from the image sensor 101. The body controller 150 stops the wobbling lens 220 at the focusing operation detection position (step S104 in FIG. 11), then drives the focus lens 210 in the driving direction (step S105 in FIG. 11), and the focus evaluation value peaks. When the value is reached (time T1), the focus lens 210 is stopped at a position separated by a predetermined amount (L1) from the position of the focus lens 210 (step S110 in FIG. 11). After that, the body controller 150 drives the wobbling lens 220 in the direction opposite to the driving direction by the focus position correction amount D _AR while the focus lens 210 is stopped (step S204 in FIG. 11). According to the present invention, after the peak of the focus evaluation value is detected, the focus lens 210 is not driven, but the wobbling lens 220, which has a smaller mass than the focus lens 210, is driven to correct the focus shift. The occurrence can be suppressed.

Further, in the third embodiment, after the deceleration of the focus lens 210 to the drive speed V _FOCUS (> 0) is started, until the peak value of the focus evaluation value is detected while driving the focus lens 210. , The wobbling operation is performed by the wobbling lens 202. This makes it possible to detect the peak value of the focal evaluation value more accurately and quickly during the mountain climbing operation.

The third embodiment described above can be modified and implemented as follows.
(Modification 3-1) Similar to the first embodiment and the second embodiment, the position of the wobbling lens 220 when starting the mountain climbing operation is not limited to the in-focus detection operation position. For example, the position of the wobbling lens 220 at the start of the mountain climbing operation may be the reference position 23.

(Modification 3-2) The focus detection process shown in FIG. 11 is a process in which steps S301 and S303 are substantially added to the focus detection process shown in FIG. A process in which step S301 is inserted between step S108 and step S109 in FIG. 3, step S303 is inserted immediately before step S110 in FIG. 3, and step S109 in FIG. 3 is replaced with step S302 is also performed in the third embodiment. It is within the range of morphology.

(Fourth Embodiment)
A fourth embodiment of the present invention will be described. FIG. 12 is a block diagram of an interchangeable lens digital camera equipped with a focus adjustment device according to a fourth embodiment. The interchangeable lens digital camera of FIG. 12 includes a camera body 300 and a photographing lens 400. The photographing lens 400 is detachably attached to the camera body 300. Of the parts included in FIG. 12, the parts similar to those in FIG. 1 will be omitted.

The photographing lens 400 has a focus lens 210 for adjusting the focus, a focus lens drive unit 211 composed of a motor and a drive circuit for driving the focus lens 210, and a position for detecting the position of the focus lens 210 in the optical axis direction. It has a detection unit 212 and a lens controller 450. The point that the wobbling lens 220 does not exist is a difference from the photographing lens 200 in the first embodiment.

The camera body 300 includes an analog signal processing unit 102, an A / D converter 103, a digital signal processing unit 111, a buffer memory 112, an Enc / Dec processing unit 113, an external storage medium 115, and a VRAM 120 included in the camera body 100. It has an LCD monitor 121 and an operation unit 180. Further, the camera body 300 includes an image sensor 301, an image sensor drive unit 302, and an image sensor position detection unit 303.

The image pickup element 301 is composed of a CCD image pickup element, a MOS type image pickup element, and the like. The image pickup element 301 outputs an electric signal (imaging signal) corresponding to the light intensity of the subject image formed on the image pickup surface to the analog signal processing unit 102. Unlike the image pickup element 101, the image pickup element 301 is driven in the optical axis direction by the image pickup element drive unit 302. Further, the image sensor 301 detects the position in the optical axis direction by the image sensor position detection unit 303. The image sensor drive unit 302 is composed of a motor and a drive circuit.

The body controller 350 includes a focus evaluation calculation unit 151, an AE calculation unit 152, an AWB calculation unit 153, and other calculation units, and controls the entire camera. The body controller 350 can give a drive instruction to the focus lens 210 via the lens controller 250. Further, the body controller 350 can control the drive of the image pickup element 301.

FIG. 13 is a diagram for explaining driving of the focus lens 210 and the image pickup device 301 in the fourth embodiment. FIG. 13A shows the drive range 21 of the focus lens 210 and the drive range 32 of the image pickup device 301. Similar to FIG. 2, the drive range 21 has an infinity side end 21b on the subject side and a close end 21a on the photographer side. The drive range 32 has a close end 32b on the subject side and an infinity side end 32a on the photographer side.

When the focus lens 210 is driven toward the photographer along the optical axis 40, it focuses on the subject on the closest side, and conversely, when it is driven toward the subject along the optical axis 40, it focuses on the subject on the infinity side. do. It is assumed that the focusing position of the photographing lens 200 is simply moved by driving the focus lens 210. On the other hand, when the image sensor 301 is driven toward the subject along the optical axis 40, it focuses on the subject on the nearest side, and when it is driven toward the photographer along the optical axis 40, it focuses on the subject on the infinity side. It shall be impatient.

In FIG. 13A, the image pickup device 301 is positioned at the center position of the drive range 32 thereof. Hereinafter, the central position of the drive range 32 of the image pickup device 301 will be referred to as a reference position 33 of the image pickup element 301.

The image sensor 301 is offset from the reference position 33 when the focusing lens 210 starts driving. As shown in FIG. 13B, when the focusing lens 210 starts driving toward the image sensor side (closest direction in the image sensor 301), the image sensor 301 has a predetermined second offset amount D _OFS2 from the reference position 33. It is driven toward the closest end 32b (closest direction) and positioned at the focusing operation detection position 34b. On the other hand, as shown in FIG. 13C, when the focusing lens 210 starts driving toward the subject side (in the infinity direction in the image sensor 301), the image sensor 301 has a predetermined second offset amount from the reference position 33. Only D _OFS2 is driven toward the infinity side end 32a side (infinity direction) and positioned at the focusing operation position 34a.

The focus detection process of the interchangeable lens digital camera according to the fourth embodiment will be described with reference to FIG. FIG. 14 is a flowchart of the focus detection process of the mountain climbing contrast method. The process of FIG. 14 is started when the user performs an operation corresponding to the focus detection operation such as pressing the release button halfway. Of the flows in FIG. 14, the same steps as in FIG. 3 will be omitted.

In step S401, the body controller 350 determines the driving direction of the focus lens 210. In step S401, the driving direction of the focus lens 210 is determined to be, for example, "not driven", "infinity direction", or "closest direction".

The drive direction of the focus lens 210 in step S401 can be determined by, for example, the following method. First, the body controller 350 positions the image sensor 301 at the reference position 33. Next, the body controller 350 acquires the focus evaluation value from the focus evaluation value calculation unit 151 while reciprocating the image pickup element 301. The body controller 350 compares the focus evaluation value when the image sensor 301 is closer to the subject than the reference position 33 with the focus evaluation value when the image sensor 301 is closer to the photographer than the reference position 33. When the focus evaluation value does not change due to the reciprocating drive of the image pickup element 301, the body controller 350 determines that the drive direction of the focus lens 210 is "not driven". When the focus evaluation value when the image sensor 301 is closer to the subject than the photographer side is larger, the body controller 350 determines the drive direction of the focus lens 210 to be the "closest direction". When the focus evaluation value when the image sensor 301 is closer to the photographer than the subject side is larger, the body controller 350 determines the drive direction of the focus lens 210 to be "infinity direction".

In step S402, the body controller 350 determines whether the drive direction of the focus lens 210 determined in step S401 is "not driven", "infinity direction", or "closest direction". If the body controller 350 decides not to drive the focus lens 210 in step S401, the focus detection process of FIG. 14 proceeds from step S401 to step S110. When the drive direction of the focus lens 210 is determined to be the "infinity direction", the body controller 350 proceeds with the focus detection process of FIG. 14 from step S401 to step S403b. When the drive direction of the focus lens 210 is determined to be the "closest direction", the body controller 350 advances the focus detection process of FIG. 14 from step S401 to step S403a.

In step S403a, the body controller 350 calculates the second offset amount D _OFS2 by the following equation (6), and subtracts the calculated second offset amount D _OFS2 from the reference position 33 of the image pickup device 301, thereby focusing the focusing operation position. Calculate the position of 34b. L _OVS in the equation (6) is an estimated value of the amount of overshoot (overrun) of the peak position by the focus lens 210 when the peak of the focus evaluation value is detected by the mountain climbing operation of the focus detection process. It can be calculated by the formula (1). α is the image plane movement coefficient of the focus lens 210, and is the ratio of the movement amount of the focus lens 210 to the movement amount of the image plane position as represented by the above equation (3).
D _OFS2 = L _OVS / α ・ ・ ・ (6)

In step S403b, the body controller 350 calculates the second offset amount D _{OFS2 by the above equation (6), and adds the calculated second offset amount D OFS2 to} the reference position 33 of the image pickup element 301 to perform the focusing operation. The position of the position 34a is calculated.

In step S404, the body controller 350 drives the position of the image pickup element 301 to the focusing operation position by the image pickup element drive unit 302. The body controller 350 is driven to the position of the focusing operation position 34b calculated in step S303a when the driving direction of the focus lens 210 is in the closest direction, and is calculated in step S303b when the driving direction of the focus lens 210 is in the infinity direction. It is driven to the position of the focused operation position 34a. When the body controller 350 drives the image sensor 301 to the focusing operation detection position, the body controller 350 starts driving the focus lens 210 in step S105 of FIG. 14 and starts acquiring the focus evaluation value in step S106. The peak detection operation of the mountain climbing contrast method is started.

FIG. 15 is a diagram for explaining the operation of the focus lens 210 and the image pickup device 301 during the peak detection operation. FIG. 15 (a) is a graph showing an example of the time change of the focus evaluation value in the peak detection operation, and shows the same example as in FIG. 5 (a). FIG. 15 (b) shows an example of a time change of the drive speed of the focus lens 210 in the peak detection operation, and shows the same example as in FIG. 5 (b). FIG. 15 (c) shows an example of the time change of the position of the focus lens 210 in the peak detection operation, and shows the same example as in FIG. 5 (c). FIG. 15D shows an example of the time change of the position of the image pickup device 301 in the peak detection operation. In the example of FIGS. 15A to 15D, the peak detection operation when it is determined in step S401 to drive the focus lens 210 in the close direction is shown.

As shown in FIG. 15D, the position of the image sensor 301 is already at the focusing operation position 34b driven from the reference position 33 to the nearest end 32b side by the second offset amount D _OFS2 at the time T0. It is positioned. When the peak value of the focal evaluation value is detected at time T2 (YES in step S109 in FIG. 14), the image sensor 301 is driven to the infinity side end 32a side by the second offset amount D _OFS2 in step S405 in FIG. It is driven to the reference position 33.

In step S406 of FIG. 14, the body controller 350 confirms that both the focus lens 210 and the image pickup element 301 are stopped. The stop of the focus lens 210 is confirmed based on the change in the position of the focus lens 210 acquired by the lens controller 450 from the focus lens position detection unit 212. The stoppage of the image pickup element 301 is confirmed based on the change in the position of the image pickup element 301 acquired from the image pickup element position detection unit 303.

In step S407, the body controller 350 performs a wobbling operation by the image sensor 301 to finely adjust the focusing position. Then, when the fine adjustment of the focusing position is completed, the process of FIG. 14 is completed.

In the fourth embodiment, the image pickup element 301 is driven by the second offset amount D _OFS2 in the drive direction of the focus lens 210, and the image pickup element 301 is moved to the image plane position of the photographing lens 400. As described in the first embodiment, the estimated overshoot amount L _OVS accurately estimates the overshoot amount L ₁ of the actual focus lens 210. Therefore, for the second offset amount D _OFS2 , D _OFS2 = L _OVS / α = L ₁ / α is established. Therefore, by driving the image pickup device 301 in the drive direction of the focus lens 210 by the second offset amount D _OFS2 , it is possible to correct the focus shift caused by the overshoot of the focus lens 210.

According to the fourth embodiment described above, the following effects are exhibited.
The camera of FIG. 12 includes a photographing lens 400 having a focus lens 210. In the camera body 300, the body controller 350 controls the focus lens driving unit 211 via the lens controller 450 of the photographing lens 400 to drive the focus lens 210. The camera body 300 includes an image pickup device 301 that receives an image of a subject imaged by a photographing lens 400 and outputs an image signal. In the camera body 300, the body controller 350 controls the image sensor driving unit 302 to drive the image sensor 301 in the optical axis direction. In step S401 of FIG. 14, the body controller 350 determines the driving direction of the focus lens 210 by the wobbling operation of the image pickup element 301. Further, the camera body 300 includes a focus evaluation value calculation unit 151 that detects a focus evaluation value representing a focus adjustment state of the photographing lens 400 based on an image signal output from the image sensor 301. The body controller 350 stops the image sensor 301 at the focusing operation detection position (step S404 in FIG. 14), then drives the focus lens 210 in the driving direction (step S105 in FIG. 14), and the focus evaluation value peaks. When the value is reached (time T1), the focus lens 210 is stopped at a position separated by a predetermined amount (L ₁ ) from the position of the focus lens 210 (step S110 in FIG. 14). After that, the body controller 350 drives the image pickup device 301 in the drive direction to the reference position 33 with the focus lens 210 stopped (step S405 in FIG. 14). According to the present invention, after the peak of the focus evaluation value is detected, the focus lens 210 is not driven but the image pickup device 301 is driven to correct the out-of-focus shift, so that the generation of driving noise and vibration can be suppressed.

The fourth embodiment described above can be modified and implemented as follows.
(Modification 4-1) In the explanation using the flowchart of FIG. 14, after driving the image sensor 301 to the in-focus detection operation position in step S403, the mountain climbing operation by the focus lens 210 is started in step S105, and the mountain climbing operation by the focus lens 210 is started in step S110. After the focus lens 210 stopped, the wobbling lens 220 was driven to the reference position 33 in step S404. However, if the image sensor 301 is driven by the second offset amount D _OFS2 in the direction corresponding to the drive direction of the focus lens 210 from the position when the peak value of the focus evaluation value is detected, the mountain climbing operation is performed. The position of the image pickup device 301 at the time of starting may remain the reference position 33.

FIG. 16 is a modification of the focus detection process of the mountain climbing contrast method shown in FIG. In the example of FIG. 16, when the mountain climbing operation by the focus lens 210 is started (step S105), the image sensor 301 is at the position of the reference position 33. Since each flow of FIG. 16 is the same as the flow of FIGS. 6 and 14, the description thereof will be omitted.

(Modification 4-2) In step S405 of FIG. 14, the image pickup device 301 is driven by the second offset amount D _OFS 2 and moved to the reference position 33. However, as in the _second embodiment, the actual overshoot amount L1 of the focus lens 210 is detected, and the focusing position correction amount based on the overshoot amount L1 (of the _second embodiment). It may be driven only by the in-focus position correction amount D _AR ).

(Modification 4-3) As in the third embodiment, after the focus lens 210 starts decelerating to the drive speed V _FOCUS , the peak value of the focus evaluation value is detected while driving the focus lens 210. Until then, the body controller 350 may perform a wobbling operation by the image pickup element 301.

The embodiment described above can be modified and implemented as follows.
(Modification 5-1) In step S101 in the first to third embodiments and step S401 in the fourth embodiment, the drive direction of the focus lens 210 is changed by the wobbling operation by the wobbling lens 220 and the image pickup element 301. Were determined. However, the method of determining the driving direction of the focus lens 210 is not limited to the method based on the wobbling operation. For example, a focus detection element for performing the focus detection process of the phase difference detection method is further provided in the camera body 100 or 300, and the positive / negative of the defocus amount calculated based on the focus detection signal output from the focus detection element. The drive direction of the focus lens 210 may be determined from the above. The method of determining the drive direction using this focus detection element is auxiliary in steps S101 and S401 to confirm that the focus lens 210 does not have to be driven when the focus evaluation value does not change due to the wobbling operation. It may be carried out.

(Modification 5-2) In the first to fourth embodiments, in step S105, the focusing lens 210 is set to a speed faster than the predetermined drive speed V _FOCUS , but the predetermined drive speed V _FOCUS is set. It may be set to. As a result, step S107 and step S108 can be omitted, the number of times of accelerating and decelerating the focus lens 210 can be further reduced, and the generation of driving noise and vibration can be further suppressed.

(Variation Example 5-3) In the first to fourth embodiments, the image plane movement coefficient of the focus lens 210 and the wobbling lens 220 is assumed to be a constant value, but the image plane movement coefficient varies depending on the shooting distance and the focal length. It may change. In this case, the image plane movement coefficient is calculated by the body controller 150, and the offset amount D _OFS , the in-focus position correction amount D _AR , and the second offset amount D _OFS 2 are calculated based on the image plane movement coefficient. good.

(Modification 5-4) In the first to fourth embodiments, the case where the body controller 150 or 350 and the lens controller 250 or 450 are individually present is shown, but the body controller 150 or 350 is driven by the focus lens. The unit 211, the focus lens position detection unit 212, the wobbling lens drive unit 221 and the wobbling lens position detection unit 222 may be directly controlled.

(Modification 5-5) In the first to third embodiments, it is assumed that the positive and negative of the power of the focus lens 210 and the positive and negative of the power of the wobbling lens 220 match. However, the positive / negative of the power of the focus lens 210 and the positive / negative of the power of the wobbling lens 220 do not necessarily have to match. If the positive and negative powers of the focus lens 210 and the wobbling lens 220 do not match, the wobbling lens 220 is used in FIGS. 2 (b), 2 (c), 3, 6, 6, 8, 9, and 11. The driving direction is reversed.

The above embodiments may be carried out in combination as long as the characteristics of the invention are not impaired. Further, the above-described embodiment is merely an example, and the present invention is not limited to these contents as long as the features of the invention are not impaired.

22a, 22b, 32a, 32b Focusing operation detection position 23,33 Reference position 100,300 Camera body 101,301 Image sensor 150,350 Body controller 200,400 Imaging lens 210 Focus lens 211 Focus lens drive unit 212 Focus lens position detection Unit 220 Wobbling lens 221 Wobbling lens drive unit 222 Wobbling lens position detection unit 302 Image sensor drive unit 303 Image sensor position detection unit

Claims (5)

An image sensor that captures an image by an optical system having a first lens and a second lens and outputs a signal,
An evaluation value calculation unit that calculates an evaluation value of an image generated based on a signal output from the image sensor, and an evaluation value calculation unit.
An instruction unit that instructs a focusing operation for focusing an image of the optical system on the image sensor, and
When the focusing operation is instructed by the instruction unit , the control unit that calculates the evaluation value a plurality of times while moving the first lens in one direction, and the control unit.
Have ,
The control unit moves the first lens in one direction and the first control of moving the second lens so that the evaluation value increases after the evaluation value starts to decrease and the first lens is stopped. While doing so, the second control of repeatedly moving the second lens in the first direction and the second direction opposite to the first direction is performed.
Focus detector. An image sensor that captures an image by an optical system having a first lens and a second lens and outputs a signal,
An evaluation value calculation unit that calculates an evaluation value of an image generated based on a signal output from the image sensor, and an evaluation value calculation unit.
An instruction unit that instructs a focusing operation for focusing an image of the optical system on the image sensor, and
When the focusing operation is instructed by the instruction unit, the control unit that calculates the evaluation value a plurality of times while moving the first lens in one direction, and the control unit.
Have,
The control unit stops the first lens when the evaluation value starts to decrease, stops the first lens, and then moves the second lens, and moves the first lens in one direction. While moving, the second control of repeatedly moving the second lens in the first direction and the second direction opposite to the first direction is performed.
In the first control, the control unit determines the amount of movement of the image of the optical system per unit movement amount of the first lens and the amount of movement of the image of the optical system per unit movement amount of the second lens. The second lens is moved based on the above.
In the first control, the control unit makes the direction in which the image of the optical system moves due to the movement of the second lens opposite to the direction in which the image of the optical system moves due to the movement of the first lens. To drive the second lens,
Focus detector. In the focus detection device according to claim 1 or 2 .
The control unit is a focus detection device that stops the second lens while the first lens is being moved in the first control . The focus detection device according to any one of claims 1 to 3 .
The control unit is a focus detection device that moves the second lens before moving the first lens and starts moving the first lens after the movement of the second lens is completed. An imaging device having the focus detection device according to any one of claims 1 to 4 .

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