JP4721395B2 - LENS CONTROL DEVICE, OPTICAL DEVICE, AND LENS CONTROL METHOD - Google Patents

Description

  The present invention relates to lens control in an optical apparatus such as a video camera.

  Consumer-use lens-integrated cameras are required to be compact and to be able to shoot at a position as close as possible to the subject. For this reason, the correction lens and the variable magnification lens are not mechanically linked by a cam, but the movement locus of the correction lens is stored in advance in the microcomputer as lens cam data, and the correction lens is determined according to the lens cam data. A so-called inner focus type lens, which is driven and further adjusted in focus by this correction lens, has become mainstream.

  FIG. 7 is a diagram showing a configuration of a conventional inner focus type lens system. In the figure, 901 is a fixed front lens, 902 is a zoom lens (also referred to as a variator lens: first lens unit) for zooming, 903 is an aperture, 904 is a fixed lens, 905 Is a focus lens (second lens unit) as a correction lens having both a focus adjustment function and a function (so-called compensator function) for correcting movement of the image plane due to zooming. Reference numeral 906 denotes an imaging surface.

  In the lens system configured as shown in FIG. 7, since the focus lens 905 has both a compensator function and a focus adjustment function, the position of the focus lens 905 for focusing on the imaging surface 906 even when the focal lengths are equal. Depends on the subject distance. When the subject distance is changed at each focal length, the position of the focus lens 905 for focusing the subject image on the imaging surface 906 is continuously plotted as shown in FIG. During zooming, if a trajectory corresponding to the subject distance is selected from the plurality of trajectories shown in FIG. 8 and the focus lens 905 is moved along the selected trajectory, the in-focus state is maintained. Scaling (zoom) becomes possible.

  In a lens system that performs focusing with the front lens, a focus lens independent of the zoom lens is provided, and the zoom lens and the focus lens are mechanically coupled to a cam ring. Therefore, for example, when the cam ring is manually rotated to change the focal length, the cam ring follows the rotation no matter how fast the cam ring is moved. Since the zoom lens and the focus lens move in the optical axis direction along the cam formed on the cam ring, if the focus lens is at the in-focus position, the image is not blurred by zooming.

  On the other hand, in the inner focus type lens system, the lens position is variable even with the information of a plurality of trajectories (also referred to as electronic cam trajectories) shown in FIG. 8 or information corresponding thereto (that is, information indicating the trajectory itself). In general, the function is stored in advance, a locus is selected based on the positions of the focus lens and the zoom lens, and zooming is performed while following the selected locus.

  However, when the zoom lens moves from the tele to the wide direction, as shown in FIG. 8, the plurality of trajectories are converged from a state having a certain interval. Can be maintained. However, in the wide-to-tele direction, it is not known which locus the focus lens at the convergence point should follow (the same focus position is the focal point from infinity to several tens of centimeters on the wide side). Then we cannot maintain focus.

Therefore, in Patent Document 1, an AF evaluation value signal (sharpness signal) obtained from a high-frequency component of a video signal by the TV-AF method is used to adjust the focus lens when the zoom lens is moved (magnification). Disclosed is a control method (zigzag operation) that forcibly moves the focus lens so that it is out of focus and then switches the focus lens so that it moves in the in-focus direction (changes the tracking speed with respect to the trajectory). ing. As a result, the tracking locus is corrected. In Patent Document 1, the change rate of the tracking speed is changed in accordance with the subject, the focal length, and the depth of field, thereby changing the sharpness signal increase / decrease period and improving the selection (specification) accuracy of the tracking locus. The technique which aimed at is also disclosed.
Japanese Patent No. 2795439 (Claims, FIGS. 3, 4 and description thereof)

  In the zigzag operation disclosed in Patent Document 1, the tracking locus is specified based on the change in the AF evaluation value. However, the AF evaluation value not only changes depending on the blurred state of the image, but also changes depending on the pattern change of the subject. For this reason, when the moving direction of the focus lens is switched, it may be switched to an incorrect direction. If the trajectory deviates from the original trajectory, image blur will occur before returning to the correct trajectory. In addition, when the moving direction of the focus lens is wrong, a correct locus can be found, particularly when an image blur state that greatly reduces the AF evaluation value level occurs or when a low-contrast subject is shot. There is also a possibility that the phenomenon of reaching the tele end while dragging the image blur may occur.

  In particular, when starting zooming from the wide side where the intervals of the cam trajectory are narrow, if the driving start direction by zigzag driving is opposite to the direction of the cam trajectory (focusing trajectory) to be specified, focusing is performed. Even if the amount of positional deviation from the trajectory is small, image blur is likely to be noticeable because the depth of focus is shallow on the wide side. Furthermore, as described above, if a plurality of objects with different subject distances exist within a wide angle of view on the wide side where subjects from infinity to several tens of centimeters are in focus at the same focus position, the images of these subjects are simultaneously displayed. The image will be blurred and the quality of the image will be extremely poor.

  The present invention provides a lens control device, an optical device, and a lens control method capable of performing high-quality zooming without being influenced by a shooting scene or camera work while reliably maintaining an in-focus state even in high-speed zoom. With the goal.

To achieve the above object, the present invention is, upon movement of the first lens unit for zooming, a lens control apparatus for controlling the movement of the second lens unit for correcting image plane movement, a predetermined including the storage means for storing data indicating the position of the second lens unit according to the created position of the first lenses unit relative to the focusing distance, the first lens unit and the second lens unit Based on first information indicating a movement target position of the second lens unit, an acquisition unit that acquires a focus signal representing a focused state of the optical system based on a photoelectric conversion signal of an optical image formed by the optical system. a control means for controlling the movement of said second lens unit, and a distance detecting means for detecting a second information corresponding to a distance to the focusing target. The control unit weights the moving operation of the second lens unit based on the second information when generating the first information according to the data and the focus signal during the zooming operation. I do.

The present invention also relates to a lens control method for controlling the movement of the second lens unit in order to correct the movement of the image plane when the first lens unit for zooming is moved, and includes the first lens unit and the second lens unit. An acquisition step of acquiring a focus signal representing an in-focus state of the optical system based on a photoelectric conversion signal of an optical image formed by an optical system including the lens unit; and a first indicating a movement target position of the second lens unit . and a step of detecting a control step for controlling the movement of the second lens unit on the basis of the information, the second information corresponding to a distance to focus the object. In the control step, data indicating the position of the first lens unit and the position of the second lens unit created for a predetermined focusing distance stored in the storage means during the zooming operation; When generating the first information according to the focus signal, the moving operation of the second lens unit is weighted based on the second information .

  Here, as the weighting, weighting related to the driving direction and driving speed of the second lens unit, and driving conditions when driving the second lens unit while switching its driving conditions (driving speed, driving direction, etc.) are used. There is a weight related to the condition for switching (the condition of the focus signal when driving while switching the driving condition of the second lens unit based on the focus signal).

The first information may be trajectory information indicating the position of the second lens unit with respect to the first lens unit or a parameter for specifying the trajectory, or position information for driving the second lens unit. It may be.

According to the present invention, when controlling the driving of the second lens unit for generating the first information (trajectory information or the like), based on the second information corresponding to the detected distance to the in- focus object. Since the weighting is performed, it is possible to suppress the driving of the second lens unit that increases the image blur.

For example, if weighting based on the second information is performed with respect to the driving direction of the second lens unit for generating the first information, driving in the direction in which the image blur of the second lens unit increases is avoided. it can.

Further, if weighting based on the second information is performed with respect to the driving speed of the second lens unit for generating the first information, the second lens unit can be driven faster in the direction of reducing the image blur.

Further, when the second lens unit is driven while switching its driving conditions in order to generate the first information , weighting based on the second information is performed with respect to the conditions for switching the driving conditions. For example, the driving condition of the second lens unit can be switched according to the second information , and the information can be generated quickly.

As described above, according to the present invention, it is possible to perform weighting according to the second information corresponding to the distance to the in- focus object in the drive control of the second lens unit when generating the first information. This makes it possible to generate information quickly and smoothly while suppressing the occurrence of image blur. As a result, the in-focus object can be reliably maintained in focus (following zooming by the first lens unit).

  And when this invention produces | generates the said information using the focus signal showing the focus state of the said optical system obtained from the photoelectric conversion signal of the optical image formed by the optical system containing the 1st and 2nd lens unit ( For example, the focus signal is focused not only on the distance change but also on the setting of the driving control of the second lens unit in the regeneration process) and the setting of the driving condition switching condition of the second lens unit in the so-called zigzag operation. The second lens unit is driven under the influence of the change in the pattern of the object, and the problem that the image blur is conspicuous can be avoided.

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

(Prerequisite technology)
First, prior to the description of the embodiments of the present invention, a technique which is a premise of the present invention will be described.

  FIG. 9 is a diagram for explaining an example of a locus tracking method of the focus lens in the inner focus type lens system.

9, Z ₀ , Z ₁ , Z ₂ ,... Z ₆ indicate the positions of the zoom lenses, and a ₀ , a ₁ , a ₂ ,... A ₆ and b ₀ , b ₁ , b ₂ , · · b ₆ is a position of the focus lens in accordance with the subject distance stored in advance in a microcomputer (not shown). A group of these focus lens positions (a ₀ , a ₁ , a ₂ ,... A ₆ and b ₀ , b ₁ , b ₂ ,... B ₆ ) follow the focus lens for each representative subject distance. It becomes a power focus locus (representative locus).

Further, p ₀ , p ₁ , p ₂ ,... P ₆ are positions on the in-focus locus that the focus lens should follow, calculated based on the two representative loci. A formula for calculating the position on the in-focus locus is shown below.

p _{(n + 1)}
= | P _(n) -a _(n) | / | b _(n) -a _(n) | × | b _{(n + 1)} -a _{(n + 1)} | + a _{(n + 1)} (1)
According to the above equation (1), for example, when the focus lens is at p ₀ in FIG. 9, the ratio that p ₀ internally divides the line segment b ₀ -a ₀ is obtained, and the line segment b ₁ -a _{1 is} calculated according to this ratio. Let p ₁ be the point that internally divides. From the position difference of p ₁ -p ₀ and the time required for the zoom lens to move from Z _{0 to} Z ₁ , the moving speed of the focus lens for maintaining the focus can be found.

  Next, a case where there is no restriction that the stop position of the zoom lens is only on the boundary of the zoom area having the stored representative trajectory data will be described. FIG. 10 is a diagram for explaining an interpolation method in the moving direction of the zoom lens. A part of FIG. 9 is extracted to arbitrarily set the position of the zoom lens.

In FIG. 10, the vertical axis indicates the position of the focus lens, and the horizontal axis indicates the position of the zoom lens. When the focus lens position on the representative trajectory stored in the microcomputer is Z ₀ , Z ₁ ,... Z _k-1 , Z _k ..Z _n , the focus lens position is the subject distance. Apart from
_{a 0, a 1, ·· a} k-1, a k ·· a n
_{b 0, b 1, ·· b} k-1, b k ·· b n
It is said.

Now, there is a Z _x zoom lens position is not on the zoom area boundary, the seek a _x, b _x when the focus lens position is p _{x,
a x = a k - (Z} k -Z x) × (a k -a k-1) / (Z k -Z k-1) ... (2)
b _x = b _k − (Z _k −Z _x ) × (b _k −b _k−1 ) / (Z _k −Z _k−1 ) (3)
It becomes. That is, according to the internal ratio obtained from the current zoom lens position and the two zoom area boundary positions (for example, Z _k and Z _k-1 in FIG. 10) between them, the stored four representative trajectory data (FIG. 11 _ak , a _k−1 , b _k , b _k−1 ) at the same subject distance is internally divided by the above internal ratio, whereby a _x , b _x can be obtained.

Then, according to the internal ratio obtained from a _x , p _x , b _x , among the four representative data stored in advance, the data with the same focal length is expressed by the above internal ratio as shown in the equation (1). By dividing internally, p _k and p _k−1 can be obtained.

At the time of zooming from the wide to telephoto, the difference between the follow-up the destination of the focus position p _k and the current focus position p _x, zoom lens and a time required to move to the Z _x to Z _k, the focus You can see the moving speed of the focus lens necessary to keep.

From Further, at the time of zooming to wide from the telephoto, the difference between the follow-up the destination of the focus position p _k-1 and the current focus position p _x, the zoom lens is the time required to move to the Z _x ~Z _k-1 The moving speed of the focus lens for maintaining the in-focus state can be known.

At this time, an example of table data of focusing locus information stored in advance in the microcomputer is shown in FIG. FIG. 11 shows focus lens position data A _{(n, v)} for each subject distance, which varies depending on the zoom lens position. The subject distance changes in the column direction of the variable n, and the zoom lens position (focal length) changes in the row direction of the variable v. Here, n = 0 represents a subject distance at infinity, and the subject distance changes to the closest distance side as n increases. n = m indicates a subject distance of 1 cm.

  On the other hand, v = 0 represents the wide end. Furthermore, the focal length increases as v increases, and v = s represents the zoom lens position at the tele end. Therefore, one representative trajectory is drawn with one column of table data.

  Next, as described above, a locus tracking method for solving the problem that it becomes difficult to know which locus the focus lens should follow during zooming from wide to telephoto will be described.

12A and 12B, the horizontal axis indicates the position of the zoom lens. In FIG. 12A, the vertical axis indicates the AF evaluation signal obtained from the image pickup signal by the TV-AF method. This AF evaluation signal indicates the level of the high-frequency component (sharpness signal) of the imaging signal. Further, in FIG. 12 (B), the vertical axis represents the position of the focus lens. In FIG. 12B, it is assumed that 1304 is a cam locus (collection of focus lens positions) that the focus lens should follow when performing zooming while focusing on a subject located at a certain distance.

Here, the standard moving speed for tracking the in-focus locus on the wide side from the zoom lens position 1306 (Z ₁₄ ) is positive (moves in the direction closer to the focus lens), and the focus lens is infinite on the telephoto side from the position 1306. The standard moving speed for following the in-focus locus when moving in the far direction is negative. When the focus lens follows the target locus 1304 while maintaining the in-focus state, the magnitude of the AF evaluation signal becomes a level indicated by 1301 in FIG. In general, in zooming while maintaining in-focus, the AF evaluation signal level is a substantially constant value.

In FIG. 12B, the standard moving speed of the focus lens that traces the target locus 1304 during zooming is V _f0 . When the actual moving speed of the focus lens is set to V _f and zooming is performed while the moving speed V _f is made larger or smaller than the standard moving speed V _f0 , the locus becomes a zigzag locus as 1305 (hereinafter referred to as this). "Zigzag correction operation").

At this time, the AF evaluation signal level changes so as to generate peaks and valleys as indicated by reference numeral 1303 in FIG. Here, at the position where the target locus 1304 and the actual zigzag locus 1305 intersect, the AF evaluation signal level 1303 becomes the maximum level 1301 (even points of Z ₀ , Z ₁ , Z ₂ ,... Z ₁₆ ), and the actual locus The AF evaluation signal level 1303 becomes the minimum level 1302 at odd points of Z ₀ , Z ₁ , Z ₂ ,... Z ₁₆ where the moving direction vector of 1305 switches.

  On the contrary, the value TH1 of the minimum level 1302 of the AF evaluation signal level 1303 is set in advance (that is, an in-focus allowable range with the lower limit of the AF evaluation signal of the minimum level TH1 that can be regarded as in-focus is set), and AF evaluation is performed. If the moving direction vector of the locus 1305 is switched every time the signal level 1303 becomes equal to TH1, the moving direction of the focus lens after switching can be set to a direction approaching the target locus 1304. That is, every time an image is blurred by the difference between the maximum level 1301 and the minimum level 1302 (TH1) of the AF evaluation signal, the driving direction and the driving speed, which are driving conditions of the focus lens, are controlled so as to reduce the blur. Zooming can be performed while suppressing the generation of the amount.

By using such a method, as shown in FIG. 8, in the zooming from wide to tele, where the focus locus for each subject distance diverges from convergence, the standard movement speed V _f0 that maintains the focus temporarily. Is not optimal for the subject distance at that time, while controlling the moving speed V _f of the focus lens with respect to the standard moving speed (calculated using p _{(n + 1)} obtained from the equation (1)), By repeating the switching operation as indicated by the locus 1305 according to the change in the AF evaluation signal level, the AF evaluation signal level does not fall below the minimum level 1302 (TH1), that is, no blur of a certain amount or more occurs, and the in-focus locus is restored. Can be identified (regenerated). Further, by appropriately setting TH1, zooming in which image blur is not apparent to the eye is possible.

Here, the moving speed V _f of the focus lens is V _{f +} as the correction speed in the positive direction applied to the standard movement speed, and V _{f− as} the correction speed in the negative direction.
V _f = V _f0 + V _{f +} (4)
Or
V _f = V _f0 + V _f− (5)
It becomes. At this time, the correction velocities V _{f +} and V _f− are the internal angles of the two direction vectors of V _f obtained by the expressions (4) and (5) so that no deviation occurs when the tracking locus is selected by the zooming method. Is bisected by the direction vector of V _f0 .

  The zooming control described above is generally performed in synchronization with the vertical synchronization signal of the video because of focus detection using the image pickup signal from the image pickup device.

  FIG. 6 is a flowchart of zooming control performed in the microcomputer. When processing is started in step (denoted as S) 701, initial setting is performed in S702. In the initial setting, the RAM and various ports in the microcomputer are initialized.

  In S703, the state of the operation system of the camera body is detected. The microcomputer receives information on the zoom switch unit operated by the photographer here, and displays on the display zooming operation information such as the zoom lens position for notifying the photographer that zooming is being performed.

  In S704, AF processing is performed. That is, automatic focus adjustment processing is performed in accordance with changes in the AF evaluation signal.

  In S705, zooming processing is performed. That is, a compensator operation process is performed to maintain the focus during zooming. Specifically, the standard drive direction and standard drive speed of the focus lens are calculated in order to substantially trace the locus shown in FIG.

  In S706, during AF or zooming, it is selected which of the driving direction and driving speed of the zoom lens and focus lens calculated in the processing routine of S704 to S705 is used, and the zoom lens and the focus lens are respectively mechanically operated. This is a routine that is driven between the telephoto end and the wide end on the control, or between the close end and the infinite end on the control, which are provided so as not to hit the end.

  In step S707, a control signal is output to the motor driver according to the zoom and focus drive direction information and drive speed information determined in step S706 to control driving / stopping of the lens. After the process of S707 ends, the process returns to S703.

  Note that the series of processing shown in FIG. 6 is executed in synchronization with the vertical synchronization signal (wait until the next vertical synchronization signal is input in the processing of S703).

  3 to 5 show a control flow executed in the microcomputer once in one vertical synchronization time, and show details of the processing executed in S705 of FIG.

  Hereinafter, description will be made with reference to FIGS. 3 to 5 and FIG. 9.

In S400 of FIG. 3, the zoom motor drive speed _Zsp is set in accordance with the operation information of the zoom switch unit so that a natural zooming operation can be performed.

  In S401, the distance (subject distance) from the current zoom lens and focus lens positions to the subject being photographed is specified (estimated), and the subject distance information is obtained as three trajectory parameters (information) α, β, γ. Is stored in a memory area such as a RAM. Here, the process shown in FIG. 4 is performed. For the sake of simplicity, the processing shown in FIG. 4 will be described below assuming that the in-focus state is maintained at the current lens position.

In S501 of FIG. 4, calculates the current zoom lens position Z _x is on the data table shown in FIG. 11, whether present in the ordinal number of the zoom area v of which were s aliquoted from the wide-angle end to the telephoto end To do. The calculation method will be described with reference to FIG.

In S601, the zoom area variable v is cleared. In S602, the zoom lens position Z _(v) on the boundary of the zoom area v is calculated according to the following equation (6). This Z _(v) corresponds to the zoom lens positions Z ₀ , Z ₁ , Z ₂ ,... Shown in FIG.

Z _(v) = (tele end zoom lens position−wide end zoom lens position) × v / s
+ Wide end zoom lens position (6)
In S603, _{Z (v)} obtained in S602, it is determined whether or equal to the current zoom lens position _{Z x.} If they are equal, it is assumed that the zoom lens position Z _x is located on the boundary of the zoom area v, and 1 is set to the boundary flag in S607.

If they are not equal in S603, it is determined in S604 whether Z _x <Z _(v) . S604 is If Yes, _{Z x} will be in the between _{Z (v-1)} and _{Z (v),} the boundary flag to 0 in S606. If No in S604, the zoom area v is incremented in S605 and the process returns to S602.

By repeating the above processing, when exiting the flow of FIG. 5, the current zoom lens position Z _x is present in v = k th zoom area on the data table in FIG. 11, further Z _x zoom area You can know if it is on the boundary.

  Returning to FIG. 4, since the current zoom area is determined by the processing of FIG. 5 in S501, the following processing calculates where the focus lens is located on the data table of FIG.

  First, in S502, the subject distance variable n is cleared, and in S503, it is determined whether or not the current zoom lens position exists on the boundary of the zoom area. If the boundary flag is 0, it is determined that the boundary is not on the boundary, and the process proceeds to S505.

In S505, sets the _{Z (v)} the _{Z k,} also sets _{Z (v-1)} to _{Z k-1.} Next, in S506, four table data A _{(n, v-1)} , A _{(n, v)} , A _{(n + 1, v-1)} , A _{(n + 1, v)} are read, and in S507, the above-mentioned ( A _x and b _x are calculated from the equations 2) and (3).

On the other hand, if the boundary flag is determined to be 1 in S503, in S504, the zoom is performed at the focusing position A _{(n, v)} and the subject distance n + 1 with respect to the zoom lens position (here _{, v) at the} subject distance n. Call A _{(n + 1, v)} for the lens position and store them as a _x and b _x respectively.

In S508, the current focus lens position _{p x} is determined whether there are more than _{a x.} When it is a _x or more, the current focus lens position _{p x} at S509 it is determined whether or _{b x.} If not b _x or more, the focus lens position p _x will be located between the object distance n and n + 1, it stores the locus parameters at this time from the S513 to the memory in S515. In S513, α = p _x −a _x is set, β = b _x −a _x is set in S514, and γ = n is set in S515.

S508 of the No In a case where the focus lens position p _x is ultra infinity position. At this time, in S512, α = 0 is set, and the process proceeds to S514 to store a trajectory parameter at infinity.

If the Yes at S509, a case where the focus lens position _{p x} is more close side, in this case, increments the object distance n in S510, infinite from position m to n is in correspondence to the closest distance S511 Determine whether it is the far side. If it is infinitely far from the closest distance position m, the process returns to S503. If the No in S511 is a case where the focus lens position p _x is very short position, the processing proceeds to the S512 this time, the memory locus parameters for the closest distance.

  Returning to FIG. 3, the description will be continued. As described above, in S401, a trajectory parameter for knowing which trajectory shown in FIG. 8 is the current zoom lens position and focus lens position is stored.

In step S402, the zoom lens position (the position of the movement destination from the current position) Z _x ′ reached by the zoom lens after one vertical synchronization time (1 V) is calculated. Here, assuming that the zoom speed determined in S400 is Z _sp (pps), the zoom lens position Z _x ′ after one vertical synchronization time is given by the following equation (7). pps is a unit representing the rotation speed of the stepping motor, and indicates a step amount (1 step = 1 pulse) to be rotated per second. Further, in the sign of the expression (7), the tele direction is + and the wide direction is −, depending on the moving direction of the zoom lens.

Z _x '= Z _x ± Z _sp / vertical synchronization frequency (7)
Next, in which zoom area v ′ Z _x ′ is present is determined in S403. In S403, performs processing similar to the processing of FIG. 5 is obtained by replacing the _{Z x} in FIG. 5 ', v and v' _{Z x} on.

Next, in S404, it is determined whether or not the zoom lens position Z _x ′ after one vertical synchronization time exists on the boundary of the zoom area. If the boundary flag = 0, it is determined that the zoom lens position is not on the boundary. move on.

In S405, Z _k ← Z _{(v ′)} and Z _k−1 ← Z _(v′−1) are set. Next, in S406, four table data A _{(γ, v′−1)} , A _{(γ, v ′)} , A _{(γ + 1, v′−1)} , in which the subject distance γ is specified by the processing of FIG. A _{(γ + 1, v ′)} is read, and a _x ′ and b _x ′ are calculated from the expressions (2) and (3) described above in S407. Meanwhile, S40 if it is determined Yes at 4, at S408, the focus for the zoom area v of the object distance gamma 'focus with respect to the position A _{(γ, v'),} and the zoom area v of the object distance gamma + 1 ' Call position A _{(γ + 1, v ′)} and store each as a _x ′, b _x ′.

Then, in S409, 'focus position of the focus lens when reaching the (target position) p _x' zoom lens position Z _x is calculated. Using the equation (1), the follow target position after one vertical synchronization time can be expressed as the following equation (8).

p _x ′ = (b _x ′ −a _x ′) × α / β + a _x ′ (8)
Therefore, the difference ΔF between the tracking target position and the current focus lens position is
ΔF = (b _x ′ −a _x ′) × α / β + a _x ′ −p _x
It becomes.

Next, in S410, a focus standard movement speed _Vf0 is calculated. V _f0 is obtained by dividing the focus lens position difference ΔF by the zoom lens moving time required to move this distance.

  Hereinafter, a correction speed calculation method for performing the movement speed correction (zigzag operation) of the focus lens shown in FIG.

In S411, various parameters are initialized and “inversion flag” used in the subsequent processing is cleared. In S412, correction speeds V _{f +} and V _f− for “zigzag correction operation” are calculated from the focus standard movement speed V _f0 obtained in S410.

Here, the correction amount parameter δ and the correction speeds V _{f +} and V _f− are calculated as follows. FIG. 13 is a diagram for explaining a method of calculating the correction speeds V _{f +} and V _f− according to the correction amount parameter δ. In FIG. 13, the horizontal axis indicates the zoom lens position, and the vertical axis indicates the focus lens position. Reference numeral 1304 denotes a target locus to be followed.

Now, when the zoom lens position changes by x, the focus lens position changes by y (that is, reaches the target position), the focus speed is the standard speed V _f0 calculated in 1403, and the zoom lens position changes by x. The focus speed at which the focus lens position changes by n or m with respect to the displacement y is the correction speeds V _{f +} and V _{f− to be obtained} , respectively. Here, a direction vector 1401 of a speed that drives further closer to the displacement y (a speed obtained by adding a correction speed V _{f +} in the positive direction to the standard speed V _f0 ), and a speed that drives to the infinity side from the displacement y (standard speed). the direction vector 1402 of the velocity) obtained by adding the negative direction compensation velocity _{V f-} the V _f0 is, n to have an equal angle δ away direction vector with respect to the direction vector 1403 standard speed _{V f0,} the m decide.

First, m and n are obtained. From FIG.
tanθ = y / x, tan (θ-δ) = (ym) / x, tan (θ + δ) = (y + n) / x (9)
Also,
tan (θ ± δ) = (tanθ ± tanδ) / {1 ± (-1) × tanθ × tanδ) (10)
Holds.

From the equations (9) and (10),
^{m = (x 2 + y 2} ) / (x / k + y) ... (11)
n = ( x ² + y ² ) / (x / ky) (12)
However, tanδ = k
Thus, n and m can be calculated.

  Here, the correction angle δ is a variable having parameters such as the depth of field and the focal length. Thereby, the increase / decrease period of the AF evaluation signal level that changes according to the driving state of the focus lens can be kept constant with respect to a predetermined focus lens position change amount, and the focus that the focus lens should follow during zooming. It is possible to reduce the possibility of missing the locus.

  According to the value of δ, the value of k is stored as a data table in the memory of the microcomputer and is read out as necessary, thereby calculating the equations (11) and (12).

Here, when the zoom lens position changes by x per unit time,
Zoom speed Zsp = x
Focus standard speed V _f0 = y
Correction speed V _{f +} = n, V _f− = m
Thus, the correction speeds V _{f +} and V _f− (negative speed) are obtained from the equations (11) and (12).

  In S413, it is determined whether zooming is being performed according to the information indicating the operation state of the zoom switch unit obtained in S703 of FIG. If it is during zooming, the processing from S416 is performed. If not during zooming, a value obtained by subtracting an arbitrary constant μ from the current value of the AF evaluation signal level in S414 is set to TH1. This TH1 determines the AF evaluation signal level that serves as the reference for switching the vector in the correction direction (switching reference for the zigzag correction operation) described with reference to FIG. This TH1 is determined immediately before the start of zooming, and this value corresponds to the minimum level 1302 in FIG.

  Next, in S415, the correction flag is cleared and the present process is exited. Here, the correction flag is a flag indicating whether the trajectory tracking state is a state where correction in the positive direction is applied (correction flag = 1) or a correction state in the negative direction (correction flag = 0).

If it is determined in S413 that zooming is in progress, it is determined in S414 whether the zooming direction is from wide to tele. If the direction is tele to wide, V _{f +} = 0 and V _f− = 0 in S419, and the processing from S420 is performed. If the direction is wide to tele, it is determined in S417 whether or not the current AF evaluation signal level is lower than TH1. If it is equal to or higher than TH1, the process proceeds to S420. If it is smaller than TH1, the current AF evaluation signal level is lower than the level of TH1 (1302) in FIG. Set 1 to.

In S420, it is determined whether or not the reverse flag is 1. If the reverse flag = 1, it is determined whether or not the correction flag is 1 in S421. If the correction flag is not 1 in S421, the correction flag is set to 1 (correction state in the positive direction) in S424, and further according to the equation (4),
Focus lens moving speed V _f = V _f0 + V _{f +} (where V _{f +} ≧ 0)
And

On the other hand, if the correction flag = 1 in S421, the correction flag = 0 (negative correction state) in S423, and the equation (5):
Focus lens moving speed V _f = V _f0 + V _f− (where V _f− ≦ 0)
And

  If the reverse flag is not 1 in S420, it is determined in S422 whether the correction flag = 1. If the correction flag = 1, the process proceeds to S424, and if not, the process proceeds to S423.

  After the completion of this process, the driving direction and driving speed of the focus lens and zoom lens are selected according to the operation mode in S706 shown in FIG. In the zooming operation, the focus lens drive direction is set to the near direction and the infinity direction depending on whether the focus lens moving speed Vf obtained in S423 or S424 is positive or negative, respectively. In this way, the zigzag drive of the focus lens is performed, and the locus to be traced is re-specified.

  The above is the base technology of the present invention, and the embodiments of the present invention will be described below with a focus on differences from the base technology.

  FIG. 1 shows a configuration of a video camera as an image pickup apparatus (optical apparatus) equipped with a lens control apparatus according to an embodiment of the present invention. In this embodiment, an example in which the present invention is applied to an imaging device integrated with a photographing lens will be described. ). In this case, the microcomputer in the lens performs a zooming operation described below in response to a signal transmitted from the camera body side. The present invention is not limited to a video camera and can be applied to various imaging devices such as a digital still camera.

  In FIG. 1, in order from the object side, 101 is a front lens unit 101 and 102 that are fixed, a zoom lens unit (first lens unit) that moves in the direction of the optical axis and performs zooming, 103 is an aperture, and 104 is A fixed lens unit 105, which is fixed, is a focus lens unit (second lens unit) that moves in the optical axis direction and has a focus adjustment function and a compensator function that corrects image plane movement due to zooming. The photographing optical system constituted by these lens units is a rear focus optical system constituted by four lens units having positive, negative, positive and positive optical powers in order from the object side (left side in the figure). In the drawing, each lens unit is described as being configured by a single lens, but in actuality, it may be configured by a single lens or by a plurality of lenses. It may be configured.

  Reference numeral 106 denotes an image sensor constituted by a CCD or CMOS sensor. The light beam from the object that has passed through the photographing optical system forms an image on the image sensor 106. The imaging element 106 photoelectrically converts the formed object image and outputs an imaging signal. The imaging signal is amplified to an optimum level by an amplifier (AGC) 107 and input to the camera signal processing circuit 108. The camera signal processing circuit 108 converts the input imaging signal into a standard television signal, and then outputs it to the amplifier 110. The television signal amplified to the optimum level by the amplifier 110 is output to the magnetic recording / reproducing apparatus 111 where it is recorded on a magnetic recording medium such as a magnetic tape. Other recording media such as a semiconductor memory and an optical disk may be used as the recording medium.

  The television signal amplified by the amplifier 110 is also sent to the LCD display circuit 114 and displayed on the LCD 115 as a photographed image. The LCD 115 also displays an image that informs the photographer of the shooting mode, shooting state, warning, and the like. Such an image is displayed by being superimposed on the photographed image by the camera microcomputer 116 controlling the character generator 113 and mixing the output signal therefrom with the television signal by the LCD display circuit 114.

  On the other hand, the image pickup signal input to the camera signal processing circuit 108 can be simultaneously compressed using an internal memory and then recorded on a still image recording medium 112 such as a card medium.

  The imaging signal input to the camera signal processing circuit 108 is also input to the AF signal processing circuit 109 serving as focus information generating means. The AF evaluation value signal (focus signal) generated by the AF signal processing circuit 109 is read as data by communication with the camera microcomputer 116.

  Further, the camera microcomputer 116 reads the states of the zoom switch 130 and the AF switch 131 and further detects the state of the photo switch 134.

  When the photo switch 134 is half-pressed, the focusing operation by AF is started and the focus is locked in the focused state. Further, in the fully-pressed (deep-pressed) state, the focus is locked regardless of the in-focus state, the image is taken into a memory (not shown) in the camera signal processing circuit 108, and is stored in the magnetic tape or the still image recording medium 112 Record still images.

  The camera microcomputer 116 determines whether the moving image shooting mode or the still image shooting mode is selected according to the state of the mode switch 133, and controls the magnetic recording / reproducing device 111 and the still image recording medium 112 via the camera signal processing circuit 108. To do. As a result, a television signal suitable for the recording medium is supplied thereto, or when the mode switch 133 is set to the reproduction mode, the television signal recorded on the magnetic recording / reproduction device 111 or the still image recording medium 112 is stored in the reproduction mode. Perform playback control.

  The computer zoom unit (control means) 119 in the camera microcomputer 116 zooms with respect to the zoom motor driver 122 according to a program in the computer zoom unit 119 when the AF switch 131 is off and the zoom switch 130 is operated. A signal for driving the lens unit 102 in the tele or wide direction corresponding to the direction in which the zoom switch 130 is operated is output. The zoom motor driver 122 receives this signal and drives the zoom lens unit 102 in this direction via the zoom motor 121. At this time, the computer zoom unit 119 is also based on lens cam data (representative trajectory data and trajectory parameter data corresponding to a plurality of subject distances as shown in FIG. 8) stored in advance in the cam data memory 120. Then, the focus motor 125 is driven via the focus motor driver 126, and the focus lens unit 106 is driven so as to correct the image plane movement accompanying the zooming.

  Further, the AF control unit 117 in the camera microcomputer 116 needs to perform a zooming operation while keeping the focused state when the AF switch 131 is on and the zoom switch 130 is operated. The zoom unit 119 is obtained not only from the lens cam data stored in the cam data unit 120 but also from the AF evaluation value signal sent from the AF signal processing circuit 109 and the output from the subject distance detection circuit 127 by an internal program. The zoom lens unit 102 and the focus lens unit 105 are driven based on the distance information to the subject (focused object).

  The output signal from the subject distance detection circuit 127 is processed by the distance information processing unit 128 in the camera microcomputer 116 and output to the computer zoom unit 119 as subject distance information.

  When the AF switch 131 is on and the zoom switch 130 is not operated, the AF control unit 117 moves the focus lens 105 so that the AF evaluation value signal sent from the AF signal processing circuit 109 is maximized. A signal is output to the focus motor driver 126 to drive, and the focus lens lens unit 105 is driven via the focus motor 125. Thereby, an automatic focus adjustment operation is performed.

  Here, the subject distance detection circuit 127 measures the distance to the subject by a triangulation method using an active sensor, and outputs distance information that is the measurement result. As an active sensor in this case, an infrared sensor often used for a compact camera can be used.

  In this embodiment, a case where distance detection is performed by the triangulation method will be described as an example. However, other distance detection means in the present invention can be used. For example, distance detection by a TTL phase difference detection method may be performed. In this case, an element (half prism or half mirror) that divides the light that has passed through the exit pupil of the photographing lens is provided, and the light emitted from the element is guided to at least two line sensors via the sub mirror and the imaging lens. Then, the correlation between the outputs of these line sensors is taken to detect the deviation direction and deviation amount of these outputs, and the distance to the subject is obtained from these detection results.

  FIGS. 14 and 15 show the principle of distance calculation by the triangulation and the phase difference detection method, respectively. In FIG. 14, 201 is a subject, 202 is an imaging lens for the first optical path, 203 is a line sensor for the first optical path, 204 is an imaging lens for the second optical path, and 205 is for the second optical path. This is a line sensor. Both line sensors 203, 204 are installed apart by a base line length B. Of the light from the subject 201, the light passing through the first optical path by the imaging lens 202 forms an image on the line sensor 203, and the light passing through the second optical path by the imaging lens 204 is applied to the line sensor 205. Form an image. Here, FIG. 15 shows an example of signals read from the line sensors 203 and 205 that have received two subject images formed through the first and second optical paths. Since the two line sensors are separated by the base line length B, the subject image signal is shifted by the number of pixels X as can be seen from FIG. Therefore, X can be calculated by calculating the correlation between the two signals while shifting the pixels and obtaining the pixel shift amount that maximizes the correlation. From this X, the base length B, and the focal length f of the imaging lenses 202 and 204, the distance L to the subject is determined by L = B × f / X based on the principle of triangulation.

  Furthermore, as a distance detection means, a method of detecting the distance to the subject by measuring the propagation speed using an ultrasonic sensor can be employed.

  The distance information from the subject distance detection circuit 127 is sent to the distance information processing unit 128. The distance information processing unit 128 performs the following three types of processing.

  1. It is calculated which distance on the cam locus in FIG. 8 corresponds to the current positions of the zoom lens unit 102 and the focus lens unit 105. For example, as described in step S401 in FIG. 3, the cam locus is calculated based on the current lens unit position in the γ column and γ + 1 column in the column direction of FIG. 11 using the locus parameters α, β, and γ. It outputs how many meters the virtual cam trajectory that internally divides the cam trajectory into the ratio of α / β corresponds to the subject distance. The trajectory parameters α, β, γ and subject distance are converted by predetermined correlation table data so that the actual distance of the main subject can be output.

  2. The actual trajectory of the subject from the subject distance detection circuit 127 is inversely transformed in the above correlation table 1 to obtain the cam trajectory in FIG. 8 represented by the trajectory parameters α, β, γ. At this time, the inverse conversion processing of the correlation table is performed using data on the tele side as much as possible, with the locus being dispersed, without using the data on the wide side where the cam locus in FIG. 8 is converged. A trajectory parameter with high resolution is obtained.

  3. The actual distance difference and the difference direction of 1.2 are calculated.

  Of these 1, 2, and 3 processes, the above-described process 2 can identify cam trajectory data corresponding to the detected distance detected by the subject distance detection circuit 127.

  On the other hand, the camera microcomputer 116 also performs exposure control. The camera microcomputer 116 refers to the luminance level of the television signal generated by the camera signal processing circuit 108, controls the iris driver 124 so that the luminance level is appropriate for exposure, drives the IG meter 123, and opens the aperture 103. To control. The opening amount of the diaphragm 103 is detected by an iris encoder 129, and feedback control of the diaphragm 103 is performed. In addition, when appropriate exposure control cannot be performed only with the aperture 103, the exposure time of the image sensor 106 is controlled by a timing generator (TG) 132, and it corresponds to a high-speed shutter to a long-time exposure called a so-called slow shutter. Further, when the exposure is insufficient such as shooting under low illumination, the gain of the television signal is controlled through the amplifier 107.

  The photographer can manually operate the shooting mode and camera function switching suitable for the shooting conditions by operating the menu switch unit 135.

  Next, an algorithm during the zooming operation will be described with reference to FIGS. 2A and 2B. In the present embodiment, the computer zoom unit 119 in the camera microcomputer 116 executes the processing of the operation flow described below including each operation flow (program) described above. In FIGS. 2A and 2B, portions with the same circled numbers are connected to each other.

In this embodiment, the cam locus (first information) to be followed is specified (generated) according to the distance information (second information) obtained from the subject distance detection circuit 127, and the zooming operation is performed. The operation flow of FIG. 3 is an example of a method of performing a zooming operation while accurately identifying (generating) a zoom tracking curve that is a cam locus to be followed using distance information. In particular, this method is effective for reducing image blur at the start of the zooming operation and for recovering image blur when the focus lens unit 105 deviates from the focus cam locus during zooming.

  2A and 2B are the processes performed in S705 of FIG. 6 described above in the present embodiment, and the same processes (steps) as those in FIG.

  In S400, the zoom speed during the zoom operation is determined. In S401, from the current zoom lens position and focus lens position, it is determined which position on the cam locus in FIG. 8 corresponds to the main subject being shot. Here, the current zoom lens and focus lens positions including the virtual cam trajectory are obtained by interpolation processing based on the cam trajectory data table (FIG. 11) storing the representative trajectory shown in FIG. 8 as discrete data. Is calculated as three trajectory parameters α, β, and γ, and stored in a memory area such as a RAM. This process is the same as the process described above with reference to FIG.

In S300, the calculated trajectory parameters α, β, and γ are temporarily stored as α _now , β _now , and γ _now , and the trajectory parameters α, β, and γ are how many m in actual subject distance (estimated distance). Is calculated. The correlation between the trajectory parameter and the estimated distance can be calculated in advance by making the correlation between the estimated distance and the trajectory parameter into table data in a range where the cam curve shape of a typical subject distance is uniform, and inputting the trajectory parameter. At the subject distance where the cam curve shape changes, a lookup table representing another correlation is used, and by having a plurality of these tables, the estimated distance B can be obtained for every zoom lens position and focus lens position.

  Next, in S301, an output from the subject distance detection circuit 127 is obtained. Then, the distance (actual distance) A to the photographing subject indicated by the output of the subject distance detection circuit 127 is compared with the estimated distance B obtained from the current lens position in S300, and the actual distance A is compared with the estimated distance B. Check whether it is near side (closest direction) or far side (infinity direction).

Next, in S302, it is determined whether or not the “AF correction flag” is set. If it is in the set state, the process proceeds to S303, and trajectory parameters α _AF , β _AF , and γ _AF determined in S311 described later are set (stored in the memory) to α, β, and γ, respectively. Here, the trajectory parameters α _AF , β _AF , and γ _AF are cams when the change of the AF evaluation signal is detected while the focus lens unit 105 performs the zigzag operation and the peak level 1301 in FIG. It is a trajectory parameter. That is, the cam locus information itself in which the peak level of the AF evaluation signal is detected while performing the zigzag operation, and represents the true in-focus cam locus and the cam locus recognized by the microcomputer 116.

The trajectory parameters α, β, and γ updated in S303 in this way represent cam trajectories re-specified based on the AF evaluation signal, and the result of continuing to re-specify cam trajectories repeatedly in a continuous zooming operation is obtained as a result. Thus, the focus lens unit 105 can be traced (followed) with the true focus cam locus.

  On the other hand, if the “correction flag” is clear in S302, the trajectory parameters α, β, γ specified based on the distance information by the subject distance detection circuit 127 already determined in S300 are held, The focus lens 105 is controlled to trace the cam trajectory specified by the trajectory parameters α, β, γ.

  Here, the “correction flag” is a flag indicating whether or not a cam locus to be followed is re-specified by an AF evaluation signal described later, and once set (when the following cam locus is re-specified), It is not cleared unless the switching of the zooming direction or the zooming operation is stopped. The information (α, β, γ) of the re-specified cam track is continuously re-specified (updated) based on the detection result of the AF evaluation signal. Will be identified.

Thereafter, the same processing as in FIG. 3 is performed. In step S402, a position (position of movement destination from the current position) Z _x ′ reached by the zoom lens 102 after one vertical synchronization time is calculated. If the zoom speed determined in S400 is Z _sp (pps), the zoom lens position Z _x ′ after one vertical synchronization time is given by the above-described equation (7). Here, pps is a unit representing the rotation speed of the stepping motor, which is the zoom motor 121, and indicates a rotation step amount per second (1 step = 1 pulse). The sign of equation (7) is + for the tele direction and-for the wide direction, depending on the moving direction of the zoom lens 102, respectively.

Z _x '= Z _x ± Z _sp / vertical synchronization frequency (7)
Next, in S403, it is determined in which zoom area v ′ Z _x ′ is present. S403 is the same process as the process shown in FIG. 5, in which Z _x in FIG. 5 is replaced with Z _x ′ and v is replaced with v ′.

Next, in S404, it is determined whether or not the zoom lens position Z _x ′ after one vertical synchronization time (1V) exists on the boundary of the zoom area. If the boundary flag = 0, it is determined that the zoom lens position Z _x ′ is not on the boundary. Proceed to processing from. In S405, it sets Z _{(v ')} to _{Z k,} sets the Z _(v'-1) to _{Z k-1.}

Next, in S406, four table data A _{(γ, v′−1)} , A _{(γ, v ′)} , A _{(γ + 1, v′−1 )} in which the subject distance γ is specified by the processing shown in FIG. ₎ , A _{(γ + 1, v ′)} are read out, and in step S407, a _x ′ and b _x ′ are calculated from the above-described equations (2) and (3).

On the other hand, if YES is determined in S403, the focus lens positions A _{(γ, v ′)} and A _{(γ + 1, v ′)} with respect to the zoom area v ′ at the subject distance γ are called in S408, and a _x ', _{b x'} memory as. Then, in S409, 'in-focus position of the focus lens 105 when reaching the (target position) _{p x'} zoom lens position _{Z x} is calculated. Using the equation (1), the target position of the focus lens 105 after one vertical synchronization time can be expressed as the following equation (8).

p _x ′ = (b _x ′ −a _x ′) × α / β + a _x ′ (8)
Therefore, the difference between the target position and the current focus lens position is
ΔF = (b _x ′ −a _x ′) × α / β + a _x ′ −p _x
It becomes.

Next, in S410, a focus standard movement speed _Vf0 is calculated. V _f0 is obtained by dividing the focus lens position difference ΔF by the moving time of the zoom lens unit 102 required to move this distance.

  Then, the process is terminated, and the process proceeds to S706 in FIG. 6. If the zooming operation is being performed, the sign direction of the focus speed at the focus speed determined in S410 (the close direction is positive and the infinity direction is negative). And the compensator operation is performed.

In S411, various parameters are initialized. Here, the “inversion flag” used in the subsequent processing is cleared. In S412, correction speeds V _{f +} and V _f− for zigzag operation are calculated from the focus standard movement speed Vf0 obtained in S410. Here, the correction amount parameter δ and the correction speeds V _{f +} and V _f− are calculated using the equations (9) to (12) as described above with reference to FIG.

In S413, it is determined whether zooming is being performed according to the information indicating the operation state of the zoom switch 130 obtained in S703 shown in FIG. If Yes, the processing from S416 is performed. If it is determined No, the “zoom flag” and “ AF correction flag” are cleared in S313, and the zooming operation in the tele direction from the next wide is prepared. In S414, the value obtained by subtracting an arbitrary constant μ from the current value of the AF evaluation signal level is set to TH1 (the level indicated by 1302 in FIG. 12A), and the above-described correction direction vector switching reference (zigzag operation is performed). The AF evaluation signal level that is the switching reference) is determined. This TH1 is determined immediately before the start of zooming, and this value is the level 1302 in FIG.

  Next, in S415, the “correction flag” is cleared and the process is exited. Here, as described above, the “correction flag” is a state in which the follow-up state of the cam trajectory is a state where correction in the positive direction is applied (correction flag = 1) or a state where correction in the negative direction is applied (correction flag = 0). ) Is a flag indicating whether or not.

If it is determined in S413 that zooming is in progress, it is determined in S414 whether the zooming direction is from wide to tele. If No, as in S313, the “zoom flag” and “correction flag” are cleared, and the zooming operation in the tele direction from the next wide is prepared (S312). In step S419, V _{f +} = 0 and V _f− = 0 are set, and the processing from step S420 is performed to substantially not perform the zigzag driving.

  If Yes in S413, it is determined in S304 whether the “zoom flag” is in a clear state. In the case of clear, since this is the first time that the zoom has been zoomed from the wide to the tele direction for the first time, the process proceeds to S305 to set the “zoom flag”. The distance information obtained from the output of the subject distance detection circuit 127 is compared with the distance corresponding to the current focus lens position in order to correctly match the correction direction (drive start direction of the focus lens unit 105) with the object distance direction of the main subject. Then, it is determined whether the direction is close or infinity.

  Here, the process of S306 is to determine the relationship between the estimated distance B based on the lens position determined in S300 and the actual distance A based on the output of the subject distance detection circuit 127 determined in S301. If the actual distance A is closer to the estimated distance B than the estimated distance B, that is, the closest direction, the process proceeds to S424, and the correction direction in which the zigzag operation is positive is started from the close direction. If No in S306, that is, if the actual distance A is farther than the estimated distance B, the process proceeds to S423 to start the correction operation from the infinity direction.

  As described above, in this embodiment, when zooming is started, the distance (estimated distance B) corresponding to the position of the focus lens unit 105 is set as the correction direction for the cam locus specifying operation using the AF evaluation signal. The first feature is that the distance is set so as to approach the distance (actual distance A) based on the output of the distance detection circuit 127, that is, the weighting is set for the drive direction of the focus lens unit 105.

  By performing such an operation, especially when starting zooming from the wide side where the interval of the cam trajectory is narrow, the driving start direction of the focus lens unit 105 in the zigzag operation is the direction in which the focus cam trajectory is present. Even if the positional deviation from the in-focus locus is small due to the reverse direction, it is possible to avoid the phenomenon that the image blur is conspicuous because the depth of focus is shallow. Accordingly, when the direction of the focusing cam locus on the wide side and the driving direction (correction direction) of the focus lens unit 105 are reversed, the images of objects at various subject distances are blurred simultaneously, and the quality of the captured image is reduced. It is possible to prevent the occurrence of the problem of worsening.

Returning to S304, the description will be continued. Once the “zoom flag” is set in S306, the process proceeds to S307 according to the determination result (zoom flag = 1) in S304 from the next time. In S307, as in S306, it is determined whether the distance information (actual distance A) based on the output of the subject distance detection circuit 127 is closer to the estimated distance B. If Yes, _{Vf +} is set to a double value in S309 in order to weight the zigzag operation with priority in the near direction. On the other hand, if No in S307, the process proceeds to S308, in which V _f− is doubled and weighted. This is based on the detected actual distance A (according to the relationship between the actual distance A and the estimated distance B), and the correction operation for respecifying the cam trajectory using the AF evaluation signal is weighted. It is the 2nd characteristic of an example.

  With this weighting correction process, for example, when specifying a cam trajectory based on a change in the AF evaluation signal, the AF evaluation signal not only changes depending on the image blurring state, but also changes due to a change in the pattern of the subject. It is possible to avoid the problem that the correction direction is switched incorrectly (the problem that the image blurs for a long time before returning to the correct trajectory again, or the camera reaches the telephoto end while dragging the image blur).

  In this embodiment, as an example of the weighting process, the case where the driving speed (correction speed) of the focus lens unit 105 in the correction process is doubled based on the detected actual distance A has been described. Not exclusively.

  For example, the weighting ratio of the correction speed may be changed according to the difference between the detected actual distance A and the estimated distance B based on the lens position and the direction thereof.

  Further, instead of increasing the correction speed in the direction approaching the actual distance A, the correction speed in the reverse direction may be decreased.

  Also, the AF evaluation value switching level (TH1) 1302 as a condition for switching the correction direction shown in FIG. 12A is set low in the direction approaching the focus lens position corresponding to the actual distance A. The level 1302 is set high in the correction direction away from the focus lens position corresponding to the actual distance A so that the frequency of the correction operation in the direction approaching the focus lens position corresponding to the actual distance A is increased. Also good.

  In this way, the zigzag operation is executed by performing the processing after S417 while performing the weighting process of the zigzag operation during the zoom operation based on the detected distance information. First, in S417, it is determined whether or not the current AF evaluation signal level is lower than TH1. If Yes, the current AF evaluation signal level is lower than the level of TH1 (1302) in FIG. 12A. Therefore, in order to switch the correction direction, an inversion flag is set in S418.

In S420, it is determined whether or not the inversion flag = 1. If Yes, the process proceeds to S421, and it is determined whether or not the correction flag is 1. If No in S421, the process proceeds to S424, and 1 (correction state in the positive direction) is set in the correction flag,
Focus speed V _f = V _f0 + V _{f +} (however, V _{f +} ≧ 0)
And

On the other hand, if Yes at S421, the process proceeds to S42 3, sets 0 (negative correction state) to the correction flag, the (5),
Focus speed V _f = V _f0 + V _f− (where V _f− ≦ 0)
And

  If it is determined No in S420, it is determined in S422 whether the correction flag is 1. If Yes, the process proceeds to S424, and if No, the process proceeds to S423.

  After the completion of this process, the driving direction and the driving speed of the focus lens 105 and the zoom lens 102 are selected according to the operation mode in S706 shown in FIG.

  In the zoom operation, here, the driving direction of the focus lens 105 is set to the closest direction or the infinite direction depending on whether the focus speed Vf obtained in S423 or S424 is positive or negative. In this way, the cam locus to be traced is re-specified while performing the zigzag drive of the focus lens 105.

While performing zigzag driving, it is detected that the AF evaluation signal in the TV-AF has reached the peak level 1301 shown in FIG. 12A by the processing from S417 to S424. If No in S417, it is determined whether or not a peak level 1301 is detected in S310. When the peak level is detected, in S311, "correction flag = 1" and the current value of the trajectory parameter are used as the re-specific trajectory parameter by TV-AF.
α _AF ← α _now , β _AF ← β _now , γ _AF ← γ _now
And set. Then, in the next S302, it is determined that “ AF correction flag = 1”, so that the specific cam locus is updated in S303.

This time, the re-specified locus parameters updated in S303, or stopped zooming operation, unless the zooming direction is not or reverse, each time a new peak level is detected (S310), alpha _AF in S311, beta _While repeatedly updating _AF and γ _AF , the optimal cam locus is updated at any time during the zooming operation.

  If it is not detected in S310 that the AF evaluation value level has reached the peak level, the process directly proceeds to S420, and the focus is corrected while correcting to the previously determined correction direction without switching the correction direction by the zigzag operation. The lens 105 is driven.

  As described above, according to the present embodiment, since the weighting setting is made based on the detected distance information with respect to the driving start direction of the focus lens unit 105 in the zigzag operation, the occurrence of image blur during the zigzag operation can be suppressed. .

  In addition, during the zooming operation, there is a possibility that the distance of the main subject may fluctuate, but in this embodiment, weighting is performed for driving in the direction approaching the focus lens position corresponding to the detection distance and the driving speed. , Cam trajectory can be captured quickly and smoothly. Furthermore, even when the focus lens unit 105 is erroneously driven in a direction away from the correct cam locus that should be followed by the correction operation by the AF evaluation signal, the occurrence of image blur is reduced and the correct cam locus is smoothly achieved. It is possible to return.

  Further, by using the method of the present embodiment, it is possible to improve the accuracy of specifying the tracking cam locus based on the TV-AF signal (AF evaluation signal). For this reason, the detection accuracy of the subject distance detection circuit 127 can be roughened to some extent, and a small and inexpensive type of the subject distance detection circuit 127 can be selected.

1 is a block diagram illustrating a configuration of a video camera that is an embodiment of the present invention. The flowchart which shows the operation | movement in the video camera of an Example. The flowchart which shows the operation | movement in the video camera of an Example. The flowchart which shows the premise technique of this invention. The flowchart which shows the premise technique of this invention. The flowchart which shows the premise technique of this invention. The flowchart which shows the premise technique of this invention. Schematic which shows the structure of the conventional imaging | photography optical system. The conceptual diagram which shows the focusing locus | trajectory according to to-be-photographed object distance. The figure explaining a focus locus. The figure for demonstrating the interpolation method of the moving direction of a zoom lens. The figure which shows the example of the data table of a focus locus | trajectory. (A), (B) is a conceptual diagram which shows the premise technique of this invention. The conceptual diagram which shows the premise technique of this invention. The figure for demonstrating the triangulation method. The figure for demonstrating the distance measurement method by phase difference detection.

Explanation of symbols

DESCRIPTION OF SYMBOLS 102 Zoom lens unit 105 Focus lens unit 106 Image pick-up element 116 Camera microcomputer 117 AF control unit 120 Cam data memory 127 Subject distance detection circuit

Claims (14)

A lens control device that controls movement of the second lens unit to correct image plane movement when the first lens unit for zooming is moved,
Storage means for storing data indicating the position of the second lens unit in accordance with the position before Symbol first lenses units created for a given focus distance,
An acquisition means for acquiring a focus signal representing a focused state of the optical system based on a photoelectric conversion signal of an optical image formed by an optical system including the first lens unit and the second lens unit;
Control means for controlling movement of the second lens unit based on first information indicating a movement target position of the second lens unit;
Distance detecting means for detecting second information corresponding to the distance to the in-focus object;
The control unit weights the moving operation of the second lens unit based on the second information when generating the first information according to the data and the focus signal during the zooming operation. A lens control device.   The lens control device according to claim 1, wherein the first information is locus information representing a position of the second lens unit with respect to the first lens unit. The lens control device according to claim 1, wherein the control unit weights a moving direction when moving the second lens unit based on the second information . The lens control device according to claim 3, wherein the control unit sets a moving direction when starting the movement of the second lens unit to a direction corresponding to the second information. The lens control device according to claim 1, wherein the control unit weights a moving speed for moving the second lens unit based on the second information . The said control means sets the moving speed of the said 2nd lens unit to the direction according to the said 2nd information to a speed faster than the moving speed to the opposite direction. Lens control device. 3. The lens control device according to claim 1, wherein the control unit weights a condition for reversing a moving direction when moving the second lens unit based on the second information . The control means performs regeneration processing for generating new first information by moving the second lens unit with reference to the generated first information, and performs the regeneration processing in the regeneration processing. lens control apparatus according to any one of claims 1 to 7, characterized in that performs weighting based on the second information on the movement control of the second lens unit. The control means generates the first information based on the data and the second information, and is obtained from a photoelectric conversion signal of an optical image formed by an optical system including the first and second lens units. The lens control device according to claim 8 , wherein the regeneration process is performed using a focus signal representing a focus state of the optical system. Moving the control means, wherein the regeneration process, the focus signal so that the most-focus toward state the position shown the second lens unit causes movement, while switching the movement condition of the second lens unit is allowed, the lens control apparatus according to claim 9 with respect to the conditions of the focus signal for switching the moving condition, and performing the weighting based on the second information. The control means is configured to focus on the current position of the second lens unit when controlling the movement of the second lens unit to generate the first information based on the second information. 3. The lens according to claim 1, wherein weighting is performed on the movement operation of the second lens unit in a direction in which the distance of the second lens unit approaches the distance to the in-focus object detected by the distance detection unit. Control device.   An optical apparatus comprising: an optical system including the first and second lens units; and the lens control device according to any one of claims 1 to 11.   The optical apparatus according to claim 12, further comprising an imaging unit that photoelectrically converts an optical image formed by the optical system. A lens control method for controlling movement of the second lens unit in order to correct image plane movement when moving the first lens unit for zooming,
An acquisition step of acquiring a focus signal representing an in-focus state of the optical system based on a photoelectric conversion signal of an optical image formed by an optical system including the first lens unit and the second lens unit;
A control step for controlling movement of the second lens unit based on first information indicating a movement target position of the second lens unit;
Detecting second information corresponding to the distance to the in-focus object,
In the control step, during the zooming operation, the data indicating the position of the first lens unit and the position of the second lens unit created with respect to the predetermined focusing distance stored in the storage means and the focus A lens control method , wherein when generating the first information in response to a signal, weighting is performed on the movement operation of the second lens unit based on the second information .

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