JP3387120B2 - Automatic focusing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION The present invention relates to tracking a moving subject.
The present invention relates to an automatic focusing device that drives and controls a taking lens. [0002] 2. Description of the Related Art A photographing lens is driven by tracking a moving subject.
Automatic focusing devices for controlling are known. This kind of equipment
When the charge accumulation time of the sensor and the focus detection calculation
Defocus amount of focus detection result for a certain time
Current and past defocus amount
The moving speed of the subject is calculated based on the detection time interval
Is done. Then, the defocus amount is calculated at the calculated moving speed.
To obtain the drive amount of the taking lens,
The driving amount is set to drive and control the photographing lens. [0003] SUMMARY OF THE INVENTION However, the conventional
The automatic focus adjustment device uses the amount of defocus and the
Moving speed depends on charge accumulation time and focus detection calculation time
Calculated with the time interval
Since the drive amount is set intermittently, the movement of the taking lens
It became jerky, and the
The movement of the subject image is also jerky
There is a problem that the usability is poor. [0004] In particular, during the charge accumulation period by the sensor,
This is not possible with the so-called intermittent servo method, which does not drive the shadow lens.
The phenomenon of appears remarkably. On the other hand, shooting during the charge accumulation period
A so-called overlap servo system that drives the lens
Now, the drive amount newly calculated while driving the taking lens is
Because it is reset, the shooting lens is
The movement becomes smooth. However, the next drive amount is set
Approaching the servo target before
The servo motor may slow down in
When the unavoidable, the movement of the shooting lens is jerky
Therefore, the same problem as described above occurs. SUMMARY OF THE INVENTION It is an object of the present invention to move a taking lens to a subject.
The focus is on smooth tracking. [0006] [Means for Solving the Problems] FIG.
1 and FIG. 2 showing the configuration of one embodiment of the present invention.
To explain the invention, the present invention relates to the focusing of the taking lens 10.
Focus detection that repeatedly detects the amount of defocus indicating a nodal state
Output means 15, 16, 20 and focus detection means 15, 16,
Time measuring means 20 for measuring a focus detection time interval by 20
And the defocus amount detection value and the focus detection time interval measurement value
Plane speed calculation to calculate the moving speed of the subject image plane based on
Movement for detecting the movement amount of the projection means 20 and the photographing lens 10
Amount detection means 23, a defocus amount detection value,
Based on the movement amount detection value of the zoom 10 and the image plane movement speed calculation value.
And the shooting interval is shorter than the focus detection time interval.
Defocus Estimation for Estimating Defocus Amount
Means 20 and a speed correction value according to the estimated defocus amount
And a speed correction value calculating means 20 for calculating
According to the speed command value to which the speed correction value is added,
Drive control means 20, 21, 22 for driving and controlling the laser 10.
To achieve the above object. [0007] [Action] Based on the defocus amount and the focus detection time interval
To determine the moving speed of the object image plane (for example, see Equation (1)).
Along with the amount of defocus and the amount of movement of the taking lens
Shorter than the focus detection time interval based on the image plane movement speed
Estimate the amount of defocus of the shooting lens at different time intervals
(For example, Equation (10) and the speed control timer interrupt (FIG. 1
3)). Then, the speed according to the estimated defocus amount is calculated.
Degree correction value is calculated (for example, see Equation (3)), and image plane movement is performed.
Speed command value obtained by adding speed correction value to speed (for example, formula
The drive of the photographing lens is controlled according to (5)). [0008] FIG. 2 shows an embodiment of the present invention. From the subject
The light beam passes through the taking lens 10 and reaches the main mirror 11
Part of the light is reflected by the main mirror 11
Led to the finder screen 12 and the finder screen
A subject image is formed on the image 12. This object image is
It is observed by the photographer via the prism 13. Also, Mei
Some of the light flux from the subject that has reached the mirror 11
The light passes through the in-mirror 11 and is reflected by the sub-mirror 14,
A charge storage type photoelectric converter 16 by a focus detection optical system 15
Led to. FIG. 3 shows the focus detection optical system and the photoelectric converter.
An example of the configuration is shown. Focus detection optical system 15 is a condenser lens
17, re-imaging lenses 18a, 18b, etc.
Has passed through different areas of the exit pupil plane 19 of the taking lens 10
A pair of light beams are received by a pair of light receiving units on the charge storage type photoelectric converter 16.
It leads to the parts 16a and 16b. Each light receiving section 16a, 16b
Of photoelectric conversion elements, and each element is
a, electricity corresponding to the light intensity of the subject image formed on 16b
Output a signal. A microcomputer (hereinafter referred to as a CPU)
20) 20 is a timer 20a for counting time, and an event counter 2
0b, A / D converter 20c, memory 20d, and other peripheral components
And performs various calculations and sequence control of the camera.
The lens drive circuit 21 includes a lens calculated by the CPU 20.
Drives the lens motor 22 according to the drive amount and drive direction
Then, the photographing lens 10 is moved. The pulse generator 23
Driven in conjunction with the lens motor 22, the lens motor 2
2A pulse signal is generated for each predetermined driving amount. This pa
The pulse signal is counted by the event counter 20d of the CPU 20.
Is Here, the operation of the automatic focusing device of the present invention.
The principle will be described. FIG. 4 shows the movement X of the moving subject and the photographing lens.
The horizontal axis represents time, and the vertical axis represents the photographing lens.
10 shows the image plane movement amount in the optical axis direction of No. 10. Stop lens position P
Ti1, accumulation of charge storage type photoelectric converter 16 at time Ti1
The charge accumulation time, the accumulated charge transfer time,
At time T1 after the point detection calculation time,
The scrap amount D1 is obtained. The subject is moving at this time
It is not possible to determine whether or not
The drive control of the lens motor 22 is started as the moving amount. Shooting
When the shadow lens 10 is driven, it is ready for the next focus detection.
At the tilt position PTi2 and the time Ti2,
Load accumulation is performed. In the same procedure, the subject
The body defocus amount D2 is obtained. These two defaults
The moving speed of the object image plane is calculated based on the focus amount.
Movement of the taking lens 10 from time Ti1 to time Ti2
(PTi2-PTi)
If 1) is Dlns, the moving speed S of the object image plane is
It is calculated by the formula.   S = (D2-D1-Dlns) / (Ti2-Ti1) (1) The moving speed S of the object image plane is calculated.
After time T2, the image plane moving speed of the photographing lens 10 is calculated.
The shooting lens is set to be equal to the speed of the
Drive 10 is controlled. However, actually, at time T2,
There is a focus amount def. Photographing at time T2
If the position of the lens 10 is PT2, the data at the time T2
The focus amount def is expressed by the following equation.   def = {D2- (PT2-PTi2)} + (T2-Ti2) × S                                                           ... (2) Here, the first term on the right side of the equation (2) is
Changes from the defocus amount D2 due to the movement of the lens itself
The second term is the time T2 from the time Ti2.
Is the image plane movement amount of the subject up to. While the defocus amount def exists,
Drives the taking lens 10 at the same image surface speed S as the moving subject.
The out-of-focus state is not eliminated by moving. Therefore, this differential
The focus amount def must be introduced into the drive control amount
Absent. The control amount corresponding to this defocus amount def is f
(Def), f (def) is equal to the defocus amount.
A corresponding acceleration component is obtained. The actual value of this control amount f (def)
Various methods are possible for the introduction into the control system. rear
It is generated according to the driving amount of the lens motor 22 as described below.
In the control method using the monitor pulse as feedback,
When the contribution rate of the control amount f (def) is low, the response becomes slow,
The defocus amount def does not easily converge. Conversely,
If the feeding rate is too high, the overshoot amount and control vibration will appear significantly.
It is. In this embodiment, the focus detection time interval (usually the shortest
About 50ms) and feedback for speed control
From the detection time interval of the monitor pulse, the control amount f (def)
Is a non-linear function as follows. In addition, feedback
Monitor pulse detection time interval is longer than focus detection time interval
Set shorter.   f (def) = K × log (def) (3) Further, in this embodiment, the speed control
Feedback is pulse-based and exchangeable
Depending on the lens, the ratio between the image plane movement and the pulse is also constant.
No defocus amount is converted to the number of drive pulses (n)
It is more convenient to set the above equation (3). Therefore,
Equation (3) is   f (def) = K × log (n) where n ≧ 1 (4) And The control speed calculated in this way,   S + f (def) (5) Drive control of the lens motor 22 with
You. FIG. 5 shows a main program executed by the CPU 20.
Show grams. Referring to this flowchart,
The operation will be described. The CPU 20 is a camera main body (not shown).
When the power switch is turned on, this control program is executed.
Start. First, in step S1, the timer 20a,
Event counter 20b, AD converter 20c, memory 2
Initialization such as 0d is performed, and the focus shown in FIG.
The defocus amount is calculated by executing a point detection routine.
Further, the speed detection routine shown in FIG.
Execute to calculate the moving speed of the object image plane, and follow the steps
At S4, the lens drive start routine shown in FIG.
The shadow lens 10 is driven. The focus detection routine shown in FIG.
The detection operation will be described. In step S11, the photoelectric converter 16
Is started, and in the following step S12, this charge storage is performed.
Reads the start time of the product from internal clock into memory 20d
No. In the following, the minimum unit of time is 1 ms. Ma
In step S13, the pulse generated by the pulse generator 23
The current value of the event counter 20b that counts
Read in the memory 20d. This event counter 2
The current value of 0b is the lens position at the accumulation start time. Stay
Whether the charge accumulation of the photoelectric converter 16 has been completed in step S14,
In other words, the preset accumulation at which the charge accumulation level becomes appropriate
It is determined whether or not the time has elapsed, and if so, step S
15 to determine the end time of the charge accumulation from the internal clock.
Read in the memory 20d. Charge accumulation period in step S16
Is calculated as the charge accumulation time Ti1.
In step S17, the time is stored in the memory 20d.
You. If the charge storage time is short enough,
The time may be the accumulation time Ti1. The photographing lens 10 is driven even during the charge accumulation period.
However, to simplify the calculation, the lens position during the accumulation period
Is assumed to be constant, and in step S18, the following hand
The position is calculated in order. Now, as shown in FIG.
Start accumulation based on the count value of the
A sufficiently short time interval tw of, for example, 500 μS from the time
And the number of pulses generated by the pulse generator 23 are counted. Soshi
The time tw and the pulse count value of each period are defined as sides.
Calculated for each period, and the sum of those areas is stored.
Calculate the equivalent input pulse number Piw1 by dividing by the product time
You. This value is calculated in terms of pulses starting from the accumulation start time.
3 shows the virtual lens position. And the memory 20d
The virtual lens calculated at the lens position at the accumulation start time stored in
Lens position PTi during the charge accumulation period.
1 is stored in the memory 20d. The charge accumulation time
If is short enough, the lens position at the accumulation start time is
The middle lens position PTi1 may be used. In step S19, the AD from the photoelectric converter 16
The focus detection signal is input via the converter 20c, and
In step S20, focus detection calculation is performed based on those signals.
U. Next, a speed detection routine shown in FIG.
The processing for calculating the moving speed of the object image plane will now be described. Step
In step S31, the focus is detected in the past to detect the defocus amount.
It is determined whether or not the camera is out of focus, and the defocus amount is detected.
If so, the process proceeds to step S32; otherwise, the object image plane
Since the moving speed cannot be calculated, the process proceeds to step S38.
In step S32, the focus detection routine shown in FIG.
Based on the previous and current lens positions stored in the
Lens movement amount (PTi2-PTi1), and
The lens movement amount (PTi2-PT) calculated in step S33
i1) is converted into the image plane movement amount Dlns. This conversion is
The defocus amount is calculated from the number of pulses according to the following equation (6).
What is necessary is just to calculate. In step S34, the focus detection loop shown in FIG.
Last and current charge stored in memory 20d
The time difference (Ti2-Ti1) is obtained, and in step S35
The image plane moving speed S is calculated by the above equation (1). S
In step S36, the moving object of the subject is determined. this
The determination of the moving object can be made simply by calculating the image plane moving speed S.
I can't. For example, the detection speed
The focus detection error varies greatly, and the speed
Because the degree decreases, for example, the calculation speed exceeds a predetermined threshold
Or the sign of the image plane moving speed is the same as the previous time
The moving object is determined by comprehensively taking into account the Stay
In step S37, it is determined that the subject is
Is determined, and if it is determined that the subject is a stationary subject,
Proceed to step S38 to clear the moving subject flag Flag.
If it is determined that the subject is a moving subject, the process proceeds to step S39.
To set the flag Flag. By the lens drive start routine shown in FIG.
The lens driving operation will be described. Moving subject in step S41
It is determined whether or not the body flag Flag is set,
If the moving subject flag Flag is set,
Proceed to step S42, otherwise proceed to step S43
No. In step S42, the lens speed control shown in FIG.
Execute the quantity set routine and return to the main program
On. On the other hand, in step S43, the
Focus determination is performed, and in the subsequent step S44, is the determination result in-focus?
It is determined whether or not. If the taking lens 10 is in focus,
Return to main program as it is and focus must be
For example, the lens position control amount setting routine shown in FIG. 10 is executed.
And return to the main program. Next, a lens position control amount set shown in FIG.
The operation of setting the lens position control amount will be described using a routine.
You. In step S51, the defocus amount is set to the drive pulse.
Number N. Here, the defocus amount is the focus detection
The amount of movement of the photographing lens 10 is added to the defocus amount of the calculation result.
This is the corrected amount, which is the amount that should be driven at the time of this calculation.
is there. The number N of drive pulses is the image plane movement amount of the photographing lens 10.
And the rotation amount of the lens motor 22, and
And the number of pulses generated by the pulse generator 23,
Is calculated based on the relationship For example, an image plane movement amount of 1 m
The rotation speed of the lens motor 22 per m is Kl (rev /
mm), monitor pal per rotation of the lens motor 22
Assuming that the number of pulses is Kb (/ rev), the defocus amount de
The pulse number N for f is obtained by the following equation.   N = def × K1 × Kb (6) A zone is set according to the calculated pulse number N.
Set. Zone is the stop position to improve the stop accuracy
Are provided in front of each zone, and each time they pass through each zone,
The motor 22 is decelerated. Driving should be performed in step S52.
To determine whether the number of pulses N is greater than the number of pulses n1,
If it is larger, the process proceeds to step S53.
Proceed to 54. In step S54, the zone 1
PWM duty of drive voltage applied to the step motor 22
Is set to 25% and a predetermined number of pulses are input.
Then, an event count interrupt that generates an interrupt
Is set, and the process proceeds to step S59. The number N of pulses to be driven is greater than the number n1 of pulses.
If the number is large, the number N of drive pulses is pulsed in step S53.
It is determined whether the number is greater than the number (n1 + n2).
Proceed to step S55, and proceed to step S56 if less.
No. In step S56, the PWM due
Set tee to 50% and count events
Set (N-n1) for the interrupt and proceed to step S59
No. The number N of driving pulses is the number of pulses (n1 + n2).
If it is larger, the number N of drive pulses is increased in step S55.
It is determined whether the number is greater than the number of looses (n1 + n2 + n3),
If the number is larger, the process proceeds to step S57.
Proceed to 58. In step S58, PW is set as zone 3.
Set M duty to 75% and set event
Set (N-n1-n2) for the count interrupt and
Proceed to step S59. The driving pulse number N is equal to the pulse number (n1 + n2 +
n3), the zone 4 is set in step S57.
To set the PWM duty to 100%
Event count interrupt (N-n1-n2-n3)
Is set and the process proceeds to step S59. In step S59
Is set for each zone by the lens driving circuit 21.
When the lens motor 22 is driven with the PWM duty
In both cases, the event count interrupt is enabled. For example, the number of pulses n1 is 20, and n2 is 3
Assuming that 0 and n3 are 40, when the number N of driving pulses is 58
Starting from zone 3, count 8 monitor pulses after driving
75% PWM duty in Zone 3 until reset
The lens motor 22 is driven by the
50% PW in Zone 2 until you count
The lens motor 22 is driven at M duty, and finally
Zone 1 until 0 monitor pulses are counted
Drive the lens motor 22 with a PWM duty of 25%
Move. FIG. 11 shows an event count interrupt routine.
To indicate Lens drive activation set routine shown in FIG.
The mode of the pulse number N set for the event count interrupt
When the number of pulses has been counted, the CPU 20 determines the number of pulses.
Execute the nesting routine. First, in step S61,
It is determined whether it is zone 1 or not, and if it is zone 1, step S6
Go to step S2, otherwise go to step S63. Stay
In step S62, the speed in zone 1 that has been sufficiently decelerated is
Since the driving of the lens motor 22 is completed, the lens motor 2
2 to brake and stop
Disables the interrupt and terminates the interrupt. In the step S63, it is determined whether or not the zone 2 is set.
If it is zone 2, the process proceeds to step S63.
If so, the process proceeds to step S64. In step S63,
The number of pulses N to be driven in zone 1 with the
= N1 is set as the event count interrupt
, The PWM duty is set to 25%, and step S
Proceed to 67. If it is not the zone 2, in step S64
It is determined whether it is zone 3 or not.
Proceed to step S65, otherwise proceed to step S66
No. In step S65, zone 2 is set to zone 2
The number of drive pulses N = n2 in the event count
And PWM duty to 50%
After setting, go to step S67. Zone2If not zone3Is
In step S66, the zone is set to 3 and the zone 3 is set.
Drive pulse number N = n3 as event count interrupt
Set the PWM duty to 75%
Then, the process proceeds to step S67. In step S67, the event
Event count interrupt and terminate the interrupt routine.
Complete. FIG. 12 shows a lens speed control amount processing routine.
Show. In step S71, the control parameters per unit time
Calculate the number of looseness Ns. The speed detector shown in FIG.
The moving speed S of the object image plane was calculated by the routine. This speed
Is the defocus amount per 1 mS of unit time. Speed
Detection time of feedback monitor pulse for degree control
If the interval is 10 ms, for example,
The number of pulses to be calculated is calculated here. Unit image plane movement amount 1
Kl (rev)
/ Mm), the monitor generated per rotation of the lens motor 22
If the number of tap pulses is Kb (/ rev),Of the subject image plane
Moving speed SPulse number Ns per control time for
Is determined by the following equation.   Ns =S× Kl × Kb × 10 (7) Next, at step S72, at this calculation time,
Is calculated by using the equation (2).
It is converted into the pulse number Ns by the equation (7). Next steps
Based on the number of pulses Ns converted in S73,
More acceleration correction is obtained. In step S74, the target
Based on target pulse number corresponding to speed and acceleration correction
To calculate the control amount Q. Already in step S75
It is determined whether or not the speed control is being executed.
Steps S76 to S77 are skipped. Step S76
Now, the PWM duty set in advance for the control amount Q
Refer to the look-up table of FIG.
The initial PWM duty is read and set. Step
In step S77, the PW set by the lens drive circuit 21
The drive of the lens motor 22 is controlled at M duty. S
At step S78, the event counter 20b
The count value is stored as ECNTm in the memory 20d.
Reset the speed control timer interrupt in step S79
Then, for example, it is set to 10 mS and started. FIG. 13 shows a timer interrupt routine for speed control.
To indicate The speed control amount setting routine shown in FIG.
This speed control timer interrupt occurs after the specified time
The CPU 20 executes the speed control interrupt routine.
Start a line. In step S81, the event count
The count value ECNTt of the data 20b is read, and
In step S82, the count value ECNTt and the memory 20d
The difference from the count value ECNTm stored in
The actual number of pulses ECNTJ input during 10 ms
Ask. In step S83, the calculated actual number of pulses
The difference between ECNTJ and the previously calculated target control amount Q (EC
NTJ-Q) and calculate the error rate DELQ by the following formula
I do.   DELQ = (ECNTJ-Q) / Q (8) Next, in step S84, the calculated error rate
Refresh the PWM duty with DELQ. You
That is,   (PWM duty) = (PWM duty) × (1-DELQ)                                                           ... (9) In step S85, the speed control tie
Calculate the defocus amount at the time of the interrupt using the following formula.
You.   def = {D2- (PT2'-PTi2)} + (T2'-Ti2) * S                                                         ... (10) Note that PT2 'and T2' in the above equation are expressed in the equation (2).
Corresponding to PT2 and T2. Calculated defocus amount
Is converted into the pulse number N in the following step S86, and
In step S87, the acceleration component is calculated by equation (4).
Then, in step S88, the next speed control tag is calculated by the following equation.
The target control amount Q at the time interruption is calculated.   Q = Ns + K × log (N) (11) In step S89, the stored value ECN of the event count value
Tm is refreshed with ECNTt, and the following step S9
At 0, the speed control timer is reset and started. The PW caused by this speed control timer interrupt
M duty control (speed control) is a new focus detection
Until the latest speed and defocus amount are detected
Is run several times, each time receiving feedback,
The photographing lens 10 almost follows the trajectory of the subject. As described above, the calculated movement of the object image plane is performed.
Speed command value based on speed, that is, per unit time
Calculate and detect the target monitor pulse generation number Ns
The calculated defocus amount is converted into the number N of monitor pulses, and
The logarithmic compression of the converted value N of
Then, the acceleration correction {K × log (N)} is calculated. Soshi
The target monitor pulse generation number and the acceleration correction
To calculate the speed command value Q.
Feedback to control the speed of the taking lens
Focus on the moving subject and slide
You can track the crab and focus on it with the viewfinder.
Observe how the moving subject image moves smoothly.
Can be. In the configuration of the above embodiment, the focus detection light
The system 15, photoelectric converter 16 and CPU 20 detect the focus
The CPU 20 includes a time measuring means, an image surface speed calculating means,
The focus amount estimating means and the speed correction value calculating means
The looseness generator 23 detects the movement amount detecting means by the CPU 20 and the lens.
Drive circuit 21 and lens motor 22 serve as drive control means.
Respectively. [0040] As described above, according to the present invention,De
Subject image based on focus amount and focus detection time interval
Calculate the moving speed of the surface, defocus amount and shooting
Focus detection based on lens movement and image plane movement speed
Defocusing of the shooting lens at a time interval shorter than the time interval
Speed is estimated and the speed is corrected according to the estimated defocus value.
Calculate the speed and add the speed correction value to the image plane moving speed.
Drives the taking lens according to the degree command valueTo control
Focus on the moving subject
Can be tracked, and focus can be adjusted with the viewfinder.
Observe how the moving subject image moves smoothly
Can be.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram corresponding to claims. FIG. 2 is a block diagram showing a configuration of one embodiment. FIG. 3 is a diagram showing a configuration example of a focus detection optical system and a photoelectric converter. FIG. 4 is a view for explaining the operation principle of tracking a shooting lens with a moving subject. FIG. 5 is a flowchart showing a focus adjustment main program. FIG. 6 is a flowchart illustrating a focus detection routine. FIG. 7 is a diagram illustrating a procedure for determining a lens position during a charge accumulation period. FIG. 8 is a flowchart showing a speed detection routine. FIG. 9 is a flowchart illustrating a lens drive start routine. FIG. 10 is a flowchart showing a lens position control amount setting routine. FIG. 11 is a flowchart showing an event count interrupt routine. FIG. 12 is a flowchart illustrating a lens speed control amount setting routine. FIG. 13 is a flowchart showing a speed control timer interrupt routine. DESCRIPTION OF SYMBOLS 10, 100 Shooting lens 15 Focus detection optical system 16 Photoelectric converter 16a, 16b Light receiving unit 17 Condenser lens 18a, 18b Re-imaging lens 19 Exit pupil 20 Microcomputer (CPU) 20a Timer 20b Event counter 20c AD Converter 20d Memory 21 Lens driving circuit 22 Lens motor 23 Pulse generator 101, 101A Driving means 102 Focus detecting means 103 Time measuring means 104 Subject speed calculating means 105, 105A Speed controlling means 106, 106A Speed correcting means 107 Moving amount monitor pulse generation means

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G02B 7/28 G02B 7/08 G03B 13/36

Claims (1)

(57) and Patent Claims 1] Taking the focus detecting means for detecting repeatedly defocus amount indicating a focus adjustment state of the shadow lens, and timer means for measuring a focus detection time interval by said focus detecting means , before the focus detection time interval measured Kide focus amount detection value
An image plane speed calculating unit that calculates a moving speed of a subject image plane based on the value , a moving amount detecting unit that detects a moving amount of the photographing lens, the defocus amount detected value, Shooting lens movement
Based on the detected value and the image plane moving speed calculated value,
The photographing lens at a time interval shorter than the focus detection time interval.
Defocus amount estimating means for estimating the defocus amount of the object
And calculating a speed correction value according to the defocus amount estimation value.
Speed correction value calculating means, and a speed command obtained by adding the speed correction value to the image plane moving speed.
Drive control for driving and controlling the taking lens according to the value
Means for auto-focusing.