JP2013186313A - Focus adjustment apparatus and camera body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress drive sound and vibration caused by the driving of a focus lens during focus detection processing of hill-climbing contrast system.SOLUTION: A focus lens 210 is driven in a predetermined direction to perform hill-climbing operation of focus evaluation values of contrast AF. When a peak of focus evaluation values is detected, an image surface displacement caused by overshoot of the focus lens 210 is corrected by driving a wobbling lens 220 and an image pickup device in optical axis direction.

Description

  The present invention relates to a focus adjustment device and a camera body.

  In general hill-climbing contrast type focus detection processing, the high-frequency component of the imaged image of the image sensor is replaced with sharpness while performing a so-called wobbling operation that moves the focus adjustment optical system back and forth in small increments. Focus evaluation values are acquired sequentially. Then, the drive direction and focus position of the focus adjustment optical system are determined from the change in focus evaluation value.

  The interchangeable lens of a digital single-lens reflex camera has a large mass of a focus lens corresponding to an optical system for focus adjustment. For this reason, when the wobbling operation is performed using the focus lens, the wobbling operation cannot be performed at high speed, and the driving sound and vibration of the focus lens during the mountain climbing operation are problems. The driving sound and vibration of the focus lens are particularly noticeable when the focus lens is accelerated or decelerated.

  Patent Document 1 discloses a method for causing a wobbling operation to be performed at a high speed by minutely driving an optical system or an imaging device having a mass smaller than that of a focus lens in the optical axis direction with respect to the problem of the wobbling operation speed. .

Patent 4437244

  In the invention of Patent Document 1, it is determined whether or not the focus lens needs to be driven based on the focus evaluation value obtained during the wobbling operation, and the focus lens is determined each time it is determined that the focus lens needs to be driven. Is accelerated and decelerated and moved by a predetermined distance. Since the focus lens is repeatedly accelerated and decelerated during the focus detection process of the hill-climbing contrast method, it cannot be said that the problem of driving sound and vibration of the focus lens has been solved.

  The focus adjustment apparatus according to the first aspect of the present invention includes an imaging optical system having a first focus lens and a second focus lens having a smaller mass than the first focus lens, and a first focus lens that drives the first focus lens in the optical axis direction. 1 focus lens drive means, 2nd focus lens drive means for driving the second focus lens in the optical axis direction, drive direction determination means for determining the drive direction of the first focus lens, and subject imaged by the imaging optical system An imaging device that receives an image and outputs an image signal, a focus evaluation value detection unit that detects a focus evaluation value that indicates a focus adjustment state of the imaging optical system based on the image signal, and after the second focus lens is stopped The first focus lens is driven in the driving direction by the first focus lens driving means, and the position where the focus evaluation value becomes the peak value is set to the first predetermined amount. The drive control means for stopping the first focus lens at the stop position, and the second focus lens at the first position so that the imaging optical system is in a focused state with the first focus lens stopped at the stop position. Focusing means for driving a second predetermined amount corresponding to the fixed amount.

  The focus adjustment apparatus according to the second aspect of the present invention includes an imaging optical system having a focus lens, focus lens driving means for driving the focus lens in the optical axis direction, and drive direction determining means for determining the drive direction of the focus lens. An image sensor that receives a subject image formed by the image pickup optical system and outputs an image signal; an image sensor drive unit that drives the image sensor in the optical axis direction; and a focus adjustment state of the image pickup optical system based on the image signal A focus evaluation value detecting means for detecting a focus evaluation value indicating the position of the focus evaluation value, and a focus lens driving means for driving the focus lens in the driving direction after stopping the imaging device, and the position where the focus evaluation value becomes a peak value The drive control means that stops the focus lens at the stop position that has passed a predetermined amount, and the imaging optical system are combined with the focus lens stopped at the stop position. Characterized in that it comprises a focusing means for the second by a predetermined amount driven corresponding to the image pickup device to a first predetermined amount so that the state, the.

  A camera body according to a third aspect of the present invention is a camera body to which an interchangeable lens having a first focus lens and a second focus lens having a mass smaller than that of the first focus lens is detachably connected. First focus lens driving means for driving the lens in the optical axis direction, second focus lens driving means for driving the second focus lens in the optical axis direction, and drive direction determining means for determining the driving direction of the first focus lens An image sensor that receives a subject image formed by the imaging optical system and outputs an image signal; a focus evaluation value detection unit that detects a focus evaluation value that represents a focus adjustment state of the imaging optical system based on the image signal; After the second focus lens is stopped, the first focus lens is driven in the driving direction by the first focus lens driving means, and the focus is Drive control means for stopping the first focus lens at a stop position that has passed a first predetermined amount through the position where the value is a peak value, and the imaging optical system is in a focused state with the first focus lens stopped at the stop position And a focus adjusting means for driving the second focus lens by a second predetermined amount corresponding to the first predetermined amount.

  A camera body according to a fourth aspect of the present invention is a camera body to which an interchangeable lens having a focus lens is detachably connected, the focus lens driving means for driving the focus lens in the optical axis direction, and the driving of the focus lens A driving direction determining means for determining a direction; an imaging element that receives a subject image formed by an imaging optical system and outputs an image signal; an imaging element driving means that drives the imaging element in the optical axis direction; A focus evaluation value detecting means for detecting a focus evaluation value representing a focus adjustment state of the imaging optical system based on the focus evaluation value is obtained by driving the focus lens in the driving direction by the focus lens driving means after stopping the imaging device. Drive control means for stopping the focus lens at a stop position that has passed the first predetermined amount of the position that becomes the peak value, and focus at the stop position In a state where the lens is stopped, characterized in that it comprises a focusing means for imaging optical system driving a second predetermined amount corresponding to the first predetermined amount of the image pickup element so that the focus state, the.

  According to the present invention, it is possible to suppress the generation of driving sound and vibration by reducing the number of times the focus lens is driven during the hill-climbing contrast method focus detection processing.

It is a block block diagram of the digital camera by the 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 the 1st Embodiment of this invention. It is a figure for demonstrating the peak detection of a focus evaluation value. It is a figure explaining operation | movement of each optical system in the focus detection process in the 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 operation | movement of each optical system in the focus 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 operation | movement of each optical system in the focus detection process in the 3rd Embodiment of this invention. It is a flowchart of the focus detection process in the 3rd Embodiment of this invention. It is a block block diagram of the digital camera by the 4th Embodiment of this invention. It is a figure explaining the drive of a focus lens and an image sensor. It is a flowchart of the focus detection process in the 4th Embodiment of this invention. It is a figure explaining operation | movement of each optical system in the focus detection process in the 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 adjusting apparatus according to a first embodiment of the present invention. The interchangeable lens digital camera in FIG. 1 includes a camera body 100 and a photographing lens 200. The taking lens 200 is detachably attached to the camera body 100.

  The photographing lens 200 includes a focus lens 210 for performing focus adjustment, a focus lens driving unit 211 including a motor and a drive circuit for driving the focus lens, and a position for detecting the position of the focus lens 210 in the optical axis direction. And a detection unit 212. The photographic lens 200 detects the wobbling lens 220 for performing the wobbling operation, the wobbling lens driving unit 221 including a motor and a driving circuit for driving the wobbling lens 220, and the position of the wobbling lens 220 in the optical axis direction. Position detecting unit 222. Note that the power of the focus lens 210 is positive or negative (whether the focus lens 210 is a convex lens or a concave lens) and the power of the wobbling lens 220 is positive or negative (whether the wobbling lens 220 is a convex lens or a concave lens). And

  Furthermore, the taking lens 200 has a lens controller 250. The lens controller 250 calculates target positions or driving speeds of the focus lens 210 and the wobbling lens 220 in the photographing lens 200 in accordance with instructions from the camera body 100, and outputs the lens output 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 performs focus adjustment 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 sensor 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. A body controller 150 and an operation unit 180 are included.

  The image sensor 101 is configured by a CCD image sensor, a MOS type image sensor, or the like. The subject image formed by the photographing lens 200 is projected on the imaging surface of the imaging element 101. The imaging element 101 outputs an electrical signal (imaging signal) corresponding to the light intensity of the subject image formed on the imaging 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 types of analog signal processing on the imaging signal output from the imaging element 101. The imaging signal processed by the analog signal processing unit 102 is output to the A / D converter 103. The A / D converter 103 converts the imaging signal processed by the analog signal processing unit 102 from an analog signal to a digital signal. The image 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 signal processing circuits 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 edge enhancement, gamma correction, and white balance adjustment on the image signal A / D converted by the A / D converter 103.

  The buffer memory 112 is a frame memory that can store data for a plurality of frames captured by the image sensor 101. The digital signal processing unit 111 uses the buffer memory 112 as a work area when executing various image processing such as contour enhancement, gamma correction, and white balance adjustment. The imaging signal input to the digital signal processing unit 111 is stored in the buffer memory 112. The imaging signal stored in the buffer memory 112 is read each time various image processing such as contour enhancement, gamma correction, and white balance adjustment is performed, and the processed imaging signal is stored in the buffer memory 112. The imaging signal that has been subjected to a series of processing by the digital signal processing circuit 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 data encoding process on the imaging signal, which has been subjected to a series of processing by the digital signal processing circuit 111 and stored in the buffer memory 112, into a predetermined data format, and as an image data, an external memory card Record in the storage medium 115. The data format encoded by the Enc / Dec processing unit 113 is, for example, a JPEG format for a still image and a format such as MPEG2 or H264 / AVC for a moving image. The Enc / Dec processing unit 113 performs data decoding when reading encoded image data 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.

  Image signals picked up at predetermined time intervals by the image pickup device 101 are 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 View Finder) at the time of shooting, and the image data stored in the VRAM 120 is displayed as an image called a through image. The LCD monitor 121 can display the image data stored in the external storage medium 115 as an image. The LCD monitor 121 transfers image data read from the external storage medium 115 to the VRAM 120 and reproduces and displays it 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 issue driving instructions for 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 set in advance on the imaging screen, and integrates the absolute value of the extracted high-frequency component to thereby obtain a focus evaluation value. Is calculated. When a plurality of AF areas of a predetermined size are arranged at a predetermined position in the imaging screen, the integrated value of the plurality of AF areas is a focus evaluation value, and the specific subject area set as the AF area or the AF area Represents the contrast of the image inside.

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

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

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

  When the focus lens 210 is driven along the optical axis 20 toward the image sensor 101, the focus lens 210 is focused on the subject on the near side. And The in-focus position of the photographic lens 200 is simply moved by driving the focus lens 210. Similarly, when the wobbling lens 220 is driven along the optical axis 20 toward the image sensor 101, the object on the near side is focused, and when driven toward the subject along the optical axis 20, the object on the infinity side is focused. And Hereinafter, the direction in which the focus lens 210 and the wobbling lens 220 are driven toward the image sensor 101 along the optical axis 20 is referred to as the closest direction. 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 infinite direction.

  In FIG. 2A, the wobbling lens 220 is positioned at the center position of the driving range 22 of the wobbling lens 220. Hereinafter, the center position of the driving range 22 of the wobbling lens 220 is 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 optimal 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 to be driven toward the image sensor (closest direction), the wobbling lens 220 is driven in the closest direction by a predetermined offset amount D _OFS from the reference position 23. Thus, 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 (infinite direction), the wobbling lens 220 is driven in the infinite 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 hill-climbing contrast method focus detection process. The process of FIG. 3 is started when the user performs an operation corresponding to the focus detection operation such as half-pressing the release button. 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 drive”, “infinite direction”, or “closest direction”.

  The determination of the driving direction of the focus lens 210 in step S101 can be performed by the following method, for example. 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 a focus evaluation value from the focus evaluation value calculation unit 151 while driving the wobbling lens 220 back and forth (wobbling operation). The body controller 150 compares the focus evaluation value when the wobbling lens 220 is on the subject side with respect to the reference position 23 and the focus evaluation value when the wobbling lens 220 is on the image sensor side with respect to the reference position 23. When the focus evaluation value does not change due to the reciprocating driving of the wobbling lens 220, the body controller 150 determines that the driving 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 driving direction of the focus lens 210 to be “infinite direction”. When the focus evaluation value when the wobbling lens 220 is closer to the image sensor than the subject is larger, the body controller 150 determines the driving direction of the focus lens 210 as the “closest direction”.

  In step S102, the body controller 150 determines whether the driving direction of the focus lens 210 determined in step S101 is “not driving”, “infinity direction”, or “closest direction”. When it is determined in step S101 that the focus lens 210 is not driven, the body controller 150 advances the focus detection process of FIG. 3 from step S101 to step S110. When the driving direction of the focus lens 210 is determined to be “infinite direction”, the body controller 150 advances the focus detection process of FIG. 3 from step S101 to step S103b. When the driving 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 by the following equation (1), and adds the calculated offset amount D _OFS to the reference position 23, thereby calculating the position of the focusing operation position 24a. L _OVS in Equation (1) is an estimated value of the amount by which the focus lens 210 overshoots (overruns) the peak position when the peak of the focus evaluation value is detected by the hill-climbing operation of the focus detection process. It can be calculated by equation (2). α is an image plane movement coefficient of the focus lens 210 and is a ratio of the movement amount of the focus lens 210 to the movement amount of the image plane position as expressed by the following expression (3). β is the image plane movement coefficient of the wobbling lens 220, which is the ratio of the movement amount of the wobbling lens 220 to the movement amount of the image plane position as expressed 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. T _S of the formula (2) is a sampling period the body controller 150 acquires the focus evaluation value from the focus evaluation value calculation unit 151. n is the number of subsequent samples to be sampled to determine whether or not the focus evaluation value is a peak. V _FOCUS is a 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 at the driving speed V _FOCUS when the peak of the focus evaluation value is detected.
D _OFS = L _OVS / α × β (1)
L _OVS = (T _S × n × V _FOCUS + L ₀ ) (2)
α = movement amount of focus lens / movement amount of image plane position accompanying movement of focus lens (3)
β = movement amount of wobbling lens / movement amount of image plane position accompanying movement of wobbling lens (4)

In step S103b, the body controller 150 calculates the offset amount D _OFS by the above equation (1), and subtracts the calculated offset amount D _OFS from the reference position 23, thereby calculating the position of the focusing operation position 24b.

  In step S104, the body controller 150 drives the position of the wobbling lens 220 to the in-focus operation position via the lens controller 250. When the drive direction of the focus lens 210 is the closest direction, the body controller 150 drives the focus operation position 24a calculated in step S103a. When the drive direction of the focus lens 210 is the infinity direction, the body controller 150 calculates in step S103b. It drives 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 that has started driving in step S105 is set to a driving speed that is faster than _VFOCUS at the peak time. The body controller 150 that 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. Acquisition of the focus evaluation value at step S106 is performed at the sampling period _{T S} of the above formula (2). In step S105, the driving of the focus lens 210 is started, and the focus evaluation value is acquired in step S106, whereby the peak detection operation of the hill-climbing contrast method is started.

The peak detection operation performed by the body controller 150 will be described with reference to FIG. FIG. 4 is a diagram illustrating a temporal change in the focus evaluation value. The horizontal axis in 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 value _{X p-1 ~X} p _{+ 4} is obtained for each sampling period _{T S.} In FIG. 4, _Xp is the peak focus evaluation value. When the body controller 150, n pieces obtained after the focus evaluation value _{X p} (n subsequent samples of an expression (2)) is smaller than the focus evaluation value _{X p +} 1 _~X p + _n is the focus evaluation value _{X p,} the focus the evaluation value X _p is detected as a peak value of the focus evaluation value. If 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. Instead, 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} . Note that the number n of subsequent samples may be n> 1 in consideration of the influence of noise. For example, when a subsequent sample number n = 4, the focus evaluation value _{X p} is detected as a peak when the subsequent four larger focus evaluation value _{X p + 1 ~X p + 4} .

  FIG. 5 is a diagram for explaining the operations of the focus lens 210 and the wobbling lens 220 during the peak detection operation. FIG. 5A is a graph showing an example of a temporal change in the focus evaluation value in the peak detection operation. FIG. 5B illustrates an example of a temporal change in the driving speed of the focus lens 210 in the peak detection operation. FIG. 5C illustrates an example of a temporal change in the position of the focus lens 210 in the peak detection operation. FIG. 5D shows an example of a temporal change in the position of the wobbling lens in the peak detection operation. FIGS. 5A to 5D show an example of peak detection operation when it is determined in step S101 that the focus lens 210 is driven in the closest direction.

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

Time T1 is the time when the focus evaluation value reaches a peak. Time T2 is a time during which the peak focus evaluation value is detected as a peak value. Focus evaluation value peak by the time is actually detected to have been the peak value, to obtain the subsequent sample number of n of the focus evaluation value at a sampling period T _S. In other words, the difference between the times T1 and T2 is a value based on the subsequent sample number n and the sampling period T _S. The speed of the focus lens 210 is controlled so that the focus lens 210 has a predetermined speed V _FOCUS at a time when the focus evaluation value reaches a peak as at time T1. As shown in FIG. 5B, the focus lens 210 starts decelerating when the peak value is detected at time T2, and stops at time T3.

In the graph of FIG. 5B, the range from when the focus evaluation value reaches the peak value at time T1 to when the focus lens 210 stops at time T3 is shaded. When integrating the shaded portion shown in FIG. 5 (b), the overshoot amount L ₁ of the focus lens 210 has actually overshot.

Time T4 is a time to start decelerating the driving speed of the focus lens 210 toward a predetermined driving speed V _FOCUS at the time of peak detection. At time T4, the focus lens 210 is at the position P4. The position P4 is located at a position away from the position P1 where the focus lens 210 reaches a peak by a predetermined amount on the side opposite to the driving direction of the focus lens 210. In the example of FIG. 5C, the driving direction of the focus lens 210 is the closest direction, so the position P4 is closer to the subject than the position P1.

In step S107 in FIG. 3, the body controller 150 determines whether or not to reduce the driving speed of the focus lens 210 to a predetermined driving 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. Body controller 150, estimates the overall position P4 from the focus evaluation value and the amount of change that is repeatedly obtained at a sampling period T _S (differential value) from the time T0. For example, the position where the change amount of the focus 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. If it is determined that the drive speed of the focus lens 210 is not decelerated, the process proceeds to step S106 and the next focus evaluation value is obtained. get. In step S <b> 108, the body controller 150 reduces the drive speed of the focus lens 210 to the drive speed V _FOCUS via the lens controller 250. Thereafter, the driving speed of the focus lens 210 is maintained at the driving 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 the focus evaluation value _{X p} in FIG. 4, it is determined whether or not the focus evaluation value of the next n _X p + 1 _{to X p + n} is less 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 has been detected, the process proceeds to step S110. If it is determined that the peak value of the focus evaluation value has not been detected, the process proceeds to step S106 and the next focus evaluation is performed. 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 controlled in speed by the lens controller 250 with high accuracy, decelerates, and finally stops.

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

  In step S <b> 112, 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 a 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 a change in the position of the wobbling lens 220 acquired from the wobbling lens position detection unit 222 by the lens controller 250.

  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. When the fine adjustment of the in-focus position is completed, the process in FIG.

In the focus detection processing of FIG. 3, the focus lens 210 at time T3 is stopped in a state of overshooting by overshoot L _1. The focus shift caused by the overshoot is corrected by driving the wobbling lens 220 in step S111. When the focus lens 210 is moved by the overshoot amount L _1, image plane position moves by L _{1 /} alpha. 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. It can be said that the in-focus deviation is corrected if the deviation of the image plane position caused by the overshoot of the focus lens 210 and the deviation of the image plane position caused by the driving of the wobbling lens 220 in step S111 substantially coincide.

A period from time T1 to time T3 in which the focus lens 210 is overshooting is considered to be divided into a period from time T1 to time T2 and a period from time T2 to time T3. In step S108, the drive speed of the focus lens 210 from time T1 to time T2 is maintained at a predetermined drive speed _VFOCUS . Therefore, actually the distance the focus lens 210 overshoots during the time T1 to time T2, the subsequent sample number of n times in a predetermined driving speed V to the focus evaluation value is obtained at a sampling period T _{S Since} it is the distance that the focus lens 210 is driven by _FOCUS, it is accurately estimated by T _S × n × V _FOCUS in the above equation (2).

From time T2 to time T3, the focus lens 210 is decelerated by the lens controller 250 from a predetermined drive speed V _FOCUS until it stops (drive speed is zero). When the speed of the focus lens 210 can be controlled so that the lens controller 250 always decelerates at a constant speed transition, the amount of overshoot from time T2 to time T3 can be measured at the design stage of the taking lens 200. If the estimated distance L ₀ of the aforementioned and so the value measured can be estimated accurately overshoot amount of the focus lens 210 from the time T2 to time T3.

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

Therefore, by driving the wobbling lens 220 by a predetermined offset amount D _{OFS in the} direction opposite to the driving direction of the focus lens 210 in step S111, the focus shift due to the overshoot of the focus lens 210 can be corrected. .

According to 1st Embodiment described above, there exists the following effect.
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 drive direction of the focus lens 210 in step S101 of FIG. The camera body 100 includes an image sensor 101 that receives a subject image formed by the photographing lens 200 and outputs an image signal. In addition, the camera body 100 includes a focus evaluation value calculation unit 151 that detects a focus evaluation value representing the focus adjustment state of the photographing lens 200 based on the image signal output from the image sensor 101. The body controller 150 stops the wobbling lens 220 at the focus 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 reaches a peak. 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). Thereafter, 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 focus evaluation value peak is detected, the focus lens 210 is not driven, and the wobbling lens 220 having a mass smaller than that of the focus lens 210 is driven to correct the focus shift. Occurrence can be suppressed.

The first embodiment described above can be modified as follows.
(Modification 1-1) In the description using the flowchart of FIG. 3, the wobbling lens 220 is driven to the focus detection operation position in step S104, and the mountain climbing operation by the focus lens 210 is started in step S105, and in step S111. The wobbling lens 220 was returned to the reference position 32. However, if there is a process for driving the wobbling lens 220 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 when starting the operation may remain at the reference position.

  FIG. 6 is a modification of the focus detection process of the hill-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 S <b> 105), the wobbling lens 220 is at the reference position 23. Among the flows in FIG. 6, the description of the same flow as in FIG. 3 is omitted.

In step S <b> 121 of FIG. 6, the body controller 150 determines whether or not the focus lens 210 needs to be driven by the wobbling operation of the wobbling lens 220. That is, it is determined whether or not it is already in focus. In step S121, if it is determined in step S101 that the drive direction of the focus lens 210 is “not driven”, the focus lens 210 need not be driven and the process proceeds to step S110 in FIG. On the other hand, if the driving 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 in FIG. To do. In step S122 of FIG. 6, the body controller 150 drives the wobbling lens 220 through the lens controller 250 by a predetermined offset amount D _{OFS in the} direction opposite to the driving direction of the focus lens 210 determined in step S101. To do.

In the case of performing the hill-climbing contrast type focus detection process according to the flowchart of FIG. 6, even if the wobbling lens 220 is at a position shifted from the reference position 23 by a predetermined offset amount D _OFS , the optical characteristics (aberration) It is desirable to design such that characteristics, etc.) are good.

(Second Embodiment)
A second embodiment of the present invention will be described. The focus adjustment apparatus according to the second embodiment of the present invention is different from the first embodiment in the focus detection processing of the hill-climbing contrast method. The focus detection process in the second embodiment of the present invention can be performed using the interchangeable lens digital camera of FIG.

In the focus detection processing 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 over which the focus lens 210 actually overshoots, that is, overshoot. detecting the amount _{L 1.} Then, the overshoot amount L ₁ which is detected by substituting the following equation (5), calculates a focus position correction amount D _AR for driving the wobbling lens 220 for focusing deviation correction. After the focus lens 210 is stopped, the wobbling lens 220 is driven by the in-focus position correction amount D _{AR in the} direction opposite to the drive direction of the focus lens 210. When the wobbling lens 220 is driven by the focus position correction amount D _AR from the focus detection operation position, the image plane position moves by D _AR / β. This movement amount coincides with the magnitude of the movement amount 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 in-focus deviation caused by the overshoot of the focus lens 210.
D _AR = L ₁ / α × β (5)

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

  FIG. 8 shows a flowchart of focus detection processing using the hill-climbing contrast method according to the second embodiment. Description of steps in FIG. 8 that are the same as those in FIG. 3 is omitted.

  In step S201, the body controller 150 determines whether the driving direction of the focus lens 210 determined in step S101 is “not driving”, “infinitely far direction”, or “closest direction”. If it is determined in step S101 that the focus lens 210 is not driven, the body controller 150 advances the focus detection process in FIG. 8 from step S101 to step S113. When the driving direction of the focus lens 210 is determined to be “infinite direction”, the body controller 150 advances the focus detection process of FIG. 8 from step S101 to step S103b. When the driving direction of the focus lens 210 is determined to be “closest direction”, the body controller 150 advances the focus detection process of FIG. 8 from step S101 to step S103a.

  In step S <b> 202, 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 a 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 performs overshooting based on the position of the focus lens 210 acquired in step S202 when the focus evaluation value reaches a peak and the position of the focus lens 210 acquired after the focus lens 210 stops. to get a shot amount of _{L 1.} 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 through the lens controller 250 by the in-focus position correction amount D _AR calculated in step S203.

According to 2nd Embodiment demonstrated above, there exists the following effect.
The camera including the focus adjustment apparatus according to 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 drive direction of the focus lens 210 in step S101 of FIG. The camera body 100 includes an image sensor 101 that receives a subject image formed by the photographing lens 200 and outputs an image signal. In addition, the camera body 100 includes a focus evaluation value calculation unit 151 that detects a focus evaluation value representing the focus adjustment state of the photographing lens 200 based on the image signal output from the image sensor 101. The body controller 150 stops the wobbling lens 220 at the in-focus operation detection position (step S104 in FIG. 8), and then drives the focus lens 210 in the driving direction (step S105 in FIG. 8). 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). Thereafter, the body controller 150 drives the wobbling lens 220 by the in-focus position correction amount D _{AR in the} direction opposite to the driving direction with the focus lens 210 stopped (step S204 in FIG. 8). According to the present invention, after the focus evaluation value peak is detected, the focus lens 210 is not driven, and the wobbling lens 220 having a mass smaller than that of the focus lens 210 is driven to correct the focus shift. 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 detected more accurately 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 drive speed of the focus lens 210.

The second embodiment described above can be modified as follows.
(Modification 2-1) In the description using the flowchart of FIG. 8, after the wobbling lens 220 is driven to the focus detection operation position in step S104, the hill climbing operation by the focus lens 210 is started in step S105, and in step S110. driving the wobbling lens 220 only in-focus position correction amount _{D AR} at step S204 after the focus lens 210 is stopped. However, if there is a process for driving the wobbling lens 220 by the in-focus position correction amount D _{AR 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 is performed. The position of the wobbling lens 220 when starting the operation may remain at the reference position.

  FIG. 9 is a modification of the focus detection process of the hill-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 S <b> 105), the wobbling lens 220 is at the reference position 23. Each flow in FIG. 9 is the same as the flow in FIG. 6 and FIG.

(Third embodiment)
A third embodiment of the present invention will be described. The focus adjustment apparatus according to the third embodiment of the present invention is different from the first embodiment in the focus detection processing of the hill-climbing contrast method. The focus detection process in the third embodiment of the present invention can be performed using the interchangeable lens digital camera of FIG. In the third embodiment of the present invention, after decelerating the focus lens 210 to the drive speed V _FOCUS (> 0), the wobbling is performed until the peak value of the focus evaluation value is detected while the focus lens 210 is driven. A wobbling operation by the lens 220 is performed.

FIG. 10 is a diagram for explaining the operations 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 a temporal change in 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 when the focus lens 210 starts to decelerate to the predetermined drive speed V _FOCUS (> 0) until the time T3 when the focus lens 210 stops. It has been broken. FIG. 10A is a graph showing an example of the temporal change of the focus evaluation value in the peak detection operation. The portion from time T4 to time T3 when the wobbling lens 220 is performing the wobbling operation is shown in FIG. Different.

  FIG. 11 shows a flowchart of focus detection processing using the hill-climbing contrast method according to the third embodiment. In the flow of FIG. 1, the description of the same steps as those in FIGS. 3 and 8 is 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. If the peak value of the focus evaluation value is not detected, the process proceeds to step S106, and the next focus evaluation value is acquired. In step S303, the body controller 150 instructs the lens controller 250 to stop the wobbling operation.

According to 3rd Embodiment demonstrated above, there exists the following effect.
A camera including the focus adjustment apparatus according to 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 drive direction of the focus lens 210 in step S101 of FIG. The camera body 100 includes an image sensor 101 that receives a subject image formed by the photographing lens 200 and outputs an image signal. In addition, the camera body 100 includes a focus evaluation value calculation unit 151 that detects a focus evaluation value representing the focus adjustment state of the photographing lens 200 based on the image signal output from the image sensor 101. The body controller 150 stops the wobbling lens 220 at the focus detection position (step S104 in FIG. 11), and then drives the focus lens 210 in the driving direction (step S105 in FIG. 11), so that the focus evaluation value reaches its peak. 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 by the in-focus position correction amount D _{AR in the} direction opposite to the driving direction with the focus lens 210 stopped (step S204 in FIG. 11). According to the present invention, after the focus evaluation value peak is detected, the focus lens 210 is not driven, and the wobbling lens 220 having a mass smaller than that of the focus lens 210 is driven to correct the focus shift. Occurrence can be suppressed.

In the third embodiment, after the focus lens 210 is decelerated to the drive speed V _FOCUS (> 0), the focus evaluation value is detected while the focus lens 210 is driven. A wobbling operation is performed by the wobbling lens 202. Thereby, the peak value of the focus evaluation value can be detected more accurately and quickly during the hill-climbing operation.

The third embodiment described above can be implemented with the following modifications.
(Modification 3-1) As in the first embodiment and the second embodiment, the position of the wobbling lens 220 when starting the hill-climbing operation is not limited to the focus detection operation position. For example, the position of the wobbling lens 220 when starting a mountain climbing operation may be the reference position 23.

(Modification 3-2) The focus detection process illustrated in FIG. 11 is substantially a process in which steps S301 and S303 are added to the focus detection process illustrated in FIG. The 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. Within the scope of the form.

(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 apparatus according to the fourth embodiment. The interchangeable lens digital camera of FIG. 12 includes a camera body 300 and a photographing lens 400. The taking lens 400 is detachably attached to the camera body 300. Of the parts included in FIG. 12, the description of the same parts as in FIG. 1 is omitted.

  The taking lens 400 includes a focus lens 210 for performing focus adjustment, a focus lens driving unit 211 including a motor and a driving circuit for driving the focus lens, 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 difference from the photographic lens 200 in the first embodiment is that the wobbling lens 220 does not exist.

  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. An LCD monitor 121 and an operation unit 180 are included. 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 sensor 301 is configured by a CCD image sensor, a MOS image sensor, or the like. The imaging element 301 outputs an electrical signal (imaging signal) corresponding to the light intensity of the subject image formed on the imaging surface to the analog signal processing unit 102. Unlike the image sensor 101, the image sensor 301 is driven in the optical axis direction by the image sensor drive unit 302. In addition, the position of the image sensor 301 is detected by the image sensor position detector 303 in the optical axis direction. The image sensor driving unit 302 includes a motor and a driving 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 issue an instruction to drive the focus lens 210 via the lens controller 250. The body controller 350 can control driving of the image sensor 301.

  FIG. 13 is a diagram for explaining the driving of the focus lens 210 and the image sensor 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 sensor 301. Similarly to FIG. 2, the driving range 21 has an infinite 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 infinitely far end 32a on the photographer side.

  When the focus lens 210 is driven along the optical axis 40 toward the photographer, the focus lens 210 is focused on the subject on the near side. On the other hand, when the focus lens 210 is driven along the optical axis 40 toward the subject, the focus lens 210 is focused on the subject at infinity. To do. The in-focus position of the photographic lens 200 is simply moved by driving the focus lens 210. On the other hand, when the image sensor 301 is driven to the subject side along the optical axis 40, it is focused on the subject on the near side, and conversely, when it is driven toward the photographer side along the optical axis 40, it is focused on the subject on the infinity side. Shall be scorched.

  In FIG. 13A, the image sensor 301 is positioned at the center position of the drive range 32. Hereinafter, the center position of the drive range 32 of the image sensor 301 is referred to as a reference position 33 of the image sensor 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 to be driven toward the image sensor side (the closest direction in the image sensor 301), the image sensor 301 has a predetermined second offset amount D _OFS2 relative to the reference position 33 _. Only the closest end 32b side (closest direction) is driven 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 (in the direction of infinity in the image sensor 301), the image sensor 301 has a predetermined second offset amount from the reference position 33. D _OFS2 is driven toward the infinity side end 32a (in the 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 focus detection processing using a hill-climbing contrast method. The process in FIG. 14 is started when the user performs an operation corresponding to the focus detection operation such as half-pressing the release button. Description of steps in FIG. 14 that are the same as those in FIG. 3 is omitted.

  In step S401, the body controller 350 determines the drive direction of the focus lens 210. In step S401, the driving direction of the focus lens 210 is determined to be, for example, “not drive”, “infinite direction”, or “closest direction”.

  The determination of the driving direction of the focus lens 210 in step S401 can be made, for example, by the following method. First, the body controller 350 positions the image sensor 301 at the reference position 33. Next, the body controller 350 obtains a focus evaluation value from the focus evaluation value calculation unit 151 while reciprocatingly driving the image sensor 301. The body controller 350 compares the focus evaluation value when the image sensor 301 is on the subject side with respect to the reference position 33 and the focus evaluation value when the image sensor 301 is on the photographer side with respect to the reference position 33. When the focus evaluation value does not change due to the reciprocating drive of the image sensor 301, the body controller 350 determines that the drive direction of the focus lens 210 is "not drive". When the focus evaluation value is larger when the image sensor 301 is closer to the subject than the photographer, the body controller 350 determines the driving direction of the focus lens 210 as the “closest direction”. When the focus evaluation value when the imaging element 301 is closer to the photographer than the subject is larger, the body controller 350 determines the driving direction of the focus lens 210 as “infinite direction”.

In step S402, the body controller 350 determines whether the driving direction of the focus lens 210 determined in step S401 is “not driving”, “infinity direction”, or “closest direction”. If it is determined in step S401 that the focus lens 210 is not to be driven, the body controller 350 advances the focus detection process in FIG. 14 from step S401 to step S110. When the driving direction of the focus lens 210 is determined to be “infinite direction”, the body controller 350 advances the focus detection process of FIG. 14 from step S401 to step S403b. When the driving direction of the focus lens 210 is determined to be “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 according} to the following equation (6), and subtracts the calculated second offset amount D _OFS2 from the reference position 33 of the image sensor 301, so that the in-focus operation position. The position of 34b is calculated. L _OVS in equation (6) is an estimated value of the amount by which the focus lens 210 overshoots (overruns) the peak position when the peak of the focus evaluation value is detected by the hill-climbing operation of the focus detection process. It can be calculated by equation (1). α is an image plane movement coefficient of the focus lens 210 and is a ratio of the movement amount of the focus lens 210 to the movement amount of the image plane position as expressed 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 sensor 301, thereby _{performing the} focusing operation. The position 34a is calculated.

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

  FIG. 15 is a diagram for explaining the operation of the focus lens 210 and the image sensor 301 during the peak detection operation. FIG. 15A is a graph showing an example of the temporal change of the focus evaluation value in the peak detection operation, and shows the same example as FIG. FIG. 15B shows an example of the temporal change of the driving speed of the focus lens 210 in the peak detection operation, and shows the same example as FIG. FIG. 15C shows an example of the temporal change of the position of the focus lens 210 in the peak detection operation, and shows the same example as FIG. FIG. 15D illustrates an example of a temporal change in the position of the image sensor 301 in the peak detection operation. In the example of FIGS. 15A to 15D, the peak detection operation in the case where it is determined in step S401 that the focus lens 210 is driven in the closest direction is shown.

As shown in FIG. 15 (d), the position of the image sensor 301 is already at the focusing operation position 34b that has been driven from the reference position 33 toward the closest end 32b by the second offset amount D _OFS2 at time T0. It is positioned. When the peak value of the focus evaluation value is detected at time T2 (YES in step S109 in FIG. 14), the image sensor 301 is driven by the second offset amount D _{OFS2 toward} the infinity side end 32a in step S405 in FIG. To the reference position 33.

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

  In step S407, the body controller 350 performs a wobbling operation by the image sensor 301 and finely adjusts the in-focus position. When the fine adjustment of the in-focus position is completed, the process in FIG.

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

According to 4th Embodiment demonstrated above, there exists the following effect.
The camera in 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 sensor 301 that receives a subject image formed by the 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. The body controller 350 determines the drive direction of the focus lens 210 by the wobbling operation of the image sensor 301 in step S401 in FIG. In addition, the camera body 300 includes a focus evaluation value calculation unit 151 that detects a focus evaluation value representing the focus adjustment state of the photographing lens 400 based on the image signal output from the image sensor 301. The body controller 350 stops the imaging device 301 at the focus operation detection position (step S404 in FIG. 14), and then drives the focus lens 210 in the driving direction (step S105 in FIG. 14), so that the focus evaluation value reaches a peak. 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). Thereafter, the body controller 350 drives the image sensor 301 in the driving direction to the reference position 33 in a state where the focus lens 210 is stopped (step S405 in FIG. 14). According to the present invention, after detecting the peak of the focus evaluation value, the focus lens 210 is not driven, and the imaging element 301 is driven to correct the focus shift. Therefore, it is possible to suppress the generation of driving sound and vibration.

The fourth embodiment described above can be modified as follows.
(Modification 4-1) In the description using the flowchart of FIG. 14, after the imaging element 301 is driven to the focus detection operation position in step S <b> 403, the mountain climbing operation by the focus lens 210 is started in step S <b> 105, and in step S <b> 110. After the focus lens 210 stopped, the wobbling lens 220 was driven to the reference position 33 in step S404. However, if there is a process for driving the image sensor 301 by the second offset amount D _OFS2 in the direction corresponding 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 image sensor 301 when starting the operation may remain at the reference position 33.

  FIG. 16 is a modification of the focus detection process of the hill-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 S <b> 105), the image sensor 301 is at the reference position 33. Each flow of FIG. 16 is the same as the flow of FIG. 6 and FIG.

(Modification 4-2) In step S _< b _> 405 of FIG. 14, the image sensor 301 is driven by the second offset amount D _{OFS <} b _> 2 and moved to the reference position 33. However, as in the second embodiment, by detecting the actual overshoot amount L ₁ of the focus lens 210, the focus position correction amount based on the amount of overshoot L ₁ (the second embodiment corresponding to the in-focus position correction amount D _AR) only may be driven.

(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 sensor 301.

The embodiment described above can be implemented with the following modifications.
(Modification 5-1) In step S101 in the first to third embodiments and step S401 in the fourth embodiment, the driving direction of the focus lens 210 is changed by the wobbling operation by the wobbling lens 220 or the image sensor 301. Were determined. However, the method for determining the drive 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 focus detection processing of a phase difference detection method is further provided in the camera body 100 or 300, and the defocus amount calculated based on the focus detection signal output from the focus detection element is positive or negative From this, the driving direction of the focus lens 210 may be determined. The driving direction determination method using the focus detection element is supplementary 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 in step S101 or step S401. You may decide to carry out.

(Modification 5-2) first to the fourth embodiment, in step S105, has been to set a focusing lens 210 to a speed higher than a predetermined driving speed _{V FOCUS,} predetermined driving speed _{V FOCUS} You may decide to set. Thereby, step S107 and step S108 can be omitted, the number of times of acceleration / deceleration of the focus lens 210 can be further reduced, and the generation of drive sound and vibration can be further suppressed.

(Modification 5-3) In the first to fourth embodiments, the image plane movement coefficients of the focus lens 210 and the wobbling lens 220 are constant, but the image plane movement coefficient varies depending on the shooting distance and the focal distance. It is possible to change. In this case, the image plane movement coefficient is calculated by the body controller 150, and the offset amount D _OFS , the focus position correction amount D _AR, and the second offset amount D _OFS2 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 exist individually is shown. However, the body controller 150 or 350 drives the focus lens. The unit 211, the focus lens position detection unit 212, the wobbling lens driving unit 221, and the wobbling lens position detection unit 222 may be directly controlled.

(Modification 5-5) In the first to third embodiments, the power of the focus lens 210 and the power of the wobbling lens 220 are the same. 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 match. When the powers of the focus lens 210 and the wobbling lens 220 do not coincide with each other, the wobbling lens 220 in FIGS. 2B, 2C, 3, 6, 8, 9, and 11 is used. The driving direction is reversed.

  The above embodiments may be executed in combination as long as the features of the invention are not impaired. Moreover, said embodiment is an example to the last, and this invention is not limited to these content, unless the characteristic of invention is impaired.

22a, 22b, 32a, 32b In-focus operation detection position 23, 33 Reference position 100, 300 Camera body 101, 301 Image sensor 150, 350 Body controller 200, 400 Shooting lens 210 Focus lens 211 Focus lens driving unit 212 Focus lens position detection Unit 220 wobbling lens 221 wobbling lens driving unit 222 wobbling lens position detecting unit 302 imaging element driving unit 303 imaging element position detecting unit

Claims (26)

An imaging optical system having a first focus lens and a second focus lens having a smaller mass than the first focus lens;
First focus lens driving means for driving the first focus lens in the optical axis direction;
Second focus lens driving means for driving the second focus lens in the optical axis direction;
Driving direction determining means for determining a driving direction of the first focus lens;
An image sensor that receives a subject image formed by the imaging optical system and outputs an image signal;
Focus evaluation value detection means for detecting a focus evaluation value representing a focus adjustment state of the imaging optical system based on the image signal;
After stopping the second focus lens, the first focus lens driving means drives the first focus lens in the driving direction, and passes a position where the focus evaluation value becomes a peak value by a first predetermined amount. Drive control means for stopping the first focus lens at a stop position;
A focus for driving the second focus lens by a second predetermined amount corresponding to the first predetermined amount so that the imaging optical system is in a focused state with the first focus lens being stopped at the stop position. Adjusting means;
A focus adjusting apparatus comprising: The focus adjustment apparatus according to claim 1,
The drive control means stops the second focus lens at a position separated by the second predetermined amount from a reference position in a range where the second focus lens drive means can drive the second focus lens. Starting driving the first focus lens by the first focus lens driving means;
The focus adjustment device, wherein the focus adjustment unit returns the second focus lens to the reference position in a state where the first focus lens is stopped at the stop position. The focusing apparatus according to claim 2, wherein
The focus adjustment apparatus, wherein the reference position is a center position of a range in which the second focus lens driving unit can drive the second focus lens. The focus adjustment apparatus according to claim 1,
The drive control means stops the second focus lens at a center position within a range in which the second focus lens drive means can drive the second focus lens, and then the first focus lens drive means performs the first focus control by the first focus lens drive means. A focus adjustment device which starts driving a focus lens. In the focus adjustment apparatus according to any one of claims 1 to 4,
The drive control means controls the speed so that the drive speed of the first focus lens becomes a predetermined speed when the focus evaluation value becomes a peak value,
The focus adjusting means drives the second focus lens by the second predetermined amount determined based on the predetermined speed while the first focus lens is stopped at the stop position. Adjusting device. The focus adjustment device according to claim 1 or 4,
A distance detecting means for detecting an overshoot amount of the first focus lens from a position where the focus evaluation value becomes a peak value to the stop position;
The focus adjusting means moves the second focus lens to the second position determined based on the overshoot amount detected by the distance detecting means in a state where the first focus lens is stopped at the stop position. A focus adjustment device characterized by being driven in a fixed amount. In the focus adjustment apparatus according to any one of claims 1 to 6,
It further comprises wobbling means for performing a wobbling operation by the second focus lens from when the drive control means drives the first focus lens to when the first focus lens is stopped at the stop position. Focusing device. An imaging optical system having a focus lens;
Focus lens driving means for driving the focus lens in the optical axis direction;
Drive direction determining means for determining the drive direction of the focus lens;
An image sensor that receives a subject image formed by the imaging optical system and outputs an image signal;
Image sensor driving means for driving the image sensor in the optical axis direction;
Focus evaluation value detection means for detecting a focus evaluation value representing a focus adjustment state of the imaging optical system based on the image signal;
After the image sensor is stopped, the focus lens is driven in the driving direction by the focus lens driving means, and the focus lens is set to a stop position where the focus evaluation value has reached a peak value through a first predetermined amount. Drive control means for stopping
Focus adjusting means for driving the imaging element to a second predetermined amount corresponding to the first predetermined amount so that the imaging optical system is in a focused state in a state where the focus lens is stopped at the stop position;
A focus adjusting apparatus comprising: The focus adjustment device according to claim 8.
The drive control means stops the image sensor at a position away from the second predetermined amount from the center position of the range in which the image sensor drive means can drive the image sensor, and then the focus lens drive means Start driving the focus lens,
The focus adjustment device, wherein the focus adjustment unit returns the image sensor to the center position so that the imaging optical system is in a focused state in a state where the focus lens is stopped at the stop position. The focus adjustment device according to claim 8.
The drive control means starts driving the focus lens by the focus lens driving means after stopping the image pickup element at a center position in a range where the image pickup element driving means can drive the image pickup element. Focus adjustment device. In the focus adjustment apparatus according to any one of claims 8 to 10,
The drive control means controls the speed so that the drive speed of the focus lens becomes a predetermined speed when the focus evaluation value reaches a peak value,
The focus adjustment device, wherein the focus adjustment unit drives the image sensor to the second predetermined amount based on the predetermined speed in a state where the focus lens is stopped at the stop position. The focusing apparatus according to claim 8 or 10,
Distance detecting means for detecting an overshoot amount of the focus lens from a position where the focus evaluation value becomes a peak value to a position where the focus evaluation value where the drive control means stops the focus lens exceeds a peak value. Further comprising
The focus adjustment unit drives the image sensor to the second predetermined amount based on the overshoot amount detected by the distance detection unit while the focus lens is stopped at the stop position. Focusing device. The focusing apparatus according to any one of claims 8 to 12,
It further comprises wobbling means for performing a wobbling operation by the image sensor from when the drive control means drives the focus lens until the focus lens is stopped at a position where the focus evaluation value exceeds a peak value. Focus adjustment device characterized. A camera body to which an interchangeable lens having a first focus lens and a second focus lens having a smaller mass than the first focus lens is detachably connected,
First focus lens driving means for driving the first focus lens in the optical axis direction;
Second focus lens driving means for driving the second focus lens in the optical axis direction;
Driving direction determining means for determining a driving direction of the first focus lens;
An image sensor that receives a subject image formed by the imaging optical system and outputs an image signal;
Focus evaluation value detection means for detecting a focus evaluation value representing a focus adjustment state of the imaging optical system based on the image signal;
After stopping the second focus lens, the first focus lens driving means drives the first focus lens in the driving direction, and passes a position where the focus evaluation value becomes a peak value by a first predetermined amount. Drive control means for stopping the first focus lens at a stop position;
A focus for driving the second focus lens by a second predetermined amount corresponding to the first predetermined amount so that the imaging optical system is in a focused state with the first focus lens being stopped at the stop position. Adjusting means;
A camera body characterized by comprising: The camera body according to claim 14,
The drive control means stops the second focus lens at a position separated by the second predetermined amount from a reference position in a range where the second focus lens drive means can drive the second focus lens. Starting driving the first focus lens by the first focus lens driving means;
The camera body according to claim 1, wherein the focus adjustment unit returns the second focus lens to the reference position in a state where the first focus lens is stopped at the stop position. The camera body according to claim 15,
The camera body according to claim 1, wherein the reference position is a center position of a range in which the second focus lens driving means can drive the second focus lens. The camera body according to claim 14,
The drive control means stops the second focus lens at a center position within a range in which the second focus lens drive means can drive the second focus lens, and then the first focus lens drive means performs the first focus control by the first focus lens drive means. A camera body that starts driving a focus lens. The camera body according to any one of claims 14 to 17,
The drive control means controls the speed so that the drive speed of the first focus lens becomes a predetermined speed when the focus evaluation value becomes a peak value,
The focus adjustment means drives the second focus lens by the second predetermined amount determined based on the predetermined speed in a state where the first focus lens is stopped at the stop position. body. The camera body according to claim 14 or 17,
A distance detecting means for detecting an overshoot amount of the first focus lens from a position where the focus evaluation value becomes a peak value to the stop position;
The focus adjusting means moves the second focus lens to the second position determined based on the overshoot amount detected by the distance detecting means in a state where the first focus lens is stopped at the stop position. A camera body characterized by being driven in a fixed amount. The camera body according to any one of claims 14 to 19,
It further comprises wobbling means for performing a wobbling operation by the second focus lens from when the drive control means drives the first focus lens to when the first focus lens is stopped at the stop position. Camera body to do. A camera body to which an interchangeable lens having a focus lens is detachably connected,
Focus lens driving means for driving the focus lens in the optical axis direction;
Drive direction determining means for determining the drive direction of the focus lens;
An image sensor that receives a subject image formed by the imaging optical system and outputs an image signal;
Image sensor driving means for driving the image sensor in the optical axis direction;
Focus evaluation value detection means for detecting a focus evaluation value representing a focus adjustment state of the imaging optical system based on the image signal;
After the image sensor is stopped, the focus lens is driven in the driving direction by the focus lens driving means, and the focus lens is set to a stop position where the focus evaluation value has reached a peak value through a first predetermined amount. Drive control means for stopping
Focus adjusting means for driving the imaging element to a second predetermined amount corresponding to the first predetermined amount so that the imaging optical system is in a focused state in a state where the focus lens is stopped at the stop position;
A camera body characterized by comprising: The camera body according to claim 21, wherein
The drive control means stops the image sensor at a position away from the second predetermined amount from the center position of the range in which the image sensor drive means can drive the image sensor, and then the focus lens drive means Start driving the focus lens,
The camera body according to claim 1, wherein the focus adjusting unit returns the image sensor to the center position so that the imaging optical system is in a focused state in a state where the focus lens is stopped at the stop position. The camera body according to claim 21, wherein
The drive control means starts driving the focus lens by the focus lens driving means after stopping the image pickup element at a center position in a range where the image pickup element driving means can drive the image pickup element. Camera body. The camera body according to any one of claims 21 to 23,
The drive control means controls the speed so that the drive speed of the focus lens becomes a predetermined speed when the focus evaluation value reaches a peak value,
The camera body according to claim 1, wherein the focus adjustment unit drives the image sensor to the second predetermined amount based on the predetermined speed in a state where the focus lens is stopped at the stop position. The camera body according to claim 21 or 23,
Distance detecting means for detecting an overshoot amount of the focus lens from a position where the focus evaluation value becomes a peak value to a position where the focus evaluation value where the drive control means stops the focus lens exceeds a peak value. Further comprising
The focus adjustment unit drives the image sensor to the second predetermined amount based on the overshoot amount detected by the distance detection unit while the focus lens is stopped at the stop position. Camera body to do. The camera body according to any one of claims 21 to 25,
It further comprises wobbling means for performing a wobbling operation by the image sensor from when the drive control means drives the focus lens until the focus lens is stopped at a position where the focus evaluation value exceeds a peak value. Characteristic camera body.

Images