JP4721394B2 - 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. 8 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. 8, 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 is the same even if the focal length is the same. Depends on the subject distance. When the position of the focus lens 905 for focusing the subject image on the imaging surface 906 is continuously plotted when the subject distance is changed at each focal length, the result is as shown in FIG. During zooming, if a trajectory corresponding to the subject distance is selected from the plurality of trajectories shown in FIG. 9 and the focus lens 905 is moved according to 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. 9 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. 9, since the plurality of trajectories are converged from a state having a certain interval, the above-mentioned trajectory tracking method is also in focus. Can be maintained. However, in the wide-to-tele direction, it is not possible to know which locus the focus lens at the convergence point should follow, so that the focus cannot be maintained by the similar locus following method.

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, considering that the focus lens may switch to the wrong direction when switching the direction of movement, the tracking locus correction range is wide so that the correct locus can be restored even if the direction is once incorrect. Is set.

  However, when a wide correction range is set in this way, if it deviates from the trajectory that should be followed, 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.

  Further, when shooting a subject having a high frequency, a slight image blur may occur when an attempt is made to specify a tracking locus by a zigzag operation. It is possible to adjust the AF evaluation value level that determines the inversion timing of the driving direction of the focus lens in the zigzag operation according to the subject condition so that such an image blur becomes difficult to see. Therefore, it is difficult to eliminate the image blur caused by the zigzag motion.

  In the TV-AF method, since the signal detection cycle for obtaining the AF evaluation value is the vertical synchronization signal cycle, the higher the zooming speed, the lower the trajectory selection accuracy. Therefore, the frequency of mistaking the tracking locus increases.

  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, when the 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 between a position of the first lens unit, which is created for focus distance and position of the second lens unit and storage means for storing data indicative of the optical system including the first lens unit and the second lens unit obtaining means for obtaining a focus signal representing a focusing state of the optical system based on the photoelectric conversion signal of the optical image formed by, on the basis of the first information indicating the movement target position of the second lens unit first Control means for controlling the movement of the two-lens unit and detection means for detecting second information corresponding to the distance to the in-focus object. Then, the control unit, during zooming operation, when generating the first information in response to the data and the focus signal, the moving range of the second lens unit on the basis of the second information restrictions Is provided .

Further, the present invention, upon movement of the first lens unit for zooming, a lens control method for controlling the movement of the second lens unit for correcting image plane movement, the first lens unit and the second 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. Then, in the control step, said during zooming operation, the data indicating the position of the first lens unit that is created for a given focus distance stored in the storage means and the position of the second lens unit When the first information is generated in accordance with a focus signal, a limit is provided on a moving range of the second lens unit based on the second information .

Here, 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 a position where the second lens unit is to be driven. It may be information.

According to the present invention, the range of the first information (trajectory information and the like) generated to control the movement of the second lens unit based on the second information corresponding to the detected distance to the in- focus object. Therefore, it is possible to avoid the generation of the first information that does not correspond to the distance to the object to be actually focused, and to suppress the occurrence of image blur during zooming.

Here, the first information is generated on the basis of the data and the detected second information , and a focus signal representing a focus state of the optical system is used with the generated first information as a reference. in the case of performing the regeneration process of generating a new first information, based on the second information issued該検, so as to limit the scope of the first information generated in該再generation process Also good. As a result, there are disadvantages associated with the detection period of the focus signal, and the problem that the focus signal is affected not only by a change in distance but also by a change in the pattern of the in-focus object, and erroneous first information is regenerated. In addition, it is possible to avoid a problem of malfunction such as a wrong timing for switching the zigzag operation, and it is possible to perform high-precision focus maintaining control during zooming while suppressing the occurrence of image blur in the regeneration process.

Further, in the regeneration process, the movement conditions of the lens unit such that the second lens unit toward the position shown the state in which the focus signal has the most focus moves, based on the first information to the reference moving In the case where the moving condition is changed with respect to the moving condition, the moving range of the second lens unit may be limited based on the second information . As a result , it is possible to avoid the second lens unit from being driven based on erroneous first information. Moreover, even when be fitted in the specified switching timing of the zigzag motion, while suppressing decrease the image blur amount it can be performed quickly Noriutsuri to the drive based on the correct information.

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

10, 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. 10, 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. 11 is a diagram for explaining an interpolation method in the moving direction of the zoom lens. A part of FIG. 10 is extracted to arbitrarily set the position of the zoom lens.

In FIG. 11, 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 Zx 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 division ratio obtained from the current zoom lens position and two zoom area boundary positions (for example, Z _k and Z _k-1 in FIG. 11) between them, four stored 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.

Further, when zooming from tele to wide, from the difference between the focus position p _k−1 of the follow-up movement destination and the current focus position P _x and the time required for the zoom lens to move from Z _{x to} Z _k−1. The moving speed of the focus lens for maintaining the in-focus state can be known.

FIG. 12 shows an example of table data of focusing locus information stored in advance in the microcomputer at this time. FIG. 12 shows focus lens position data A _{(n, v)} for each subject distance, which changes 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.

13A and 13B, the horizontal axis indicates the position of the zoom lens. In FIG. 13A, the vertical axis indicates an 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. 13 (B), the vertical axis represents the position of the focus lens. In FIG. 13B, 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 movement speed for tracking the in-focus locus on the wide side from the zoom lens position 1306 (Z14) is positive (moves in the direction closer to the focus lens), and the focus lens is at infinity on the telephoto side from the position 1306. The standard moving speed for following the in-focus locus when moving in the 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. 13B, 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. 9, in the zooming from wide to tele, in which 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. 7 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. 7 is executed in synchronization with the vertical synchronization signal (wait until the next vertical synchronization signal is input in the processing of S703).

5 and 6 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. 4 to 7 and FIG.

In S400 of FIG. 4, the zoom motor drive speed Zsp is set so that natural zooming operation can be performed according to the operation information of the zoom switch unit.

  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 used as three trajectory parameters (for obtaining target position information). Data) is stored as α, β, γ in a memory area such as a RAM. Here, the process shown in FIG. 5 is performed. For the sake of simplicity, the process shown in FIG. 5 will be described below assuming that the in-focus state is maintained at the current lens position.

In S501 of FIG. 5, calculating whether the current zoom lens position Z _x is on the data table shown in FIG. 12, to present to 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, it is determined whether Z _(v) obtained in S602 is equal to the current zoom lens position Zx. 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. 6, the current zoom lens position Z _x is present in v = k th zoom area on the data table in FIG. 12, further Z _x zoom area You can know if it is on the boundary.

  Returning to FIG. 5, since the current zoom area is determined by the processing of FIG. 6 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. 4, the description will be continued. As described above, in S401, a trajectory parameter for knowing on which trajectory shown in FIG. 9 the current zoom lens position and focus lens position are 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, when the zoom speed determined in S400 is Zsp (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 ± Zsp / vertical synchronization frequency (7)
Next, in which zoom area v ′ Z _x ′ is present is determined in S403. In S403, it performs processing similar to the processing in FIG. 6 is obtained by replacing the _{Z x} in FIG. 6 'to, v a 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. On the other hand, if Yes is determined in S403, in S408, the in-focus position A _{(γ, v ′)} with respect to the zoom area v ′ at the subject distance γ and the in-focus position with respect to the zoom area v ′ at the subject distance γ + 1. Call 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. 13B will be described.

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. 14 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. 14, 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. The TH evaluation signal level serving as the reference for switching the vector in the correction direction (switching reference for the zigzag correction operation) described in FIG. 13A is determined for TH1. 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. 13A. 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. 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 that is Embodiment 1 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 or trajectory parameter data corresponding to a plurality of subject distances as shown in FIG. 11) stored in the cam data memory 120 in advance. 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. 15 and 16 show the principle of distance calculation by the triangulation and phase difference detection methods, respectively. In FIG. 15, 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. 16 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. 9 corresponds to the current positions of the zoom lens unit 102 and the focus lens unit 105. For example, as described in the process S401 of FIG. 4, the cam locus is calculated based on the current lens unit position in the γ and γ + 1 columns in the column direction of FIG. 12 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 from the correlation table described above to obtain the cam trajectory in FIG. 9 represented by trajectory parameters α, β, and 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. 9 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 FIG. 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 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 in FIG. 3 is an example of a method for performing a zooming operation while specifying (generating) a zoom tracking curve that is a cam locus to be followed using distance information. In particular, this method is effective when the AF evaluation value detection cycle becomes rough, such as ultra-high-speed zoom, and the accuracy of zoom tracking curve identification cannot be increased by using only the TV-AF reference signal (AF evaluation value signal). It is.

  FIG. 3 shows the processing performed in S705 of FIG. 7 described above in the present embodiment, and the same processing (steps) as in FIG.

In S400, the zoom speed during the zoom operation is determined. In S300, in accordance with the output signal of the subject distance detection circuit 127, it is determined which cam trajectory corresponds to the current main subject shooting distance among the representative trajectories shown in FIG. , Γ is calculated. At the same time, the trajectory parameters α _now , β _now , γ _now corresponding to the current zoom lens position and focus lens position described in S401 of FIG. 4 are calculated.

Here, α _now , β _now , and γ _now are stored in the memory under the names α _now , β _now , and γ _now , respectively, calculated in the processing from S512 to S515 in FIG. .

  On the other hand, the trajectory parameters based on the distance information obtained by the subject distance detection circuit 127 are calculated as α, β, γ, for example, by the following method.

  First, in order to obtain the correlation between the output distance information and the representative trajectory (cam trajectory) shown in FIG. The correlation with the trajectory parameter is converted into table data. Thus, the trajectory parameter is calculated using the distance information as an input. For subject distances where the cam trajectory shape changes, a lookup table representing another correlation is provided, and by providing a plurality of these tables, trajectory parameters can be obtained for every subject distance.

  Regarding the focal length, the trajectory parameter on the long focal length side having the highest resolution of the trajectory parameters α, β, γ can be output from the discrete cam trajectory information of FIG. 9 held as data in the memory. To. As a result, as shown in FIG. 9, even if the current lens position is present at the position where the cam locus is converged on the wide side, the telescopic point where the cam locus is diverging is determined according to the distance information. It is possible to extract the trajectory parameters. Therefore, when the zoom lens 102 is positioned on the wide side, it is possible to specify one cam locus that the focus lens 105 should follow by performing (interpolation) calculation based on the locus parameter on the tele side. It becomes possible.

  Note that S300 is executed every predetermined period (for example, one vertical synchronization period). For this reason, even if the subject distance changes during zooming, the latest cam trajectory to be followed is sequentially updated according to the output of the subject distance detection circuit 127.

  Next, in S301, the cam locus correction range, which is a feature of the present invention, is determined based on the output of the subject distance detection circuit 127 (that is, α, β, γ calculated in S300). This correction range corresponds to the correction range in the tracking cam locus correction operation using the TV-AF signal (AF evaluation value), and is, for example, a range sandwiched between the upper limit 201 and the lower limit 202 shown in FIG. .

  Here, in this embodiment, for example, when the output from the subject distance detection circuit 127 corresponds to a subject distance (203) of 5 m, the correction range is limited to a range of ± 50 cm of the subject distance. That is, the upper limit 201 corresponds to a cam trajectory corresponding to a subject distance of 4.5 m, and the lower limit 202 corresponds to a cam trajectory corresponding to a subject distance of 5.5 m. The correction range may be determined according to the detection accuracy of the subject distance detection circuit 127.

  That is, the above-described correction range is obtained by specifying a cam track that should be roughly tracked based on distance information by the subject distance detection circuit 127 and then performing a precise tracking cam track by a correction operation (zigzag operation) using a TV-AF signal. It is set to limit the re-specific range when performing re-specification.

  In this way, the detection resolution (detection accuracy) of the subject distance detection circuit 127 does not have to be so high, and as a result, an inexpensive and small imaging device can be provided. In addition, by limiting the correction range of the tracking cam trajectory, the frequency of switching the direction of the zigzag operation when re-specifying the tracking cam trajectory using the TV-AF signal and continuing correction in the same correction direction By reducing, it is possible to prevent the occurrence of blurring that repeats jaspin and slight image blur periodically according to the movement of the zigzag motion, which may have occurred when shooting high frequency subjects. It becomes. Furthermore, it is possible to suppress the occurrence of image blur when the following cam trajectory is mistaken or image blur when recovering to the correct cam trajectory.

  As an actual operation, the tracking cam locus correction operation (zigzag driving) using the TV-AF signal is performed only within the range between the upper limit 201 and the lower limit 202, and when this range is exceeded, The driving direction of the focus lens 105 is reversed so as to return to the correction range. As a result, re-specification of the cam trajectory outside the range between the upper limit 201 and the lower limit 202 is prohibited.

  In the present embodiment, a correction range is set in accordance with the detection resolution of the subject distance detection circuit 127, and the specification of the precise tracking cam locus by the TV-AF signal is permitted only within the range, whereby the TV-AF signal Suppression of malfunction and blurring caused by combined use is suppressed. In other words, the identification results of the two types of cam trajectory identification methods, the cam trajectory identification method based on the output from the subject distance detection circuit 127 and the cam trajectory identification method based on the in-focus state detection signal of the TV-AF signal match. By permitting re-specification of the tracking cam trajectory only in this case, it is possible to realize an extremely accurate cam trajectory tracking method that combines only the advantages of the respective specifying methods.

  In particular, when specifying the tracking locus by the TV-AF signal described in the base technology, the speed at which the focus lens drive speed (correction speed) for zigzag operation can be covered from the infinite cam locus to the closest cam locus. Had to be set to On the other hand, in this embodiment, by limiting the correction range of the cam trajectory, for example, even if the correction speed of the focus lens is the same as that of the base technology, the drive range is narrowed. It is possible to increase the number of operations to the first number. Therefore, it is possible to improve the cam locus specifying accuracy by the TV-AF signal even at high speed zoom.

  On the other hand, if the number of zigzag movements is not increased to the first number, it is possible to reduce the setting value of the correction speed, so that the jaspin and slight image blur in the correction operation when shooting a high-frequency subject are possible. It is possible to suppress the occurrence of blurring that repeats the above periodically (details will be described in Example 2). Therefore, even with the same technique, it is possible to provide a zooming system having a high degree of freedom for realizing zoom performance by a zoom speed priority, a visual priority, and an optimal control method according to the product specifications of the provided imaging apparatus. This is another advantage of this embodiment and the present invention.

Returning to the description of FIG. 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 in S311 to be described later, the trajectory parameters α _AF and β _AF updated each time it is detected that the AF evaluation value has reached the level of the peak state 1301 described with reference to FIG. , Γ _AF is included in the correction range shown in FIG. 2 (the range between the upper limit 201 and the lower limit 202). If it is within the correction range, α _AF , β _AF , and γ _AF are set to α, β, and γ, respectively, in S304, and the focus lens 105 traces the cam locus re-specified by the correction operation. Control.

On the other hand, if the trajectory parameters α _AF , β _AF , and γ _AF are out of the correction range in S303, or if the “AF correction flag” is clear in S302, the subject distance already determined in S300. The focus lens 105 is controlled to hold the trajectory parameters α, β, γ specified based on the distance information by the detection circuit 127 and trace the cam trajectory specified by the trajectory parameters α, β, γ.

  Here, the “AF correction flag” is a flag indicating whether or not the follow-up cam trajectory has been re-specified by a TV-AF signal to be described later, and is only specified based on distance information by the subject distance detection circuit 127 ( If the re-specification has not been performed or if the cam trajectory to be re-specified is out of the correction range in FIG. 2 and there is a high possibility of erroneous specification), the “AF correction flag” is cleared in S305 and the next and subsequent times Until the cam trajectory is re-specified by the correction operation, the trajectory trace control is performed with priority given to the specifying result based on the distance information.

Thereafter, the same processing as in FIG. 4 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 Zsp (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 ± Zsp / 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. 6, in which Z _x in FIG. 6 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 it is determined Yes at S40 4, 'focus lens position A (gamma, v for') the zoom area v of the object distance gamma in step S408 and A (γ + 1, v ' ) calls the each ax', Memory as bx ′. In S409, the focus position (target position) px ′ of the focus lens 105 when the zoom lens position reaches Zx ′ 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 102 required to move this distance.

  Then, the process is terminated, and the process proceeds to S706 in FIG. 7. If the zooming operation is being performed, the sign direction of the focus speed is determined 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 V _f0 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 “AF correction flag” is cleared in S309, 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. 13A), 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.

  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 S309, the “AF correction flag” is cleared and preparation for the zooming operation in the tele direction from the next wide is performed (S308). 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 S306 whether the focus lens position with respect to the current zoom lens position exceeds the upper limit 201 of the correction range shown in FIG. If so, the process advances to step S423 to return the focus lens position to the correction range.

In S423, a negative correction speed V _f− is added to the calculated focus speed (standard movement speed) V _f0 (corrected toward infinity). As a result, the focus lens 105 is forcibly returned to the lower limit 202 direction from the upper limit 201 of the correction range.

If the upper limit 201 is not exceeded in S306, it is determined in S307 whether or not the focus lens position with respect to the current zoom lens position exceeds the lower limit 202 of the correction range in FIG. If it exceeds, the process proceeds to S424 to return the focus lens position to within the correction range. In S424, a positive correction speed V _{f +} is added to the calculated focus speed (standard movement speed) V _f0 (corrected in the closest direction). Thereby, the focus lens 105 is forcibly returned to the upper limit 201 direction from the lower limit 202 of the correction range. In this way, the driving range of the focus lens 105 is limited within the correction range, and as a result, the cam trajectory re-specified by the zigzag operation is also limited within the correction range.

  If the focus lens position does not exceed the correction range in S306 and S307, it is determined in S417 whether or not the current AF evaluation signal level is lower than TH1 in order to execute the zigzag operation. If Yes, the current AF evaluation signal level is lower than the level of TH1 (1302) in FIG. 13A, so the inversion flag is set in S418 to switch the correction direction.

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 Vf = Vf0 + Vf− (where Vf− ≦ 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 case of the zooming 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. 13A 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. If the peak level is detected, in S311, "AF 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. If the conditions at the next S302 and S303 are satisfied (when the determination results of both steps are both Yes), the specific cam trajectory is updated at S304.

  The trajectory parameter updated and re-specified in S304 is changed to distance information when the correction range is changed in S301 due to a change in the detected distance information, the zooming operation is stopped, or the zooming direction is reversed. It is updated to the cam locus specified on the basis.

When the conditions in the next S302 or S303 are not satisfied, each time a new peak level is detected (S310), the update of α _AF , β _AF , γ _AF is repeated in S311, and it is optimal during the zooming operation. The cam trajectory is updated from time to time.

  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.

  By performing the above processing, the TV-AF is limited by limiting the specific range (correction range) when specifying the cam locus to be followed using the TV-AF signal based on the distance information to the subject. The identification accuracy of the cam trajectory using the signal can be greatly improved. Therefore, the defect associated with the detection cycle of the AF evaluation value in TV-AF and the TV-AF signal are affected not only by the change in distance but also by the change in the pattern of the subject. It is possible to suppress the occurrence of erroneous determination problems and erroneous operation problems such as wrong switching timing of the zigzag operation. Therefore, occurrence of image blur can be suppressed.

  In particular, by using the method of the present embodiment in which a cam trajectory serving as a reference is specified by distance information, and the cam trajectory is corrected (re-specified) using a TV-AF signal while limiting the correction range, -The tracking cam locus correction accuracy based on the AF signal can be improved. 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.

  In the first embodiment, the case has been described in which the correction speed in the correction operation of the focus lens 105 by the TV-AF signal is the same as that of the base technology described in FIG. For this reason, in Example 1, the movement distance (driving range) of the focus lens 105 decreases due to the limitation of the correction range, and as a result, the frequency of the zigzag operation within the correction range increases. Therefore, the system has a high ability to specify the tracking cam locus even at high speed zoom or the like.

  On the other hand, in the second embodiment, the correction speed is set slower than that in the first embodiment, thereby reducing periodic image blur such as an image that is blurred or in focus due to the zigzag operation. Yes.

  For example, when the correction speed is set to ½ that of the first embodiment, the driving direction inversion timing of the focus lens 105 shown in FIG. 13B (the timing at which the AF evaluation value signal becomes level 1302 or less). Since the amount of overshoot is reduced, it is possible to reduce periodic changes such as an image that is visually blurred or in focus.

In order to reduce the correction speed to 1/2, for example, a process for _{reducing the} correction speeds V _{f +} and V _f− calculated in S412 shown in FIG. 3 to 1/2 may be added. In addition, a coefficient is provided in equations (4) and (5),
Focus speed _Vf = _Vf0 + _{Vf +} / 2 ( _{Vf +} ≧ 0) (4) '
Focus speed V _f = V _f0 + V _f− / 2 (where V _f− ≦ 0) (5) ′
It may be calculated as

  In each of the above embodiments, a case has been described in which the range when the cam locus (α, β, γ) to be followed is specified (generated) based on the distance information to the subject is limited. When calculating (generating) the target position of the focus lens, the present invention can be applied to a case where the range is limited based on distance information to the subject.

1 is a block diagram showing a configuration of a video camera that is Embodiment 1 of the present invention. FIG. 3 is a conceptual diagram illustrating a correction range in a cam locus correction operation according to the first embodiment. 3 is a flowchart illustrating an operation in the video camera according to the first exemplary embodiment. 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 (13)

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 said second lens unit 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;
Detecting means for detecting second information corresponding to the distance to the in-focus object;
The control means limits the movement range 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 control means generates the first information based on the data and the second information, and is formed by an optical system including the first and second lens units on the basis of the first information. Performing a regeneration process for generating new first information using a focus signal representing a focus state of the optical system obtained from a photoelectric conversion signal of an optical image;
On the basis of the second information, the lens control apparatus according to claim 1 or claim 2, characterized in that to limit the scope of the first information generated in該再generation process. In the regeneration process, the control means sets the movement condition of the second lens unit as the reference so that the second lens unit moves toward a position indicating a state where the focus signal is most focused. Changing the moving condition when moving based on the first information,
The lens control device according to claim 3 , wherein a movement range of the second lens unit in the regeneration process is limited based on the second information. The lens control according to claim 4 , wherein the control unit changes the movement condition so that a movement range of the second lens unit in the regeneration process is limited based on the second information. apparatus. 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 5 . The optical apparatus according to claim 6 , further comprising an imaging unit that photoelectrically converts an optical image formed by the optical system. The control means includes a zoom speed priority operation for moving the second lens unit at a first speed based on the first information, and a second speed slower than the first speed based on the first information. 6. The lens control device according to claim 1, wherein an appearance priority operation for moving the second lens unit at a speed of is controlled. 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 according to a signal, a limit is provided for a moving range of the second lens unit based on the second information .   The lens control method according to claim 9, wherein the first information is locus information representing a position of the second lens unit with respect to the first lens unit. In the control step, the first information is generated based on the data and the second information, and is formed by an optical system including the first and second lens units on the basis of the first information. Performing a regeneration process for generating new first information using a focus signal representing a focus state of the optical system obtained from a photoelectric conversion signal of an optical image;
The lens control method according to claim 9 or 10 , wherein a range of the first information generated in the regeneration process is limited based on the second information. In the regeneration process, the first information is based on the movement condition of the second lens unit as the reference so that the second lens unit moves toward a position that indicates the most focused state of the focus signal. Change the movement conditions when moving based on
The lens control method according to claim 11 , wherein a movement range of the second lens unit in the regeneration process is limited based on the second information. The lens control method according to claim 12 , wherein in the regeneration process, the movement condition is changed so that a movement range of the second lens unit is limited based on the second information.

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