JP2013142880A - Imaging apparatus and interchangeable lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging apparatus capable of reducing focus variation due to minute vibration of a focus lens by ensuring satisfactory responsiveness of AF control.SOLUTION: An imaging apparatus C100 generates a focal signal using output from an imaging element C101 to vibrate a focus lens L105 in a direction where the focal signal increases to shift the vibration center in a focusing direction where the focal signals increase. The imaging apparatus calculates the vibration amplitude amount and the shift amount of the vibration center using position control resolution and the degree of positional sensitivity of the focus lens to calculate the focal depth using a diameter of permissible circle of confusion and an F-value obtained from the interchangeable lens of the imaging element. When the focus lens is determined to shift outside of the focal depth when the shift amount of the focus lens is set to an added shift amount in which the shift amount of the vibration center is added to the vibration amplitude amount, the imaging apparatus causes the focus lens to shift by a distance of a shift amount smaller than the added shift amount while shifting the vibration center in the focusing direction.

Description

  The present invention relates to an imaging apparatus such as a video camera capable of exchanging lenses.

  In the autofocus (AF) control in the above-described lens-interchangeable image pickup apparatus, as disclosed in Patent Document 1, the image contrast state (that is, the photographing optical system) on the image pickup apparatus (camera body) side is disclosed. The focus signal indicating the focus state) is generated. In general, AF control is performed on the interchangeable lens (lens unit) side by moving the focus lens based on a focus signal acquired from the camera body.

  Also, in the AF control using the focus signal, the focus lens is reciprocated by a minute amount in the near direction and the infinity direction (hereinafter referred to as minute vibration) to detect the increase / decrease of the focus signal, and in the direction in which the focus signal increases. A certain in-focus direction is determined. Then, the center position of the minute vibration of the focus lens (hereinafter referred to as the vibration center) is moved in the in-focus direction. When the movement of the vibration center in the in-focus direction is repeated a predetermined number of times, it is determined that the direction is the true in-focus direction, the focus lens is moved in the in-focus direction at a constant speed, and the focus signal is The maximum in-focus position is searched. This is also called mountain climbing driving in AF control. In the vicinity of the in-focus position, the minute vibration of the focus lens is again performed to determine whether or not the in-focus state is obtained.

  In such a case, the focus signal is generated on the camera body side according to the characteristics of the attached lens unit and AF control is performed on the lens unit side. Determined by the combination.

  On the other hand, the number of pixels of an image sensor such as a CMOS sensor on the camera body side has recently increased dramatically, and an image sensor with a fine pixel pitch has a small depth of focus. Required.

Japanese Patent No. 3943609

  However, in general, an actuator that moves the focus lens is often used with a drive resolution limit such as a stepping motor. For this reason, there is a limit to the position control resolution of the focus lens. In this case, if the focus lens is subjected to minute vibration (including movement of the vibration center) near the in-focus position with respect to the shallow depth of focus of the image sensor with a fine pixel pitch, the image captured by the image sensor is brought into focus. Focus fluctuations approaching and moving away occur.

  FIG. 9 shows the movement of the focus lens during hill-climbing driving. The horizontal axis indicates the position of the focus lens (focus position), and the vertical axis indicates the value of the focus signal. The focus signal has a mountain shape whose value increases as it approaches the in-focus position. In hill-climbing driving, the focus lens is moved toward the focus position where the value of the focus signal is maximum (peak) at a constant speed, and the focus position is searched.

  In FIG. 9, in the movement of the focus lens shown in A, the focus signal decreases beyond the peak. Therefore, the hill-climbing drive is terminated by passing the in-focus position, and the focus lens is moved to the position where the focus signal reaches the peak. Return and start micro-vibration. On the other hand, in the movement of the focus lens shown in B, since the focus signal decreases without peaking, the movement direction of the focus lens is reversed and the hill-climbing driving is continued assuming that the direction to be the in-focus direction is wrong. . In the minute vibration after detecting the focus position where the focus signal value reaches the peak by hill-climbing driving, the focus is determined by whether or not the focus lens position is within the range of the focal depth shown as the hatched area in the figure. Make a decision. If the subject is in focus, the focus lens is stopped and the AF control is terminated.

  FIG. 10 shows a state of minute vibration near the focus position of the focus lens for focus determination. The horizontal axis represents time, and the vertical axis represents the position of the focus lens (focus position). A thin horizontal dotted line indicates a position where the focus lens can be stopped (a position corresponding to the control resolution of the actuator). A hatched area indicates the width of the depth of focus. The depth of focus has a width equal to the near direction and the infinity direction with respect to the center of vibration indicated by the two-dot chain line (here, the focus position). The vibration amplitude amount and the movement amount of the vibration center in the minute vibration are set smaller than the width of the focal depth.

  This figure shows that the focus lens moves from the center of vibration to the near side and the infinity side by a vibration amplitude amount corresponding to one driving step of the stepping motor, and also the vibration center of the moving amount corresponding to one driving step of the stepping motor. The state of repeating the movement of is shown. Then, when the vibration center is continuously within the range of the depth of focus for a predetermined number of times (for example, three times), the focus determination is made and the movement of the focus lens is stopped.

  Here, the movement amount of the focus lens when the vibration center moves is set to an amount obtained by adding the movement amount of the vibration center to the vibration amplitude amount (addition movement amount). For this reason, as shown in the vicinity of the center of the figure, there arises a situation where the position after movement of the focus lens including the movement of the vibration center exceeds the depth of focus, and the focus variation of the image is recognized by the user. .

  If the vibration amplitude and center movement amount can be set very small and the focus lens movement amount including the movement of the vibration center can be set small, the focus lens can be sufficiently vibrated within the shallow depth of focus. The focus fluctuation is not recognized.

  However, since the minimum values of the vibration amplitude and the movement amount of the vibration center are determined by the position control resolution of the focus lens corresponding to the driving resolution of the stepping motor, they cannot be made too small. Moreover, even if the vibration amplitude and the amount of movement of the vibration center can be reduced, the movement of the focus lens in the focusing direction in the AF control becomes slow, and the responsiveness of the AF control is reduced.

  According to the present invention, even when various interchangeable lenses and an imaging device are combined, it is possible to suppress the focus fluctuation of the image due to the minute vibration of the focus lens when the depth of focus is shallow while the responsiveness of the AF control is good. An imaging device and an interchangeable lens are provided.

An imaging apparatus according to one aspect of the present invention includes an imaging optical system that includes a focus lens, a focus actuator that moves the focus lens, and a lens control unit that controls the position of the focus lens by driving the focus actuator. The lens can be attached and detached. The imaging apparatus includes an imaging element that photoelectrically converts a subject image formed by the imaging optical system, a focus signal generation unit that generates a focus signal indicating a focus state of the imaging optical system using an output from the imaging element, And an imaging device control unit that vibrates the focus lens in a direction in which the focus signal increases or decreases through the lens control unit and moves the vibration center of the focus lens in a focusing direction in which the focus signal increases. The imaging device controller uses the focus lens position control resolution and position sensitivity obtained from the interchangeable lens to calculate the vibration amplitude of the focus lens and the amount of movement of the vibration center, and replaces it with the permissible circle of confusion of the image sensor. The depth of focus is calculated using the F value of the photographing optical system acquired from the lens. Then, the imaging device control unit performs the addition when the movement amount of the focus lens when moving the vibration center in the in-focus direction is set to an addition movement amount obtained by adding the movement amount of the vibration center to the vibration amplitude amount. In the first case where it is determined whether or not the focus lens moves outside the predetermined range set based on the depth of focus due to the movement amount, and it is determined that the focus lens does not move out of the predetermined range, the lens control unit In the second case where the focus lens is moved in the in-focus direction by the addition movement amount and it is determined that the focus lens moves out of the predetermined range, the focus lens is moved while moving the vibration center in the in-focus direction. Is moved by a movement amount smaller than the addition movement amount.

  An interchangeable lens according to another aspect of the present invention includes a photographing optical system including a focus lens, a focus actuator that moves the focus lens, and a lens control unit that drives the focus actuator to control the position of the focus lens. And have. The interchangeable lens includes an imaging element that photoelectrically converts a subject image formed by the imaging optical system, a focus signal generation unit that generates a focus signal indicating a focus state of the imaging optical system using an output from the imaging element, The focus lens is vibrated in the direction in which the focus signal increases or decreases through the lens control unit, and is attached to and detached from the image pickup device having the image pickup device control unit that moves the vibration center of the focus lens in the focusing direction in which the focus signal increases. Is possible. In the imaging apparatus, the imaging apparatus control unit calculates the vibration amplitude amount and the movement amount of the vibration center of the focus lens using the position control resolution and the position sensitivity of the focus lens acquired from the interchangeable lens, and allows the image sensor to be allowed. The depth of focus is calculated using the confusion circle diameter and the F value of the photographing optical system acquired from the interchangeable lens, and the movement amount of the focus lens when moving the vibration center in the in-focus direction is the vibration amplitude amount. When the added movement amount is set by adding the amount, it is determined whether or not the focus lens moves outside a predetermined range set based on the depth of focus due to the movement of the added movement amount. In the interchangeable lens, the lens control unit moves the focus lens in the in-focus direction by the addition movement amount in the first case where the imaging device control unit determines that the focus lens does not move out of the predetermined range, and controls the imaging device. In the second case where the focus lens is determined to move out of the predetermined range by the unit, the focus lens is moved by a movement amount smaller than the addition movement amount while moving the vibration center in the focusing direction.

  An interchangeable lens according to another aspect of the present invention includes a photographing optical system including a focus lens, a focus actuator that moves the focus lens, and a lens control unit that drives the focus actuator to control the position of the focus lens. And have. The interchangeable lens includes an imaging element that photoelectrically converts a subject image formed by the imaging optical system, a focus signal generation unit that generates a focus signal indicating a focus state of the imaging optical system using an output from the imaging element, The focus lens is vibrated in the direction in which the focus signal increases or decreases through the lens control unit, and is attached to and detached from the image pickup device having the image pickup device control unit that moves the vibration center of the focus lens in the focusing direction in which the focus signal increases. Is possible. In the interchangeable lens, the lens control unit calculates the vibration amplitude amount of the focus lens and the movement amount of the vibration center using the position control resolution and position sensitivity of the focus lens, and obtains the F value of the photographing optical system and the imaging device. The depth of focus is calculated using the permissible circle of confusion of the image sensor, and the amount of movement of the focus lens when moving the center of vibration in the in-focus direction is the sum of the amount of vibration plus the amount of movement of the center of vibration And determining whether or not the focus lens moves outside the predetermined range set based on the depth of focus due to the movement of the addition movement amount, and determines that the focus lens does not move outside the predetermined range. In the case of 1, the focus lens is moved in the in-focus direction by the addition movement amount, and in the second case where it is determined that the focus lens moves out of the predetermined range, The while moving the focusing direction and moving the focus lens by a small amount of movement than the addition amount of movement.

  An imaging apparatus according to another aspect of the present invention includes a photographing optical system including a focus lens, a focus actuator that moves the focus lens, and a lens control unit that drives the focus actuator to control the position of the focus lens. It is possible to attach and detach an interchangeable lens having The imaging apparatus includes an imaging element that photoelectrically converts a subject image formed by the imaging optical system, a focus signal generation unit that generates a focus signal indicating a focus state of the imaging optical system using an output from the imaging element, And an imaging device control unit that vibrates the focus lens in a direction in which the focus signal increases or decreases through the lens control unit and moves the vibration center of the focus lens in a focusing direction in which the focus signal increases. The imaging device control unit supplies the allowable confusion circle diameter of the image sensor to the lens control unit, and causes the lens control unit to calculate the depth of focus using the allowable confusion circle diameter and the F value of the photographing optical system, and The lens control unit calculates the focus lens vibration amplitude and vibration center movement using the focus lens position control resolution and position sensitivity, and moves the focus lens when moving the vibration center in the in-focus direction. Whether or not the focus lens moves out of the predetermined range set based on the depth of focus when the amount is set to the addition movement amount obtained by adding the movement amount of the vibration center to the vibration amplitude amount. To determine. Then, in the first case where it is determined that the focus lens does not move out of the predetermined range, the imaging device control unit causes the lens control unit to move the focus lens in the in-focus direction by the addition movement amount, so that the focus lens is predetermined. In the second case where it is determined to move out of the range, the lens control unit moves the focus lens by a movement amount smaller than the addition movement amount while moving the vibration center in the in-focus direction.

  According to another aspect of the present invention, there is provided a method for controlling an imaging apparatus, comprising: a photographing optical system including a focus lens; and a focus actuator for moving the focus lens; and driving the focus actuator to adjust the position of the focus lens. The present invention is applied to an imaging device in which an interchangeable lens to be controlled can be attached and detached. The control method includes a step of generating a focus signal indicating a focus state of the photographic optical system using an output from an image sensor that photoelectrically converts a subject image formed by the photographic optical system, and a focus signal increases or decreases the focus lens. And a focus control step of moving the vibration center of the focus lens in a focusing direction in which the focus signal is increased. Then, in the focus control step, the vibration amplitude amount of the focus lens and the movement amount of the vibration center are calculated using the position control resolution and position sensitivity of the focus lens obtained from the interchangeable lens, and the allowable confusion circle diameter of the image sensor is calculated. The depth of focus is calculated using the F value of the photographing optical system acquired from the interchangeable lens, and the amount of movement of the focus lens when moving the vibration center in the in-focus direction is the sum of the vibration amplitude and the movement amount of the vibration center When the movement amount is set, it is determined whether or not the focus lens moves outside the predetermined range set based on the depth of focus due to the movement of the addition movement amount, and if the focus lens does not move outside the predetermined range, In the determined first case, the focus lens is moved in the in-focus direction by the additional movement amount to the interchangeable lens, and the focus lens is within a predetermined range. If the second determining to move, to the interchangeable lens, characterized in that moving as few moving amount than the addition amount of movement of the focus lens while moving the vibration center focus direction.

  The interchangeable lens control method according to another aspect of the present invention includes a photographing optical system including a focus lens and a focus actuator that moves the focus lens, and drives the focus actuator to adjust the position of the focus lens. This is an interchangeable lens to be controlled, generates a focus signal indicating the focus state of the photographic optical system using the output from the image sensor that photoelectrically converts the subject image formed by the photographic optical system, and passes the focus lens through the interchangeable lens. The present invention is applied to an interchangeable lens that can be attached to and detached from an imaging apparatus that vibrates in a direction in which the focus signal increases and decreases and moves the vibration center of the focus lens in a focusing direction in which the focus signal increases. The imaging device calculates the vibration amplitude amount of the focus lens and the movement amount of the vibration center using the position control resolution and position sensitivity of the focus lens acquired from the interchangeable lens, and calculates the allowable confusion circle diameter of the image sensor and the interchangeable lens. The depth of focus is calculated using the acquired F value of the photographic optical system, and the amount of movement of the focus lens when moving the vibration center in the in-focus direction is the sum of movement amounts obtained by adding the movement amount of the vibration center to the vibration amplitude amount Is set, it is determined whether or not the focus lens moves out of a predetermined range set based on the depth of focus due to the movement of the addition movement amount. The control method includes a step of moving the focus lens in the in-focus direction by the addition movement amount when the focus lens is determined not to move out of a predetermined range by the imaging device, and the focus lens is predetermined by the imaging device. And moving the focus lens by a movement amount smaller than the addition movement amount while moving the vibration center in the focusing direction in the second case where it is determined that the movement is out of the range.

  The interchangeable lens control method according to another aspect of the present invention includes a photographing optical system including a focus lens and a focus actuator that moves the focus lens, and drives the focus actuator to adjust the position of the focus lens. This is an interchangeable lens to be controlled, generates a focus signal indicating the focus state of the photographic optical system using the output from the image sensor that photoelectrically converts the subject image formed by the photographic optical system, and passes the focus lens through the interchangeable lens. The present invention is applied to an interchangeable lens that can be attached to and detached from an imaging apparatus that vibrates in a direction in which the focus signal increases or decreases and moves the vibration center of the focus lens in a focusing direction in which the focus signal increases. The control method includes a step of calculating a vibration amplitude amount of the focus lens and a movement amount of the vibration center using the position control resolution and the position sensitivity of the focus lens, the F value of the photographing optical system, and the imaging acquired from the imaging device. The step of calculating the depth of focus using the permissible circle of confusion of the element, and the amount of movement of the focus lens when moving the vibration center in the in-focus direction is the addition movement amount obtained by adding the movement amount of the vibration center to the vibration amplitude amount. When set, the step of determining whether or not the focus lens moves outside the predetermined range set based on the depth of focus by the movement of the addition movement amount, and the focus lens is determined not to move out of the predetermined range In the first case, the step of moving the focus lens in the in-focus direction by the addition movement amount, and the step of determining that the focus lens moves out of the predetermined range In the case of, and having a step of moving as few moving amount than the addition amount of movement of the focus lens while moving the vibration center focus direction.

  According to another aspect of the present invention, there is provided a method for controlling an imaging apparatus, comprising: a photographing optical system including a focus lens; and a focus actuator for moving the focus lens; and driving the focus actuator to adjust the position of the focus lens. The present invention is applied to an imaging device in which an interchangeable lens to be controlled can be attached and detached. The control method includes a step of generating a focus signal indicating a focus state of the photographic optical system using an output from an image pickup device that performs photoelectric conversion on a subject image formed by the photographic optical system, and a focus signal through the interchangeable lens. And a focus control step of moving the vibration center of the focus lens in a focusing direction in which the focus signal increases. In the focus control step, the permissible circle of confusion of the image sensor is supplied to the interchangeable lens, and the interchangeable lens is caused to calculate the depth of focus using the permissible circle of confusion and the F value of the photographing optical system, and further the interchangeable lens In addition, the amount of vibration of the focus lens and the amount of movement of the vibration center are calculated using the position control resolution and position sensitivity of the focus lens, and the amount of movement of the focus lens when moving the vibration center in the in-focus direction is the vibration amplitude. When the addition movement amount obtained by adding the movement amount of the vibration center to the amount is determined, it is determined whether or not the focus lens moves out of a predetermined range set based on the depth of focus due to the movement of the addition movement amount. In the first case where it is determined that the focus lens does not move out of the predetermined range, the focus lens is moved in the in-focus direction by the additional movement amount to the interchangeable lens, and the focus lens is moved. If Surenzu second that is determined to move out of the predetermined range, the interchangeable lens, characterized in that moving as few moving amount than the addition amount of movement of the focus lens while moving the vibration center focus direction.

  In the present invention, whether or not the focus lens moves out of a predetermined range set based on the depth of focus due to the movement of the addition movement amount of the focus lens with respect to the depth of focus calculated using the F value of the interchangeable lens. Is determined. If it is determined that the focus lens is not moved out of the predetermined range even if the focus lens is moved by the additional movement amount, the AF lens can be moved by the additional movement amount to ensure good responsiveness of the AF control. it can. On the other hand, if it is determined that the focus lens moves out of the predetermined range when it is moved by the addition movement amount, the center of vibration is moved in the in-focus direction without moving the focus lens out of the range of at least the depth of focus. Focus variation can be avoided. As described above, according to the present invention, even when various interchangeable lenses and an imaging device are combined, it is possible to ensure good AF control responsiveness and to focus an image due to vibration of the focus lens when the depth of focus is shallow. Variations can be prevented from being recognized by the user.

1 is a block diagram illustrating a configuration of a lens interchangeable camera system that is Embodiment 1 of the present invention. FIG. 5 is a flowchart showing AF control in the first embodiment. 3 is a flowchart showing minute vibration control by a subtraction method in the first embodiment. 3 is a flowchart showing minute vibration control by an addition method in the first embodiment. The conceptual diagram which shows the minute vibration control by the said subtraction system. The conceptual diagram which shows the minute vibration control by the said addition system. FIG. 6 is a block diagram illustrating a configuration of a lens interchangeable camera system that is Embodiment 2 of the present invention. 9 is a flowchart showing AF control in the second embodiment. The conceptual diagram which shows the hill-climbing drive control in AF control. The figure which shows the relationship between a focus depth and the position of the focus lens which carries out a micro vibration. The figure which shows the relationship between a focus depth and the position of the focus lens which vibrates minutely by a subtraction method. The conceptual diagram which shows the minute vibration control which considered the focus position sensitivity for every focus lens position. The figure which shows the example of the table data which shows the focus position sensitivity for every focus lens position.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows a configuration of an interchangeable lens camera system that includes an imaging apparatus and an interchangeable lens that are Embodiment 1 of the present invention. L100 is a lens unit as an interchangeable lens. C100 is a camera body as an imaging apparatus. The lens unit L100 is detachable from the camera body C100.

  The lens unit L100 supplies (transmits) information on an F value corresponding to the position control resolution of the focus lens (drive resolution of the focus actuator), the position sensitivity of the focus lens, and the aperture value, which will be described later. On the other hand, the camera body C100 calculates a vibration amplitude amount and a movement amount of the vibration center in a minute vibration (to be described later) of the focus lens based on information received from the lens unit L100, and information on an allowable confusion circle diameter of the image sensor. In combination, the depth of focus is calculated. The camera body C100 determines whether or not the focus lens moves out of a predetermined range set based on the depth of focus due to the movement of the addition movement amount (to be described later) of the focus lens. Switch the center movement method. The lens unit L100 receives the center movement method selected from the camera body C100, and controls the movement of the vibration center by the center movement method. The center moving method will be described later.

  In FIG. 1, light from a subject passes through a photographing optical system in a lens unit L100, and forms a subject image on an image sensor C101 in a camera body C100. The photographing optical system is fixed in order from the subject side, a first fixed lens unit L101 that is fixed, a zoom lens L102 that moves in the optical axis direction and zooms, and an aperture L103 that adjusts the amount of light. And a second fixed lens unit L104. Further, the photographing optical system includes a focus lens L105 that has both a function of correcting image plane variation accompanying zooming and a focus function. The focus lens L105 is moved in the optical axis direction by a focus actuator L107 configured by a stepping motor, a DC motor, a vibration motor, a voice coil motor, and the like.

  In the drawing, each lens group is described as being composed of a single lens. However, in actuality, it may be composed of a single lens or a plurality of lenses. It may be configured. In this embodiment, a so-called rear focus type photographing optical system will be described. However, a so-called front focus type photographing optical system may be used.

  On the other hand, in the camera body C100, the image sensor C101 is a photoelectric conversion element configured by a CCD sensor or a CMOS sensor, and photoelectrically converts the subject image and outputs an analog signal. One image sensor C101 may be provided for each of the three primary colors red (R), green (G), and blue (B).

  C102 is a CDS / AGC / AD converter that samples the output of the image sensor C101, and further performs gain adjustment and digital conversion. C103 is a camera signal processing circuit that performs various kinds of image processing on the output signal from the CDS / AGC / AD converter C102 to generate an image signal. C1031 in the camera signal processing circuit C103 is an AF signal processing circuit.

  The AF signal processing circuit C1031 generates a high-frequency component and a luminance difference generated from the high-frequency signal from the output signal of the pixel in the region used for focus detection among the output signals of all the pixels of the image sensor C101 from the CDS / AGC / AD converter C102. A component or the like is extracted to generate a focus signal. The focus signal is also called a contrast evaluation value signal, and represents the sharpness (contrast state) of an image generated based on the output signal from the image sensor C101. Since the sharpness changes depending on the focus state of the photographing optical system, as a result, the focus signal becomes a signal representing the focus state of the photographing optical system. The AF signal processing circuit C1031 corresponds to a focus signal generation unit.

  C104 is a display device that displays an image signal from the camera signal processing circuit C103, and C105 is a recording device that records the image signal from the camera signal processing circuit C103 on a recording medium such as a magnetic tape, an optical disk, or a semiconductor memory. C106 is a camera microcomputer (imaging device controller: hereinafter referred to as a camera microcomputer). Based on the output from the camera signal processing circuit C103, the camera microcomputer C106 outputs information used for AF control to a lens microcomputer (lens controller: hereinafter referred to as a lens microcomputer) L106 in the lens unit L100.

  In the AF control in this embodiment, the focus lens L105 is vibrated by a minute amount in the direction in which the focus signal (value) increases or decreases (closest / infinite direction), and the focus direction in which the focus signal (value) increases. In this control, the center of vibration of the focus lens L105 is moved. In the following description, a minute amount of vibration is referred to as minute vibration, and the amplitude amount of the minute vibration is referred to as vibration amplitude amount. The center of the minute vibration is called the vibration center, the movement is called the center movement, and the movement amount is called the center movement amount.

  Information used for AF control (hereinafter referred to as AF control information) includes a micro-vibration operation step, a focus direction, a vibration amplitude amount, and a movement direction of a vibration center (a focus direction in the near / infinity direction: (Referred to as “center movement direction”), the amount of movement thereof, and information on the center movement method.

  The AF control is mainly performed by the AF control unit C1061 in the camera microcomputer C106. Details of the operation of the AF control unit C1061 will be described later.

  The lens microcomputer L106 can transmit and receive information to and from the camera microcomputer C106, and receives AF control information from the camera microcomputer C106. In the lens microcomputer L106, a lens specific data storage unit L1061 is provided. The lens-specific data storage unit L1061 stores data specific to the lens unit including information on the driving resolution of the focus actuator L107 (that is, the position control resolution of the focus lens L105), information on the position sensitivity of the focus lens L105, and the like. Yes.

  In addition, a focus lens control unit L1062 is provided in the lens microcomputer L106. The focus lens control unit L1062 calculates a target position and a target speed for moving the focus lens L105 based on the data stored in the lens specific data storage unit L1061 and the AF control information received from the AF control unit C1061. Then, the drive of the focus actuator L107 is controlled according to these calculation results. In this way, the position of the focus lens L105 is controlled so that a focused state is obtained.

  Next, AF control performed by the lens microcomputer L106 (mainly the focus lens control unit L1062) and the camera microcomputer C106 (mainly the AF control unit C1061) will be described with reference to FIGS. FIG. 2 is a flowchart showing AF control performed by the lens microcomputer L106 and the camera microcomputer C106. The AF control is executed by the lens microcomputer L106 and the camera microcomputer C106 according to a computer program.

  In Step L201, the lens microcomputer L106 transmits the drive resolution of the focus actuator L107 (position control resolution of the focus lens L105) and the position sensitivity information of the focus lens L105 corresponding to the vibration center of the minute vibration to the camera microcomputer C106.

  In the following description, the drive resolution of the focus actuator L107 and the position control resolution of the focus lens L105 are both referred to as focus control resolution. For example, high focus control resolution means that the moving amount of the focus lens L105 per driving step of the focus actuator L107 is small. The position sensitivity of the focus lens L105 indicates the ratio of the focus movement amount to the movement amount of the focus lens L105, and the position sensitivity of the focus lens L105 corresponding to the vibration center of the minute vibration is simply referred to as the focus position in the following description. It is called sensitivity. For example, high focus position sensitivity means that the focus movement amount is larger than the movement amount of the focus lens L105.

  Furthermore, the lens microcomputer L106 transmits the F value of the photographing optical system determined from the aperture value of the aperture L103 to the camera microcomputer C106 at Step L201. Then, it progresses to StepL201.

  On the other hand, the camera microcomputer C106 acquires the focus signal generated by the AF signal processing circuit C1031 in the camera signal processing circuit C103 in Step C201.

  Next, in Step C202, the camera microcomputer C106 determines whether or not the focus control resolution, the focus position sensitivity, and the F value have been received from the lens microcomputer L106, and proceeds to Step C203 only when it has been received.

  In Step C203, the camera microcomputer C106 calculates the focal depth Fδ from the permissible circle of confusion δ obtained from the size of one pixel (pixel pitch) determined by the size of the image sensor C101 and the number of pixels and the received F value. Thereafter, the process proceeds to Step C204.

  In Step C204, the camera microcomputer C106 determines the defocus amount (image plane amplitude amount) on the imaging surface of the imaging device C101 due to minute vibration of the focus lens L105 in AF control based on the focus control resolution and the focus position sensitivity. Convert to vibration amplitude. Further, the camera microcomputer C106 converts the defocus amount (image plane center movement amount) on the imaging surface due to the center movement into the center movement amount based on the focus control resolution and the focus position sensitivity. Thereafter, the process proceeds to Step C205.

Here, in general, the image plane amplitude amount and the image plane center movement amount are set based on the focal depth Fδ, and are set to values smaller than the focal depth Fδ so as not to blur the image. For example, the image plane amplitude is set to a value obtained by multiplying the depth of focus Fδ by a predetermined ratio α (<1). At this time, considering the focus control resolution ΔF, that is, the movement amount of the focus lens L105 per driving step of the focus actuator L107 and the focus position sensitivity γc, the vibration amplitude amount is calculated by the equation (1).
Vibration amplitude amount = (Fδ × α / γc) / ΔF (1)
Further, the amount of movement of the image plane center is set to a value obtained by multiplying the focal depth Fδ by a predetermined ratio β (<1). At this time, considering the focus control resolution ΔF and the focus position sensitivity γc, the center movement amount is calculated by the equation (2).
Center movement amount = (Fδ × β / γc) / ΔF (2)
When the focus control resolution ΔF is large (coarse) or the focus position sensitivity γc is high, there are few positions where the focus lens L105 can be stopped within the range of the focal depth Fδ (hereinafter referred to as the focal depth width). The possibility that the focus lens L105 moves beyond the depth of focus range (moves outside the range of the focus depth) is increased only by driving the focus actuator L107 with a small number of drive steps.

  In Step C205, the camera microcomputer C106 determines whether or not the focus movement amount, which is an addition movement amount obtained by adding the center movement amount to the vibration amplitude amount obtained in Step C204, exceeds the depth of focus range, that is, the focus lens L105 determines the depth of focus range. Judge whether to move beyond. The depth of focus range corresponds to a predetermined range set based on the depth of focus. When it is determined that the focus lens L105 moves beyond the depth of focus (second case), the process proceeds to Step C206, and when it is determined that the focus lens L105 does not move beyond the depth of focus (first case), the process proceeds to Step C207. That is, in the camera body using the image sensor C101 in which the pixel pitch is small and the focal depth is likely to be shallow, when the minute vibration is performed with the coarse focus control resolution, the center of the image is not changed when the center is moved. Switch the movement method. In this embodiment, the center movement method includes a subtraction method and an addition method described below.

  As shown in FIG. 10, when the focus lens L105 is moved by the above-described focus movement amount during the center movement, when the focus lens L105 moves beyond the depth of focus range, the process proceeds to Step C206 and the subtraction method is changed. select. The subtraction method will be described in detail later. In Step C206, the above-described AF control information including the subtraction method as the stop movement method is generated.

  On the other hand, even if the movement amount of the focus lens L105 is the same, if the depth of focus is deep, in other words, if the focus control resolution is sufficiently small (fine) with respect to the depth of focus, the focus lens L105 exceeds the depth of focus. The possibility of moving is low. Even if the depth of focus range is exceeded, the amount that exceeds is small. For this reason, the focus fluctuation | variation of the image at the time of center movement does not arise or is not conspicuous. In this case, the process proceeds to Step C207 and the addition method is selected. The addition method will be described later in detail. In Step C207, the above-described AF control information including the addition method as the stop movement method is generated.

  In Step C208, the camera microcomputer C106 performs in-focus direction determination and in-focus determination, and proceeds to Step C209. The in-focus direction determination is performed when the center movement in the in-focus direction in which the focus signal detected by the minute vibration of the focus lens L105 increases is continuously performed a predetermined number of times, and the in-focus direction is the true in-focus position. It is to determine that the direction exists. When the in-focus direction is determined, hill-climbing driving is performed to search for an in-focus position where the focus signal reaches a peak while moving the focus lens L105 at a constant speed in the in-focus direction. Since this hill-climbing driving operation is well known, detailed description thereof is omitted here.

  Further, when the in-focus position is found by hill-climbing driving, the focus lens L105 is again vibrated slightly to monitor the increase / decrease of the focus signal. The in-focus determination is to determine that the minute vibration has been repeated a predetermined number of times within the same range, and that this is the true in-focus position.

  In Step C209, the camera microcomputer C106 transmits the AF control information set in Step C206 and Step C207 to the lens microcomputer L106. Thereafter, the process returns to Step C201.

  Next, the AF control in the subtraction method will be described using the flowchart of FIG. In Step C301, the camera microcomputer C106 determines the current micro-vibration operation step. If it is 0, the process proceeds to Step C302. Otherwise, the process proceeds to Step C303.

  In Step C302, the camera microcomputer C106 holds a focus signal as a process when the focus lens L105 is positioned on the closest side. The focus signal here is generated from the output signal of the image sensor C101 when the focus lens L105 is positioned on the infinity side.

  In Step C303, the camera microcomputer C106 determines the current operation step. If it is 1, the process proceeds to Step C304 and the subsequent processes, and otherwise, the process proceeds to Step C307.

  In Step C304, the camera microcomputer C106 compares the level (value) of the focus signal on the infinity side held in Step C302 with the level of the close focus signal held in Step C308 described later. When the latter is large, the process proceeds to Step C305, and when the former is large, the process proceeds to Step C306.

  In Step C305, the camera microcomputer C106 sets the center moving direction in the AF control information to “infinite direction”.

  In Step C306, the camera microcomputer C106 sets the center movement direction to “none”. The camera microcomputer C106 transmits AF control information including information on the center movement direction to the lens microcomputer L106 in a process described later. This causes the lens microcomputer L106 to control the driving of the focus actuator L107 (the position of the focus lens L105) based on this AF control information.

  In Step C307, the camera microcomputer C106 determines the current operation step. If it is 2, the process proceeds to Step C309 when the focus lens of Step C308 is on the infinity side, otherwise proceeds to Step C309.

  In Step C308, the camera microcomputer C106 holds a focus signal as a process when the focus lens L105 is positioned on the infinity side. The focus signal here is generated from the output signal of the image sensor C101 when the focus lens L105 is positioned on the closest side.

  In Step C309, the camera microcomputer C106 compares the level of the focus signal on the near side held in Step C308 with the level of the focus signal on the infinity side held in Step C302. When the latter is large, the process proceeds to Step C310, and when the former is large, the process proceeds to Step C311.

  In Step C310, the camera microcomputer C106 sets the center moving direction in the AF control information to the “closest direction”. In Step C311, the center movement direction is set to “none”.

  In Step C312, the camera microcomputer C106 increments the operation step of minute vibration by one. However, when the current operation step is 3, it is cleared to 0.

  Next, the AF control by the addition method will be described using the flowchart of FIG. In Step C401, the camera microcomputer C106 determines the current micro-vibration operation step. If it is 0, the process proceeds to Step C402. Otherwise, the process proceeds to Step C403.

  In Step C402, the camera microcomputer C106 holds a focus signal as a process when the focus lens L105 is positioned on the closest side. The focus signal here is generated from the output signal of the image sensor C101 when the focus lens L105 is positioned on the infinity side.

  In Step C403, the camera microcomputer C106 determines the current operation step. If it is 1, the process proceeds to Step C404 and subsequent steps, and otherwise, the process proceeds to Step C407.

  In Step C404, the camera microcomputer C106 compares the level (value) of the focus signal on the infinity side held in Step C402 with the level of the focus signal on the near side held in Step C408 described later. If the former is large, the process proceeds to Step C405, and if the latter is large, the process proceeds to Step C406.

  In Step C405, the camera microcomputer C106 sets the center moving direction in the AF control information to “infinite direction”.

  In Step C406, the camera microcomputer C106 sets the center movement direction to “none”. The camera microcomputer C106 transmits AF control information including this information to the lens microcomputer L106 in processing to be described later. This causes the lens microcomputer L106 to control the driving of the focus actuator L107 (the position of the focus lens L105) based on this AF control information.

  In Step C407, the camera microcomputer C106 determines the current operation step. If it is 2, the process proceeds to Step C408, and otherwise, the process proceeds to Step C409.

  In Step C408, the camera microcomputer C106 holds the focus signal as a process when the focus lens L105 is positioned on the infinity side. The focus signal here is generated from the output signal of the image sensor C101 when the focus lens L105 is positioned on the closest side.

  In Step C409, the camera microcomputer C106 compares the level of the focus signal on the near side held in Step C408 with the level of the focus signal on the infinity side held in Step C402. If the former is large, the process proceeds to Step C410, and if the latter is large, the process proceeds to Step C411.

  In Step C410, the camera microcomputer C106 sets the center moving direction in the AF control information to the “closest direction”. In Step C411, the camera microcomputer C106 sets the center movement direction to “none”.

  In Step C412, the camera microcomputer C106 increments the operation step of minute vibration by one. However, when the current operation step is 3, it is cleared to 0.

  Returning to the description of the processing of the lens microcomputer L106 in FIG. In Step L202, the lens microcomputer L106 determines whether or not the AF control information described above can be received from the camera microcomputer C106 in the camera main body C100 to which the lens unit L100 is attached. Only when the lens microcomputer L106 has received the StepL203. Proceed to

  In Step L203, the lens microcomputer L106 determines whether the center movement method included in the received AF control information is the subtraction method or the addition method, and proceeds to Step L204 if the method is the subtraction method, or proceeds to Step L205 if the method is the addition method.

In Step L204, the lens microcomputer L106 calculates a focus movement amount as a subtraction movement amount by subtracting the center movement amount b from the vibration amplitude amount a included in the received AF control information. That is,
Focus movement amount = vibration amplitude amount a−center movement amount b
Calculate

On the other hand, in Step L205, the lens microcomputer L106 calculates the focus movement amount as the addition movement amount by adding the center movement amount b to the vibration amplitude amount a included in the received AF control information. That is,
Focus movement amount = vibration amplitude amount a + center movement amount b
Calculate

  In Step L206, the lens microcomputer L106 calculates the target position and moving speed of the focus lens L105 from the calculated focus movement amount, and proceeds to Step L207.

  In Step L207, the lens microcomputer L106 moves the focus lens L105 by controlling the drive of the focus actuator L107 according to the calculated target position and moving speed. Then, it returns to StepL201.

  FIG. 11 shows the relationship between the position of the focus lens L105 moved by the focus movement amount calculated by the subtraction method and the depth of focus. The horizontal axis represents time, and the vertical axis represents the position (focus position) of the focus lens L105. A horizontal dotted line indicates a position where the focus lens L105 corresponding to the focus control resolution can be stopped.

  In this figure, the depth of focus is 4 pulses in terms of the amount of movement of the focus lens L105, whereas the vibration amplitude is set to 1 pulse each from the vibration center to the near side and the infinity side (2 pulses in total). Shows the case. The vibration center repeats moving toward the near side and the infinity side.

  At the time of center movement in AF control using this subtraction method, a focus movement amount (two pulses) obtained by subtracting the center movement amount from the vibration amplitude amount is set. That is, in the AF control using the subtraction method, a focus movement amount smaller than the focus movement amount (three pulses) that is set when the center movement is performed using the addition method and the center movement amount is added to the vibration amplitude amount is set.

  In other words, in the addition method, the focus lens L105 is moved by the vibration amplitude amount (2 pulses) in the same direction as the center movement direction, which is the in-focus direction, together with the center movement amount (1 pulse). On the other hand, in the subtraction method, the focus lens L105 is moved in the direction opposite to the center movement direction by an amount obtained by subtracting the center movement amount (1 pulse) from the vibration amplitude amount (2 pulses).

  By such subtractive AF control, the center of vibration can be moved in the in-focus direction at the time of center movement, and the amount of focus movement can be reduced compared to the AF control of the addition method, and the focus lens L105 has a shallow depth of focus. The possibility of moving outside the width can be reduced. As a result, the focus variation of the image due to the minute vibration of the focus lens L105 including the center movement does not occur or is not noticeable.

  In the subtraction method, when the focus lens L105 is moved by a minute vibration in the direction opposite to the center movement direction, it is desirable to prohibit the determination of the in-focus direction using the change in the focus signal at this time.

  On the other hand, by the addition type AF control, the focus movement amount during the center movement can be sufficiently increased, and the responsiveness of the AF control can be improved.

  FIG. 5 shows a state in which the focus lens L105 is minutely vibrated by AF control using the subtraction method. The horizontal axis represents time, and here, the vertical synchronization signal of the video signal generated by the image sensor C101 is set as a unit time. The vertical axis indicates the position (focus position) of the focus lens L105.

Time A focus signal EV _A generated from the electric charge accumulated in the imaging element C101 (indicated by hatching ellipse), the captured at time _{T A} to the camera microcomputer C106. Also, the focus signal EV _B generated from the electric charge accumulated in the image sensor C101 at time _B is taken into the camera microcomputer C106 at time T _B. Moreover, the focus signal EV _C generated from the electric charge accumulated in the imaging device C101 at time C are incorporated into the camera microcomputer C106 at time _{T C.}

At time _{T C,} the camera microcomputer C106 is focus signal _{EV A,} EV B, compares the EV _C, performs a center movement if EV _B> a EV _A and EV _B> EV _C, the center movement otherwise Not performed. FIG. 5 shows a state where the vibration center is moved to the closest side by b when EV _B > EV _A and EV _B > EV _C , and the focus lens L105 is moved from the lens position LPB to the closest lens position LPC. The amount of movement when moving is a vibration amplitude amount a-a center movement amount b. That is, the center of vibration is moved by setting the amount of focus movement when the direction of moving the center of vibration corresponds to the direction of actual movement of the focus lens L105 as vibration amount a-center movement amount b. .

  After the center movement is performed, it is determined whether or not the center movement is performed after the focus lens L105 is slightly vibrated with respect to a new vibration center to newly acquire a focus signal. As a result, there is a possibility that the time from the AF control in the addition method to the completion of the focus determination may be slightly longer. However, since it is less likely that the center movement is continuously performed in the same direction, as illustrated in FIG. The amount of movement of the focus lens L105 including the center movement can be reduced.

  That is, in the subtraction method, the maximum amplitude amount of the focus lens L105 is the same as the vibration amplitude amount, and after the center movement, a small focus vibration is performed from the vibration center to newly acquire a focus signal. For this reason, when the focus signal starts to decrease, the determination is delayed and the focus lens L105 overshoots, or the focus lens L105 moves far beyond the depth of focus and the focus fluctuation of the image occurs or becomes conspicuous. It is possible to perform AF control without any problems.

  FIG. 6 shows a state in which the focus lens L105 is slightly vibrated by AF control using the addition method. Similar to FIG. 5, the horizontal axis indicates the time with the vertical synchronization signal as a unit time, and the vertical axis indicates the position (focus position) of the focus lens L105.

Similar to FIG. 5, the time A focus signal EV _A generated from the electric charge accumulated in the imaging element C101 (indicated by hatching ellipse), the captured at time T _A to the camera microcomputer C106. Also, the focus signal EV _B generated from the electric charge accumulated in the image sensor C101 at time _B is taken into the camera microcomputer C106 at time T _B. Moreover, the focus signal EV _C generated from the electric charge accumulated in the imaging device C101 at time C are incorporated into the camera microcomputer C106 at time _{T C.}

At time _{T C,} the camera microcomputer C106 is focus signal _{EV A,} EV B, compares the EV _C, performs a center movement if EV _A> EV _B and EV _C> EV _B, the center movement otherwise Not performed. FIG. 6 shows a state where the vibration center is moved by b toward the closest side when EV _A > EV _B and EV _C > EV _B , and the focus lens moves from the lens position LPB to the lens position LPC on the infinity side. The amount of movement when moving through L105 is vibration amplitude amount a + center movement amount b. That is, the center of vibration is moved by setting the amount of focus movement when the direction of moving the center of vibration is opposite to the direction of actually moving the focus lens L105 as the amount of vibration amplitude a + the amount of center movement b. .

  In the addition method, the maximum amplitude of the focus lens L105 is the vibration amplitude amount + the center movement amount, and the center movement is continuously performed. For this reason, when the focus signal starts to decrease, the determination may be delayed and the focus lens L105 may overshoot. However, when moving continuously in the same direction, a focused state can be obtained quickly. For this reason, good responsiveness of AF control can be ensured.

  As described above, according to the present embodiment, when the depth of focus of the camera body C100 is shallow, the amount of focus movement during the center movement during minute vibration is reduced (subtraction) compared to when the depth of focus is deep. Select a method). As a result, even when the focus control resolution of the lens unit L100 is rough, it is possible to prevent the focus lens L105 from moving beyond the shallow depth of focus and causing the focus variation or conspicuous of the image. In addition, when the focal depth is deep, the focus movement amount at the time of moving the center during minute vibration is increased (the addition method is selected) as compared with the case where the focal depth is shallow. Therefore, the AF control having a good responsiveness. It can be performed. Therefore, even when various lens units and the camera body are combined, it is possible to suppress a focus variation due to a minute vibration of the focus lens while ensuring a good response of AF control.

  In the present embodiment, the case where the focus lens L105 is switched by the addition movement amount that is the sum of the vibration amplitude amount and the center movement amount to switch between the addition method and the subtraction method depending on whether or not the depth of focus range is exceeded will be described. did. However, the addition method and the subtraction method may be switched depending on whether or not the focus lens L105 exceeds a predetermined ratio of the depth of focus (a predetermined range set based on the depth of focus).

  In the first embodiment, the camera body calculates the vibration amplitude amount, the center movement amount, and the focal depth of the focus lens based on the lens unit specific data received from the lens unit, and uses them to determine the center movement method in the AF control. The case of switching was explained. However, the vibration amplitude and center movement calculated by the camera itself are sensitive to the focus position at the current vibration center based on the defocus amount (image plane amplitude and image center movement) on the imaging surface. It is a value calculated considering the degree.

  That is, it is not a value that takes into account the position sensitivity of the focus lens after moving by the vibration amplitude amount or the position of the focus lens after moving the center. For this reason, it may happen that it is not accurately determined whether or not the actual position of the focus lens exceeds the depth of focus range. Therefore, even if the vibration amplitude is set so that the change in the focus signal due to minute vibrations is the same on the near side and the infinity side, the center position is moved in consideration of the change in the focus position sensitivity according to the position of the focus lens. It is better to calculate the subsequent vibration amplitude based on the subsequent focus position sensitivity.

  In the second embodiment of the present invention, such a more desirable vibration amplitude is calculated. FIG. 12 shows the relationship between the focus lens position and the focus position sensitivity during minute vibrations in the AF control of this embodiment. The horizontal axis represents time, and the vertical axis represents the position of the focus lens (focus position). The horizontal dotted line indicates a position where the focus lens corresponding to the focus control resolution can be stopped.

  In the figure, the focus position sensitivity γ2 at the vibration center (focus position L2) after the first center movement is 2/3 of the focus position sensitivity γ1 at the vibration center (focus position L1) before the center movement. It is said that. Further, the focus position sensitivity γ3 at the vibration center (lens position L3) after the second center movement is ½ of the focus position sensitivity γ1 of the vibration center (lens position L1) before the center movement. There is. Also, it is shown that the vibration amplitude amount (amplitude 2, amplitude 3) after the first and second center movements is 1.5 times and twice the vibration amplitude amount (amplitude 1) before the center movement, respectively. Yes.

  In the first embodiment, a case has been described in which control is performed so that the position after movement of the focus lens including center movement hardly exceeds the depth of focus. However, in practice, as shown in FIG. 12, the amount of vibration amplitude after the center movement toward the closest side may increase. In this case, even if the subtraction method is used, the position of the focus lens exceeds the depth of focus range, and there is a possibility that the focus variation of the image is recognized.

  That is, even if the addition movement amount is obtained considering only the focus position sensitivity γc at the current vibration center as in the first embodiment and the center movement method is switched to the subtraction method based on the addition movement amount, There is a possibility that the position of the focus lens exceeds the depth of focus range.

  For this reason, in this embodiment, not only the focus position sensitivity at the current vibration center but also the position sensitivity at the position after the movement of the focus lens is considered. If the position sensitivity for each position of the focus lens is known in advance, the position of the focus lens after moving by the amount of vibration amplitude and the amount of vibration amplitude and center movement at the position of the focus lens after moving the center more accurately. Can be calculated. Therefore, it can be determined more accurately than in the first embodiment whether or not the focus lens moves beyond the depth of focus range.

  As shown in FIG. 13, the focus position sensitivity is data unique to the lens unit determined for each position of the zoom lens (zoom position) and each position of the focus lens (focus position). Such focus position sensitivity data may be held in a memory as focus position sensitivity table data corresponding to a plurality of zoom positions and a plurality of focus positions, as shown in FIG.

In the table data of FIG. 13, the zoom position (focal distance) is taken in the row direction where the variable v changes, and the focus position (subject distance) is taken in the column direction where the variable n changes. n = 0 indicates a subject distance at infinity, and the subject distance changes to the closest side as n increases. V = 0 indicates the wide end. The focal length increases as v increases, and v = s indicates the tele end. The focus position sensitivity corresponding to the zoom position v and the focus position n is represented by γ _vn .

  If such table data is supplied (transmitted) from the lens unit to the camera body, it is possible to determine whether or not the focus lens moves beyond the depth of focus range even more accurately than in the first embodiment. It is. However, the data amount of the focus position sensitivity is enormous, and it is not realistic to transmit the table data to the camera body by communication every time the interchangeable lens is replaced. Since the focus position sensitivity is determined not only by the position of the focus lens but also by the relationship with other lenses, table data corresponding to a large number of interchangeable lenses having various optical systems is preliminarily stored on the camera body side. It is also difficult to keep in memory.

  Therefore, in this embodiment, the allowable confusion circle diameter of the image sensor, AF control information (operation step of minute vibration drive, direction of center movement and defocus amount) and the like are transmitted from the camera body to the lens unit. The lens unit calculates the amount of movement of the focus lens based on information received from the camera body, and controls the position of the focus lens. Furthermore, the lens unit determines whether or not to switch the center movement method using data unique to the lens unit such as the focus control resolution and the focus position sensitivity and the AF control information acquired from the camera body. When switching the center movement method, the instruction is transmitted from the lens unit to the camera body. The camera body receives the instruction and switches the center movement method.

  FIG. 7 shows the configuration of an interchangeable lens camera system that includes an interchangeable lens and an image pickup apparatus that are Embodiment 2 of the present invention. L100 'is a lens unit as an interchangeable lens. C100 'is a camera body as an imaging apparatus. The lens unit L100 'can be attached to and detached from the camera body C100'. In the present embodiment, the lens microcomputer L106 'is provided with an AF control change instruction unit L1063. The AF control change instruction unit L1063 switches the center movement method in the AF control based on the lens unit specific data stored in the lens specific data storage unit L1061 and the AF control information generated by the focus lens control unit L1062 ( Change). Then, the AF control change instruction unit L1063 transmits the change instruction to the AF control unit C1061 in the camera microcomputer C106 'provided in the camera body C100'. Other configurations are the same as those of the first embodiment, and the same components as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and the description is omitted.

  Next, AF control performed by the lens microcomputer L106 '(mainly the focus lens control unit L1062) and the camera microcomputer C106' (mainly the AF control unit C1061) will be described with reference to the flowchart of FIG. The AF control is executed by the lens microcomputer L106 'and the camera microcomputer C106' according to a computer program.

  In Step L801, the lens microcomputer L106 'determines whether or not the permissible circle of confusion δ has been received from the camera microcomputer C106', and proceeds to Step L802 only when it has been received.

  On the other hand, the camera microcomputer C106 'acquires the focus signal generated in the AF signal processing circuit C1031 in the camera signal processing circuit C103 in Step C801.

  In Step C802, the camera microcomputer C106 'transmits information on the allowable confusion circle diameter δ to the lens microcomputer L106'.

  In Step C803, the camera microcomputer C106 'determines whether or not the lens microcomputer L106' has received an instruction to change the center movement method, which will be described later. If there is a change instruction, the process proceeds to Step C804, and if there is no change instruction, the process proceeds to Step C805.

  In Step C804, the camera microcomputer C106 'performs the AF control by the subtraction method described in the first embodiment using the focus signal acquired in Step C801. Information indicating the operation step of minute driving in the AF control, the center moving direction (infinite direction / closest direction), the defocus amount on the image plane (image plane amplitude amount and image plane center moving amount), and the center moving method. AF control information such as is set.

  In Step C805, the camera microcomputer C106 'performs AF control using the addition method described in Embodiment 1 using the focus signal acquired in Step C801, and sets AF control information in the same manner as in Step C204.

  In Step C806, the camera microcomputer C106 'performs the focus direction determination and the focus determination described in the first embodiment, and the process proceeds to Step C807.

  In Step C807, the camera microcomputer C106 'transmits the AF control information set in Step C804 and Step C805 to the lens microcomputer L106.

  On the other hand, in Step L802, the lens microcomputer L106 'calculates the focal depth Fδ based on the allowable confusion circle diameter δ received from the camera microcomputer C106' and the F value determined by the aperture value.

  In Step L803, the lens microcomputer L106 'determines whether or not the AF control information described above has been received from the camera microcomputer C106', and proceeds to Step L804 only when it has been received.

  In Step L804, the lens microcomputer L106 'calculates the vibration amplitude amount and the center movement amount based on the received AF control information, the focus control resolution and the focus position sensitivity stored in the lens specific data storage unit L1061. Then, the process proceeds to Step L805.

For example, the image plane amplitude amount is set to a value obtained by multiplying the depth of focus Fδ by a predetermined ratio α (<1). At this time, in consideration of the focus control resolution ΔF and the focus position sensitivity γ _vn according to the zoom position v and the focus position n, the vibration amplitude amount can be calculated by Expression (3).
Vibration amplitude amount = (Fδ × α / γ _vn ) / ΔF (3)
The image plane center moving amount is set to a value obtained by multiplying the focal depth Fδ by a predetermined ratio β (<1). At this time, considering the focus control resolution ΔF and the focus position sensitivity γ _vn according to the zoom position v and the focus position n, the center movement amount can be calculated by the equation (4).
Center movement amount = (Fδ × β / γ _vn ) / ΔF (4)
In Step L805, the lens microcomputer L106 ′ determines whether the center movement method received from the camera microcomputer C106 ′ is a subtraction method or an addition method. If the method is the subtraction method, StepL806 is used. Proceed to

In Step L806, the lens microcomputer L106 ′ calculates the focus movement amount as the subtraction movement amount by subtracting the center movement amount from the vibration amplitude amount included in the AF control information received from the camera microcomputer C106 ′. That is,
Focus movement amount = vibration amplitude amount−center movement amount is calculated.

  Similar to the first embodiment, when the center movement is performed in the AF control using the subtraction method, a focus movement amount (two pulses) obtained by subtracting the center movement amount from the vibration amplitude amount is set. That is, in the AF control using the subtraction method, a focus movement amount smaller than the focus movement amount (three pulses) that is set when the center movement is performed using the addition method and the center movement amount is added to the vibration amplitude amount is set.

  In other words, in the subtraction method, the focus lens L105 is moved in a direction opposite to the center movement direction, which is the in-focus direction, by an amount obtained by subtracting the center movement amount (1 pulse) from the vibration amplitude amount (2 pulses).

  As a result, it is possible to reduce the focus movement amount compared to the addition type AF control while moving the vibration center in the in-focus direction, and to reduce the possibility that the focus lens L105 moves outside the shallow depth of focus range. Can do. As a result, the focus variation of the image due to the minute vibration of the focus lens L105 including the center movement does not occur or is not noticeable.

On the other hand, in Step L807, the lens microcomputer L106 ′ calculates the focus movement amount as the addition movement amount by adding the center movement amount b to the vibration amplitude amount a included in the AF control information received from the camera microcomputer C106 ′. That is,
Focus movement amount = vibration amplitude amount a + center movement amount b
Calculate

  Similar to the first embodiment, in the addition method, the focus lens L105 is moved by the vibration amplitude amount (2 pulses) in the same direction as the center movement direction together with the center movement amount (1 pulse). Thereby, the focus movement amount including the center movement can be sufficiently increased, and the responsiveness of the AF control can be improved.

  In Step L808, the lens microcomputer L106 ′ determines whether or not the focus movement amount, which is an addition movement amount obtained by adding the center movement amount to the vibration amplitude amount, exceeds the depth of focus range, that is, the focus lens L105 exceeds the depth of focus range. To determine whether to move. The depth of focus range corresponds to a predetermined range set based on the depth of focus. If it is determined that the focus lens L105 moves beyond the depth of focus (second case), the process proceeds to Step L809. If it is determined that the focus lens L105 does not move beyond the depth of focus (first case), the process proceeds to Step L801.

  In Step L809, the lens microcomputer L106 'transmits an instruction to change the center movement method from the addition method to the subtraction method to the camera microcomputer C106.

  In Step L810, the lens microcomputer L106 'calculates the target position and moving speed of the focus lens L105 from the calculated focus movement amount, and proceeds to Step L811.

  In Step L811, the lens microcomputer L106 'controls the drive of the focus actuator L107 according to the calculated target position and moving speed, and moves the focus lens L105. Thereafter, the process returns to Step L801.

  On the other hand, the camera microcomputer C106 'receives the instruction to change the center movement method transmitted from the lens microcomputer L106' in Step C807. In response to this change instruction, the camera microcomputer C106 'switches the center movement method to the subtraction method or the addition method in the processing of Step C803 to Step C805.

  Thus, in this embodiment, the allowable confusion circle diameter and AF control information are supplied from the camera body C100 'to the lens unit L100'. Then, in the lens unit L100 ′, the depth of focus width and the focus movement amount are calculated using the information, and whether or not the focus variation of the image is generated (conspicuous) due to the minute vibration of the focus lens including the center movement from these relationships. Or more accurately. Further, the lens unit L100 'transmits an instruction to switch the center movement method to the camera body from the determination result. Thereby, even when the focal depth of the camera body C100 ′ is shallow and the focus control resolution of the lens unit L100 ′ is rough, it is possible to avoid the occurrence of focus variation or conspicuous due to the minute vibration of the focus lens including the center movement. be able to. On the other hand, when the depth of focus is deep, good responsiveness of AF control can be ensured.

  Therefore, even when various lens units and the camera body are combined, it is possible to suppress a focus variation due to a minute vibration of the focus lens while ensuring a good response of AF control.

  Each embodiment described above is only a representative example, and various modifications and changes can be made to each embodiment in carrying out the present invention.

  It is possible to provide an imaging apparatus and an interchangeable lens that can perform AF control with good responsiveness while suppressing focus fluctuation of an image due to minute vibration of the focus lens.

L100 Lens unit L105 Focus lens L106 Lens microcomputer L1061 Lens specific data storage unit L107 Focus actuator C100 Camera body C101 Image sensor C1031 AF signal processing circuit C106 Camera microcomputer

Claims (12)

An imaging device capable of attaching and detaching an interchangeable lens having a photographing optical system including a focus lens, a focus actuator that moves the focus lens, and a lens control unit that drives the focus actuator to control the position of the focus lens There,
An image sensor that photoelectrically converts a subject image formed by the photographing optical system;
A focus signal generation unit that generates a focus signal indicating a focus state of the imaging optical system using an output from the imaging device;
An imaging device control unit that vibrates the focus lens in a direction in which the focus signal increases or decreases through the lens control unit and moves a vibration center of the focus lens in a focusing direction in which the focus signal increases;
The imaging device control unit calculates a vibration amplitude amount of the focus lens and a movement amount of the vibration center using the position control resolution and position sensitivity of the focus lens acquired from the interchangeable lens, and Calculate the depth of focus using the permissible circle of confusion and the F value of the photographing optical system acquired from the interchangeable lens,
The imaging device controller is
When the movement amount of the focus lens when moving the vibration center in the in-focus direction is set to an addition movement amount obtained by adding the movement amount of the vibration center to the vibration amplitude amount, the movement of the addition movement amount To determine whether the focus lens moves outside a predetermined range set based on the depth of focus,
In the first case where it is determined that the focus lens does not move out of the predetermined range, the lens control unit moves the focus lens in the in-focus direction by the addition movement amount,
In the second case where it is determined that the focus lens moves out of the predetermined range, the lens control unit moves the focus lens in the in-focus direction while moving the focus lens by a movement amount smaller than the addition movement amount. An imaging apparatus characterized by being moved.   In the second case, the imaging device control unit causes the lens control unit to move the focus lens in a direction opposite to the in-focus direction by a subtraction movement amount obtained by subtracting the movement amount of the vibration center from the vibration amplitude amount. The imaging apparatus according to claim 1, wherein the imaging apparatus is moved. A taking optical system including a focus lens;
A focus actuator for moving the focus lens;
An interchangeable lens having a lens control unit that drives the focus actuator to control the position of the focus lens;
An imaging element that photoelectrically converts a subject image formed by the imaging optical system, a focus signal generation unit that generates a focus signal indicating a focus state of the imaging optical system using an output from the imaging element, and the lens control An imaging apparatus control unit that vibrates the focus lens in a direction in which the focus signal increases or decreases through the unit and moves an oscillation center of the focus lens in a focusing direction in which the focus signal increases, The imaging device control unit calculates the vibration amplitude amount of the focus lens and the movement amount of the vibration center using the position control resolution and position sensitivity of the focus lens acquired from the interchangeable lens, and allows the image sensor to Depth of focus is calculated using the confusion circle diameter and the F-number of the photographing optical system acquired from the interchangeable lens, and in the in-focus direction. When the movement amount of the focus lens when moving the vibration center is set to an addition movement amount obtained by adding the movement amount of the vibration center to the vibration amplitude amount, the focus lens is moved by the movement of the addition movement amount. An interchangeable lens that can be attached to and detached from an imaging device that determines whether or not to move outside a predetermined range set based on the depth of focus,
The lens control unit
In the first case where the focus lens is determined not to move out of the predetermined range by the imaging device control unit, the focus lens is moved in the in-focus direction by the addition movement amount;
In the second case where the focus lens is determined to move out of the predetermined range by the imaging device control unit, the movement amount of the focus lens is smaller than the addition movement amount while moving the vibration center in the in-focus direction. An interchangeable lens characterized by only moving.   In the second case, the lens control unit moves the focus lens in a direction opposite to the in-focus direction by a subtraction movement amount obtained by subtracting a movement amount of the vibration center from the vibration amplitude amount. The interchangeable lens according to claim 3. A taking optical system including a focus lens;
A focus actuator for moving the focus lens;
An interchangeable lens having a lens control unit that drives the focus actuator to control the position of the focus lens;
An imaging element that photoelectrically converts a subject image formed by the imaging optical system, a focus signal generation unit that generates a focus signal indicating a focus state of the imaging optical system using an output from the imaging element, and the lens control The focus lens is vibrated in a direction in which the focus signal increases or decreases through the unit, and is attached to and detached from the image pickup apparatus having an image pickup apparatus control unit that moves the vibration center of the focus lens in a focusing direction in which the focus signal increases. A possible interchangeable lens,
The lens control unit calculates a vibration amplitude amount of the focus lens and a movement amount of the vibration center using the position control resolution and the position sensitivity of the focus lens, and the F value of the photographing optical system and the imaging device Depth of focus is calculated using the permissible circle of confusion of the image sensor acquired from
The lens control unit
When the movement amount of the focus lens when moving the vibration center in the in-focus direction is set to an addition movement amount obtained by adding the movement amount of the vibration center to the vibration amplitude amount, the movement of the addition movement amount Determining whether the focus lens moves out of a predetermined range set based on the depth of focus;
In the first case where it is determined that the focus lens does not move out of the predetermined range, the focus lens is moved in the in-focus direction by the addition movement amount,
In the second case where it is determined that the focus lens moves outside the predetermined range, the focus lens is moved by a movement amount smaller than the addition movement amount while moving the vibration center in the focusing direction. Interchangeable lens.   In the second case, the lens control unit moves the focus lens in a direction opposite to the in-focus direction by a subtraction movement amount obtained by subtracting a movement amount of the vibration center from the vibration amplitude amount. The interchangeable lens according to claim 5. An imaging device capable of attaching and detaching an interchangeable lens having a photographing optical system including a focus lens, a focus actuator that moves the focus lens, and a lens control unit that drives the focus actuator to control the position of the focus lens There,
An image sensor that photoelectrically converts a subject image formed by the photographing optical system;
A focus signal generation unit that generates a focus signal indicating a focus state of the imaging optical system using an output from the imaging device;
An imaging device control unit that vibrates the focus lens in a direction in which the focus signal increases or decreases through the lens control unit and moves a vibration center of the focus lens in a focusing direction in which the focus signal increases;
The imaging device controller is
Supplying the permissible circle of confusion of the image sensor to the lens control unit, and causing the lens control unit to calculate the depth of focus using the permissible circle of confusion and the F value of the photographing optical system;
The imaging device controller is
The lens control unit is configured to calculate a vibration amplitude amount of the focus lens and a movement amount of the vibration center using the position control resolution and position sensitivity of the focus lens, and move the vibration center in the in-focus direction. When the movement amount of the focus lens at the time is set to an addition movement amount obtained by adding the movement amount of the vibration center to the vibration amplitude amount, the focus lens is moved based on the depth of focus by the movement of the addition movement amount. To determine whether to move outside the set range,
In a first case where it is determined that the focus lens does not move outside the predetermined range, the focus control lens is moved in the in-focus direction by the addition movement amount to the lens control unit,
In the second case where it is determined that the focus lens moves out of the predetermined range, the lens control unit moves the focus lens in the in-focus direction while moving the focus lens less than the addition movement amount. An imaging apparatus characterized by being moved only by the distance.   In the second case, the imaging device control unit causes the lens control unit to move the focus lens in a direction opposite to the in-focus direction by a subtraction movement amount obtained by subtracting the movement amount of the vibration center from the vibration amplitude amount. The imaging apparatus according to claim 7, wherein the imaging apparatus is moved. An imaging apparatus control method comprising a photographing optical system including a focus lens and a focus actuator for moving the focus lens, wherein the interchangeable lens for driving the focus actuator to control the position of the focus lens is detachable. And
Generating a focus signal indicating a focus state of the photographing optical system using an output from an image sensor that photoelectrically converts a subject image formed by the photographing optical system;
A focus control step of causing the focus lens to vibrate in the direction in which the focus signal increases or decreases through the interchangeable lens and moving the vibration center of the focus lens in a focusing direction in which the focus signal increases;
In the focus control step,
Using the position control resolution and position sensitivity of the focus lens acquired from the interchangeable lens, the vibration amplitude amount of the focus lens and the movement amount of the vibration center are calculated, and the permissible circle of confusion of the image sensor and the interchange Depth of focus is calculated using the F value of the photographing optical system acquired from the lens,
When the movement amount of the focus lens when moving the vibration center in the in-focus direction is set to an addition movement amount obtained by adding the movement amount of the vibration center to the vibration amplitude amount, the movement of the addition movement amount To determine whether the focus lens moves outside a predetermined range set based on the depth of focus,
In the first case where it is determined that the focus lens does not move outside the predetermined range, the focus lens is moved in the in-focus direction by the addition movement amount to the interchangeable lens,
In the second case where it is determined that the focus lens moves out of the predetermined range, the focus lens is moved by a movement amount smaller than the addition movement amount while moving the vibration center in the focusing direction. A method for controlling an imaging apparatus, comprising: A taking optical system including a focus lens;
A focus actuator for moving the focus lens;
An interchangeable lens for controlling the position of the focus lens by driving the focus actuator;
A focus signal indicating a focus state of the photographic optical system is generated using an output from an image sensor that photoelectrically converts a subject image formed by the photographic optical system, and the focus signal is increased or decreased through the interchangeable lens. An imaging device that vibrates in the direction of movement and moves the vibration center of the focus lens in a focusing direction in which the focus signal increases, using the position control resolution and position sensitivity of the focus lens acquired from the interchangeable lens And calculating the depth of focus using the permissible circle of confusion of the image sensor and the F value of the photographing optical system obtained from the interchangeable lens. The moving amount of the focus lens when moving the vibration center in the in-focus direction is the vibration amplitude amount during the vibration. An imaging device that determines whether or not the focus lens moves out of a predetermined range set based on the depth of focus due to the movement of the additional movement amount when the additional movement amount is set to An interchangeable lens control method that can be attached to and detached from
Moving the focus lens in the in-focus direction by the amount of addition movement when the imaging device determines that the focus lens does not move outside the predetermined range; and
In the second case where the focus lens is determined to move out of the predetermined range by the imaging device, the focus lens is moved by a movement amount smaller than the addition movement amount while moving the vibration center in the focusing direction. And a step of controlling the interchangeable lens. A taking optical system including a focus lens;
A focus actuator for moving the focus lens;
An interchangeable lens for controlling the position of the focus lens by driving the focus actuator;
A focus signal indicating a focus state of the photographic optical system is generated using an output from an image sensor that photoelectrically converts a subject image formed by the photographic optical system, and the focus signal is increased or decreased through the interchangeable lens. A control method for an interchangeable lens that is attachable to and detachable from an imaging device that vibrates in a focusing direction and moves a vibration center of the focus lens in a focusing direction in which the focus signal increases.
Calculating a vibration amplitude amount of the focus lens and a movement amount of the vibration center using the position control resolution and position sensitivity of the focus lens;
Calculating a depth of focus using an F value of the imaging optical system and an allowable circle of confusion of the imaging element acquired from the imaging device;
When the movement amount of the focus lens when moving the vibration center in the in-focus direction is set to an addition movement amount obtained by adding the movement amount of the vibration center to the vibration amplitude amount, the movement of the addition movement amount Determining whether the focus lens moves out of a predetermined range set based on the depth of focus;
In a first case where it is determined that the focus lens does not move out of the predetermined range, the focus lens is moved in the in-focus direction by the addition movement amount;
And moving the focus lens by a movement amount smaller than the addition movement amount while moving the vibration center in the in-focus direction in a second case where it is determined that the focus lens moves outside the predetermined range. A control method for an interchangeable lens. An imaging apparatus control method comprising a photographing optical system including a focus lens and a focus actuator for moving the focus lens, wherein the interchangeable lens for driving the focus actuator to control the position of the focus lens is detachable. And
Generating a focus signal indicating a focus state of the photographing optical system using an output from an image sensor that photoelectrically converts a subject image formed by the photographing optical system;
A focus control step of causing the focus lens to vibrate in the direction in which the focus signal increases or decreases through the interchangeable lens and moving the vibration center of the focus lens in a focusing direction in which the focus signal increases;
In the focus control step,
Supplying an allowable confusion circle diameter of the image sensor to the interchangeable lens, and causing the interchangeable lens to calculate a depth of focus using the allowable confusion circle diameter and the F value of the photographing optical system;
The interchangeable lens is caused to calculate the vibration amplitude amount of the focus lens and the movement amount of the vibration center using the position control resolution and position sensitivity of the focus lens,
When the movement amount of the focus lens when moving the vibration center in the in-focus direction is set to an addition movement amount obtained by adding the movement amount of the vibration center to the vibration amplitude amount, the movement of the addition movement amount To determine whether the focus lens moves out of a predetermined range set based on the depth of focus,
In the first case where it is determined that the focus lens does not move out of the predetermined range, the interchangeable lens is moved the focus lens in the in-focus direction by the addition movement amount,
In the second case where it is determined that the focus lens moves out of the predetermined range, the focus lens is moved by a movement amount smaller than the addition movement amount while moving the vibration center in the focusing direction. A method for controlling an imaging apparatus, characterized by being moved.