JP2007256977A - Imaging apparatus, and method of controlling same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain a pleasant automatic focusing operation and a zooming operation. <P>SOLUTION: If a target position obtained by an estimating means is beyond the end of a movement range, the moving speed of the first lens group is controlled so that the position of the first lens group after a prescribed time may be located at the end. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an imaging apparatus such as a video camera employing an inner focus type lens system, for example, and more particularly to an imaging apparatus using a linear motor as an actuator for driving a focus lens, and a control method thereof.

  2. Description of the Related Art Conventionally, in an imaging apparatus such as a video camera equipped with a two-dimensional imaging device or the like, the sharpness of a screen displayed based on the video signal is detected using a video signal obtained by photographing a subject, and the detection is performed. A method is adopted in which the focus lens is controlled by controlling the position of the focus lens so that the sharpness is maximized.

  In the evaluation of the sharpness, generally, the intensity of the high frequency component of the video signal extracted by the band pass filter or the blur width detection intensity of the video signal extracted by the differentiation circuit or the like is used. When the subject is normally photographed, the intensity of the image is small when the subject is out of focus, increases when the subject is in focus, and reaches a maximum value when the subject is completely in focus.

  Therefore, when the sharpness is small, the focus lens is moved as quickly as possible in the direction in which the sharpness increases. (Top of the mountain) is controlled so as to stop accurately, that is, in focus.

  The focusing method (autofocus method) by controlling the position of the focus lens as described above is generally called hill-climbing autofocus (hereinafter referred to as “mountain-climbing AF”), which is simplified as the camera becomes smaller and lighter. Since auto focus (AF) can be realized by the system, it has become mainstream in recent video cameras and the like.

  Further, in order to further reduce the size and weight, it is mainstream to use an inner focus lens type lens system 500 as shown in FIG. 13 for a lens system such as a video camera.

  As shown in FIG. 13, the lens system 500 includes a fixed first lens group 501 and a second lens group configured to perform zooming (hereinafter also referred to as a zoom lens or a zoom lens). 502, a stop 503, a fixed third lens group 504, a focus adjustment function, and a fourth lens group (hereinafter referred to as a focus lens) having a function (competing function) for correcting movement of the focal plane due to zooming. 505).

  In the lens system 500, light from a subject (not shown) is charged coupled via the first lens group 501, the variable power lens 502, the stop 503, the third lens group 504, and the focus lens 505 in order. An image is formed on an imaging surface 506 of an imaging element made up of an element (CCD: Charge Coupled Device) or the like.

Here, the focal plane changes depending on the relative positional relationship between the focus lens 505 and the imaging surface 506 in the optical axis direction.
For this reason, for example, the focus lens 505 is used as a movable part, an imaging element having an imaging surface 506 is provided as a fixed part, and the focus lens 505 is moved to perform focusing.
This is because the focus lens 505 is generally configured to be lighter than the above-described image sensor, so that an actuator (not shown) for driving the movable unit for moving the focus lens 505 is provided by using the focus lens 505 as a movable unit. This is because the size and weight can be reduced.

  In the lens system 500 as described above, since the focus lens 505 has both the focus adjustment function and the competition function, the position of the focus lens 505 for focusing on the imaging surface 506 is the same even if the focal length is equal. It depends on the subject distance.

  Therefore, when the subject distance is changed at each focal length, the position of the focus lens 505 for focusing on the imaging surface 506 is continuously plotted, the focal length (variable lens 502 shown in FIG. 14). The relationship between the position Z) and the position P of the focus lens 505 is obtained.

  Therefore, during zooming with the zoom lens 502, the locus shown in FIG. 14 (hereinafter also referred to as a cam locus) is selected according to the subject distance, and the focus lens 505 is moved according to the selected locus. Zoom without blur is possible.

  On the other hand, a compensator lens (front lens) independent of the variable power lens 502 is provided for the inner focus type lens system as described above, and the variable power lens and the compensator are mechanical cam rings. There is a lens system that is coupled in.

In this front-lens focus type lens system, for example, when a knob for manual zoom is provided on the cam ring and the focal length is changed manually, the cam ring rotates following this operation when the knob is moved. The variable power lens and the competition lens move along the cam groove of the cam ring.
Therefore, in this front lens focus type lens system, no matter how fast the knob is moved, as long as the focus lens is in focus, no blur is caused by the operation of the knob as described above.

  However, since the front lens is generally the largest lens, when the front lens is driven by a motor for focusing, the motor drive system becomes large, power consumption increases, and high-speed driving is difficult. Such problems arise.

  On the other hand, since the lens system 500 of the inner focus type described above drives the rear focus lens 505, the lens to be driven (focus lens 505) can be configured to be small and movable for moving the focus lens 505. An actuator (not shown) for part driving can be reduced in size and weight, can be driven at high speed, and optically, the maximum near focal length can be reduced with respect to the subject.

  Such an inner focus type lens system 500 is controlled by, for example, a memory in which information on a plurality of trajectories as shown in FIG. 14 is provided in a lens control microcomputer (hereinafter referred to as a microcomputer). In general, an appropriate trajectory is selected from a plurality of trajectories according to the position P of the focus lens 505 and the position Z of the zoom lens 502, and zooming is performed while following the selected trajectory.

  At this time, when obtaining the position P of the focus lens 505 with respect to the position Z of the zoom lens 502, that is, when reading the information of the position P of the focus lens 505 with respect to the position Z of the zoom lens 502 from the information stored in the memory. In order to use the read information for the control of the lens system 500, it is necessary to perform the read operation with a certain degree of accuracy.

In particular, as apparent from FIG. 14, when the zoom lens 502 moves at a constant speed or a speed close thereto, the inclination of the locus of the focus lens 505 changes every moment due to the change in the focal length.
This indicates that the moving speed and the moving direction of the focus lens 505 change every moment. In other words, the actuator for moving the focus lens 505 has a high accuracy speed from 1 Hz to several hundred Hz. Indicates that you need to respond.

  Therefore, in order to satisfy the above-described requirements, in the inner focus type lens system 500, for example, a stepping motor is mainly used as an actuator for moving the focus lens 505.

  This stepping motor rotates in complete synchronization with the stepping pulse output from the lens control microcomputer as described above, and the stepping angle per pulse is constant. By using such a stepping motor, it is possible to obtain high speed responsiveness, stop accuracy, and position accuracy. Further, since this stepping motor has a constant rotation angle with respect to the number of stepping pulses, the stepping pulse can be used as an incremental encoder as it is, and a special position for detecting the moving state of the focus lens 505. There is an advantage that it is not necessary to provide an additional encoder.

  Hereinafter, a trajectory tracking method used when performing a zoom operation while maintaining a focused state by the stepping motor as described above will be described.

  First, as described above, in the lens control microcomputer, the trajectory information as shown in FIG. 14 is used, for example, the trajectory itself as information, or the function information using the position of the zoom lens 502 as a variable. The trajectory information is read out according to the position or moving speed of the zoom lens 502, and the focus lens 505 is moved based on the read trajectory information.

  Here, FIG. 15 is a diagram for explaining an example of the trajectory tracking method.

  15, z0, z1, z2,..., Z6 indicate the positions of the variable magnification lens 502, and a0, a1, a2,..., A6 and b0, b1, b2,. Represents representative trajectory information (information on the position of the focus lens 505 with respect to the position of the zoom lens 502) stored in the lens control microcomputer.

Further, p0, p1, p2,..., P6 are loci calculated based on two loci of a0, a1, a2,..., A6 and b0, b1, b2,. Show.
The trajectories of p0, p1, p2,..., P6 are
p (n + 1) = | p (n) −a (n) | / | b (n) −a (n) | × | b (n + 1) −a (n + 1) | + a (n + 1) (1)
It is calculated by the following formula (1).

According to the above equation (1), for example, in FIG. 15, when the focus lens 505 exists at p0, a ratio by which p0 internally divides the line segment (b0-a0) is obtained, and the line segment (b1 The point that internally divides -a1) is defined as p1.
The standard moving speed of the focus lens 505 for maintaining the focus can be found from the positional difference of (p1−p0) and the time required for the variable power lens 502 to move from z0 to z6.

  Next, a description will be given of a case where the stop position of the zoom lens 502 is not restricted only on the boundary that owns the stored representative trajectory information.

  FIG. 16 is a diagram for explaining an interpolation method in the position direction of the zoom lens 502. A part of FIG. 15 (broken line portion in FIG. 15) is extracted, and the position of the zoom lens 502 is arbitrarily set. It is a thing.

  In FIG. 16, the vertical axis and the horizontal axis indicate the position of the focus lens 505 and the position of the variable power lens 502, respectively, and representative trajectory information stored in the lens control microcomputer, that is, the variable power lens 502. The position of the focus lens 505 relative to the position is Z0, Z1,..., Zk-1, Zk,..., Zn, and the position of the focus lens 505 at that time is a0, a1,. 1, ak,..., An, and b0, b1,..., Bk-1, bk,.

Now, if the position of the zoom lens 502 is at the position of Zx that is not on the zoom boundary and the position of the focus lens 505 is px, ax and bx are respectively
ax = ak− (Zk−Zx) × (ak−ak−1) / (Zk−Zk−1)
... (2)
bx = bk− (Zk−Zx) × (bk−bk−1) / (Zk−Zk−1)
... (3)
It is calculated | required by Formula (2) and (3) which become.

  That is, according to the internal division ratio obtained from the current position of the zoom lens 502 and two zoom boundary positions (for example, Zk and Zk-1 in FIG. 16), the stored four representative trajectory information ( For example, in FIG. 16 above, among ak, ak-1, bk, and bk-1), those having the same subject distance are internally divided by the internal ratio as shown by the above equation (1), so that px and px -1 can be obtained.

When zooming from wide to tele, the position difference between the position pk of the follow-up focus lens 505 and the current position px of the focus lens 505, and the time required for the zoom lens 502 to move from Zx to Zk. From this, the moving speed of the focus lens 505 for maintaining the in-focus is known.
Further, when zooming from tele to wide, the position difference between the position pk-1 of the follow-up focus lens 505 and the current position px of the focus lens 505, and the zoom lens 502 move from Zx to Zk-1. From the time required for this, the moving speed of the focus lens 505 for maintaining the in-focus state can be known.

  In general, the zoom operation control by the trajectory tracking method as described above is performed in synchronization with a vertical synchronization signal.

  However, in recent years, the zoom speed has increased, and for example, the zoom lens 502 may move to the positions z4 to z6 shown in FIG. 15 in a time within one vertical synchronization period.

  At this time, when lens control is performed in synchronization with the vertical synchronizing signal, the standard moving speed of the focus lens 505 remains at a speed aimed at p4 to p5, and the standard moving speed is reached until the position of the zoom lens 502 reaches z6. Will not be updated. For this reason, when the position of the variable magnification lens 502 is z6, the position of the focus lens 505 is the point p6 ′ on the same straight line of p4 and p5 in FIG. 15, and is blurred by the difference amount of (p6−p6 ′). As a result, an accurate trajectory tracking (tracing) could not be performed during zooming.

  Therefore, in order to solve the above-described problem, the position of the zoom lens 502 after one vertical synchronization period is predicted, and the correction position of the focus lens 505 for correcting the focal plane at the predicted position is determined. There is a method of calculating and controlling the lens so that the focus lens 505 reaches the correction position after one vertical synchronization period.

  In this method, as a driving actuator for the focus lens 505, for example, a linear motor with low driving noise and driving vibration and excellent high-speed performance is used instead of the stepping motor described above.

  First, advantages of using the linear motor as an actuator for driving the focus lens 505 will be described.

  In a camera or the like equipped with the inner focus type lens system 500 as shown in FIG. 13 above, when the variable power lens 502 is moved at a constant speed, the cam locus has a steep inclination in order to maintain the in-focus state. It is necessary to increase the moving speed of the focus lens 505 in the vicinity of the telephoto end. When a stepping motor is used as the actuator, the desired speed is set when the moving speed of the focus lens 505 is set to a desired speed. The speed may exceed the step-out limit speed.

  In order to prevent this, it is common to maintain the in-focus state by reducing the driving speed of the motor for moving the zoom lens 502 while maintaining the stepping motor speed within the step-out limit speed. It is a method that has been adopted.

  However, when a linear motor is used as the actuator, the linear motor is excellent in high-speed driving, so there is no need to decelerate the driving speed of the motor for moving the zoom lens 502, and at the same time at the same speed. Since the moving zoom speed itself can be increased, it is possible to realize an ultra-high speed zoom.

  In addition, when a stepping motor or a DC motor is used as an actuator for driving the focus lens 505, a driving force transmission mechanism that converts a rotational force generated by driving the motor into a driving force for linear movement is necessary for lens driving. For this reason, it is difficult to reduce the size and weight of the mechanism.

  On the other hand, when a linear motor is used, a driving force transmission mechanism becomes unnecessary, and the mechanism can be reduced in size and weight.

  As a linear motor as described above, for example, a lens moving mechanism to which a moving coil type voice coil motor is applied is shown in FIGS.

  Note that FIG. 17B is a cross-sectional view taken along the line BB in FIG.

  In the lens moving mechanism 700 shown in FIGS. 17A and 17B, the yoke 717a and the coil 716 wound around the hobbin 719 are disposed on the outer periphery of the lens holding frame 711 that holds the lenses 701b1 to 701b3, and the yoke 717a. A yoke 717 b and a magnet 715 bonded to the yoke 717 b are disposed outside the coil 716 so that the yokes 717 a and 717 b and the magnet 715 are attached to the fixed cylinder 702.

  The lens holding frame 711 is held so as to be movable in the optical axis direction by two guide bars 703a and 703b parallel to the optical axis.

  Further, the magnet 715 is provided to be magnetized. As a result, a magnetic field is formed in the radial direction between the yokes 717a and 717b.

  Furthermore, the coil 716 exists between the yokes 717a and 717b and is wound in the circumferential direction.

  Accordingly, when a current is passed through the coil 716, a driving force in the optical axis direction is generated, and the lens holding frame 711 and the lenses 701b1 to 701b3 that integrally form the hobbin 719 are driven in the optical axis direction. It becomes.

  An imaging apparatus to which the lens moving mechanism 700 as described above is applied for driving the focus lens 505 in FIG. 13 has a configuration as shown in FIG. 18, for example.

  First, a series of operations of the imaging apparatus 800 will be described.

  First, light (image light) from a subject (not shown) sequentially passes through the first lens group 501, the variable power lens 502, the stop 503, the third lens group 504, and the focus lens 505 in order. An image is formed on the imaging surface 506.

  Video light imaged on the imaging surface 506 is converted into a video signal by photoelectric conversion, amplified to an optimal signal level by an amplifier 807, and supplied to the camera signal processing circuit 808.

  The camera signal processing circuit 808 performs predetermined signal processing on the video signal from the amplifier 807 to generate and output a standard television signal.

  On the other hand, the video signal amplified by the amplifier 807 is also supplied to the AF signal processing circuit 809.

  At this time, the AF frame generation circuit 810 gates a predetermined area of the imaging screen on the imaging surface 506 by a vertical synchronization signal and a horizontal synchronization signal from the timing generator 811 in accordance with AF frame control described later of the AF microcomputer 812. A gate signal is generated for the AF signal processing circuit 809.

  The AF signal processing circuit 809 extracts only the high-frequency component of the video signal in the AF from the video signal from the amplifier 807 by the gate signal from the AF frame generation circuit 810, and generates the AF evaluation signal as described above. Perform processing.

The AF microcomputer 812 performs lens control processing, and adjusts the focus according to the intensity of the AF evaluation signal generated by the AF signal processing circuit 809, and performs the cam locus tracking as described above to adjust the in-focus state. The zoom control to be maintained, the lens drive control such as the motor control for driving the focus lens 505 and the variable power lens 502 at the time of AF and zooming, the AF frame control for changing the distance measurement area, and the like are performed.
Further, the AF microcomputer 812 drives the zoom motor 813 by sending a drive command for the zoom lens 502 to the zoom motor driver 814 in response to a signal indicating the switch state from the zoom switch 823.

  Here, when the zoom motor 813 is a stepping motor as described above, the AF microcomputer 812 determines the drive speed of the zoom motor 813 according to a built-in processing program, and uses the drive speed as a rotation frequency signal, so that the zoom motor This is supplied to a zoom motor driver 814 for driving 813.

Further, the AF microcomputer 812 supplies a drive / stop signal for the zoom motor 813 and a rotation direction command signal to the zoom motor driver 814.
The drive / stop signal and the rotation direction command signal are in accordance with the switch state of the zoom switch 823, and the zoom motor driver 814 has four-phase motor excitation in accordance with the rotation direction command signal from the AF microcomputer 812. The phase of the phase is set to forward rotation and reverse rotation, and the applied voltage or current of the four-phase motor excitation phase is changed according to the drive / stop signal from the AF microcomputer 812 with respect to the zoom motor 813. Output.
As a result, the output from the zoom motor driver 814 to the zoom motor 813 is turned ON / OFF according to the drive / stop signal while the rotation direction and the rotation frequency of the zoom motor 813 are controlled.

  The position of the focus lens 505 is detected by a position encoder 815, and the detection result is subjected to appropriate gain adjustment by an amplification circuit 816 and supplied to a comparison circuit 817.

  At this time, a target signal for moving the focus lens 505 to the target position is supplied from the AF microcomputer 812 to the comparison circuit 817.

  The comparison circuit 817 compares the signal from the amplification circuit 816 with the target signal from the AF microcomputer 812, generates a deviation signal corresponding to the difference between the two signals, and supplies the deviation signal to the integration circuit 818.

  The integration circuit 818 performs integration processing on the deviation signal from the comparison circuit 817 and supplies the integration result to the addition circuit 819.

  At this time, the result obtained by differentiating the detection result of the position encoder 815 by the differentiating circuit 820, that is, the current driving speed information of the focus lens 505 is supplied to the adding circuit 819.

  The addition circuit 819 adds the integration result of the integration circuit 818 and the differentiation result of the differentiation circuit 820, and supplies the addition result to the motor driver 821.

  The motor driver 821 applies a current corresponding to the addition result from the addition circuit 819 to the motor coil 822.

At this time, a reference voltage is applied to one side of the motor coil 822.
For this reason, the motor driver 821 applies a voltage that is positive or negative with respect to the reference voltage to the opposite side of the motor coil 822 (the side to which the reference voltage is not applied). By changing the polarity, the moving direction of the focus lens 505 is changed, and by changing the level of the voltage applied to the motor coil 822, the drive amount of the focus lens 505 is changed.

The loop control is performed as described above. The reason why the driving speed of the focus lens 505 (the differentiation result of the differentiation circuit 820) is fed back by the differentiation circuit 820 is to stabilize the loop control system. Further, by suppressing the rapid movement of the focus lens 505, a natural shot image is obtained, and the focus lens 505 is prevented from colliding with the mechanical member of the imaging apparatus 800 beyond the moving range.
Further, the target signal supplied from the AF microcomputer 812 to the comparison circuit 817 is given in advance a correlation of the level of the target signal output with respect to the position of the focus lens 505, for example, and the correlation is stored in the AF microcomputer 812. As a data table, it is generated by referring to the data table for the position to be moved.

  Next, zoom operation control processing of the AF microcomputer 812 will be described.

  For example, the AF microcomputer 812 performs the zoom operation control process once in one vertical synchronization period in accordance with the flowchart shown in FIG.

Here, FIG. 20 is a flowchart specifically showing the process of step S905 of FIG. 19, and FIG. 21 is a flowchart specifically showing the process of step S1001 of FIG.
FIG. 22 is a flowchart specifically showing the process of step S914 in FIG.

Further, FIG. 23 is a data table TB of cam trajectory information as shown in FIG. 14 stored in the AF microcomputer 812, for example.
In FIG. 23, the focus position of the focus lens 505 that changes depending on the position of the zoom lens 502 for each subject distance is indicated by A (n, v).

As seen in this data table TB, the position of the focus lens 505 (subject distance) changes in the column direction of the variable (subject distance variable) n, and the row direction of the variable (hereinafter also referred to as an area or zoom area variable) v The position (focal length) of the variable magnification lens 502 is changed.
Here, it is assumed that n = 0 is a subject distance at infinity, the subject distance changes to a close distance as n increases, and n = m is a subject distance of 1 cm. On the other hand, v = 0 is the position of the zoom lens 502 at the wide end, the focal length increases as v increases, and v = s is the position of the zoom lens 502 at the tele end. Therefore, one cam locus is drawn by one column of table data.

  Hereinafter, the zoom operation control process of the AF microcomputer 812 will be described with reference to FIGS.

  First, when the zoom operation control process is started by the AF microcomputer 812 (step S901), the switch state of the zoom switch 823 is read (step S902).

Next, it is determined whether or not zooming is being performed according to the state of the switch 823 read in step S902 (step S903). If the zooming is not being performed, control for prohibiting driving of the variable power lens 502 is performed. Then, it is in a standby state until the next vertical synchronization period (step S916).
On the other hand, if the zoom is being performed, the drive speed (hereinafter referred to as zoom speed) Zsp of the zoom motor 813 for zoom operation is set (step S904), and the processing after the next step S905 is performed.

  That is, the shooting distance of the subject being photographed is determined from the current position of the zoom lens 502 and the focus lens 505, and the subject distance information is provided in the AF microcomputer 812 as three trajectory parameters α, β, and γ. The data is stored in a RAM (Random Access Memory) not shown (step S905).

  The processing in step S905 will be specifically described. As shown in FIG. 20, for example, when the in-focus state is maintained at the current lens position, first, the current position Zx of the variable magnification lens 502 is the above-described figure. On the 23 data table TB, it is calculated what number area v is divided into s equally from the wide end to the tele end (step S1001).

  Step S1001 will be described more specifically. First, as shown in FIG. 21, the zoom area variable v is cleared (step S1101).

next,
Z (v) = (zoom position at tele end−zoom position at wide end) × v / s + zoom position at wide end (6)
According to the following formula (6), the position Z (v) of the variable power lens 502 on the boundary of the area v is calculated (step S1102).
This Z (v) corresponds to the positions Z0, Z1, Z2,... Of the variable power lens 502 shown in FIG.

  Next, it is determined whether or not Z (v) calculated in step S1102 is equal to the current position Zx of the variable power lens 502 (step S1103). If they are equal, the current position Zx of the variable power lens 502 is the area v. The boundary flag is set to “1” (step S1107).

  If the determination result in step S1103 is false, it is determined whether or not Z (v) calculated in step S1102 is larger than the current position Zx of the zoom lens 502 (step S1104). For example, the current position Zx of the variable magnification lens 502 is recognized as being between Z (v−1) and Z (v), and the boundary flag is set to “0” (step S1106).

  If the determination result in step S1104 is false, the area v is incremented (v = v + 1), and the process returns to step S1102.

  By repeatedly performing the processes of steps S1101 to S1107 as described above, when the process of step S1001 consisting of steps S1101 to S1107 is exited, the current position Zx of the variable magnification lens 502 is the data table 1200 of FIG. It can be recognized whether it exists in the upper v = kth zoom area and exists on the boundary.

  When the area v is determined by the processing in step S1001 as described above, the position where the position of the focus lens 505 is present on the data table TB in FIG. 23 is obtained in the processing after the next step S1002.

  First, the subject distance variable n is cleared (step S1002).

Next, whether or not the current position Zx of the variable magnification lens 502 exists on the boundary of the area v is determined based on the boundary flag described above (step S1003). Recognizing that it does not exist above, Zk ← Z (v) and Zk−1 ← Z (v−1) are set (step S1005).
Then, the four table data A (n, v−1), A (n, v), A (n + 1, v−1), and A (n + 1, v) are read from the data table TB in FIG. S1006), ax and bx are calculated from the above equations (2) and (3) (step S1007).

  On the other hand, from the determination result of step S1003, if the boundary flag = 1, it is recognized that it exists on the boundary, and from the data table TB in FIG. 23, the subject distance variable n and the in-focus positions A (n, v) and A ( n + 1, v) are read out and set as ax and bx, respectively (step S1016).

  If ax and bx are obtained by the processing in step S1007 or step S1016, it is next determined whether or not the current position Px of the focus lens 505 is greater than or equal to ax (step S1008).

  If the determination result in step S1008 is true, it is determined whether or not the current position Px of the focus lens 505 is greater than or equal to bx (step S1009).

If the determination result in step S1009 is false,
α = Px−ax
(Step S1013),
β = bx−ax
(Step S1014),
γ = n
(Step S1015).

On the other hand, if the determination result in step S1008 is false, it is recognized that the position Px of the focus lens 505 exists infinitely,
α = 0
(Step S1012), the processing of Steps S1014 and S1015 described above is performed and stored as infinite trajectory parameters.

If the determination result in step S1009 is true, it is recognized that the position Px of the focus lens 505 exists on the close side, and the subject distance variable n is incremented (n = n + 1) (step S1010).
Then, it is determined whether or not the subject distance variable n is equal to or less than the closest subject distance m (step S1011). If the determination result is true, the process returns to step S1003.
If the determination result in step S1011 is false, it is recognized that the position Px of the focus lens 505 is extremely close, the above-described processing from step S1012 is performed, and the locus parameter of the closest distance is stored.

  In step S905 including steps S1001 to S1015 as described above, a trajectory parameter indicating where the current positions of the variable power lens 502 and the focus lens 505 exist on the cam trajectory in FIG. 14 is stored. .

Next, the position Zx ′ reached by the variable power lens 502 after one vertical synchronization period is calculated (step S906).
Here, if the zoom speed set in step S904 is Zsp (pps), the position Zx ′ of the zoom lens 502 after one vertical synchronization period is
Zx ′ = Zx ± Zsp / vertical synchronization frequency (7)
It is calculated by the following formula (7).
In the above formula (7), “pps” is a unit indicating the rotation speed of the zoom motor 813, that is, the stepping motor, and indicates a step amount (1 step = 1 pulse) that rotates per second. “±” is “+” in the tele direction and “−” in the wide direction depending on the moving direction of the zoom lens 502.

Next, in which area v ′ the position Zx ′ calculated in step S906 exists is calculated (step S907).
Note that the processing in step S907 is similar to the processing shown in FIG. 20, and in FIG. 20, processing is performed with Zx as Zx ′ and v as v ′.

Next, based on the boundary flag set in step S907, it is determined whether or not the position Zx ′ of the zoom lens 502 after one vertical synchronization period exists on the boundary of the area v ′ (step S908). Based on the determination result, if the boundary flag = 0, it is recognized that it does not exist on the boundary, and Zk ← Z (v ′) and Zk−1 ← Z (v′−1) are set (step S909).
Then, the four table data A (γ, v′−1), A (γ, v ′), A (γ + 1, v′−1), A ( (γ + 1, v ′) is read (step S910), and ax ′ and bx ′ are calculated from the above equations (2) and (3) (step S911).

  On the other hand, from the determination result of step S908, if the boundary flag = 1, it is recognized that the object exists on the boundary, and the in-focus positions A (γ, v ′) and A (γ + 1, v ′) is read out and set as ax ′ and bx ′, respectively (step S912).

When ax ′ and bx ′ are obtained in step S911 or step S912, the in-focus position Px ′ of the focus lens 505 when the variable power lens 502 reaches the position Zx ′ is calculated (step S913).
The in-focus focus position Px ′, that is, the follow-up target position after one vertical synchronization period is expressed by the above equation (1).
Px ′ = (bx′−ax ′) × α / β + ax ′ (8)
It is calculated by the following formula (8).

  Next, the zoom motor driver 814 is controlled so that the zoom motor 813 is driven at the zoom speed set in step S904 (step S914).

  The process of step S914 will be specifically described. First, the zoom motor 813 is driven by performing the process (interrupt process) according to the flowchart of FIG. 22 at an interrupt cycle corresponding to the drive speed. .

  Here, as described above, the zoom lens 502 is driven by supplying a frequency signal corresponding to the driving speed and a direction signal corresponding to the driving direction to the zoom motor 813.

  Therefore, first, when this processing (interrupt processing) is started (step S1201), the current driving state of the variable power lens 502 is determined (step S1202). The driving state of the lens 502 is set again to the stopped state (step S1209), the next interruption cycle is set again (step S1210), and this process is terminated (step S1211).

  Based on the determination result of step S1202, when the variable power lens 502 is in the driving state, that is, during zooming, it is determined whether or not the direction in which the variable power lens 502 should move is the tele direction (step S1203).

  If the result of determination in step S1203 is the tele direction, it is determined whether or not the zoom lens 502 has already reached the tele end (step S1204). If so, it is determined whether or not the zoom lens 502 has already reached the wide end (step S1206).

  If the result of the determination in step S1206 has already reached the wide end, the processing from step S1209 is performed to prohibit the movement of the zoom lens 502. Also, based on the determination result in step S1204, when the telephoto end has already been reached, the processing from step S1209 is similarly performed to prohibit the movement of the zoom lens 502.

On the other hand, if the result of determination in step S1206 has not yet reached the wide end, the zoom motor driver 814 is set in the reverse rotation direction and “1” is subtracted from the position Zx of the zoom lens 502 ( Step S1207).
If the result of determination in step S1204 is that the telephoto end has not been reached, the zoom motor driver 814 is set in the positive rotation direction, and “1” is added to the position Zx of the zoom lens 502 ( Step S1205).

After the processing in step S1207 or step S1205, the logic of the current frequency signal is inverted to output a frequency signal corresponding to the driving speed of the zoom lens 502 to the zoom motor driver 814 (step S1208).
That is, since this process is interrupted in accordance with the drive frequency, the output logic for the zoom motor driver 814 is sequentially inverted in step S1208. Thereby, a pulse train corresponding to the drive frequency is generated, and the zoom motor driver 814 controls the phase of the excitation phase of the zoom motor 813 and rotates the motor in accordance with the switching of the logic of the pulse train and the drive direction state. Accordingly, the variable power lens 502 moves according to the rotation of the motor.

  Then, the next interruption cycle is set again (step S1210), and this process is terminated (step S1211).

When the zoom lens 502 is moved by the process of step S914 including steps S1201 to S1211 as described above, the tracking target position Px after one vertical synchronization period of the focus lens 505 obtained by the above equation (8). A target signal corresponding to 'is supplied to the comparison circuit 817 (step S915).
Thereby, the focus lens 505 reaches the target position at the response speed determined by the loop control described above, and the position is held until the next target position is updated.

  By performing the control process according to the flowchart of FIG. 19 as described above, the movement destination of the zoom lens 502 after one vertical synchronization period is predicted, and the cam locus of the focus lens 505 is matched to the predicted position. Since the follow destination is determined, it is possible to suppress the blur at the time of following the cam locus as described above.

  Next, the AF operation control process of the AF microcomputer 812 will be described.

  For example, the AF microcomputer 812 performs AF operation control processing according to the flowchart shown in FIG.

  In FIG. 24, the drive control of the focus lens 505 is performed by constantly updating the target position of the cam track following destination as described with reference to the flowchart of FIG.

First, when this process is started (step S1301), control is performed to finely drive the focus lens 505 by a wobbling operation, and an AF evaluation signal as described above is fetched to determine whether the focus is currently in focus. Is determined (step S1302).
If it is determined that the image is blurred, it is further determined whether the pin is a front pin or a rear pin.

  Next, based on the result of the wobbling operation in step S1302, it is determined whether or not the focus lens 505 is currently in focus (step S1303).

If it is determined in step S1303 that the subject is in focus, control is performed to stop the focus lens 505, and the process proceeds to a restart monitoring process routine in step S1308 and later described.
On the other hand, if it is determined in step S1303 that the subject is not in focus, the process proceeds to a hill-climbing operation processing routine after step S1304 described later.

  In the hill-climbing operation processing routine, first, in accordance with the result of the blur determined in step S1302, that is, the result of determining whether the pin is the front pin or the rear pin, control of the hill-climbing operation that drives the focus lens 505 in the direction of the blur (Step S1304).

  Next, it is determined whether or not the in-focus point, that is, the vertex of the AF evaluation signal has been exceeded (step S1305). If the result of the determination is that the vertex has not been exceeded, the process returns to step S1304 to control the hill climbing operation. To continue.

  If the result of determination in step S1305 is that the vertex has been exceeded, drive control of the focus lens 505 is performed so that the AF evaluation signal returns to that vertex (step S1306).

  Then, it is determined whether or not the AF evaluation signal has reached the vertex (step S1307). If the determination result shows that the AF evaluation signal has not reached, the process returns to step S1306.

If the AF evaluation signal has reached the apex as a result of the determination in step S1307, the process returns to step S1302.
This is because the subject may change due to panning or the like during the operation of returning the AF evaluation signal to the apex, so if the AF evaluation signal reaches the apex, the current AF evaluation signal is surely This is because the process returns to step S1302 and the wobbling operation is performed again in order to determine whether or not the current position of the focus lens 505 has reached the focal point.

  On the other hand, in the restart monitoring processing routine, first, the signal level of the AF evaluation signal at the time of focusing is stored (step S1308).

Next, it is determined whether or not the signal level of the current AF evaluation signal has changed compared to the signal level of the AF evaluation signal stored in step S1308 at the time of focusing (step S1309).
For example, when the signal level fluctuates by a predetermined percentage or more with respect to the stored signal level, it is recognized that the subject has changed due to panning or the like, and “restart” is determined. If the fluctuation is less than the predetermined percentage, it is recognized that there is no change in the subject, and “non-restart” is determined.

Then, based on the determination result of step S1309, it is determined whether it is “restart” or “non-restart” (step S1310). If it is “non-restart”, the focus lens 505 is stopped as it is. Control is performed (step S1311), and the process returns to the restart determination process of step S1309.
If it is “restart”, the process returns to step S1302, and processing for determining the direction in which step 505 is moved is performed.

  By repeating the processes in steps S1302 to S1311 as described above, the focus lens 505 is driven so that the in-focus state is constantly maintained.

  However, in the imaging apparatus 800 as shown in FIG. 18, that is, the conventional imaging apparatus using a linear motor for driving the focus lens, the hill climbing operation at the time of focus adjustment, the direction determination operation by the wobbling operation, and the mountain top determination In operation, the focus lens is driven at a high speed by the response characteristic of the feedback loop, and the drive is stopped as soon as the target is reached. Therefore, the repetition of the drive state and the stop state appears on the photographing screen. For this reason, with the movement of the focus lens, the shooting screen became ugly and unsightly.

  In particular, even when focus determination is performed with the driving amount of the focus lens within the allowable depth, such as a wobbling operation near the summit near the in-focus point, when the focus lens is switched from the driving state to the stopped state. Due to the high frequency, when the subject that exceeds the permissible depth other than the focused subject distance is mixed in the imaging screen, the repetition of the driving state and the stopping state as described above appears particularly conspicuously on the shooting screen. It was.

  In addition, the larger the amount of movement of the focus lens to be moved, the larger the current energy applied to the linear motor. Therefore, even if the focus lens reaches the movement target position, the movement target position may be overshot. As a result, the time required for the vibration to stabilize at the moving target position is long. For this reason, the focus voltage signal corresponding to the in-focus position is affected by the vibration and may cause a malfunction. In addition, the vibration sometimes appears on the shooting screen as a blur. Further, the position error of the actual arrival position with respect to the movement target position becomes large, and a shift occurs between the recognition of the position of the focus lens by the microcomputer for lens control and the recognition of the position of the actual focus lens. There were problems such as hindering operation.

  Further, in the zoom operation, the focus lens reaches the focus correction position at the predicted position faster than the zoom lens reaches the predicted position after one vertical synchronization period, so that the angle of view change such as low-speed zoom is performed. When shooting without a low-capacity shooting screen, blurring may occur by the difference in arrival time.

  Furthermore, when each lens position is controlled by an actuator with different response characteristics, such as using a linear motor as the actuator for driving the focus lens and using a stepping motor as the actuator for driving the variable power lens, both of them are stopped. It was difficult to determine synchronization such as alignment.

  Specifically, when a stepping motor is used as the actuator for driving the focus lens, the lens movement is performed at an optimum tracking speed according to the inclination of the cam locus. The in-focus state at an arbitrary position of the variable magnification lens can be maintained in accordance with the inclination of the cam locus. On the other hand, when a linear motor or the like is used, the position loop control as described above is performed. Thus, since the moving speed of the focus lens is determined by the response characteristic of the loop, it is difficult to perform control for moving the focus lens at a moving speed according to the inclination of the cam locus.

  That is, in the zoom operation with the linear motor, as described above, the position of the zoom lens approaches the in-focus direction within one vertical synchronization period after the focus lens reaches the movement target position in advance. Although the blur time is short and does not appear on the shooting screen, the zoom lens position is faster than when the position of the zoom lens reaches the predicted position after one vertical synchronization period. In this case, the movement of the zoom lens is prohibited before one vertical synchronization period elapses, so that the focus lens does not move closer to the predicted position. Since the focus correction position has already been reached, the blur time becomes longer, and an unacceptable blur occurs when the zoom end is reached.

  In this way, the zoom operation with a linear motor can realize high-speed zoom by taking advantage of the high speed of the linear motor, but on the other hand, due to the difference in response with actuators for driving different types of variable magnification lenses, It has been difficult to determine synchronization such as stop position alignment of both the focus lens and the variable power lens.

  Therefore, the present invention has been made to eliminate the above-described problems. Even when the lens position is controlled by a linear motor, the pseudo-speed control can be performed, so that a comfortable autofocus operation or The purpose is to realize a zoom operation.

  It is another object of the present invention to realize a comfortable zoom operation by correcting a shift in response even when lens position control is performed by an actuator having different response characteristics such as a linear motor and a stepping motor.

Accordingly, the present invention provides a first lens group for performing a zooming operation, a first driving means for moving the first lens group, and a movement of a focal plane when the first lens group is moved. In order to correct the above, the second lens group and the image sensor, one of which is a movable part, movable part position detecting means for detecting the position of the movable part, and moving the movable part on the optical axis Second driving means for moving the movable part by supplying a drive signal to the actuator to be operated, and storage means for storing the in-focus position of the movable part with respect to the position of the first lens group in accordance with the subject distance , A predicting means for predicting the destination position of the first lens group after a predetermined time during zooming operation, and the focal plane at the destination position obtained by the predicting means is corrected by the information in the storage means. For calculating the correction position of the movable part for And a position control means for controlling the position of the movable part so as to reach the correction position obtained by the calculation means after the predetermined time, and the destination obtained by the prediction means When the position exceeds the end position of the movable range, the moving speed of the first lens group is controlled so that the position of the first lens group after the predetermined time becomes the end position. And
According to the present invention, in zooming operation, a position where the position of the first lens group is moved after a predetermined time (for example, after one vertical synchronization period) is predicted, and the first lens group is movable at the predicted position. When the predicted position exceeds the movable range of the first lens group during an operation (zooming operation) in which the in-focus position is set as the movement target position after a predetermined time, the first lens group after the predetermined time is moved. Since the moving speed of the first lens group can be decelerated so that the position corresponds to the end position, the blur at the time of reaching the end position (zoom end) can be inexpensively provided without providing a special circuit. Can be reduced. Therefore, even when the lens position is controlled by an actuator having different response characteristics, such as a linear motor and a stepping motor, a comfortable zoom operation can be realized by correcting the shift in response.
Further, the present invention provides a first lens group for performing a zooming operation, a first driving means for moving the first lens group, and a movement of a focal plane when the first lens group is moved. In order to correct the above, the second lens group and the image sensor, one of which is a movable part, movable part position detecting means for detecting the position of the movable part, and moving the movable part on the optical axis A second drive unit that moves the movable unit by supplying a drive signal to the actuator to be stored, and a storage unit that stores the in-focus position of the movable unit with respect to the position of the first lens group according to the subject distance And control means for controlling the position of the movable part for correcting the movement of the focal plane accompanying the change in the position of the first lens group during the zooming operation based on the information in the storage means, When the zooming operation is stopped, the first lens Characterized by the in-focus position in the stop position to forcibly move said movable portion.
According to the present invention, in the zooming operation, when the zoom operation is stopped due to the first lens group reaching the end position (zoom end) of the movable range, the stop position of the first lens group. Since the movable portion is forcibly driven at a high speed to the in-focus position, it is possible to prevent the photographer from noticing the amount of blur when zooming stops. Therefore, even when the lens position is controlled by an actuator having different response characteristics, such as a linear motor and a stepping motor, a comfortable zoom operation can be realized by correcting the shift in response.
In addition, the present invention provides a first lens group for performing a zooming operation and a second lens in which either one is a movable part in order to perform focus adjustment and focal plane correction during the zooming operation. And a first and second control means for controlling the positions of the first lens group and the movable portion in order to move the first lens group and the movable portion in the optical axis direction, respectively, and at least the first lens group. When the position is in a predetermined area, the control cycle in the second control unit is shorter than the control cycle in the first control unit.
According to the present invention, even in a system that performs position control of the first lens group in zooming operation, at least while performing pseudo position control by performing fine position control, Since the position of the first lens group is within a predetermined region and the control cycle for fine position control of the movable part is made faster than the control cycle for position control of the first lens group, the competition operation and the like are facilitated. In addition, even if the first lens group suddenly stops at an arbitrary position while realizing improved quality, the movable part can be stopped instantaneously while maintaining the in-focus state, thereby eliminating the occurrence of blurring. It becomes possible. Therefore, even when the lens position is controlled by an actuator having different response characteristics, such as a linear motor and a stepping motor, a comfortable zoom operation can be realized by correcting the shift in response.
According to the present invention, any one of the second lens group and the image sensor that are movable parts for correcting the movement of the focal plane during the movement of the first lens group for performing the zooming operation is described above. It is moved by an actuator on the optical axis formed by the second lens group and the image sensor, and the movement destination position of the first lens group after a predetermined time is predicted at the time of zooming operation, and the position relative to the position of the first lens group is predicted. Using the memory that stores the in-focus position of the movable part according to the subject distance, the correction position of the movable part for correcting the focal plane at the predicted movement destination position of the first lens group is calculated, and An imaging apparatus control method for controlling the position of the movable part so that the calculated correction position is reached after the predetermined time, wherein the predicted movement destination position of the first lens group is an end of the movable range. If it exceeds the position, Position of the first lens group of the later so that the end position, and controlling the moving speed of the first lens group.
According to the present invention, in zooming operation, a position where the position of the first lens group is moved after a predetermined time (for example, after one vertical synchronization period) is predicted, and the first lens group is movable at the predicted position. When the predicted position exceeds the movable range of the first lens group during an operation (zooming operation) in which the in-focus position is set as the movement target position after a predetermined time, the first lens group after the predetermined time is moved. Since the moving speed of the first lens group can be decelerated so that the position corresponds to the end position, the blur at the time of reaching the end position (zoom end) can be inexpensively provided without providing a special circuit. Can be reduced. Therefore, even when the lens position is controlled by an actuator having different response characteristics, such as a linear motor and a stepping motor, a comfortable zoom operation can be realized by correcting the shift in response.
According to the present invention, any one of the second lens group and the image sensor that are movable parts for correcting the movement of the focal plane during the movement of the first lens group for performing the zooming operation is described above. It is moved by an actuator on the optical axis formed by the second lens group and the image sensor, and the movement destination position of the first lens group after a predetermined time is predicted at the time of zooming operation, and the position relative to the position of the first lens group is predicted. Position control of the movable part for correcting the movement of the focal plane due to the position change of the first lens group during zooming operation by the memory storing the in-focus position of the movable part according to the subject distance. A method for controlling an imaging apparatus, wherein the movable portion is forcibly moved to a focus position at a stop position of the first lens group when a zooming operation is stopped.
According to the present invention, in the zooming operation, when the zoom operation is stopped due to the first lens group reaching the end position (zoom end) of the movable range, the stop position of the first lens group. Since the movable portion is forcibly driven at a high speed to the in-focus position, it is possible to prevent the photographer from noticing the amount of blur when zooming stops. Therefore, even when the lens position is controlled by an actuator having different response characteristics, such as a linear motor and a stepping motor, a comfortable zoom operation can be realized by correcting the shift in response.
The present invention also includes any one of the first lens group for performing a zooming operation, the second lens group serving as a movable unit for performing focus adjustment and focal plane correction during the zooming operation, and an image sensor. One of the methods is a control method for an imaging apparatus that performs position control to move each of the first lens group in the optical axis direction, and when the position of at least the first lens group exists in a predetermined region, The control period of the movable portion is shorter than the control period of the lens group.
According to the present invention, even in a system that performs position control of the first lens group in zooming operation, at least while performing pseudo position control by performing fine position control, Since the position of the first lens group is within a predetermined region and the control cycle for fine position control of the movable part is made faster than the control cycle for position control of the first lens group, the competition operation and the like are facilitated. In addition, even if the first lens group suddenly stops at an arbitrary position while realizing improved quality, the movable part can be stopped instantaneously while maintaining the in-focus state, thereby eliminating the occurrence of blurring. It becomes possible. Therefore, even when the lens position is controlled by an actuator having different response characteristics, such as a linear motor and a stepping motor, a comfortable zoom operation can be realized by correcting the shift in response.

  According to the present invention, a comfortable autofocus operation and zoom operation can be realized. Moreover, according to the present invention, a comfortable zoom operation can be realized.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  First, the first embodiment will be described.

The imaging apparatus control method according to the present invention is implemented by, for example, an imaging apparatus 100 as shown in FIG.
The imaging apparatus 100 is an example of an apparatus to which the imaging apparatus or the lens control apparatus according to the present invention is applied. Various processing programs built in the microcomputer 112 (to be described later) of the imaging apparatus 100 are related to the present invention. A storage medium is applied.

  As shown in FIG. 1, the imaging apparatus 100 includes a fixed first lens group 101, a second lens group (variable lens) 102 configured to perform zooming, a diaphragm 103, and a fixed lens unit. An inner focus type lens system including a third lens group 104, a focus adjustment function, and a fourth lens group (focus lens) 105 having a function (competition function) for correcting movement of the focal plane due to zooming is adopted. ing.

  In addition, the imaging apparatus 100 includes an imaging element 106 on which image light is imaged via the lens system, an amplifier 107 to which an output of the imaging element 106 is supplied, and camera signal processing to which an output of the amplifier 107 is supplied. Circuit 108, aperture control circuit 128 and AF signal processing circuit 109, lens control microcomputer 112 to which the output of the AF signal processing circuit 109 is supplied, timing generator 111, and AF frame to which the output of the timing generator 111 is supplied The output of the AF frame generation circuit 110 is supplied to the AF signal processing circuit 109, the output of the microcomputer 112 is supplied to the AF frame generation circuit 110, and the camera signal processing circuit is provided. A video signal obtained by photographing from 108 is output.

  Further, the imaging apparatus 100 includes a position encoder 127 that detects a position state of the focus lens 105, an amplification circuit 120 and a differentiation circuit 123 to which outputs of the position encoder 127 are supplied, and outputs of the amplification circuit 120 and the microcomputer 112, respectively. The supplied comparison circuit 121, the integration circuit 122 to which the output of the comparison circuit 121 is supplied, the addition circuit 124 to which the outputs of the differentiation circuit 123 and the integration circuit 122 are supplied, and the output of the addition circuit 124 are supplied. The motor driver 125 and the motor 126 for the focus lens 105 to which the output of the motor driver 125 is supplied are provided, and the output of the position encoder 127 is also supplied to the microcomputer 112.

  Furthermore, the imaging apparatus 100 is supplied with a motor driver 118 to which the output of the microcomputer 112 is supplied, a motor 117 for the variable power lens 102 to which the output of the motor driver 118 is supplied, and an output of the aperture control circuit 128. An iris driver 130 and an IG meter 129 to which the output of the iris driver 130 is supplied are provided.

  First, a series of operations of the imaging apparatus 100 as described above will be described.

  Light (image light) from a subject (not shown) is picked up by a CCD or the like through a first lens group 101, a variable power lens 102, a diaphragm 103, a third lens group 104, and a focus lens 105 in this order. An image is formed on the imaging surface of the element 106, converted into a video signal by photoelectric conversion in the imaging element 106, and supplied to the amplifier 107.

  The amplifier 107 amplifies the video signal from the image sensor 106 to an optimal signal level and supplies the amplified signal to the camera signal processing circuit 108.

  The camera signal processing circuit 108 performs predetermined signal processing on the video signal from the amplifier 107, generates a standard television signal, and outputs the standard television signal, for example, to a display unit or a recording unit (not shown).

  On the other hand, the video signal amplified by the amplifier 107 is also supplied to the AF signal processing circuit 109 and the aperture control circuit 128, respectively.

  The diaphragm control circuit 128 drives and controls the IG meter 129 via the iris driver 130 according to the level of the video signal from the amplifier 107. Thereby, the light quantity adjustment in the diaphragm 102 is performed.

  At this time, the AF frame generation circuit 110 gates a predetermined area of the imaging screen on the surface of the imaging element 106 by a vertical synchronization signal and a horizontal synchronization signal from the timing generator 111 according to AF frame control described later of the microcomputer 112. Are generated for the AF signal processing circuit 109.

  The AF signal processing circuit 109 performs processing for generating only an AF evaluation signal by extracting only a high-frequency component of the video signal in the AF from the video signal from the amplifier 107 using the gate signal from the AF frame generation circuit 110. .

  The microcomputer 112 is an AF microcomputer for lens control, for example, an AF program 113 for performing focus adjustment according to the intensity of the AF evaluation signal generated by the AF signal processing circuit 109, and focusing while following the cam locus. Zoom control program 114 for maintaining the state, lens cam data 115 referred to when following the cam locus, zoom motor control program 116 for driving the variable magnification lens 102 during zooming, and driving the focus lens 105 during AF And a focus control program 119 for performing lens drive control, AF frame control for changing the distance measurement area, and the like.

  Various processing programs such as the AF program 113, the zoom control program 114, the lens cam data 115, the zoom motor control program 116, and the focus control program 119 are stored in, for example, a ROM (Read Only Memory) connected to the outside of the apparatus. It is good to do.

  Further, the microcomputer 112 is supplied with information on the switch states of the zoom switch 131 and the AF switch 132 provided in the apparatus, and based on the switch state information, various programs as described above are provided. By executing the above, various control processes such as lens drive control and AF frame control are performed.

  Therefore, the microcomputer 112 supplies a drive command for the variable power lens 102 to a motor driver (hereinafter referred to as a zoom motor driver) 118 in accordance with the switch state of the zoom switch 131, so A motor (hereinafter referred to as a zoom motor) 117 is driven.

  Here, the zoom motor 117 is composed of, for example, a stepping motor, and the microcomputer 112 determines the drive speed of the zoom motor 117 by executing the zoom motor control program 116, and the determined drive speed is rotated by the motor. It is supplied to the zoom motor driver 118 as a frequency signal.

In addition, the microcomputer 112 supplies a drive / stop signal for the zoom motor 117 and a rotation direction command signal to the zoom motor driver 118.
The drive / stop signal and the rotation direction command signal are in accordance with the switch state of the zoom switch 131, and the zoom motor driver 118 has four motor excitation phases in accordance with the rotation direction command signal from the microcomputer 112. Are set to forward and reverse rotation phases, and output to the zoom motor 117 while changing the applied voltage or current of the four-phase motor excitation phase in accordance with the drive / stop signal from the microcomputer 112. .
Thus, the output from the zoom motor driver 118 to the zoom motor 117 is turned ON / OFF according to the drive / stop signal while the rotation direction and the rotation frequency of the zoom motor 117 are controlled.

  The position of the focus lens 105 is detected by the position encoder 127, and the detection result is appropriately adjusted by the amplifier circuit 120 and supplied to the comparison circuit 121.

  At this time, the target signal for moving the focus lens 105 to the target position is supplied from the microcomputer 112 to the comparison circuit 121.

  The comparison circuit 121 compares the signal from the amplifier circuit 120 with the target signal from the microcomputer 112, generates a deviation signal corresponding to the difference between the two signals, and supplies the deviation signal to the integration circuit 122.

  The integration circuit 122 performs an integration process on the deviation signal from the comparison circuit 121 and supplies the integration result to the addition circuit 124.

  At this time, the result obtained by differentiating the detection result of the position encoder 127 by the differentiation circuit 123, that is, the current drive speed information of the focus lens 105 is supplied to the addition circuit 124.

  The addition circuit 124 adds the integration result of the integration circuit 122 and the differentiation result of the differentiation circuit 123 and supplies the addition result to the motor driver 125.

  The motor driver 125 applies a current corresponding to the addition result from the addition circuit 124 to the motor 126.

The motor 126 is a linear motor such as a moving coil type voice coil motor, for example, and drives the focus lens 105 by a moving mechanism as shown in FIGS. 17A and 17B. Yes.
That is, a reference voltage is applied to one side of the motor (motor coil) 126, and the motor driver 125 is positive or negative with respect to the reference voltage on the opposite side (the side to which the reference voltage is not applied) of the motor coil 126. By switching the polarity of the current flowing through the motor coil 126 by applying a negative voltage, the moving direction of the focus lens 105 is changed, and the level of the voltage applied to the motor coil 126 is changed. The driving amount of the focus lens 105 is changed.

The loop control is performed as described above. The reason why the driving speed of the focus lens 105 (the differentiation result of the differentiation circuit 123) is fed back by the differentiation circuit 123 is to stabilize the loop control system. Further, by suppressing the sudden movement of the focus lens 105, a natural shot image is obtained and the focus lens 105 is prevented from colliding with the mechanical member of the image pickup apparatus 100 beyond the moving range.
Further, the target signal supplied from the microcomputer 112 to the comparison circuit 121 is given in advance a correlation of the level of the target signal to be output with respect to the position of the focus lens 105, for example. The data is stored as a table and is generated by referring to the data table for the position to be moved.

  Next, drive control of the focus lens 105 in the AF mode will be described.

  The imaging apparatus 100 applies the present invention to a steady movement operation of the focus lens 105 such as a hill climbing operation, and the focus lens 105 is controlled so that the average movement speed of the focus lens 105 becomes a predetermined speed in the AF mode. A driving motor coil 126, that is, a linear motor is driven.

  Therefore, for example, the focus control program 119 includes a processing program according to the flowchart of FIG. 24 described above, and this processing program is executed by the microcomputer 112. The processing contents of step S1304 (mountain climbing operation) and step S1306 (operation to return to the summit) are significantly different from the conventional ones.

FIG. 2 is a flowchart specifically showing the process of step S1304 here, and the process of step S1306 is the same as step S1304 according to the flowchart of FIG.
FIG. 3 is a flowchart showing processing for generating a target signal supplied from the microcomputer 112 to the comparison circuit 121.

  Note that the processing steps before and after Step S1304 and Step S1306 are as described above, and thus detailed description thereof will be omitted.

  First, as shown in FIG. 2, the AF evaluation signal (focus voltage signal) at the current position of the focus lens 105 is captured (step S1401), and whether the signal level of the captured AF evaluation signal is greater than the threshold value A. It is determined whether or not (step S1402).

  If the signal level of the AF evaluation signal is higher than the threshold value A based on the determination result in step S1402, it is determined whether the signal level of the AF evaluation signal is higher than the threshold value B (step S1403).

  From the determination result of step S1403, when the signal level of the AF evaluation signal is higher than the threshold value B, that is, when the signal level of the AF evaluation signal is higher than the threshold values A and B, the focus is almost in the vicinity of the top of the mountain. Recognizing that the state (small blur) is present, the processing of step S1404 described later is performed.

  If the signal level of the AF evaluation signal is not higher than the threshold value B, that is, if the signal level of the AF evaluation signal is higher than the threshold value A but lower than B, the result of the determination in step S1403 is In step S1405, which will be described later, a middle blur is recognized.

  If the signal level of the AF evaluation signal is not greater than the threshold value A from the determination result in step S1402, it is recognized that the current focus lens 105 is in a large blur state at the base of the mountain, and will be described later. The process of step S1406 is performed.

Here, as the hill climbing operation described above, it is desirable to control the moving speed of the focus lens 105 so that the position of the focus lens 105 moves as fast as possible near the base of the mountain.
In this case, the shooting screen is in a blurred state, and the movement of the focus lens 105 is not visible.

  Further, it is desirable to control the moving speed of the focus lens 105 so that the moving speed is decelerated so that the movement of the focus lens 105 does not appear on the photographing screen as it approaches the peak.

  According to the determination results of step S1402 and step S1403, in the case of a large blurred state, the moving speed Vf per unit time of the focus lens 105 is set to the highest response speed Vfmax (step S1406). The moving speed Vf is set to Vfmax / 2 (step S1405), and in the case of a small blur, the moving speed Vf is set to Vfmax / 4 (step S1404).

  After completion of the processing of each step as described above, the process proceeds to step S1305 or step S1307 in FIG. 24, and the processes in steps S1401 to S1406 in FIG. 2 are repeated until the mountain is reached or the mountain top is returned. Thus, the speed control of the focus lens 105 is performed according to the signal level of the AF evaluation signal.

  While the process according to the flowchart of FIG. 2 is performed, the position of the focus lens 105 is updated by the process according to the flowchart of FIG.

  Here, for example, the processing of FIG. 2 is performed 60 times per unit time (in the case of the NTSC system) in synchronization with the vertical synchronization period, whereas the processing cycle of FIG. Assume that n times per unit time in a faster processing cycle.

First, when this process is started (step S1407), the movement amount ΔF of the focus lens 105 per process is calculated (step S1408).
This moving amount ΔF is obtained by using the moving speed Vf of the focus lens 105 per unit time obtained by the processing of FIG.
ΔF = Vf / n (9)
This is calculated by the following formula (9).

Next, assuming that the current position of the focus lens 105 is F0, the target position Fx to be moved is
Fx = F0 ± ΔF (10)
This is calculated by the following equation (10) (step S1409).
Here, the sign “±” in the equation (10) is “+” for driving in the closest direction and “−” for driving in the infinite direction. The driving direction to be moved is obtained from the result of the wobbling operation in the process according to the flowchart of FIG. 24 or the direction to return to the peak of the mountain.

  Accordingly, the drive voltage signal corresponding to the target position Fx obtained in step S1409 is supplied from the microcomputer 112 to the comparison circuit 121, whereby the focus lens 105 is moved by the feedback loop configuration.

  By repeatedly performing the processing of steps S1407 to S1409 as described above, the moving speed of the focus lens 105 per time becomes a moving speed determined by the feedback loop characteristics. For example, in units of one vertical synchronization period The average moving speed corresponds to the moving speed Vf obtained by the process of FIG.

  Therefore, even when a linear motor is used as the motor 126 for driving the focus lens 105, pseudo speed control of the focus lens 105 is performed, and a smooth focus adjustment operation can be performed.

  Next, a second embodiment will be described.

  In the above-described first embodiment, the example in which the present invention is applied to the steady movement operation of the focus lens 105 such as a hill-climbing operation in the imaging apparatus 100 of FIG. 1 has been described. In the embodiment, an example in which the present invention is applied to a wobbling operation in the case where the moving amount of the focus lens 105, that is, the moving amount corresponding to the amplitude in the wobbling operation is determined in the imaging apparatus 100 of FIG. 1 will be described.

  First, similarly to the above-described first embodiment, for example, the focus control program 119 includes a processing program according to the above-described flowchart of FIG. 24, and this processing program is executed by the microcomputer 112. However, here, the processing content of step S1302 of the flowchart is greatly different from the conventional one.

FIG. 4 is a flowchart specifically showing the process in step S1302.
FIG. 5 is a flowchart showing the position control processing of the focus lens 105 during the wobbling operation. A processing program according to this flowchart is also included in the focus control program 119 and is executed by the microcomputer 112. Has been made.

  Here, before explaining the wobbling operation in the second embodiment with reference to FIG. 4 and FIG. 5, the wobbling operation and the amplitude thereof will be explained with reference to FIG.

FIG. 6 shows a state 1701 of the change in the signal level of the AF evaluation signal obtained when the focus lens 105 is moved from infinity to the nearest point with respect to an arbitrary subject.
In FIG. 6, the horizontal axis indicates the position of the focus lens 105, and the vertical axis indicates the signal level of the AF evaluation signal.

The in-focus point is a point 1702 where the signal level of the AF evaluation signal becomes the maximum level, and the position of the focus lens 105 is controlled so that the signal level of the AF evaluation signal always becomes the maximum level. Yes.
Note that the position of the focus lens 105 at the point 1702 where the signal level of the AF evaluation signal is the maximum level is the in-focus position 1708.

  Therefore, the wobbling operation is performed when determining whether the in-focus point is in the closest direction or the infinite direction.

  That is, in the wobbling operation, when the focus lens 105 is finely driven and an AF evaluation signal is taken in, whether the current focus state is in focus, or the subject is out of focus, or further out of focus, This is an operation for determining which of the rear pins.

  For example, when the current position of the focus lens 105 is on the infinite side with respect to the focal point (position 1709), a wobbling operation is executed, and the focus lens 105 is finely driven from the closest direction, that is, as indicated by 1703. When the position of the focus lens 105 is moved (the time axis is from top to bottom with respect to the paper surface), the AF evaluation signal obtained at that time becomes 1704.

  On the other hand, when the current position of the focus lens 105 is closer to the focal point (position 1710), as shown by 1705, when the focus lens 105 is finely driven, the AF evaluation signal obtained at that time is 1706. It becomes like this.

  Accordingly, since the phases are reversed in each of the states 1704 and 1706, the moving direction of the focus lens 105 where the in-focus point exists can be recognized by determining the phase.

  Further, when the focus lens 105 is finely driven at the top of the peak 1701 as indicated by 1711, the amplitude of the AF evaluation signal obtained at that time becomes small as indicated by 1712 and the shape thereof is different. You can recognize whether you are in focus or in focus.

Here, in the wobbling operation in the vicinity of the in-focus state, blurring may occur depending on the drive amplitude amount α that drives the focus lens 105 minutely. Therefore, the minimum amplitude amount that can sufficiently obtain the signal level of the AF evaluation signal is necessary. There is.
On the other hand, in the vicinity of the base of the mountain 1701, even if the focus lens 105 is finely driven, a signal level of the AF evaluation signal sufficient to determine the direction may not be obtained, so the drive amplitude of the focus lens 105 is increased. It is desirable to make it.

  The speed of the wobbling operation as described above is also an important parameter for performing the wobbling operation invisible.

  More specifically, first, when a plurality of subjects having different subject distances are present in the shooting screen, other subjects may be in a small blur state even when the main subject is in focus. This occurs particularly on the wide side.

Even if the amplitude at this time is minimized and the amount of amplitude is within the depth of field, the subject in the small blur state is out of the allowable depth, so that the wobbling operation is visible.
In particular, when the wobbling operation is performed at a high speed, the change in the blur of the subject in the small blur state becomes high speed, so that the wobbling operation becomes very easy to see.

Therefore, when a plurality of subjects are likely to be mixed, as in wide-angle shooting, etc., and any subject distance is focused to some extent and the signal level of the AF evaluation signal increases, the wobbling operation speed is reduced. Longer micro drive cycle leads to improved quality.
At this time, the determination of the in-focus direction is also delayed due to the delay of the wobbling operation cycle. However, in wide-angle shooting, etc., since every subject appears to be in focus to some extent, high-speed focusing is necessary. There is no sex.

  On the premise of the wobbling operation as described above, the wobbling operation in the second embodiment will be described using FIG. 4 and FIG.

  Note that the processing steps before and after step S1302 in FIG. 4 are as described above, and thus detailed description thereof is omitted.

  First, as shown in FIG. 4, an AF evaluation signal is captured (step S1501), and it is determined whether or not the signal level of the captured AF evaluation signal is greater than a threshold value A (step S1502).

  If the signal level of the AF evaluation signal is larger than the threshold value A based on the determination result in step S1502, it is determined whether or not the signal level of the AF evaluation signal is higher than the threshold value B (step S1503).

  From the determination result of step S1503, when the signal level of the AF evaluation signal is higher than the threshold value B, that is, when the signal level of the AF evaluation signal is higher than the threshold values A and B, the focus is almost in the vicinity of the top of the mountain. Recognizing that the state is small (small blur), the processing of step S1504 described later is performed.

  If the signal level of the AF evaluation signal is not higher than the threshold value B, that is, if the signal level of the AF evaluation signal is higher than the threshold value A but lower than B, the result of the determination in step S1503 is In step S1505, which will be described later, a middle blur is recognized.

  If the signal level of the AF evaluation signal is not greater than the threshold value A from the determination result in step S1502, it is recognized that the current focus lens 105 is in a large blurred state at the base of the mountain, and will be described later. The process of step S1506 is performed.

According to the determination results of steps S1502 and S1503, in the case of a large blurring state, the moving speed Vf per unit time of the focus lens 105 is set to the highest response speed Vfmax, and the amplitude α for the wobbling operation is set to The amplitude is equivalent to twice the depth of field δ according to the state (step S1506).
Note that the depth of field δ is a value at which no blur appears even if the position of the focus lens 105 is moved from the focal point by 1δ.

  In the case of the medium blurring state, the moving speed Vf is set to Vfmax / 2, and the amplitude α is set to the depth of field δ (step S1505).

  In the case of the small blurring state, the moving speed Vf is set to Vfmax / 4, and the amplitude α is set to an amplitude corresponding to half of the depth of field δ (step S1504).

  Here, the speed is set according to the signal level of the AF evaluation signal. However, if the speed is set by adding the focal length as a parameter, it is easier to optimize any subject.

  After the processing of step S1504, step S1505, or step S1506 as described above, the current wobbling operation has been made via step S1307 in FIG. 24, or has been made through step S1310 in FIG. Is determined (step S1507).

As a result of the determination in step S1507, only when the signal passes through step S1307, that is, only when the signal level of the AF evaluation signal has reached the vertex, the moving speed Vf of the focus lens 105 is halved ( Step S1508), the processing after Step S1509 described later is performed.
If the determination result in step S1507 indicates that the signal has passed through step S1310, that is, if the signal level of the AF evaluation signal has not reached the apex, the processing from step S1509 onward is performed as it is. .

  The processing after step S1509 is processing for finely driving the focus lens 105 described with reference to FIG.

First, the movement destination F1 of the focus lens 105 obtained by adding the amplitude amount α of the wobbling operation to the current position F0 of the focus lens 105,
F1 = F0 + α (11)
(11) is calculated (step S1509).

  Next, the focus lens 105 is driven in the closest direction (step S1510).

  Next, it is determined whether or not the current position F0 of the focus lens 105 has reached the movement destination F1 calculated in step S1509 (step S1511). If the determination result indicates that the movement destination F1 has not been reached. Return to step S1510 to drive the focus lens 105 in the closest direction.

If the current position F0 of the focus lens 105 has reached the movement destination F1 calculated in step S1509, that is, if driven by the amplitude amount α of the wobbling operation based on the determination result in step S1511, the AF evaluation signal at that time Is stored in a memory Dn (not shown) inside the microcomputer 112 as driving data in the nearest direction, and the movement destination F1 of the focus lens 105 in the next infinite direction is
F1 = F0-2α (12)
This is calculated by the following equation (12) (step S1512).

  Next, the focus lens 105 is driven in an infinite direction (step S1513).

  Next, it is determined whether or not the current position F0 of the focus lens 105 has reached the movement destination F1 set in step S1512 (step S1514). If the determination result indicates that the movement destination F1 has not been reached. Returns to step S1513 to drive the focus lens 105 in an infinite direction.

As a result of the determination in step S1514, if the current position F0 of the focus lens 105 has reached the movement destination F1 set in step S1512, that is, if it is driven by the amplitude amount 2α of the wobbling operation, the AF at that time In order to store the signal level of the evaluation signal in the memory Df (not shown) inside the microcomputer 112 as driving data in an infinite direction and to return to the position of the focus lens 105 before starting the wobbling operation,
F1 = F0 + α (13)
It calculates and resets by the following formula (13) (step S1515).

  Then, the focus lens 105 is driven again in the closest direction (step S1516).

  Next, it is determined whether or not the current position F0 of the focus lens 105 has reached the movement destination F1 calculated in step S1515 (step S1517). If the determination result indicates that the movement destination F1 has not been reached. Return to step S1516 to drive the focus lens 105 in the closest direction.

  If the current position F0 of the focus lens 105 has reached the movement destination F1 calculated in step S1515 based on the determination result in step S1517, that is, if it is driven by the amplitude amount α of the wobbling operation, the AF evaluation signal at that time Is stored in the memory Dc (not shown) inside the microcomputer 112 as the first position data of the focus lens 105 (step S1518), the process is terminated, and the process proceeds to step S1303 in FIG.

  Accordingly, in steps after step S1303 in FIG. 24, the hill-climbing direction determination process and the focus determination process are performed based on the signal level of each AF evaluation signal stored in the memories Dn, Df, Dc. .

  Further, while the process according to the flowchart of FIG. 4 is performed, the movement of the position of the focus lens 105 is performed by the process according to the flowchart of FIG.

  The process according to the flowchart of FIG. 5 is synchronized with the vertical synchronization period 60 times per unit time (in the case of the NTSC system), for example, as in the process according to the flowchart of FIG. On the other hand, it is performed n times per unit time in a processing cycle faster than the processing cycle of FIG.

  First, when this process is started (step S1519), it is determined whether or not the target position Fx of the focus lens 105 to be moved is already equal to the movement destination F1 (step S1520).

  If the target position Fx is equal to the movement destination F1 based on the determination result in step S1520, the standby state is set until the next control cycle.

When the target position Fx is not equal to the movement destination F1 based on the determination result in step S1520, the movement amount ΔF of the focus lens 105 per process is calculated (step S1521).
This moving amount ΔF is obtained by using the moving speed Vf of the focus lens 105 per unit time obtained by the processing of FIG.
ΔF = Vf / n (14)
It calculates with the type | formula (14) which becomes.

Next, assuming that the current position of the focus lens 105 is F0, the target position Fx to be moved is
Fx = F0 ± ΔF (15)
This is calculated by the following equation (15) (step S1522).
Here, the sign “±” in the above equation (15) is “+” for driving in the closest direction and “−” for driving in the infinite direction. The driving direction to be moved is obtained from the processing according to the flowchart of FIG.

  Next, the absolute value of the difference amount between the target position Fx calculated in step S1522 and the movement destination F1 of the focus lens 105 that is finely driven by the amplitude α in the wobbling operation is taken, and each absolute value is obtained in step S1521. It is determined whether or not the calculated movement amount ΔF of the focus lens 105 per process is less than or equal to the calculated amount (step S1523).

  As a result of the determination in step S1524, when the absolute value is less than or equal to the movement amount ΔF, it is recognized that the current focus lens 105 position is sufficiently close to the movement destination F1 and exceeds the movement destination F1 in the next processing. Then, the target position Fx is forcibly set as the movement destination F1 (step S1524), the process returns to step S1520, and is in a standby state until the next process starts.

  If the absolute value is not less than or equal to the movement amount ΔF based on the determination result in step S1524, it is recognized that the current focus lens 105 is still away from the movement destination F1, and the focus lens 105 is moved at a desired average movement speed. In order to move, the process returns to step S1520 to enter a standby state until the next process starts.

  Therefore, when the drive voltage signal corresponding to the target position Fx obtained by the processing in steps S1519 to S1524 as described above is supplied from the microcomputer 112 to the comparison circuit 121, the focus lens 105 has an average moving speed. The movement drive is performed while holding the movement destination F1.

  Further, by executing the processing of FIGS. 4 and 5 described above, it is possible to perform pseudo speed control even when the focus lens 105 is moved by a predetermined amount of movement distance. Even when the amount of movement of the focus lens 105 at the time of a small aperture is a large amplitude, the focus lens 105 can be moved to a predetermined position while gradually approaching, and vibration and overshoot with respect to the predetermined position can be suppressed with high accuracy. It is also possible to realize a predetermined amount of movement of the focus lens 105.

  Next, a third embodiment will be described.

  In the third embodiment, an example in which the present invention is applied to a zoom operation in the imaging apparatus 100 of FIG. 1 will be described.

  First, for example, the zoom motor control program 116 includes a processing program according to the flowchart of FIG. 7, and this processing program is executed by the microcomputer 112.

  The process in FIG. 7 is the same as the process in FIG. 19 described above, but is a process in which the processes in steps S1601 to S1603 are incorporated in place of steps S914 and S915 in FIG.

  Further, the process of FIG. 7 is to execute a zoom operation process using one vertical synchronization period as a control cycle, and predicts the position of the zoom lens 102 after one vertical synchronization period as described above. This is an example of processing in which the position of the focus lens 105 is controlled so as to perform focus correction at the predicted position.

  In the flowchart of FIG. 7, the same processing steps as those in the flowchart of FIG. 19 are denoted by the same reference numerals, and detailed description thereof is omitted.

On the other hand, FIG. 8 is a flowchart showing a drive control process of the focus lens 105 for performing a competition operation in accordance with the movement of the zoom lens 102. The process according to this flowchart is performed n times per unit time. Such a processing cycle.
Further, for example, a processing program according to this flowchart is also included in the zoom motor control program 116 and is executed by the microcomputer 112.

  First, as described above, the movement destination Px ′ of the focus lens 105 to be reached after one vertical synchronization period is determined by the processes in steps S901 to S912.

  Next, initialization processing for clearing the counter m used in the processing of FIG. 8 is performed, and the current position Px of the focus lens 105 is stored in a memory Px0 (not shown) provided in the microcomputer 112 (step). S1601).

  Next, the movement amount (Px′−Px) of the focus lens 105 per vertical synchronization period is divided by the vertical synchronization period to calculate a competition speed Vf per unit time (step S1602).

  Then, by driving the zoom motor (stepping motor) 117 at the zoom speed set in step S904, the zoom lens 102 is moved (step S1603), the process returns to step S902 and waits until the next processing cycle is reached. It becomes a state.

  Further, while the processing as described above is performed, the processing of FIG. 8 is executed at a processing cycle of n times per unit time.

  That is, when this process is started (step S1604), the counter m cleared in step S1601 described above is incremented (step S1605).

Then, the movement target position Fx of the focus lens 105 per process is calculated (step S1606).
This movement target position Fx is based on the position Px0 of the focus lens 105 that existed when the in-focus position after one vertical synchronization period is calculated, and the movement amount Vf / n per process is set at the reference position Px0. It is obtained by the calculation method of adding sequentially.
That is, the movement target position F is
Fx = Px0 + Vf × m / n (16)
It is calculated by the following equation (16).

Here, “n” corresponds to the number of processes per unit time, and the counter m is initialized every vertical synchronization period, which is the processing cycle of the process of FIG. 7, so that, for example, the television system is the NTSC system. If the camera is, the value of this counter m is
m = 1, 2, 3,..., n / 60
The value of is taken.
Therefore, when m = n / 60, the movement target position Fx is
Fx = Px0 + Vf / 60 = Px ′
Thus, the focus lens 105 exists at the position Px ′ after one vertical synchronization period.

  As described above, the reason for adding the counter m as a variable to the reference position Px0 is that an error occurs between the movement target position and the actual movement position due to the characteristics of the loop control. When the process is repeated so as to add the movement amount Vf / n of the focus lens 105 for one process of FIG. 8 to the position Px, the error accumulates, and the arrival position of the focus lens 105 after one vertical synchronization period is Px ′. This is to prevent the phenomenon of deviation.

  Therefore, if the movement target position Fx is determined by the above equation (16), for example, even if the actual position of the focus lens 105 is deviated from the target position in the previous movement, the target position calculated this time is Since there is no influence of the positional deviation, the previous deviation can be corrected.

  By repeatedly performing the processes of FIGS. 7 and 8 as described above, it is possible not only to maintain the focus after one vertical synchronization period, but also to move the zoom lens 102 within one vertical synchronization period. Along with this movement, the focus lens 105 can continue to move at an average competition speed for maintaining the in-focus state, so that it is possible to prevent the occurrence of blurring.

  Next, a fourth embodiment will be described.

  In the fourth embodiment, an example in which the present invention is applied to the blur removal processing when the zoom end is reached in the imaging apparatus 100 of FIG. 1 will be described.

  First, for example, the zoom motor control program 116 includes a processing program according to the flowchart of FIG. 9, and this processing program is executed by the microcomputer 112.

  The process of FIG. 9 is the same process as the process of FIG. 19 described above, but is a process in which steps S2001 to S2003 are incorporated between steps S906 and S907.

  Further, in the process of FIG. 9, when the predicted movement position of the variable magnification lens 102 after one vertical synchronization period exceeds the zoom end, the speed of the variable magnification lens 102 is adjusted to change the magnification after one vertical synchronization period. This is an example of processing when the predicted movement position of the lens 102 is set to exactly coincide with the zoom end.

  In the flowchart of FIG. 9, the same processing steps as those in the flowchart of FIG. 19 are denoted by the same reference numerals, and detailed description thereof is omitted.

First, as described above, the position (movement predicted position) Zx ′ of the variable power lens 102 after one vertical synchronization period is set to the speed of the variable power lens 102 as Zsp (pps) by the process of step S906. It is obtained by equation (7) (Zx ′ = Zx ± Zsp / vertical synchronization frequency).
In the equation (7), the sign “±” is “+” in the tele direction and “−” in the wide direction, depending on the moving direction of the zoom.

  Next, it is determined whether or not the position Zx ′ obtained in step S906 is larger than the zoom position Zt at the tele end. Alternatively, it is determined whether or not the position Zx ′ is smaller than the wide end zoom position Zw (step S2001). If the position Zx ′ is larger than the tele end zoom position Zt, or the position Zx ′ is the wide end zoom. Only when the position is larger than the position Zw, the processes of steps S2002 and S2003 described later are performed.

When the position Zx ′ is larger than the zoom position Zt at the telephoto end according to the determination result in step S2001, the above formula (7) is
Zsp = (Zt−Zx) × vertical synchronization frequency (17)
The following equation (17) is transformed. Thereby, the speed of the variable power lens 102 to be decelerated is recognized and set.
Alternatively, when the position Zx ′ is larger than the zoom position Zw at the wide end according to the determination result in step S2001, the above equation (7) is
Zsp = (Zx−Zw) × vertical synchronization frequency (18)
The following equation (18) is transformed. Thereby, the speed of the variable power lens 102 to be decelerated is recognized and set (step S2002).

  Then, the movement predicted position Zx ′ of the zoom lens 102 is reset to the zoom position Zt at the tele end or the zoom position Zw at the wide end (Zx ′ = Zt or Zx ′ = Zw) (step S2003).

  As described above, by executing the routine for resetting the speed of the variable power lens 102 as steps S2001 to S2003, it is possible to make the arrival position of the variable power lens 102 after one vertical synchronization period coincide with the zoom end. Since the focus position at the zoom end is set as the movement target position of the focus lens 105, the position of the focus lens 105 is zoomed even if the movement of the zoom lens 102 is stopped immediately upon reaching the end. An in-focus position corresponding to the end position can be set. Thereby, the malfunction which a blur arises can be prevented.

  Next, a fifth embodiment will be described.

  In the above-described fourth embodiment, when the predicted movement position of the variable magnification lens 102 after one vertical synchronization period exceeds the zoom end, the speed of the variable magnification lens 102 is set so that the predicted movement position matches the zoom end position. In the fifth embodiment, in the imaging apparatus 100 of FIG. 1, in addition to the processing described in the fourth embodiment, the blur is further suppressed. The focus lens 105 is forcibly moved to the in-focus position at the moment when the position of the zoom lens 102 reaches the zoom end, reducing the time when blur occurs, and removing the blur due to the influence of calculation error, etc. To do.

  Therefore, for example, the zoom motor control program 116 includes a processing program according to the flowchart of FIG. 10, and the AF program 113 includes a processing program according to the flowchart of FIG. These processing programs are executed by the microcomputer 112.

The process in FIG. 10 is the same as the process in FIG. 9 described above, but step S2101 is a process that is incorporated between step S914 and step S915.
11 is the same process as the process of FIG. 22 described above, but steps S2201 to S2206 are incorporated between steps S1204 and S1206 and steps S1205, S1207, and S1209.

  In the flowcharts of FIGS. 10 and 11, the same processing steps as those in the flowcharts of FIGS. 9 and 22 are denoted by the same reference numerals, and detailed description thereof is omitted.

  First, in the fifth embodiment, when the zoom lens 102 reaches the end position and stops, the focus position of the focus lens 105 at the zoom end position is calculated, and the calculated position is compulsory. The focus lens 105 is moved.

  For this reason, during the forced movement of the focus lens 105, it is necessary to prohibit the Px ′ obtained as described above in step S913 in FIG.

  Therefore, as shown in FIG. 10 described above, a process for determining a forced movement flag indicating whether or not the forced focus lens 105 is moving is performed (step S1201). If the result of this determination processing is that the focus lens 105 has been forcibly moved, the process returns to step S902 without updating the target position of the focus lens 105 in the next step S915.

  Here, as the forced movement flag, a value indicating the movement state of the focus lens 105 is set in the process of FIG. 11 described later, and unless a driving instruction is issued in a direction in which the position of the zoom lens 102 exceeds the end position, Clear (= “0”) is set.

  Next, the forced movement process of the focus lens 105 will be described. As shown in FIG. 11, when this process is started (step S1201), the zoom lens already determined in the process of FIG. Depending on the movement state of 102 (step S1202), if the variable power lens 102 is not driven, the stop of the variable power lens 102 is set again (step S1209), and the next interrupt cycle is set ( In step S1210), this process ends (step S1211).

  On the other hand, if the variable magnification lens 102 is in the drive state, the process proceeds to step S1204 if the telephoto direction is in the tele direction, and proceeds to step S1206 if the wide direction is in accordance with the drive direction of the variable magnification lens 102 to be driven (step S1203).

  In step S1204, it is determined whether or not the zoom lens 102 has already reached the telephoto end.

  If the variable magnification lens 102 has not yet reached the telephoto end according to the determination result in step S1204, the above-described forced movement flag is cleared (step S2201), and the zoom motor driver 118 is set in the normal rotation direction. At the same time, the position counter Zx of the variable magnification lens 102 is incremented (step S1205).

  On the other hand, in step S1206, it is determined whether or not the variable power lens 102 has already reached the wide end.

  If the zoom lens 102 has not yet reached the wide end according to the determination result in step S1206, the forcible movement flag is cleared (step S2202), and the zoom motor driver 118 is set in the reverse rotation direction. Then, “1” is subtracted from the position counter Zx of the variable power lens 102 (step S1207).

  After the processing of step S1205 or step S1207, the logic of the current frequency signal is inverted to output a frequency signal corresponding to the driving speed of the variable power lens 102 to the zoom motor driver 118 (step S1208).

Here, since the processing of FIG. 11 is interrupted in accordance with the driving frequency, the pulse logic corresponding to the driving frequency is generated by sequentially inverting the output logic in step S1208. The excitation phase of the zoom motor 117 (stepping motor) is controlled in accordance with the switching of the pulse train logic and the drive direction setting state. Along with this control, the variable magnification lens 102 moves.
Then, during the movement of the variable power lens 102, the position of the variable power lens 102 reaches the zoom end as the processing of FIG. 10 is repeated.

Therefore, when the variable magnification lens 102 reaches the end position, the movement of the variable magnification lens 102 is prohibited, and the focus lens 105 is forcibly moved at high speed to the in-focus position at the zoom end position, so that the photographer notices the blur. Do not let it.
Here, since the motor 126 is used as a linear motor capable of high-speed driving as described above for driving the focus lens 105, this allows the focus lens to be focused immediately after the zoom lens 102 is stopped. Therefore, it is possible for the photographer not to notice the blur.

  That is, if the tele end is reached while moving in the tele direction, the determination result in step S1204 is true.

In this case, as the forced movement target position of the focus lens 105, the in-focus position Px ′ when the position of the variable power lens 102 exists at the tele end is calculated (step S2203).
The in-focus position Px ′ is calculated as the zoom area v ′ = s (“k = s” in the data table TB in FIG. 23) using the above-described equation (8).

  On the other hand, if the wide end is reached while moving in the wide direction, the determination result in step S1206 is true.

In this case, as the forced movement target position of the focus lens 105, the in-focus position Px ′ when the position of the variable power lens 102 exists at the wide end is calculated (step S2204).
The in-focus position Px ′ is calculated as the zoom area v ′ = 0 (“k = 0” in the data table TB of FIG. 23) using the above-described equation (8).

  After the process of step S2203 or step S2204, the forced movement flag is set to “1” (step S2205), and the target position of the focus lens 105 is set to the in-focus position Px ′ calculated in step S2203 or step S2204 ( In step S2206, a drive signal is output to the motor 126 (linear motor).

  Then, the driving state of the variable power lens 102 is set to the stop state (step S1209), the next interrupt setting is performed (step S1210), and this processing is ended (step S1211).

In the fifth embodiment, similarly to the above-described fourth embodiment, the operation of the variable power lens 102 is stopped when the position of the variable power lens 102 reaches the end of the movable range. However, the photographer may interrupt the key operation for zoom operation during zooming.
In this case, for example, when switching of the driving state of the variable power lens 102 is detected, and the driving state changes from driving to stop according to the detection result, the focus position of the focus lens 105 at the stop position of the variable power lens 102 is calculated. Then, the calculated position is set as a forced movement target value of the focus lens 105.

  As described above, even when the actuator having different response characteristics, that is, the motor 117 is used as a stepping motor and the motor 126 is used as a linear motor, as actuators for driving the variable power lens 102 and the focus lens 105, the motor Even if one of them stops, it is possible to realize a comfortable zoom operation (zooming) that does not let the photographer notice the blur.

  Next, a sixth embodiment will be described.

  In the sixth embodiment, in the imaging apparatus 100 of FIG. 1 described above, the position control cycle of the focus lens 105 is set shorter than the position control cycle of the zoom lens 102, thereby When stopping, the movement of the focus lens 105 is also stopped immediately.

First, when the focus lens 105 is stopped, it is necessary to perform fine movement position control in order to maintain an in-focus state.
That is, it is necessary not only to maintain the in-focus state after one vertical synchronization period as in the prior art, but also to maintain the in-focus state even when the zoom lens 102 stops at an arbitrary position within one vertical synchronization period. is there.

  Here, as described above, when the motor for driving the focus lens is a stepping motor, the focus lens is moved at an optimum focus follow-up speed in accordance with the inclination of the cam locus. The rate of change coincides with the inclination of the cam locus, and the in-focus state at an arbitrary position of the zoom lens can be maintained.

  On the other hand, in a system with position loop control such as a linear motor, the moving speed of the focus lens is determined by the response characteristics of the loop, so the moving speed of the focus lens is adjusted according to the inclination of the cam locus. However, blurring occurs because the position of the zoom lens approaches the in-focus direction within one vertical synchronization period after the focus lens reaches the target in-focus position in advance. The time was short and never visible.

  However, when the variable power lens is stopped at an arbitrary position, the blur suppression effect due to the movement of the variable power lens is lost, which is unacceptable.

  Therefore, in the sixth embodiment, even in a system that performs position loop control, by performing fine position control, pseudo speed control is performed, and at the same time, while improving the quality of zoom performance, By making the control cycle frequency required for fine position control sufficiently higher than the frequency of the zoom control cycle, the problem caused when the zoom operation is interrupted due to the zoom end or the like is solved.

  For example, as in the third embodiment described above, the zoom motor control program 116 includes a processing program according to the flowchart of FIG. 7, and this processing program is executed by the microcomputer 112. Has been made.

On the other hand, FIG. 12 is a flowchart showing a drive control process of the focus lens 105 for performing a competition operation in accordance with the movement of the variable power lens 102, and the process of FIG. 8 used in the description of the third embodiment described above. The process is the same as that of step S1605, but step S2301 is incorporated in the preceding stage of step S1605.
The processing in FIG. 12 is also a processing cycle in which processing is performed n times per unit time. For example, a processing program according to this flowchart is also included in the zoom motor control program 116 and executed by the microcomputer 112. It is made like that.

Note that the processing of FIG. 7 is the same as described above, and thus the details thereof are omitted.
In the flowchart of FIG. 12, the same reference numerals are assigned to the same processing steps as those of the flowchart of FIG. 8, and detailed description thereof will be omitted.

  First, as described above, the movement destination Px ′ of the focus lens 105 to be reached after one vertical synchronization period is determined by the processes in steps S901 to S912.

  Next, initialization processing for clearing the counter m used in the processing of FIG. 12 is performed, and the current position Px of the focus lens 105 is stored in a memory Px0 (not shown) provided in the microcomputer 112 (step). S1601).

  Next, the movement amount (Px′−Px) of the focus lens 105 per vertical synchronization period is divided by the vertical synchronization period to calculate a competition speed Vf per unit time (step S1602).

  Then, by driving the zoom motor (stepping motor) 117 at the zoom speed set in step S904, the zoom lens 102 is moved (step S1603), the process returns to step S902 and waits until the next processing cycle is reached. It becomes a state.

  Further, while the processing as described above is performed, the processing of FIG. 12 is executed at a processing cycle of n times per unit time.

  That is, when this process is started (step S1604), the driving state of the variable power lens 102 is determined (step S2301).

  If the variable magnification lens 102 is in a stopped state based on the determination result in step S2301, the standby state is maintained as it is.

  On the other hand, if the variable power lens 102 is in the driving state based on the determination result in step S2301, the counter m cleared in step S1601 is incremented (step S1605).

Then, the movement target position Fx of the focus lens 105 per process is calculated (step S1606).
This movement target position Fx is based on the position Px0 of the focus lens 105 that exists when the focus in-focus position after one vertical synchronization period is calculated, and the movement amount Vf / n per process is set at the position Px0. It is obtained by the calculation method of adding sequentially.
That is, the movement target position Fx is calculated by the above-described equation (16) (Fx = Px0 + Vf × m / n).

Here, as described above, “n” corresponds to the number of processing times per unit time, and the counter m is initialized every vertical synchronization period, which is the processing cycle of the processing of FIG. When the John method is a camera that is an NTSC method, the value of the counter m is
m = 1, 2, 3,..., n / 60
The value of is taken.
Therefore, when m = n / 60, the movement target position Fx is
Fx = Px0 + Vf / 60 = Px ′
Thus, the focus lens 105 exists at the position Px ′ after one vertical synchronization period.

  As described above, the reason for adding the counter m as a variable to the reference position Px0 is that an error occurs between the movement target position and the actual movement position due to the characteristics of the loop control. When the process is repeated so as to add the movement amount Vf / n of the focus lens 105 for one process of FIG. 8 to the position Px, the error accumulates, and the arrival position of the focus lens 105 after one vertical synchronization period is Px ′. This is to prevent the phenomenon of deviation.

  Therefore, if the movement target position Fx is determined by the above equation (16), for example, even if the actual position of the focus lens 105 is deviated from the target position in the previous movement, the target position calculated this time is Since there is no influence of the positional deviation, the previous deviation can be corrected.

  By repeatedly performing the processes of FIGS. 7 and 12 as described above, not only the focus is maintained after one vertical synchronization period, but also during the movement of the variable magnification lens 102 within one vertical synchronization period. As the focus lens 105 moves, the movement of the focus lens 105 can be continued at an average competition speed for maintaining the in-focus state, so that occurrence of blur can be prevented.

  Further, by making the processing cycle of FIG. 12 faster than the maximum speed Vzmax of the variable power lens 102, for example, n = 3 kHz, which is about three times Vzmax, when performing one zoom end determination, Since the process shown in FIG. 12 can be performed once, it is possible to stop the movement of the focus lens 105 and maintain the in-focus state as the zoom lens 102 stops.

  Therefore, not only the operation of the zoom lens 102 at the zoom end is stopped, but also when the photographer interrupts the zoom operation by a key operation or the like, no blur occurs.

Since the above-described processing is performed by the microcomputer 112, the load on the microcomputer 112 becomes heavy due to high-speed processing. However, due to the characteristics of the cam trajectory, the focal length other than the telephoto region has a gentle cam trajectory and the subject. Since the trajectory for each distance tends to converge, even if the processing cycle of FIG. 12 is slower than the processing cycle of the position control processing of the focus lens 105 as shown in FIG. 22 or FIG. Few.
Therefore, considering the load of the microcomputer 112, the processing cycle of FIG. 12 is optimized according to the focal length, for example, the processing cycle of FIG. 12 is accelerated only near the tele end where the inclination of the cam locus is steep. It is desirable to set.

  In the first to sixth embodiments described above, a linear motor is used as the motor 126 for driving the focus lens 105. However, the present invention is not limited to this, and a high-speed control system such as a step motor is used. Also good.

It is a block diagram which shows the structure of the apparatus to which the imaging device which concerns on this invention is applied. 5 is a flowchart for explaining details of a hill-climbing drive process in the first embodiment. It is a flowchart for demonstrating the production | generation process of the drive target signal supplied to a comparison circuit from a microcomputer. 10 is a flowchart for explaining details of wobbling operation processing in the second embodiment. It is a flowchart for demonstrating the position control process of the focus lens at the time of wobbling operation | movement. It is a figure for demonstrating a wobbling operation | movement and its amplitude. 14 is a flowchart for explaining zoom operation processing in which a vertical synchronization period is a control cycle in the third embodiment. It is a flowchart for demonstrating the competition operation | movement process accompanying a zoom movement. 19 is a flowchart for explaining zoom speed resetting processing in the fourth embodiment. 15 is a flowchart for explaining processing for determining forced movement of the focus lens in the fifth embodiment. It is a flowchart for demonstrating the setting process of the forced movement flag which shows the movement of the said forced focus lens. It is a flowchart for demonstrating the competition operation | movement process accompanying a zoom movement. It is a figure for demonstrating an inner focus type lens system. It is a figure for demonstrating the locus | trajectory of a focusing point when a to-be-photographed object distance is changed in each focal distance. It is a figure for demonstrating a locus | trajectory tracking system. It is a figure for demonstrating the interpolation system of the magnification lens position direction. It is a figure for demonstrating the moving mechanism of the lens using the moving coil type voice coil motor as a linear motor. It is a block diagram which shows the structure of the conventional imaging device. It is a flowchart for demonstrating the zoom operation | movement process in the imaging device using the said linear motor. 5 is a flowchart for explaining details of trajectory parameter calculation processing in the zoom operation processing. It is a flowchart for demonstrating the detail of a zoom area calculation process in the said locus | trajectory parameter calculation process. 5 is a flowchart for explaining details of a zoom lens drive process in the zoom operation process. It is a figure for demonstrating the data table of cam locus | trajectory information. It is a flowchart for demonstrating an autofocus operation | movement process.

Explanation of symbols

100 imaging device 101 first lens group 102 second lens group (variable magnification lens)
103 Aperture 104 Third lens group 105 Fourth lens group (focus lens)
106 Image sensor 107 Amplifier 108 Camera signal processing circuit 109 AF signal processing circuit 110 AF frame generation circuit 111 Timing generator 112 Microcomputer 113 AF program 114 Zoom control program 114
115 Lens cam data 115
116 Zoom motor control program 117 Motor 118 Motor driver 119 Focus control program 120 Amplification circuit 121 Comparison circuit 122 Integration circuit 123 Differentiation circuit 124 Addition circuit 125 Motor driver 126 Motor 127 Position encoder 128 Aperture control circuit 129 IG meter 130 Iris driver 131 Zoom switch 132 AF switch

Claims (8)

A first lens group for performing zooming operation;
First driving means for moving the first lens group;
In order to correct the movement of the focal plane during the movement of the first lens group, either one of the second lens group and the image sensor, which are movable parts,
Movable part position detecting means for detecting the position of the movable part;
Second driving means for moving the movable part by supplying a drive signal to an actuator for moving the movable part on the optical axis;
Storage means for storing the in-focus position of the movable portion with respect to the position of the first lens group according to the subject distance;
Predicting means for predicting the movement destination position of the first lens group after a predetermined time during zooming operation;
Calculating means for calculating the correction position of the movable part for correcting the focal plane at the movement destination position obtained by the prediction means based on the information in the storage means;
Position control means for controlling the position of the movable part so as to reach the correction position obtained by the calculation means after the predetermined time;
With
When the movement destination position obtained by the prediction means exceeds the end position of the movable range, the first lens group is set so that the position of the first lens group after the predetermined time becomes the end position. An image pickup apparatus that controls a moving speed of the image pickup apparatus. A first lens group for performing zooming operation;
First driving means for moving the first lens group;
In order to correct the movement of the focal plane during the movement of the first lens group, either one of the second lens group and the image sensor, which are movable parts,
Movable part position detecting means for detecting the position of the movable part;
Second driving means for moving the movable part by supplying a drive signal to an actuator for moving the movable part on the optical axis;
Storage means for storing the in-focus position of the movable portion with respect to the position of the first lens group according to the subject distance;
Control means for performing position control of the movable part for correcting movement of the focal plane accompanying position change of the first lens group during zooming operation according to information in the storage means;
With
An image pickup apparatus for forcibly moving the movable portion to a focus position at a stop position of the first lens group when a zooming operation is stopped. A first lens group for performing a zooming operation, a second lens group and an imaging element, one of which is a movable part, in order to perform focal adjustment and focal plane correction during the zooming operation;
First and second control means for controlling the respective positions so as to move the first lens group and the movable part in the optical axis direction;
With
An imaging apparatus characterized in that, when at least the position of the first lens group exists in a predetermined region, the control cycle in the second control unit is shorter than the control cycle in the first control unit.   The imaging apparatus according to claim 3, wherein the predetermined region is a long focal length region on a telephoto side. One of the second lens group and the image sensor, which is a movable part for correcting the movement of the focal plane during the movement of the first lens group for zooming operation, is the second lens group and It is moved by an actuator on the optical axis formed by the image pickup device, the movement destination position of the first lens group is predicted after a predetermined time during zooming operation, and the movable portion is focused on the position of the first lens group. A correction position of the movable portion for correcting the focal plane at the predicted movement destination position of the first lens group is calculated by a memory storing the position according to the subject distance, and the correction position of the movable portion is calculated at the calculated correction position. A control method for an imaging apparatus that controls the position of the movable part so that it reaches after a predetermined time,
When the predicted movement position of the first lens group exceeds the end position of the movable range, the first lens group is positioned so that the position of the first lens group after the predetermined time becomes the end position. A method for controlling an imaging apparatus, wherein the moving speed of a lens group is controlled. One of the second lens group and the image sensor, which is a movable part for correcting the movement of the focal plane during the movement of the first lens group for zooming operation, is the second lens group and It is moved by an actuator on the optical axis formed by the image pickup device, the movement destination position of the first lens group is predicted after a predetermined time during zooming operation, and the movable portion is focused on the position of the first lens group. A method for controlling an image pickup apparatus that performs position control of the movable unit for correcting movement of a focal plane accompanying a change in position of the first lens group during a zooming operation using a memory that stores a position according to a subject distance. Because
A method for controlling an imaging apparatus, comprising: forcibly moving the movable portion to a focus position at a stop position of the first lens group when a zooming operation is stopped. One of the first lens group for performing the zooming operation and the second lens group and the image sensor that are movable parts for performing the focus adjustment and focal plane correction at the time of the zooming operation, A method of controlling an imaging apparatus that performs position control of each position to move in an axial direction,
A control method for an imaging apparatus, characterized in that, at least when the position of the first lens group is in a predetermined region, the control period of the movable part is made shorter than the control period of the first lens group.   8. The method according to claim 7, wherein the predetermined region is a long focal length region on a telephoto side.

Images