JP2005208526A - Video camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely search an approximate focusing position even when an optional interchangeable lens is mounted. <P>SOLUTION: The present invention relates to allow successively move a focus adjustment lens 21 on the basis of a total searching movement amount Δx', namely a moving speed, which is calculated to optimum to a depth of focus on the basis of the diameter (d) of an allowable circle of confusion and the ratio (b) with respect to the depth of focus at the interchangeable AF lens part 3 and an f-stop value FNO of 22 by supplying the diameter (d) of an allowable circle of confusion and the ratio (b) with respect to the depth of focus into the interchangeable AF lens part 3 from the main body part 2 of a camera, and to search the approximate focusing position regardless the mounted interchangeable AF lens part. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a video camera, and is suitable for application to, for example, a broadcast / business digital video camera in which a camera body and a replacement lens are detachably attached.

  Conventionally, home video cameras are equipped with an autofocus (AF) function that automatically adjusts the focus of the subject by automatically changing the position of the focus adjustment lens according to the distance to the subject. It is possible to accurately focus on the subject without performing manual focus adjustment (see, for example, Patent Document 1).

  Some home video cameras employ a TTL (Through the Lens) method. For example, when the focus is greatly out of focus, a high-frequency component included in an imaging signal is extracted, and the high-frequency component is extracted. By searching for a place where the level of the maximum value is searched, an approximate in-focus position can be searched (hereinafter referred to as an overall search).

  For example, as shown in FIG. 10A, the home video camera picks up images at 1/60 second intervals fixed corresponding to the field period while moving the focus adjustment lens from the h2 side to the h1 side. The captured image signals are sequentially generated.

  Subsequently, the home video camera extracts a high-frequency component (hereinafter referred to as an evaluation value v) included in each imaging signal, and, for example, two consecutive evaluation values v3 at the positions x3 and x4 of the focus adjustment lens. And v4 are both equal to or greater than a predetermined threshold value vt, and the position x4 where the difference value vd4 is equal to or smaller than the predetermined value is regarded as the vicinity of the maximum value of the evaluation value v. It is made to discriminate.

  By the way, in home video cameras, if the moving speed of the focus adjustment lens is increased in order to shorten the time for performing the entire search, the imaging interval is fixed at 1/60 seconds. Although the position interval of each lens (hereinafter referred to as the total search movement amount ΔX ′) also increases, the characteristic curve of the evaluation value v changes relatively slowly due to the relatively large aperture value and the deep focal depth. Therefore, a position x4 where two consecutive evaluation values v (evaluation values v3 and v4) are both equal to or greater than a predetermined threshold value vt and the difference value vd4 is equal to or less than a predetermined value is overlooked as an approximate focus position. Can be detected without any problem.

  However, in the home video camera, as shown in FIG. 10B, when the aperture value is relatively small and the focal depth is shallow, similarly, the movement speed of the focus adjustment lens is fast and the total search movement amount ΔX ′ is large. Depending on the evaluation values v11 to v16, the maximum value cannot be detected, and the approximate focus position is missed.

  Therefore, the home video camera changes the moving speed of the focus adjustment lens during the entire search to an optimum value according to the depth of focus at that time. For example, as shown in FIG. In addition, when the aperture value is small and the depth of focus is shallow, the evaluation value v31 can be detected as the maximum value by reducing the overall search movement amount ΔX ′ and slowing the movement speed of the focus adjustment lens. A position x31 corresponding to v31 can be recognized as an approximate in-focus position.

  Subsequently, the home video camera moves the focus adjustment lens to the position x31 of the focus adjustment lens determined to be the approximate focus position, and finally adjusts the focus by performing predetermined fine adjustment. It is made like that.

  By the way, the home video camera is configured so that the lens unit cannot be separated from the camera body. Therefore, the movable range of the focus adjustment lens of the lens unit and the response characteristics of the actuator that drives the focus adjustment lens Etc. (hereinafter referred to as “lens parameters”) can be treated as fixed values.

  Therefore, in a home video camera, it is possible to optimally perform drive control of the focus adjustment lens in the lens unit based on this lens parameter, and to search for the in-focus position in a short time.

  By the way, in broadcast / professional video cameras used in television broadcasting stations, a professional photographer (so-called cameraman) manually adjusts the focus manually, so it does not have an autofocus function. It was.

Also, in such a broadcast / professional video camera, a camera body and a lens (hereinafter referred to as an interchangeable lens) are configured to be separable, and the interchangeable lens can be used as necessary. In each situation, an optimum image can be taken using an optimum interchangeable lens.
JP-A-9-33791 (page 6, FIG. 2)

  In recent years, however, BS digital television broadcasting and terrestrial digital television that employ high definition image quality (HD: High Definition) systems with high resolution in addition to terrestrial analog broadcasting based on standard definition image quality (SD) standards. Since broadcasting has started, when focusing with a cameraman's visual observation when shooting with a broadcast / professional video camera was not possible to achieve complete focus, the out-of-focus image was clear. Will be displayed.

  Therefore, by installing an autofocus function in such broadcast and commercial video cameras as well as conventional home video cameras, the autofocus function is utilized not only by the cameraman's focus adjustment. A method for accurately adjusting the focus has been proposed.

  However, in a broadcast / professional video camera using an interchangeable lens unit, when various types of interchangeable autofocus (AF) lens units are mounted, the lens parameters of each interchangeable AF lens unit are different. If the difference in lens parameters in the interchangeable AF lens unit is not absorbed on the camera body side, there is a problem that an approximate in-focus position cannot be searched in a short time.

  The present invention has been made in consideration of the above points, and is able to reliably search for an approximate in-focus position so that the autofocus function can function properly even when an optional interchangeable lens is mounted. It is intended to propose a video camera that can accurately match the above.

  In order to solve such a problem, the video camera of the present invention is a video camera including a camera body and an interchangeable lens unit detachably attached to the camera body. It has a drive means for driving the focus adjustment lens, a speed calculation means for calculating the drive speed of the focus adjustment lens, and a diaphragm. The focus adjustment lens can be moved to the camera body via the drive means. In order to search the approximate focal point position on the imaging surface of the imaging means by sequentially moving from one end of the range to the other end, the speed calculation of the interchangeable lens unit is calculated by the allowable confusion circle diameter on the imaging surface and the ratio to the focal depth. A speed control means, a ratio to the permissible circle of confusion and the depth of focus supplied from the control section, and a diaphragm aperture. DOO calculates the driving speed of the focus adjusting lens on the basis of, the drive means sequentially to move the focus adjustment lens at a speed corresponding to the driving speed for searching the approximate focus position.

  As a result, the permissible circle of confusion and the ratio to the depth of focus are simply supplied from the camera body to the interchangeable lens unit, and the interchangeable lens unit is based on the ratio of the permissible circle of confusion and the depth of focus and the aperture value of the diaphragm. It is possible to calculate the optimal moving speed of the focus adjustment lens with respect to the focal depth at that time, and to move the focus adjustment lens in order according to the moving speed, so that an approximate in-focus position can be reliably searched. can do.

  Further, in the in-focus position searching method of the present invention, the focus adjustment lens of the interchangeable lens unit provided detachably from the camera main body unit by the control unit provided in the camera main body unit is used as the focus adjustment lens. In order to search for an approximate in-focus position on the imaging surface of the imaging means by sequentially moving from one end of the movable range to the other end, the permissible circle of confusion on the imaging surface and the ratio to the focal depth Data supply step supplied to the speed calculating means of the interchangeable lens unit from the control unit, the ratio to the permissible circle of confusion and the focal depth supplied from the control unit by the speed calculating unit, and the aperture value of the diaphragm in the interchangeable lens unit, The driving speed of the focus adjustment lens is calculated based on the above, and an approximate in-focus position is searched according to the driving speed. To be provided a focus position searching step of sequentially moving the focus adjustment lens in degrees.

  As a result, the permissible circle of confusion and the ratio to the depth of focus are simply supplied from the camera body to the interchangeable lens unit, and the interchangeable lens unit is based on the ratio of the permissible circle of confusion and the depth of focus and the aperture value of the diaphragm. It is possible to calculate the optimal moving speed of the focus adjustment lens with respect to the focal depth at that time, and to move the focus adjustment lens in order according to the moving speed, so that an approximate in-focus position can be reliably searched. can do.

  Furthermore, in the camera main body of the present invention, the driving unit for driving the focus adjusting lens, the speed calculating unit for calculating the driving speed of the focus adjusting lens, and the interchangeable lens unit having a diaphragm are driven. The focus adjustment lens is sequentially moved from one end to the other end of the movable range by the means to search for an approximate in-focus position on the image pickup surface of the image pickup means. And a ratio to the permissible circle of confusion diameter and the focal depth supplied from the control unit by the speed calculation unit of the interchangeable lens unit and the aperture value of the diaphragm. Based on this, the drive speed of the focus adjustment lens is calculated, and the drive means responds to the drive speed in order to find the approximate focus position. So as to sequentially move the focus adjustment lens in speed.

  As a result, the camera body simply supplies the permissible circle of confusion diameter and the ratio to the depth of focus to the interchangeable lens section, and the interchangeable lens section uses the ratio of the permissible circle of confusion and the depth of focus to the aperture value of the aperture. Based on this, it is possible to calculate the optimum moving speed of the focus adjustment lens with respect to the focal depth at that time, and by moving the focus adjustment lens sequentially according to the moving speed, it is possible to ensure the approximate in-focus position. Can be explored.

  Further, in the interchangeable lens unit of the present invention, a focus adjustment lens, a speed calculation means for calculating the drive speed of the focus adjustment lens, a drive means for driving the focus adjustment lens based on the drive speed, an aperture, Receiving means for receiving from the camera body the permissible circle of confusion on the imaging surface and the ratio to the depth of focus in order to search for an approximate in-focus position on the imaging surface of the imaging means provided in the camera body. The speed calculating means calculates the driving speed of the focus adjustment lens based on the permissible circle of confusion diameter and the ratio to the focal depth supplied from the camera body, and the aperture value of the aperture. The focus adjustment lens is used for the focus adjustment at a speed corresponding to the drive speed so that the approximate focus position can be searched by the control unit So as to sequentially move from one end of the movable range of the lens to the other.

  Thus, the interchangeable lens unit simply receives the allowable confusion circle diameter and the ratio to the depth of focus from the camera body, and based on the ratio to the allowable confusion circle diameter and the depth of focus and the aperture value of the aperture, It is possible to calculate the optimum movement speed of the focus adjustment lens with respect to the depth, and by moving the focus adjustment lens sequentially according to the movement speed, the camera body can reliably search for an approximate in-focus position. be able to.

  Furthermore, the video camera of the present invention is a video camera comprising a camera main body and an interchangeable lens unit that is detachably attached to the camera main body, and the focus adjustment lens is provided on the interchangeable lens unit. A driving means for driving and a speed calculating means for calculating the driving speed of the focus adjustment lens; the focus adjustment lens is sequentially moved from one end of the movable range to the other end of the camera body through the drive means. In order to search for an approximate in-focus position on the imaging surface of the imaging unit by moving, the allowable confusion circle diameter on the imaging surface, the ratio to the focal depth, and the aperture value of the aperture are transferred to the speed calculation unit of the interchangeable lens unit. A speed control means, based on the permissible circle of confusion, the ratio to the depth of focus, and the aperture value of the aperture supplied from the control unit. Calculating a driving speed of the serial focus adjustment lens, driving means so as to sequentially move the focus adjustment lens at a speed corresponding to the driving speed for searching the approximate focus position.

  As a result, the ratio of the permissible circle of confusion, the ratio to the depth of focus, and the aperture value of the aperture are simply supplied from the camera body to the interchangeable lens unit. Based on the value, it is possible to calculate the optimum moving speed of the focus adjustment lens with respect to the depth of focus at that time, and by moving the focus adjustment lens sequentially according to the moving speed, the approximate in-focus position can be determined. You can search reliably.

  Further, in the in-focus position search method of the present invention, the focus adjustment lens of the interchangeable lens unit that is detachably attached to the camera main body by the control unit provided in the camera main body is used as the focus adjustment lens. In order to search the approximate focal point position on the imaging surface of the imaging means by sequentially moving from one end to the other end of the movable range, the permissible circle of confusion on the imaging surface, the ratio to the focal depth, and the aperture value of the diaphragm Is supplied from the camera body to the speed calculator of the interchangeable lens unit, and based on the permissible circle of confusion, the ratio to the depth of focus, and the aperture value of the aperture, which are supplied from the controller by the speed calculator. To calculate the drive speed of the focus adjustment lens and to search for the approximate focus position, So as to provide the focus position searching step of sequentially moving the carcass adjusting lens.

  As a result, the ratio of the permissible circle of confusion, the ratio to the depth of focus, and the aperture value of the aperture are simply supplied from the camera body to the interchangeable lens unit. Based on the value, it is possible to calculate the optimum moving speed of the focus adjustment lens with respect to the depth of focus at that time, and by moving the focus adjustment lens sequentially according to the moving speed, the approximate in-focus position can be determined. You can search reliably.

  Furthermore, in the camera main body of the present invention, the drive means focuses the interchangeable lens section having a drive means for driving the focus adjustment lens and a speed calculation means for calculating the drive speed of the focus adjustment lens. In order to search the approximate focal position on the imaging surface of the imaging means by sequentially moving the adjustment lens from one end to the other end of the movable range, the permissible circle of confusion on the imaging surface, the ratio to the focal depth, and the aperture And a control unit that supplies the aperture value to the speed calculation means of the interchangeable lens unit, the allowable confusion circle diameter supplied from the control unit by the speed calculation unit of the interchangeable lens unit, the ratio to the depth of focus, and the aperture value of the aperture The driving speed of the focus adjustment lens is calculated based on the Rate so as to sequentially move the focus adjustment lens in the.

  As a result, the camera body simply supplies the permissible circle of confusion diameter, the ratio to the focal depth and the aperture value of the aperture to the interchangeable lens unit, and the interchangeable lens unit accepts the permissible circle of confusion, the ratio to the focal depth, and the aperture value. Based on the aperture value, the optimal moving speed of the focus adjustment lens can be calculated for the current focal depth, and the approximate focus position can be obtained by sequentially moving the focus adjustment lens according to the moving speed. Can be reliably searched.

  Furthermore, in the interchangeable lens unit of the present invention, the focus adjustment lens, the speed calculation means for calculating the drive speed of the focus adjustment lens, the drive means for driving the focus adjustment lens based on the drive speed, and the camera body Receiving means for receiving from the camera body the permissible circle of confusion on the imaging surface, the ratio with respect to the depth of focus, and the aperture value of the aperture to search for an approximate in-focus position on the imaging surface of the imaging means provided in the unit The speed calculation means calculates the driving speed of the focus adjustment lens based on the permissible circle of confusion supplied from the camera body, the ratio to the depth of focus, and the aperture value of the aperture. The focus adjustment lens can be adjusted at a speed corresponding to the drive speed so that an approximate in-focus position can be searched by the control unit of the unit. So as to sequentially move from one end of the movable range of the use lenses to the other.

  As a result, the interchangeable lens unit simply receives the permissible circle of confusion diameter, the ratio to the depth of focus and the aperture value of the aperture from the camera body, and based on the permissible circle of confusion diameter, the ratio to the depth of focus and the aperture value of the aperture It is possible to calculate the optimum moving speed of the focus adjustment lens with respect to the focal depth of the camera, and to move the focus adjustment lens sequentially according to the moving speed to ensure the approximate focus position on the camera body. Can be explored.

  According to the present invention, the ratio of the allowable confusion circle diameter and the focal depth to the interchangeable lens unit is simply supplied from the camera body to the interchangeable lens unit. Based on the value, the optimal moving speed of the focus adjustment lens can be calculated for the depth of focus at that time, and the approximate focus position can be obtained by sequentially moving the focus adjustment lens according to the moving speed. Can be reliably searched.

  Further, according to the present invention, the ratio of the permissible circle of confusion and the depth of focus and the aperture value of the aperture are supplied from the camera body to the interchangeable lens unit, and the interchangeable lens unit corresponds to the permissible circle of confusion and the depth of focus. Based on the ratio and the aperture value of the aperture, it is possible to calculate the optimum moving speed of the focus adjustment lens with respect to the depth of focus at that time, and by moving the focus adjustment lens sequentially according to the moving speed, The in-focus position can be reliably searched.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

(1) Overall Configuration of Video Camera with Autofocus Function In FIGS. 1 and 2, reference numeral 1 denotes a video camera with an autofocus function according to the present invention, which is used for broadcasting and business use that supports HDVS (High Definition Video System) as a whole. The camera body 2 and the interchangeable AF (Auto Focus) lens 3 are detachably attached.

  The camera body 2 is provided with a handle-like grip 4 and a microphone 5 and a viewfinder 6 for collecting sound.

  In the interchangeable AF lens unit 3, a lens for focus adjustment (not shown) is built in the position of the rear lens, and the lens unit 7 having a configuration in which the focus ring 9 is attached to the lens barrel 11, and a user for the focus ring 9 The lens control unit 8 is used to adjust the focus by moving the focus adjustment lens in response to the operation. A hood 12 is attached to the lens unit 7.

  The lens control unit 8 of the interchangeable AF lens unit 3 is supplied with power from the camera body 2 while attached to the camera body 2, and performs focus adjustment and the like based on the power. Has been made.

  The video camera 1 with an autofocus function having such a configuration has a configuration in which the interchangeable AF lens unit 3 can be detachably attached. Therefore, another interchangeable lens having a zoom ratio different from that of the interchangeable AF lens unit 3 is used. It can be easily exchanged for a type AF lens unit.

  In the video camera 1 with an autofocus function, the lens control unit 8 of the interchangeable AF lens unit 3 is provided with a changeover switch 10 for alternately switching between the autofocus mode and the manual focus mode. The auto focus mode and the manual focus mode can be switched according to the situation.

  In the video camera 1 with an autofocus function, when the autofocus mode is set, the focus adjustment is automatically performed under the control of the lens control unit 8, but the manual focus mode is set. In some cases, focus adjustment is performed by moving a focus adjustment lens (not shown) built in the interchangeable AF lens unit 3 in accordance with a rotation operation of the focus ring 9 by a cameraman.

  By the way, the video camera 1 with autofocus function is HDVS compatible and the image quality is much clearer than the conventional SD (Standard Definition) method, so it can be prevented from appearing in the image even if it is slightly out of focus. Therefore, an autofocus function for correcting a cameraman's focus adjustment operation is provided even in the manual focus mode.

(2) Circuit Configuration of Video Camera 1 with Autofocus Function As shown in FIG. 3, in the video camera 1 with an autofocus function, the interchangeable AF lens unit 3 is chucked with respect to the camera body unit 2 (not shown). ), A communication path 30 is formed between the camera body 2 and the interchangeable AF lens unit 3 via the electrical connection point 29.

  The camera body 2 controls the focus adjustment by the solid-state imaging device 26, the signal processing unit 27 that performs predetermined signal processing on the imaging signal obtained by the solid-state imaging device 26, and the interchangeable AF lens unit 3. A portion 28 is provided.

  On the other hand, the interchangeable AF lens unit 3 drives the focus adjustment lens 21 in the direction of the arrow h1 or h2 via the actuator 23 by the focus controller 25 under the control of the control unit 28, or the diaphragm 22 via the motor 24. The open / close state of the is controlled.

(3) Focus Adjustment Processing Procedure In the video camera 1 with an autofocus function, as shown in FIG. 4, the routine RT1 is entered from the start step, and the process proceeds to the next subroutine SRT1. The in-focus direction is recognized by driving with.

  At this time, in the video camera 1 with an autofocus function, when the focus adjustment lens 21 is far from the focus position and the focus direction cannot be recognized at all, the process proceeds to the next subroutine SRT2 for focus adjustment. An overall search is made as to where the approximate in-focus position exists within the movable range in which the lens 21 can move, and the process proceeds to the next subroutine SRT3.

  Incidentally, the video camera 1 with an autofocus function is adapted to directly shift to the subroutine SRT4 and finally search for the in-focus position when the in-focus direction can be recognized in the subroutine SRT1.

  In the subroutine SRT3, the video camera 1 with an autofocus function searches for an approximate in-focus position by an overall search, and then recognizes the in-focus direction by finely driving the focus adjustment lens 21 again, and proceeds to the next subroutine SRT4. .

  In the subroutine SRT4, the video camera 1 with an autofocus function finally searches for the in-focus position, and by positioning the focus adjustment lens 21 at the in-focus position, the subject is focused so that there is no slight defocus. The focus adjustment processing procedure is finished.

  Thus, in the video camera 1 with an autofocus function, the focus adjustment processing procedure can be roughly divided into subroutines SRT1 to SRT4. Each of the subroutines SRT1 to SRT4 will be described below.

(4) Microlens Drive The microlens drive, that is, wobbling in the subroutine SRT1, will be described with reference to FIG. In the camera body 2, first, an arbitrary confusion circle diameter d and an arbitrary depth of focus 2Δx formed on the imaging surface of the solid-state imaging device 26 via the focus adjustment lens 21 and the diaphragm 22 of the interchangeable AF lens unit 3. The ratio a is sent to the focus controller 25 of the interchangeable AF lens unit 3 via the communication path 30 by the control unit 28.

  Here, the permissible circle of confusion will be briefly described. Generally, light passing through a lens creates a point image on the focal plane. This point image is a circle having a certain diameter and is also called a blurred circle. The smaller the diameter of this blur circle is, the sharper the focus is recognized with the naked eye, and the larger the diameter is, the more blurry state is, and the permissible circle of confusion represents the limit value of the blur circle that is not perceived by humans. The diameter is the allowable circle of confusion circle d. The permissible circle of confusion d is also a value that is uniquely determined by the resolution of the optical system and the solid-state image sensor 26.

  On the other hand, the depth of focus will be briefly described. When focusing on a certain distance, objects before and after the focused subject are clearly visible to the extent that they can be used practically, and the focus range on the subject side is the depth of field, while There is also a range where the image is clearly imaged at the front and rear at equal intervals on the side, which is the depth of focus 2Δx.

  When the sum of the defocus amounts on the front side and the rear side when the blur of the perception limit occurs is 2Δx, the defocus amount Δx is the allowable confusion circle diameter d and the aperture value of the aperture 22 if the lens aberration is ignored. Based on FNO,

Can be calculated as

  Accordingly, the focus controller 25 calculates the following equation based on the allowable confusion circle diameter d and the ratio a to the focal depth 2Δx supplied from the control unit 28 of the camera body 2 and the aperture value FNO of the aperture 22.

The focus movement amount Δx ′ shown in FIG. 4 is calculated, and the actuator 23 is minutely driven by the actuator 23 by the focus movement amount Δx ′.

  Incidentally, the ratio a with respect to the focal depth 2Δx is a value arbitrarily determined within the range of 0 <a <1, and this indicates that the focal shift amount Δx ′ exceeds the defocus amount Δx, resulting in out of focus. It is designed to prevent the photographer from recognizing it.

  By the way, the meaning of wobbling is to determine whether the focus is in focus or not by moving the focus adjustment lens 21 back and forth from the current position of the focus adjustment lens 21 and detecting the change in the imaging signal obtained as a result. This is because it cannot be judged without it.

  As a result, the signal processing unit 27 of the camera body 2 forms the subject image captured by the focus adjustment lens 21 and the diaphragm 22 provided in the interchangeable AF lens unit 3 on the solid-state image sensor 26, The AF detection unit 27A extracts a high frequency component of the image pickup signal from the image pickup signal obtained as a result, and sends the extraction result to the control unit 28.

  The control unit 28 extracts a high-frequency component level of an imaging signal obtained at a 1/60 second period corresponding to a field period from the solid-state imaging device 26 as an evaluation value on the premise of a TTL (Through the Lens) mountain climbing method, By determining that the in-focus point exists in the direction h1 or h2 in which the level of the high-frequency component of the imaging signal becomes larger, the in-focus direction can be recognized.

  As a result, the control unit 28 finally moves the focus adjustment lens 21 to the predetermined position based on the recognition result of the direction h1 or h2 from which the current position of the focus adjustment lens 21 is moved. The in-focus state is obtained by driving at a feeding speed.

  When the flow of these series of processes is shown in the sequence chart of FIG. 6, in step SP1, the camera body 2 first sets an arbitrary ratio a to the focal depth 2Δx and the allowable confusion circle diameter d to the focus controller of the interchangeable AF lens unit 3. Then, the process proceeds to the next step SP2, and the process is terminated.

  On the other hand, in step SP11, the interchangeable AF lens unit 3 determines the arbitrary ratio a and the allowable circle of confusion diameter d with respect to the focal depth 2Δx supplied from the camera body unit 2, and the aperture of the diaphragm 22 included in the interchangeable AF lens unit 3. Based on the value FNO, the focal point movement amount Δx ′ is calculated according to the equation (2), and the process proceeds to the next step SP12.

  In step SP12, the interchangeable AF lens unit 3 calculates an actual drive amount L1 in consideration of the drive gain of the actuator 23 that drives the actual focus adjustment lens 21 and the gain of the optical system based on the focal shift amount Δx ′. Then, the process proceeds to the next step SP13.

  In step SP13, the interchangeable AF lens unit 3 generates a pulse corresponding to the drive amount L1 and applies it to the actuator 23 every 1/60 seconds corresponding to the field period, thereby moving the focus adjustment lens 21 in the h1 or h2 direction. Wobbling is performed, the process proceeds to the next step SP14, and the process is terminated.

  At this time, the interchangeable AF lens unit 3 wobbles the focus adjustment lens 21 in the h1 or h2 direction every 1/60 seconds, and the subject image captured through the focus adjustment lens 21 and the aperture 22 at that time is captured by the camera. An image is formed on the imaging surface of the solid-state imaging device 26 of the main body 2.

  The control unit 28 of the camera body 2 compares the level of the high-frequency component of the imaging signal sequentially obtained from the solid-state imaging device 26 every 1/60 seconds, and increases the level of the high-frequency component of the imaging signal in the h1 or h2 direction. Can be recognized as the in-focus direction.

  At this time, the interchangeable AF lens unit 3 does not wobble the focus adjustment lens 21 in the direction h1 or h2 once every 1/60 seconds, but instead moves the focus adjustment lens 21 every 1/60 seconds. In addition, by wobbling in the h1 or h2 direction many times, the accuracy of the recognition result of the in-focus direction performed by the control unit 28 of the camera body 2 can be further improved.

(5) Overall Search for In-Focus Position By the way, the video camera 1 with an auto-focus function focuses on the vicinity of the current position of the focus adjustment lens 21 when the in-focus direction cannot be recognized by the micro lens driving of the subroutine SRT1 described above. It is determined that the focal position does not exist, and an approximate in-focus position search (hereinafter referred to as an overall search) is performed from within the movable range of the focus adjustment lens 21 in the subroutine SRT2.

  The control unit 28 of the video camera 1 with an autofocus function is also configured to perform an overall search on the premise of the TTL mountain climbing method, and the focus adjustment lens 21 is moved from the end point in the h2 direction (FIG. 3) of the movable range to the h1 direction. The high-frequency component levels (evaluation values v) of the imaging signals sequentially acquired from the solid-state imaging device 26 at 1/60 second periods corresponding to the field period are extracted and compared, and the evaluation values v It is determined that the position of the focus adjustment lens 21 showing the maximum value at which the level becomes the highest in-focus position.

  Here, the video camera 1 with an autofocus function detects the in-focus position in the shortest possible time by increasing the moving speed of the focus adjustment lens 21 during the entire search, and sets the response time of the autofocus function. It needs to be shortened.

  However, in the video camera 1 with an autofocus function, since the imaging interval is fixed every 1/60 seconds corresponding to the field period, for example, as shown in FIG. 10B, the focus adjustment lens 21 is moved. When the movement speed at the time is increased, the movement amount of the focus adjustment lens 21 from the acquisition of one imaging signal to the acquisition of the next imaging signal, that is, the entire search movement amount ΔX ′ increases, and the evaluation value There is a possibility of overlooking the maximum value of v.

  Therefore, the video camera 1 with an autofocus function adjusts the moving speed of the focus adjustment lens 21 by setting the entire search movement amount ΔX ′ to an optimum value, and performs the entire search in as short a time as possible to maximize the evaluation value v. It is necessary to reliably detect the approximate focal position without overlooking the value.

  By the way, as shown in FIGS. 10A and 10B, the evaluation values v1 to v4 and the evaluation values v11 to v16 acquired by the video camera 1 with an autofocus function at an imaging interval fixed to 1/60 seconds are as follows. The values are different depending on whether the depth of focus is deep or shallow.

  For this reason, the video camera 1 with an autofocus function, for example, as shown in FIG. 10A, when the depth of focus is relatively deep, the focus adjustment lens 21 at a moving speed that does not overlook the maximum value of the evaluation value v. However, when the depth of focus is relatively shallow as shown in FIG. 10B, the change in the characteristic curves of the evaluation values v11 to v16 is steep. If the focus adjustment lens 21 is moved at a movement speed based on the entire search movement amount ΔX ′, there is a possibility that the maximum value is overlooked only by the evaluation values v11 to v16.

  Here, in the video camera 1 with an autofocus function, when the depth of focus is relatively shallow as described above, if the total search movement amount ΔX ′ is reduced as shown in FIG. The moving speed can be reduced, and in this case, although it takes a long time to search, it can be detected without overlooking the evaluation value v31 in the vicinity of the maximum value.

  In other words, the video camera 1 with an autofocus function only needs to adjust the overall search movement amount ΔX ′ in proportion to the focal depth, and therefore the following formula using an arbitrary ratio b to the focal depth is used here.

Accordingly, the total search movement amount ΔX ′ can be calculated as the product of the defocus amount Δx and the ratio b which is ½ of the focal depth (2Δx).

  By the way, in the video camera 1 with an autofocus function, the distance between the defocus amount Δx, which is ½ of the depth of focus (2Δx), the permissible circle of confusion d (FIG. 5), and the aperture value FNO of the aperture 22. The above-described relationship of the expression (1) is established.

  Here, by applying the relationship of the equation (1) to the above-described equation (3), the total search movement amount ΔX ′ is expressed by the following equation:

Can be expressed as

  By the way, in the video camera 1 with an autofocus function, since the allowable circle of confusion diameter d is a fixed value, the total search movement amount ΔX ′ is proportional to the value of the ratio b and the aperture value FNO of the aperture 22. Become.

  Here, the ratio b is a value arbitrarily determined within the range of 0 <b. However, if the ratio b is relatively large, the overall search movement amount ΔX ′ also increases, and therefore the time required for the overall search is shortened. However, since the imaging interval is 1/60 second, there is a high possibility that the evaluation value v31 near the maximum value is overlooked.

  On the other hand, when the ratio b is relatively small, the total search movement amount ΔX ′ is small, so that the time required for the total search becomes long, but the possibility of overlooking the evaluation value v31 in the vicinity of the maximum value can be kept low. .

  The overall search movement amount ΔX ′ changes in proportion to the change of the aperture value FNO of the aperture 22 even if the value of the ratio b is fixed, as is apparent from the equation (4).

  For this reason, the video camera 1 with an autofocus function is configured so that even if the aperture value FNO of the aperture 22 is set to an arbitrary value within the maximum / minimum range, the entire search can be performed reliably and in a short time. b is set to an optimum value.

  Incidentally, the video camera 1 with an autofocus function sets the ratio b to a value (for example, b = 20) larger than the ratio a (0 <a <1) in the minute lens driving described above as (b). The total search movement amount ΔX ′ obtained according to the equation (4) can be set to a value larger than the focal movement amount Δx ′ obtained according to the equation (2).

  Therefore, the control unit 28 (FIG. 3) of the camera body 2 replaces the allowable confusion circle diameter d and the ratio b (for example, b = 20) with respect to the depth of focus, and calculates an overall search movement amount ΔX ′. 3 to the focus controller 25.

  The focus controller 25 is based on the permissible circle of confusion diameter d and the ratio b to the depth of focus supplied from the control unit 28 of the camera body 2 and the aperture value FNO of the aperture 22 according to the equation (4). ΔX ′ is calculated, and the focus adjustment lens 21 is moved by the actuator 23 by the entire search movement amount ΔX ′.

  Subsequently, the signal processing unit 27 of the camera body unit 2 forms an object image captured by the focus adjustment lens 21 and the diaphragm 22 provided in the interchangeable AF lens unit 3 on the solid-state imaging device 26, and The AF detection unit 27A extracts the evaluation value v (the level of the high frequency component of the imaging signal) for the imaging signal obtained at each result imaging interval (1/60 second), and sends the extraction result to the control unit 28.

  Then, the control unit 28 determines whether or not the in-focus position is near the current position of the focus adjustment lens 21 using the obtained evaluation value v. If there is no in-focus position near the current position, Until the maximum value of the evaluation value v is detected, the permissible circle of confusion diameter d and the ratio b to the depth of focus are repeatedly sent to the focus controller 25 of the interchangeable AF lens unit 3 every imaging interval (1/60 seconds). When the evaluation value v in the vicinity of the maximum value is detected, it is determined that the approximate focus position has been detected, and the entire search is terminated.

  For example, in FIG. 10C, the video camera 1 with an autofocus function evaluates the evaluation value while moving the focus adjustment lens 21 sequentially from the position x21 closest to the h2 side to the h1 side at every imaging interval (1/60 seconds). v21, v22,... are acquired.

  Then, the video camera 1 with the autofocus function moves the focus adjustment lens 21 to the position x31 and obtains the evaluation value v31. The two consecutive evaluation values v30 and v31 are both greater than or equal to a predetermined threshold value vt, and Since the difference value vd31 is equal to or less than the predetermined value, it is determined that the evaluation value v31 is a value near the maximum value of the evaluation value v, and the position x31 from which the evaluation value v31 is acquired is an approximate focus position. Determine.

  When this series of processing is shown in the sequence chart of FIG. 7, in step SP31, the camera body 2 sets the allowable confusion circle diameter d and an arbitrary ratio b to the focal depth to the focus controller 25 of the replacement AF lens 3 through the communication path 30. Then, the process proceeds to the next step SP32 and the process is terminated.

  On the other hand, in step SP41, the replacement AF lens 3 determines an arbitrary ratio b and allowable confusion circle diameter d with respect to the focal depth supplied from the camera body 2 and the aperture value FNO of the aperture 22 included in the replacement AF lens 3. Based on the above, the total search movement amount ΔX ′ is calculated according to the equation (4), and the process proceeds to the next step SP42.

  In step SP42, the replacement AF lens 3 calculates an actual drive amount L2 in consideration of the drive gain of the actuator 23 that drives the actual focus adjustment lens 21 and the gain of the optical system based on the total search movement amount ΔX ′. Then, the process proceeds to the next step SP43.

  In step SP43, the replacement AF lens 3 drives the focus adjustment lens 21 by generating a pulse corresponding to the drive amount L2 and applying it to the actuator 23 every 1/60 seconds corresponding to the field period to drive the drive amount L2. And move to the next step SP44 to end the process.

  Then, the replacement AF lens 3 moves the focus adjustment lens 21 by the drive amount L2 every 1/60 seconds, and captures the subject image captured through the focus adjustment lens 21 and the aperture 22 in the camera body 2. The image is formed on the imaging surface of the solid-state imaging device 26.

  The control unit 28 of the camera body unit 2 sequentially moves the focus adjustment lens 21 from the end point on the h2 side of the movable range, while the high frequency component of the imaging signal sequentially obtained from the solid-state imaging device 26 every 1/60 seconds. Each level (that is, evaluation value v) is compared, and the position of the focus adjustment lens 21 where two consecutive evaluation values v are both equal to or greater than a predetermined threshold value vt and the difference value is equal to or less than a predetermined value is approximately It is determined that it is the in-focus position.

  As a result, when the optimally set ratio b (for example, b = 20) is used, the video camera with an autofocus function 1 has a large aperture value FNO of the aperture 22 and a deep depth of focus (FIG. 10A). By setting the overall search movement amount ΔX ′ to a relatively large value according to the equation (4), the moving speed of the focus adjustment lens 21 is increased, and a relatively small imaging interval fixed at 1/60 seconds (ie, The approximate focal point position x4 can be detected in a relatively short time).

  Further, in the video camera 1 with an autofocus function, even when the same ratio b (b = 20) is used, when the aperture value FNO of the aperture 22 is small and the depth of focus is shallow (FIG. 10C), equation (4) Accordingly, by setting the overall search movement amount ΔX ′ to a relatively small value, the movement speed of the focus adjustment lens 21 is slowed down and a relatively large imaging interval (that is, a relatively long time) fixed at 1/60 seconds. Thus, the approximate in-focus position x31 can be reliably detected.

(6) Micro lens drive again The video camera 1 with an autofocus function detects the approximate focal position by the overall search of the subroutine SRT2, and then executes the micro lens drive of the subroutine SRT1 again in the subroutine SRT3. Determine the in-focus direction.

(7) In-focus position search When the video camera 1 with the autofocus function recognizes the in-focus direction from the current position of the focus adjustment lens 21 by the above-described minute lens drive, the focus camera searches for the focus according to the in-focus position search subroutine SRT4. The adjustment lens 21 is accurately moved to the in-focus position.

  In the in-focus position search subroutine SRT4, similarly to the above-described in-focus position overall search subroutine SRT2, the process according to the sequence chart of FIG. 7 is performed. It is set to a value (for example, b = 2) smaller than the value of the ratio b (b = 20) in the overall search for the focal position.

  Therefore, the overall search movement amount ΔX ′ calculated by the focus controller 25 according to the above-described equation (4) is smaller than that in the above-described overall search for the in-focus position, that is, when the focus adjustment lens 21 is driven. The moving speed is also reduced.

  For example, in the case of FIG. 10C, the control unit 28 of the camera body 2 determines that the approximate in-focus position is the position x31 by the above-described in-focus position overall search subroutine SRT2, and further, the minute lens drive subroutine SRT3. It is recognized that the in-focus direction is on the h2 side from the position x31.

  Next, the focus controller 25 of the interchangeable lens unit 3 enlarges the vicinity of the maximum value of the evaluation value v in FIG. 10C, and as shown in FIG. 8, the allowable confusion circle diameter d and the focal depth acquired from the control unit 28. The overall search movement amount ΔX ′ is calculated based on the value of the ratio b to (b = 2), and the entire search movement amount of the focus adjustment lens 21 is more than the position x31 during 1/60 seconds that is the imaging interval. The position is moved to the position x41 on the h2 side by ΔX ′.

  At this time, the control unit 28 calculates a difference value vd41 between the evaluation value v41 acquired at the current position x41 of the focus adjustment lens 21 and the previous evaluation value v31, and the evaluation value v41 and the previous evaluation value v31 are obtained. It is sequentially determined whether or not both are equal to or greater than a predetermined threshold value vt and the difference value vd41 is equal to or less than a predetermined value.

  In this case, although both the evaluation value v41 and the immediately preceding evaluation value v31 are equal to or greater than the predetermined threshold value vt, the difference value vd41 is not equal to or less than the predetermined value, so the control unit 28 determines the current position (x41) of the focus adjustment lens 21. Is determined not to be the in-focus position.

  Thereafter, the control unit 28 repeats the above-described series of processing every 1/60 seconds that is the imaging interval, so that the ratio b (b = 2) to the permissible circle of confusion diameter d and the depth of focus sent from the control unit 28 is obtained. Based on this, the focus controller 25 sequentially moves the focus adjustment lens 21 from the position x41 to the position x44.

  Then, when the focus adjustment lens 21 is moved to the position x44, the control unit 28 determines that the current evaluation value v44 acquired from the AF detection unit 27A of the signal processing unit 27 and the previous evaluation value v43 are both predetermined threshold values. Since the difference value vd44 is equal to or greater than vt and the difference value vd44 is equal to or less than a predetermined value, it is determined that the current position x44 from which the evaluation value v44 is acquired is the in-focus position, and the final in-focus position search is terminated.

  As described above, the video camera 1 with an autofocus function can search for the in-focus position by moving the focus adjustment lens 21 little by little every 1/60 seconds that is the imaging interval by the focus controller 25. Finally, the focus adjustment lens 21 can be accurately moved to the in-focus position, and as a result, the subject can be accurately focused.

(8) Operation and Effect In the above configuration, the video camera with an autofocus function 1 performs the allowable confusion circle diameter d and the depth of focus from the control unit 28 of the camera body 2 when performing an overall search for an approximate in-focus position. Is sent to the focus controller 25 of the interchangeable AF lens unit 3, and the focus controller 25 uses the permissible circle of confusion diameter d and the ratio b to the depth of focus and the aperture value FNO of the aperture 22. The total search movement amount ΔX ′ is calculated according to the above-described equation (4), and the focus adjustment lens 21 is moved by the total search movement amount ΔX ′ by the actuator 23 during 1/60 seconds that is the imaging interval.

  Subsequently, the video camera 1 with an autofocus function extracts and controls the evaluation value v by the AF detection unit 27A of the signal processing unit 27 for the imaging signal obtained at every imaging interval (1/60 seconds) by the solid-state imaging device 26. The control unit 28 determines whether or not to detect the maximum value of the acquired evaluation value v, and detects the local maximum value of the evaluation value v, thereby detecting the current position of the focus adjustment lens 21. Until it is determined that there is an approximate in-focus position in the vicinity, the allowable confusion circle diameter d and the ratio b to the focal depth of the interchangeable AF lens 3 to the focus controller 25 are repeatedly transmitted at every imaging interval.

  Therefore, the video camera 1 with an autofocus function follows the formula (4) in the focus controller 25 of the interchangeable AF lens unit 3 by sending the allowable confusion circle diameter d and the ratio b to the focal depth from the camera body unit 2. The total search movement amount ΔX ′ can be calculated, that is, the moving speed at every fixed imaging interval (1/60 seconds) when the focus adjustment lens 21 is moved can be obtained.

  The video camera 1 with an autofocus function sends the permissible circle of confusion diameter d and the ratio b to the depth of focus from the camera body 2 to the focus controller 25 of the interchangeable AF lens unit 3, and the focus controller 25 uses the formula (4). Accordingly, the total search movement amount ΔX ′, that is, the movement speed of the focus adjustment lens 21 is calculated, whereby the total search movement amount ΔX ′ can be changed according to the value of the aperture value FNO of the aperture 22. .

  In other words, the video camera 1 with an autofocus function does not change the value of the ratio b with respect to the focal depth, but when the aperture value FNO of the aperture 22 increases, the focus is set so that the approximate focus position is not overlooked. The moving speed of the adjusting lens 21 can be set fast, and when the aperture value FNO of the diaphragm 22 becomes small, the moving speed of the focus adjusting lens 21 is slowed so as not to overlook the approximate focus position. Can be set.

  Furthermore, the video camera 1 with an autofocus function calculates the total search movement amount ΔX ′ that does not overlook the approximate in-focus position by simply sending the allowable confusion circle diameter d and the ratio b to the focal depth from the camera body 2. Therefore, it is not necessary for the camera body 2 to grasp the detailed lens parameters of the different types of the interchangeable AF lens unit 3, and the camera body 2 always accurately corrects the different types of the interchangeable AF lens 3. Auto focus control can be performed.

  Thus, since the video camera 1 with an autofocus function can accurately perform autofocus control for any type of interchangeable AF lens 3 in the camera body 2, the camera body 2 can change the lens parameter. Since it is not necessary to constrain the range in advance, the degree of design freedom for the interchangeable AF lens 3 can be further improved.

  Furthermore, the video camera 1 with an autofocus function changes the movement speed of the focus adjustment lens 21 by changing the overall search movement amount ΔX ′ only by changing the value of the ratio b to the focal depth in the equation (4). Therefore, by setting the ratio b with respect to the focal depth to a large value (for example, the ratio b = 20), it is possible to perform an overall search while moving the focus adjustment lens 21 at a high speed, and to the focal depth. By setting the ratio b to a small value (for example, the ratio b = 2), it is possible to perform the in-focus position search while slowly moving the focus adjustment lens 21.

  According to the above configuration, the video camera 1 with an autofocus function sends out the permissible circle of confusion diameter d and the ratio b to the focal depth from the camera body 2 when performing an overall search for an approximate in-focus position. Since the interchangeable AF lens unit 3 can calculate the optimum total search movement amount ΔX ′ according to the aperture value FNO of the diaphragm 22 at that time, various types of interchangeable AF lens units 3 are mounted. Even in this case, the focus adjustment lens 21 can always be moved at an optimum moving speed in accordance with the depth and shallowness of the focal depth, and the approximate focal position can be reliably detected.

(9) Other Embodiments In the above-described embodiment, the case where the interchangeable AF lens unit 3 has the diaphragm 22 as shown in FIG. 3 has been described. However, the diaphragm 22 may be provided in the camera body 2 as shown in FIG.

  In this case, the control unit 28 of the camera body 2 sends the aperture value FNO of the aperture 22 to the focus controller 25 of the interchangeable AF lens unit 3 via the communication path 30 in addition to the allowable circle of confusion diameter d and the ratio b to the focal depth 2Δx. , The interchangeable AF lens unit 3 calculates the overall search movement amount ΔX ′ according to the equation (4) by the focus controller 25, and the focus adjustment lens 21 at a movement speed corresponding to the overall search movement amount ΔX ′. The whole search can be performed by moving.

  In the above-described embodiment, an arbitrary ratio b with respect to the allowable confusion circle diameter d and the focal depth 2Δx is sent from the control unit 28 to the focus controller 25 of the interchangeable AF lens unit 3 via the electrical connection point 29 and the communication path 30. However, the present invention is not limited to this, and is transmitted to the focus controller 25 of the interchangeable AF lens unit 3 by a wireless communication method such as Bluetooth communication method or IEEE (Institute of Electrical and Electronics Engineers) 802.11g. You may make it do.

  Furthermore, in the above-described embodiment, the in-focus direction is determined by using, as the evaluation value v, the level of the high-frequency component of the imaging signal acquired from the solid-state imaging device 26 at a 1/60 second period corresponding to the field period. However, the present invention is not limited to this, and the entire search for the in-focus position is performed by using the level of the high-frequency component of the imaging signal acquired at the 1/30 second period corresponding to the frame period as the evaluation value v. You may make it do.

  Further, in the above-described embodiment, the case where the focus adjustment lens 21 is sequentially moved from the end point on the h2 side to the end point on the h1 side of the movable range when performing the overall search has been described. However, the focus adjustment lens 21 may be sequentially moved from the end point on the h1 side to the end point on the h2 side of the movable range when performing the entire search.

  Furthermore, in the above-described embodiment, when the two consecutive evaluation values v are both equal to or larger than the predetermined threshold value vt and the difference value is equal to or smaller than the predetermined value, it is detected that it is near the maximum value of the evaluation value v. However, the present invention is not limited to this. When the change in two consecutive evaluation values v changes from “increase” to “decrease”, it is detected that the evaluation value v is in the vicinity of the maximum value. You may make it do.

  Further, in the above-described embodiment, the interchangeable lens unit of the video camera is configured by the actuator 23 as the driving unit, the focus controller 25 as the speed calculating unit, and the aperture 22 as the aperture, and the control as the control unit The case where the camera body of the video camera is configured by the unit 28 has been described. However, the present invention is not limited to this, and the video camera is not limited to this, and includes a driving unit, a speed calculating unit, and an aperture having various circuit configurations. The interchangeable lens unit may be configured, and the camera body unit of the video camera may be configured by a control unit having various other circuit configurations.

  The present invention can also be used for a home video camera, a surveillance video camera, or the like to which an interchangeable AF lens can be attached.

It is a rough-line perspective view which shows the external appearance structure of the video camera with an autofocus function of this invention. It is a basic diagram which shows the side surface structure of a video camera with an autofocus function. It is a basic block diagram which shows the circuit structure of the video camera with an autofocus function. It is a flowchart which shows a focus adjustment processing procedure. It is an approximate line figure used for explanation of a focal depth. It is a basic diagram which shows the micro drive control processing sequence of the lens for focus adjustment. It is a basic diagram which shows the whole search process sequence of a focal point position. It is a basic diagram with which it uses for description of the mode of a focus position search. It is a basic diagram which shows the circuit structure of the video camera with an autofocus function in other embodiment. It is a basic diagram with which it uses for description of the mode of the whole search of an in-focus position.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Video camera with an autofocus function, 2 ... Camera body part, 3 ... Interchangeable AF lens part, 21 ... Focus adjustment lens, 22 ... Aperture, 23 ... Actuator, 25 ... Focus controller, 27... Signal processing unit, 28... Control unit, 30.

Claims (22)

A video camera comprising a camera body and an interchangeable lens part detachably attached to the camera body,
The interchangeable lens unit includes a driving unit that drives a focus adjustment lens, a speed calculation unit that calculates a driving speed of the focus adjustment lens, and a diaphragm.
In the camera body portion, the focus adjustment lens is sequentially moved from one end to the other end of the movable range via the driving means to search for an approximate focal position on the imaging surface of the imaging means. A controller that supplies the permissible circle of confusion on the imaging surface and the ratio to the depth of focus to the speed calculation means of the interchangeable lens unit;
The speed calculation means calculates the drive speed of the focus adjustment lens based on the allowable confusion circle diameter and the ratio to the depth of focus supplied from the control unit and the aperture value of the diaphragm, and the drive means Wherein the focus adjustment lens is sequentially moved at a speed corresponding to the driving speed in order to search for the approximate in-focus position. The control unit compares the high frequency components of the imaging signals sequentially obtained from the imaging unit by sequentially moving the focus adjustment lens by the driving unit of the interchangeable lens unit, and the level of the high frequency component is the highest. The video camera according to claim 1, wherein the position of the focus adjustment lens that is increased is determined to be the approximate focus position. The video camera according to claim 1, wherein the control unit uses a value larger than 0 as a ratio to the depth of focus. The focus adjustment lens of the interchangeable lens unit that is detachably attached to the camera body unit is sequentially moved from one end to the other end of the movable range of the focus adjustment lens by the control unit provided in the camera body unit. In order to search for an approximate in-focus position on the image pickup surface of the image pickup means, the allowable confusion circle diameter on the image pickup surface and the ratio to the depth of focus are transferred from the camera body to the speed calculation means of the interchangeable lens portion. A data supply step to supply;
The speed calculation means calculates the driving speed of the focus adjustment lens based on the permissible circle of confusion and the ratio to the depth of focus supplied from the control unit and the aperture value of the diaphragm in the interchangeable lens unit. And a focus position search step of sequentially moving the focus adjustment lens at a speed corresponding to the driving speed in order to search for the approximate focus position. In the in-focus position searching step, the focus adjustment lens that compares the high-frequency components of the imaging signals sequentially obtained from the imaging means by sequentially moving the focus adjustment lens and has the highest level of the high-frequency component. The in-focus position searching method according to claim 4, wherein the position is determined as the approximate in-focus position. The in-focus position searching method according to claim 4, wherein a value larger than 0 is used as the ratio to the focal depth in the data supplying step. The focus adjustment lens is moved by the drive means with respect to an interchangeable lens unit having a drive means for driving the focus adjustment lens, a speed calculation means for calculating the drive speed of the focus adjustment lens, and a diaphragm. In order to search for an approximate in-focus position on the imaging surface of the imaging means by sequentially moving from one end to the other end of the possible range, the permissible circle of confusion on the imaging surface and the ratio to the focal depth are set to the interchangeable lens unit. A control unit for supplying to the speed calculation means,
The drive speed of the focus adjustment lens is calculated based on the permissible circle of confusion and the ratio to the depth of focus and the aperture value of the stop, which are supplied from the control unit by the speed calculation means of the interchangeable lens unit,
The camera main body, wherein the focus adjustment lens is sequentially moved by the driving means at a speed corresponding to the driving speed in order to search for the approximate in-focus position. The control unit compares the high frequency components of the imaging signals sequentially obtained from the imaging unit by sequentially moving the focus adjustment lens by the driving unit of the interchangeable lens unit, and the level of the high frequency component is the highest. The camera body according to claim 7, wherein the position of the focus adjustment lens that is increased is determined to be the approximate focus position. The camera body according to claim 7, wherein the control unit uses a value larger than 0 as a ratio to the depth of focus. A focus adjustment lens,
Speed calculating means for calculating the driving speed of the focus adjustment lens;
Driving means for driving the focus adjustment lens based on the driving speed;
Aperture,
In order to search for an approximate in-focus position on the imaging surface of the imaging means provided in the camera main body, receiving means for receiving from the camera main body the permissible circle of confusion on the imaging surface and the ratio to the depth of focus. Prepared,
The speed calculation means calculates the driving speed of the focus adjustment lens based on the permissible circle of confusion and the ratio to the depth of focus supplied from the camera body, and the aperture value of the aperture.
The drive means moves the focus adjustment lens at one end of the movable range of the focus adjustment lens at a speed corresponding to the drive speed so that the approximate focus position can be searched by the control unit of the camera body. An interchangeable lens unit that is sequentially moved from one end to the other end. The interchangeable lens unit according to claim 10, wherein the receiving unit receives a value larger than 0 as a ratio to the depth of focus. A video camera comprising a camera body and an interchangeable lens part detachably attached to the camera body,
The interchangeable lens unit includes a driving unit that drives the focus adjustment lens, and a speed calculation unit that calculates a driving speed of the focus adjustment lens.
In the camera body portion, the focus adjustment lens is sequentially moved from one end to the other end of the movable range via the driving means to search for an approximate focal position on the imaging surface of the imaging means. A control unit that supplies an allowable confusion circle diameter on the imaging surface, a ratio to a depth of focus, and a diaphragm aperture value to the speed calculation unit of the interchangeable lens unit;
The speed calculation means calculates the driving speed of the focus adjustment lens based on the permissible circle of confusion supplied from the control unit, the ratio to the depth of focus, and the aperture value of the diaphragm, and the driving means A video camera, wherein the focus adjustment lens is sequentially moved at a speed corresponding to the driving speed in order to search for an approximate in-focus position. The control unit compares the high frequency components of the imaging signals sequentially obtained from the imaging unit by sequentially moving the focus adjustment lens by the driving unit of the interchangeable lens unit, and the level of the high frequency component is the highest. The video camera according to claim 12, wherein the position of the focus adjustment lens that is increased is determined to be the approximate focus position. The video camera according to claim 12, wherein the control unit uses a value larger than 0 as a ratio to the depth of focus. The focus adjustment lens of the interchangeable lens unit that is detachably attached to the camera body unit is sequentially moved from one end to the other end of the movable range of the focus adjustment lens by the control unit provided in the camera body unit. In order to search for an approximate in-focus position on the image pickup surface of the image pickup means, the permissible circle of confusion on the image pickup surface, the ratio to the depth of focus, and the aperture value of the stop are exchanged from the camera body to the interchangeable lens unit. A data supply step for supplying to the speed calculation means;
The speed calculation means calculates the driving speed of the focus adjustment lens based on the allowable circle of confusion supplied from the control unit, the ratio to the depth of focus, and the aperture value of the stop, and the approximate focus point. An in-focus position search method comprising: an in-focus position search step of sequentially moving the focus adjustment lens at a speed corresponding to the driving speed in order to search for a position. In the in-focus position searching step, the focus adjustment lens that compares the high-frequency components of the imaging signals sequentially obtained from the imaging means by sequentially moving the focus adjustment lens and has the highest level of the high-frequency component. The in-focus position search method according to claim 15, wherein the position is determined to be the approximate in-focus position. The in-focus position searching method according to claim 15, wherein a value larger than 0 is used as the ratio to the focal depth in the data supplying step. For an interchangeable lens unit having a driving means for driving the focus adjustment lens and a speed calculation means for calculating the driving speed of the focus adjustment lens, the focus adjustment lens can be moved within a movable range by the drive means. In order to search for an approximate in-focus position on the imaging surface of the imaging means by sequentially moving from one end to the other end, the permissible circle of confusion on the imaging surface, the ratio to the focal depth, and the aperture value of the aperture are exchanged as described above. A control unit for supplying to the speed calculation means of the lens unit,
Based on the permissible circle of confusion diameter supplied from the control unit by the speed calculation means of the interchangeable lens unit, the ratio to the depth of focus, and the aperture value of the diaphragm, the driving speed of the focus adjustment lens is calculated,
The camera main body, wherein the focus adjustment lens is sequentially moved by the driving means at a speed corresponding to the driving speed in order to search for the approximate in-focus position. The control unit compares the high frequency components of the imaging signals sequentially obtained from the imaging unit by sequentially moving the focus adjustment lens by the driving unit of the interchangeable lens unit, and the level of the high frequency component is the highest. The camera body according to claim 18, wherein the position of the focus adjustment lens that is increased is determined to be the approximate focus position. The camera main body according to claim 18, wherein the control unit uses a value larger than 0 as a ratio to the depth of focus. A focus adjustment lens,
Speed calculating means for calculating the driving speed of the focus adjustment lens;
Driving means for driving the focus adjustment lens based on the driving speed;
In order to search for an approximate in-focus position on the imaging surface of the imaging means provided in the camera body, the permissible circle of confusion on the imaging surface, the ratio to the focal depth, and the aperture value of the aperture are determined from the camera body. Receiving means for receiving, and
The speed calculation means calculates the driving speed of the focus adjustment lens based on the permissible circle of confusion supplied from the camera body, the ratio to the depth of focus, and the aperture value of the diaphragm,
The drive means moves the focus adjustment lens at one end of the movable range of the focus adjustment lens at a speed corresponding to the drive speed so that the approximate focus position can be searched by the control unit of the camera body. An interchangeable lens unit that is sequentially moved from one end to the other end. The interchangeable lens unit according to claim 21, wherein the receiving unit receives a value larger than 0 as a ratio to the depth of focus.

Images