JP3245904B2 - Camera system with automatic focusing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera system provided with an automatic focusing device for causing a photographing lens to follow a moving subject without delay.

[0002]

2. Description of the Related Art A camera equipped with an automatic focusing device for causing a photographing lens to follow a moving subject without delay is known (for example, Japanese Patent Application Laid-Open No. 63-2010, Japanese Patent Application Laid-Open No. 1-2).
No. 85907).

[0003]

In general, an automatic focusing camera requires a charge accumulation time of an image sensor and a calculation processing time of sensor data for focus detection. The system detects a defocus amount of the system and drives the photographing optical system based on the detected defocus amount to perform automatic focus adjustment.

In a camera provided with an automatic focus adjusting device disclosed in Japanese Patent Application Laid-Open No. 63-2010, the defocus amount and the focus are updated a plurality of times and in the past in order to make a photographing lens follow a moving subject without delay. The image plane moving speed of the photographing lens is detected based on the detection time interval, and the focal position after a predetermined time is predicted based on the current defocus amount and the image plane moving speed. Then, a corrected defocus amount from the current image plane position with respect to the predicted focal position is calculated, and a driving amount of the photographing optical system is determined based on the corrected defocus amount to control the driving amount.

In such control, since only the driving amount is controlled, the predicted focal position and the image plane position match after a predetermined time, but strictly speaking at other times, the predicted focal position and the image plane position are different. The position did not match, and the defocus amount remained.

In addition, when released at an arbitrary time,
The focus position at the exposure time after the mirror-up operation is predicted based on the remaining defocus amount and the image plane moving speed at the release time, and the corrected defocus amount from the current image plane position with respect to the predicted focus position is calculated. The driving amount of the photographing optical system is determined based on the corrected defocus amount, and the driving amount is controlled. Therefore, when the residual defocus amount is large, the photographing optical system cannot be driven to the predicted focus position during the mirror-up time, resulting in out-of-focus.

When the focus detection time interval is short,
The mismatch does not cause much problem, but when the brightness becomes low and the focus detection time interval becomes long, the mismatch becomes conspicuous, and when viewed on a finder, the subject is significantly blurred and unsightly.

In order to solve the above problems, not only the driving amount of the photographing optical system but also the driving speed are controlled, and the image plane position is continuously moved even for a moving subject so as to be always in focus. Can be considered. But the drive (motor)
In a self-focusing camera that has a built-in drive control unit in the camera body and supports various interchangeable lenses, it is impossible to control the drive speed because the drive characteristics such as drive torque are different for each interchangeable lens. Was.

In a camera provided with an automatic focus adjusting device disclosed in Japanese Patent Application Laid-Open No. 1-285907, a drive control unit is disposed on the photographic lens barrel side, and the drive speed is controlled by this drive control unit. The drive amount and the drive speed are sent from the camera body side to the lens side, and the photographing lens barrel only controls the drive amount and the drive speed control as instructed. However, since the lens drive characteristics such as start / stop characteristics, maximum drive speed, and required drive time are different for each lens type due to differences in load and drive motor, and even for the same type, the drive amount and drive speed to catch up with the moving subject Is determined uniformly on the body side, and drive control is performed based on such information, an error occurs.

In the method of controlling the driving speed of the driving device so as to achieve the detected image plane moving speed, when the driving speed temporarily deviates from the target speed because the speed control is not successfully performed, the speed control is thereafter performed. However, an error in the image plane position occurs even if the image is recovered.

Further, even when the subject is moving at a constant speed, the corresponding moving speed of the focused image plane changes according to the focal length of the lens and the lens position. Even if the drive control is performed at a constant speed, an error occurs between the focus control and the accurate focus position. In the case of low luminance where the focus detection interval is long, or in the case where the exposure operation is performed during the focus detection, There is a problem that the error becomes a non-negligible amount.

SUMMARY OF THE INVENTION An object of the present invention is to provide a drive control device for a motor for driving a photographing lens in a photographing lens barrel, and to perform automatic focus adjustment for performing optimal driving control on the photographing lens barrel having its own driving characteristics. An object of the present invention is to provide a camera system provided with a device.

[0013]

(1) The invention of claim 1 is applied to a camera system provided with an automatic focusing device capable of exchanging lenses, and repeatedly detects a defocus amount of a photographing lens in a camera body. A focus detection unit that predicts a trajectory of a future focus position of the photographing lens with respect to the moving subject based on the plurality of defocus amounts detected by the focus detection unit, and indicates a time change of the future focus position. Trajectory prediction means for repeatedly generating focal position trajectory prediction information, driving means for driving the photographic lens to a photographic lens barrel which incorporates the photographic lens and is attachable to the camera body, and movement of the photographic lens Transfer to detect quantity
A moving amount detecting means for detecting a moving amount of the photographing lens;
Image plane for calculating the actual image plane position after moving the taking lens
Position calculating means, based on the in-focus position trajectory prediction information
Drive speed setting means for setting the target drive speed of the taking lens
And the focus predicted based on the focus position trajectory prediction information.
The deviation between the trajectory of the focal position and the actual image plane position, and
According to the characteristics of the shadow lens and the driving means,
At a time interval shorter than the generation interval of the focus position trajectory prediction information.
Drive speed correction means for correcting a target drive speed;
By providing a braking Gosuru drive control means <br/> said driving means in accordance with the target driving velocity corrected by the speed correction means, to achieve the above object. (2) The second aspect of the present invention provides an automatic focus with interchangeable lenses.
Applies to camera systems with adjustment devices and
Repeatedly detect the defocus amount of the taking lens.
Focus detecting means for incorporating the photographic lens and
The shooting lens is attached to a shooting lens barrel that can be attached to the camera body.
Driving means for driving the lens, and the amount of movement of the photographing lens.
A moving amount detecting means for detecting the moving amount of the photographing lens;
The actual image plane position after the movement of the taking lens is calculated based on the
The image plane position calculating means and the focus detecting means detect the position.
Based on the multiple defocus amounts given to the moving subject
Predict the trajectory of the future focusing position of the taking lens with respect to
And focus position trajectory prediction indicating the temporal change of the focus position in the future
Trajectory prediction means for repeatedly generating information, and the in-focus position
Set the target drive speed of the taking lens based on the trajectory prediction information.
Drive speed setting means for determining the focus position trajectory prediction information
Of the in-focus position predicted based on the trajectory and the actual image plane
The deviation from the position, and the
Depending on the characteristics, it is shorter than the generation interval of the defocus amount.
Drive speed correction that corrects the target drive speed at different time intervals
Means and target drive after correction by the drive speed correction means
Drive control means for controlling the drive means according to speed
By providing the above, the above object is achieved. (3) The focus position trajectory of the camera system according to claim 3.
Is the prediction information a set of the defocus amount and the image plane moving speed?
It is composed of

[0014]

According to the first aspect of the present invention, the defocus amount of the photographing lens is repeatedly detected on the camera body side, and the trajectory of the future focusing position of the photographing lens with respect to the moving subject is determined based on the plurality of defocus amounts. Predict and future
The focus position trajectory prediction information representing the time change of the focus position is repeated.
Return occurs. On the lens barrel side, the amount of movement of the taking lens
To calculate the actual image plane position after moving the taking lens
And based on the focus position trajectory prediction information,
Set the drive speed and add the focus position trajectory prediction information
Of the in-focus position predicted based on the actual image plane position
And the characteristics of the taking lens and the driving means
Time interval shorter than the generation interval of the focus position trajectory prediction information
To correct the target drive speed and use the corrected target drive speed.
Therefore and to control the drive means. (2) In the second aspect , the defocus amount of the photographing lens is repeatedly detected on the camera body side . On the other hand, in the lens barrel side, the future focus trajectory of the position of the photographing lens with respect to the moving object is predicted on the basis of a plurality of defocus amounts, Masaru
Focus position trajectory prediction information indicating the time change of the next focus position
It occurs repeatedly. On the lens barrel side,
The actual image plane after the movement of the taking lens
The position is calculated and the shooting level is calculated based on the in-focus position trajectory prediction information.
Set the target driving speed of the lens
The trajectory of the in-focus position predicted based on the prediction information and the actual
Deviation from image plane position and characteristics of taking lens and driving means
For a time shorter than the defocus amount generation interval,
The target drive speed is corrected at intervals, and the corrected target drive speed is
Accordingly, the driving means is controlled.

[0015]

The Embodiment] FIGS. 1-9, one embodiment of the present invention. FIG. 1 is a block diagram showing the configuration of one embodiment.
The lens 2 is configured to be interchangeable with the body 1,
The figure shows a state where the lens 2 is mounted on the body 1. The body 1 has a main mirror 10 and a sub mirror 1
1, a finder 12, a shutter 13, an AF sensor 14, and an AFCPU 15 are incorporated. AFCP
The U15 includes a focus detection operation unit 16, a correction unit 17, and a speed detection unit 18 configured in the form of software of a computer. The lens 2 includes a photographing optical system 20, a lens CPU 21, a driving device 24, and a monitor 25. The lens CPU 21 has a drive control unit 23 configured in the form of software of a computer.

A light beam from an object passing through the photographing optical system 20 is split into a finder 12 and a sub mirror 11 by a main mirror 10 composed of a half mirror.
The light beam further deflected toward the body bottom by the sub-mirror 11 is guided to an AF sensor 14 described later. The main mirror 10 and the sub mirror 11 are retracted from the photographing optical path when a shutter release (not shown) is operated,
After a predetermined time from the shutter release after the retreat is completed, the shutter 13 is operated, and the exposure operation is performed. When the exposure operation is completed, the main mirror 10 and the sub mirror 11 are set in the photographing optical path again.

The AF sensor 14 accumulates electric charges during an accumulation time corresponding to the luminance of the object, and the photoelectrically converted object image signal is transmitted to the AF CPU 15. The charge accumulation time is controlled by the AF CPU 15. The subject image signal is A / D-converted and then subjected to arithmetic processing by the focus detection arithmetic unit 16, and after the arithmetic processing time, the defocus amount of the photographing optical system 20 is calculated. The calculated defocus amount is subjected to overlap servo correction by the correction unit 17. A monitor signal relating to the movement amount of the imaging optical system 20 is input from the monitor 25 in the lens to the correction unit 17,
The correction defocus amount is calculated based on the monitor signal, the accumulation time timing, and the calculation processing end timing. Further, the defocus amount is stored in the speed detection unit 18, and the current defocus amount, the previous defocus amount, the detection time interval between the previous and current defocus amounts, and the movement of the photographing optical system from the monitor 25. The current image plane moving speed is calculated based on the monitor signal relating to the amount. The current corrected defocus amount and the image plane moving speed are sent to the drive control unit 23, and based on the information, a drive composed of the photographing optical system 20 as a drive load and the drive unit 24 as a drive source and a transmission system. The drive characteristics and drive speed of the drive device 24 are controlled by optimizing the drive characteristics of the system. These drive amounts and drive speeds are determined from the monitor 25 by the photographing optical system 20.
Is controlled by feeding back a monitor signal relating to the amount of movement of.

The driving device 24 is mechanically connected to the photographing optical system 20, and the driving amount and the driving speed are controlled so that the photographing optical system 20 follows the moving subject without delay. In addition, a monitor 25 provided between the driving device 24 and the photographing optical system 20 monitors a driving amount and a driving speed of the driving device 24 or a moving amount and a moving speed of the photographing optical system 20. Speed detector 1
8 and the drive control unit 23.

<Regarding the AF Sensor 14> FIG. 2 shows an example of the configuration of the AF sensor 14. AF sensor 14
Is a focus detection optical system 44 composed of a field mask 40, a field lens 41, and two pairs of re-imaging lenses 42A, 42B, 43A, 43B, and two pairs of light receiving units 45A, 45.
B, 46A, 46B photoelectric converter 4 such as CCD
And 7. The light receiving units 45A, 45B, 46A,
46B is composed of a plurality of pixels. In the above configuration, the exit pupil 20 of the photographing optical system 20
1. Two pairs of regions 35 symmetrical with respect to the optical axis 202 included in 1.
Light beams passing through A, 35B, 36A, and 36B form a primary image near a field mask 40 having an opening corresponding to the focus detection area. The primary image formed at the opening of the field mask 40 is further subjected to two pairs of light receiving parts 45A, 45B, 46A, 46A of the photoelectric converter 47 by a field lens 41 and two pairs of re-imaging lenses 42A, 42B, 43A, 43B. It is formed as two pairs of secondary images on 46B. Then, the light receiving section 45
At A, 45B, 46A, and 46B, photoelectric conversion is performed to an electrical subject image signal in accordance with the light intensity distribution of the two pairs of secondary images.

<Regarding the focus detection calculation section 16> The subject image signal is AD-converted by the AF CPU 15 to become subject image data. The focus detection calculation unit 16 performs a well-known focus detection correlation calculation process on the subject image data to detect a relative positional relationship between the paired secondary images in the light receiving unit arrangement direction on the photoelectric converter 47. The imaging optical system 20
Is detected.

<Regarding the Correction Unit 17> FIG. 3 is an explanatory diagram of the overlap servo correction of the defocus amount by the correction unit 17. In the figure, the vertical axis represents the lens position z, and the horizontal axis represents time t. Focusing position z3 of subject
In contrast, at a certain time t1, the lens position is at z1, and the subject image data at this position is captured. At time t2, the focus detection calculation ends, and the defocus amount d1 corresponding to the difference between the focus position z3 and the lens position z1 at time t1 is obtained. When the lens is driven in parallel with the focus detection calculation from time t1 to time t2 (overlap servo), the lens position is driven to position z2 at time t2, so that the defocus amount d1 at time t1 is reduced. The correction is made to the defocus amount d2 at the time t2. That is, overlap servo correction is performed.

The lens drive amount from time t1 to t2 is determined by monitoring the monitor signal from the monitor 25 from time t1 to t2.
It is obtained by integrating up to 2. The monitor signal is
One pulse is generated for each predetermined drive amount of the lens, and the correction unit 17 counts the number of pulses, and converts the count number into a lens drive amount from data of the predetermined drive amount sent from the lens, Further, the drive amount is converted into a defocus amount dc. Therefore, the corrected defocus amount d2 at time t2 is obtained by the following equation. d2 = d1-dc (1) The time t1 is defined as the time between the charge accumulation start time and the accumulation end time of the AF sensor 14. Further, it is assumed that the time required for the calculation by the correction unit 17 is extremely short as compared with the focus detection calculation time.

<Regarding Speed Detector 18> FIG. 4 is an explanatory diagram of speed detection by the speed detector 18. When the subject is moving, the focus position of the lens on the subject also changes with time. The defocus amount d1 at time t1 is obtained at time t2, and the defocus amount d3 at time t3 is obtained at time t4. During the period from time t1 to t3, the photographing optical system 2
0 is driven, and the lens position is moving at time t3.
The amount of lens drive from time t1 to t3 is
From the time t1 to the time t3, and the driving amount is converted into the defocus amount ds. Therefore, the value da obtained by converting the amount of change in the in-focus position from time t1 to t3 into a defocus amount is given by the following equation. da = d3 + ds-d1 (2) When this is converted into the image plane moving speed V3 between time t1 and t3, the following equation is obtained. V3 = da / (t3-t1) (3)

On the other hand, the corrected defocus amount at the time t4 is, as described above, the following equation from the detected defocus amount d3 at the time t3 and the lens driving amount dc converted from the defocus amount from the time t3 to t4. Desired. d4 = d3-dc (4) When the image plane moving speed V3 detected by the expression (3) is equal to or less than the predetermined value A, it is determined that the subject is stationary. Further, the corrected defocus amount d4 is compared with a predetermined value B, and when the corrected defocus amount d4 is equal to or smaller than the predetermined value B, it is determined that focusing is performed, and a stop signal is sent to the lens-side drive control unit 23 at time t4. . If the corrected defocus amount d4 is larger than the predetermined value B, it is determined that the image is out of focus, and only the corrected defocus amount d4 is sent to the drive control unit 23 on the lens side.

If the detected image plane moving speed V3 is larger than the predetermined value A, it is determined that the object is moving, and the corrected defocus amount d4 is further corrected by the amount of movement of the object, and the time is calculated by the following equation. The correction defocus amount d4 'at t4 is calculated. d4 ′ = d4 + V3 × (t4−t3) (5) In order to stably determine the movement of the subject, the predetermined value A may be provided with hysteresis. In the above description, it is assumed that the time required for the calculation by the speed detection unit 18 is extremely shorter than the focus detection calculation time. Time t4
, The corrected defocus amount d4 ′ and the image plane moving speed V3
Is sent to the drive control unit 23 on the lens side.

<Regarding the Driving Control Unit 23> Upon receiving the stop signal, the driving control unit 23 stops the driving device 24 and stops the movement of the photographing optical system 20. When only the corrected defocus amount d4 is received, the defocus amount d4 is converted into a drive amount of the driving device 24, and a monitor signal is fed back from the monitor 25 to the drive amount for control. FIG. 5 is an explanatory diagram of drive amount and drive speed control by the drive control unit 23. When the corrected defocus amount d4 ′ and the image plane moving speed V3 are received at time t4,
The maximum image plane driving speed V in the direction of the corrected defocus amount d4 '
It drives until time ty at m. Here, the time ty at which the locus of the in-focus position coincides with the lens locus is obtained by the following equation. ty = d4 ′ / (Vm−V3) + t4 (6) After time ty, since the lens trajectory changes along the trajectory of the in-focus position, it corresponds to the image plane moving speed V3 until a new control signal is received at time t6. Speed control is performed at the drive speed.

In the above-described drive control method, if the speed control is temporarily deviated after time t6, then even if the speed control is recovered, the absolute image plane position will be deviated, and the image will be out of focus. Therefore, the following method can be considered as a drive control method for compensating not only the speed but also the deviation from the target position. Corrected defocus amount d4 'and image plane moving speed V3
The in-focus image plane position Ax at an arbitrary elapsed time tx with respect to the time at which the is received and the lens position is given by the following equation. Ax = d4 ′ + V3 × tx (7) On the other hand, the actual image plane position Bx at the elapsed time tx is obtained by converting the drive amount obtained by accumulating the monitor signal from the monitor 25 according to the drive direction into the unit of the defocus amount. Can be obtained by The image plane driving speed V (tx) at an arbitrary elapsed time tx is determined as in the following equation. V (tx) = V3 + K × (Ax−Bx) (8) Here, K is a proportional constant.

As described above, the difference between the image plane driving speed V (tx) at the arbitrary elapsed time tx and the target image plane moving speed V3 is calculated as the difference between the focused image plane position Ax and the actual image plane position Bx. By determining proportionally, not only the speed but also the position can be accurately controlled, and the image plane driving speed continuously changes to the target image plane moving speed as the focused image plane position and the actual image plane position approach. Since it changes smoothly, smooth driving without overrun or hunting can be obtained. The proportional constant K may be changed according to the driving characteristics of each lens or the image plane moving speed V3, or the focused image plane position Ax and the actual image plane position B may be changed.
It may be a function of the difference from x or the elapsed time. Actually, the image plane driving speed is obtained by calculating the equation (8) every predetermined time,
Until the next predetermined time elapses, speed control is performed at a drive speed corresponding to the image plane moving speed.

<Regarding Speed Control> FIG. 6 is a block diagram showing the configuration of the drive control unit 23. The drive controller 23 receives the corrected defocus amount and the image plane moving speed as control target information. Also, individual adjustment information from the individual adjustment unit 50, power supply voltage information from the power supply voltage detection unit 51, temperature information from the temperature detection unit 52, absolute distance information from the absolute distance detection unit 53, focal length information from the focal length detection unit 54, torque Torque information is input from the detecting unit 55, and speed information is input from the speed detecting unit 56. Based on the input information described above, the control output is controlled so that the driving speed of the driving device 24 is controlled so that the image plane moving speed is the target speed.
When the driving device 24 is a DC motor, the control output is the duty at the time of pulse driving or the amount of current injected into the motor. This current amount is determined by the current control unit 57
Is controlled by If the drive 24 is an ultrasonic motor, the control output is the vibration frequency or the applied voltage.

The individual adjustment information is information for individually adjusting a portion that causes a difference in speed control even if other input information is the same. This information is rewritably stored in the individual adjustment unit 50 composed of an EEPROM.
It is adjusted and stored at the time of shipment after the completion of lens assembly. Also, the drive control unit 23 determines that a temporal change has occurred if there is a long time span from the target speed even if the speed control is performed as standard using this information, and rewrites the individual adjustment information. . The power supply voltage information is used to compensate for a decrease in the rotation speed of the motor when the battery voltage decreases. This information is detected as a value averaged over a span of time longer than one driving time. The temperature information is used to compensate for the increase in the viscosity of the lubricating oil and the increase in the load torque at low temperatures. This information is detected as a value averaged over a span of time longer than one driving time.

The absolute distance information is information obtained by detecting the position of the lens distance ring by the absolute distance detector 53 with an absolute position encoder, and is represented by the object distance corresponding to the current position of the photographing optical system 20. The focal length information is transmitted to the focal length detector 54.
Is information obtained by detecting the zoom ring position by the absolute position encoder, and is represented by a focal length corresponding to the current position of the zoom optical system. These subject distance and focal length are used to correct the image plane moving speed V. When receiving the image plane moving speed V, the drive control unit 23 calculates the subject speed S by the following equation. S = (− F2 / G2) × V (9) Here, G and F are the subject distance and the focal length at the time when the image plane moving speed V is received. Assuming that the object speed S does not change for a short period of time and does not change until the next image plane moving speed is received, the image plane moving speed V changes from moment to moment according to changes in the object distance and the focal length as shown in the following equation. I do. V = (− g 2 / f 2) × S (10) Here, g and f are the momentary subject distance and the focal length. Therefore, the drive control unit 23 calculates
The image plane moving speed is corrected based on the subject distance and the focal length every moment, and the speed control is performed so that the corrected speed is obtained.
In addition, since the proportional coefficient between the image plane moving speed and the driving speed of the motor or the like also changes depending on the subject distance and the focal length,
This proportionality factor can be corrected based on the subject distance and the focal length every moment.

The torque information is information that is fed back in a short time span compared to one drive time.
This information compensates for local torque fluctuations due to the position of the lens. The speed information is information that is detected based on a pulse interval from the monitor 25 or the like, and is fed back in a short time span compared to one driving time.
Based on this information, a change in the image plane moving speed is directly detected, and feedback control is performed according to a difference from the target speed.

The relationship between the input information and the control output (feedback ratio, etc.) depends on the individual mechanical configuration of the lens, and must be set for each lens type. Therefore, it is impossible to control all kinds of lenses by a general-purpose drive control unit mounted on the body side.

The control output is referred to as a value of a table using the target speed, individual adjustment information, power supply voltage information, and temperature information as parameters. The table is stored in the ROM in the lens CPU 21. Alternatively, the control output value may be determined by fuzzy inference using the target speed, individual adjustment information, power supply voltage information, and temperature information as input parameters. The reference value of the control output is used as a standard control. Even in the standard control, the remaining speed error is compensated by feeding back the torque information and the speed information. Here, the amount of feedback from the torque information and the speed difference is determined in a range where the speed control system does not oscillate.

The above speed control is a constant speed control. However, in order to make the transition between the two speeds in a short time and without hunting, what curve is used to change the speed over time between the two speeds? It is also possible to use the above information for the optimal control. In FIG. 8, the speed changes discontinuously at time ty, but in practice this does not occur, and it is necessary to gradually reduce the speed before time ty. In such a case, a set of the elapsed time and the control output may be tabulated using the information as an input parameter. Alternatively, a control output that changes with time may be calculated by fuzzy inference using the information as an input parameter. Even when stopping at the in-focus position, it is necessary to stop without overrun. In such a case, the speed control method of the present invention can be applied to control for reducing the speed just before the in-focus point.

FIG. 7 is a flowchart showing a control program of the AF CPU 15. The operation will be described with reference to this flowchart. In step S1, when the power is turned on, the process proceeds to step S2, and the charge accumulation control of the AF sensor 14 is performed. In step S3, AD conversion of the sensor signal is performed, and the data is stored. In a succeeding step S4, a focus detection calculation is performed based on the sensor data to calculate a defocus amount. Then, in step S5, the above-described overlap correction is performed, and the correction defocus amount is calculated.
In step S6, the image plane moving speed is obtained based on the current and past defocus amounts. In subsequent step S7, it is determined whether or not the subject is stationary based on the calculated image plane moving speed. If it is stationary, proceed to step S8,
If not, the process proceeds to step S11. In step S8, it is determined whether or not the corrected defocus amount is equal to or less than a predetermined value.
If the value is equal to or smaller than the predetermined value, the process proceeds to step S9; otherwise, the process proceeds to step S10. In step S9, the lens C
A stop signal is sent to the PU 21 to stop driving the lens. In step S10, the overlap correction defocus amount is sent to the lens CPU 21. Step S
If No. 7 is determined in step S11, the lens CPU
The correction defocus amount and the image plane moving speed are sent to 21. Thereafter, the process returns to step S2 to repeat the above processing.

FIG. 8 is a flowchart showing a control program of the lens CPU 21. When the power is turned on in step S20, the process proceeds to step S21, where the AFCPU1
5 to determine whether or not information has been received, and upon receiving the information, proceeds to step S22, and determines whether or not the information is a stop signal. If it is a stop signal, the process proceeds to step S23 to stop the driving device 24, and if not, the process proceeds to step S2.
Proceed to 4. In step S24, it is determined whether or not the received information is only the overlap correction defocus amount. If the received information is only the overlap correction defocus amount, step S2 is performed.
Go to step S5, otherwise go to step S26. In step S25, drive amount control is started. On the other hand, in step S26, drive amount control and speed control are started. Thereafter, the process returns to step S21 to repeat the above processing.

[0038] Figure 9, the speed detector 18 of an alternative embodiment in AFCPU15 shown in Figure 1 of the present invention the lens CPU
Then, the process goes to 21 to form a speed detection unit 22. In such a configuration, the AF CPU 15
1, the information on the raw defocus amount and the detection time interval and the overlap correction defocus amount are sent. Based on these information, the speed detecting unit 22 calculates the image plane speed and determines whether the subject is stationary or not. Further, focus determination is performed when the camera is still, and the drive control by the drive control unit 23 is performed according to the determination result. In such a configuration, since the speed detecting unit 22 is disposed on the lens 2 side, the determination level of the still movement based on the image plane moving speed can be individually changed for each lens type. For example, in a telephoto system, a moving subject is often photographed, so that the above-described predetermined value of the image plane moving speed can be reduced.

In FIG. 4 , the drive amount from time t1 to time t3 is converted into a defocus amount ds. Since this conversion has a different nonlinearity for each lens,
If this conversion is performed by a different conversion method for each lens, the image plane moving speed can be obtained more accurately.

Further, the correction section 17 can be moved to the lens CPU 21 side. In this case, the raw defocus amount and the detection time timing information are sent from the AF CPU 15 to the lens CPU 21. In such a configuration, there is no need to send a monitor signal from the monitor 25 to the body side, so that there is an advantage that the monitor signal relay of the mount section is not required.

In the configuration of the above embodiment, the AF sensor 14 and the focus detection calculation section 16 supplement the focus detection means.
The main part 17 and the speed detectors 18 and 22 are provided with trajectory prediction means and
And the predicting means, the driving device 24 controls the driving means,
The unit 23 constitutes a drive control unit .

[0042]

According to the present invention as described in the foregoing, it can be realized precisely optimal control for differences in different driving characteristics for each type and each of the taking lens shadow lens shooting, drive control error Drive speed as well as
If it becomes possible to control not only the degree but also the position,
Also, as the focused image plane position and the actual image plane position get closer,
The drive speed changes continuously and smoothly to the target drive speed.
Smooth drive without overrun or hunting
can get. Further, according to the invention of claim 2, on which it is possible to predict the finely accurately focus position for each type and each of the taking lens shadow lens shooting, different for each type and each of the taking lens of the photographic lens Optimal control can be realized in detail with respect to the difference in drive characteristics, and drive control errors can be reduced. In addition, not only drive speed but also position
Control can be performed accurately even if the
The drive speed becomes the target drive speed as the actual image plane position approaches
Changes continuously and smoothly every time,
Smooth drive without ching is obtained. that's all

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment.

FIG. 2 is a diagram showing a focus detection optical system.

FIG. 3 is an explanatory diagram of overlap correction.

FIG. 4 is an explanatory diagram of image plane moving speed detection.

FIG. 5 is an explanatory diagram of speed control.

FIG. 6 is a block diagram illustrating a configuration of a drive control unit.

FIG. 7 is a flowchart showing a control program of the AFCPU.

FIG. 8 is a flowchart showing a control program of a lens CPU.

FIG. 9 is a block diagram showing a configuration of another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Body 2 Lens 14 AF sensor 15 AFCPU 16 Focus detection calculation part 17 Correction part 18, 22 Speed detection part 20 Imaging optical system 21 Lens CPU 23 Drive control part 24 Drive device 25 Monitor

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

Claims (3)

(57) [Claims] 1. A camera system comprising an automatic focus adjustment device capable of exchanging lenses, a camera body comprising: a focus detection unit for repeatedly detecting a defocus amount of a photographing lens; and a plurality of defocuses detected by the focus detection unit. Trajectory prediction means for predicting a trajectory of a future focus position of the taking lens with respect to a moving subject based on a focus amount, and repeatedly generating focus position trajectory prediction information representing a temporal change of a future focus position, Driving means for driving the photographic lens in a photographic lens barrel which incorporates the photographic lens and can be mounted on the camera body, and movement amount detection means for detecting the movement amount of the photographic lens
And the taking lens based on the amount of movement of the taking lens
Image plane position calculating means for calculating the actual image plane position after moving
Based on the in-focus position trajectory prediction information,
Drive speed setting means for setting a target drive speed;
Trajectory of the in-focus position predicted based on the position trajectory prediction information
Deviation from the actual image plane position,
And the focus position trajectory prediction according to the characteristics of the driving means.
The target drive speed at a time interval shorter than the measurement information generation interval.
Speed correction means for correcting the driving speed, and the drive speed correction means
The driving means according to the target driving speed corrected by
A camera system having an automatic focusing apparatus characterized by providing a braking Gosuru drive control means. 2. An automatic focusing device having a replaceable lens.
Camera system, the camera lens repeats the defocus amount of the taking lens.
Focus detecting means for detecting the position of the camera, incorporating the photographing lens, and being attachable to the camera body.
Driving means for driving the taking lens in a taking lens barrel
Moving amount detecting means for detecting the moving amount of the taking lens
And the taking lens based on the amount of movement of the taking lens
Image plane position calculating means for calculating the actual image plane position after moving
And a plurality of defaults detected by the focus detecting means.
The photographing lens of the moving object
Predict the trajectory of the future focus position, and calculate the time of the future focus position
A track that repeatedly generates focus position trajectory prediction information indicating changes
Trace prediction means and an image based on the focus position trajectory prediction information.
Drive speed setting means for setting the target drive speed of the shadow lens
And the focus predicted based on the focus position trajectory prediction information.
The deviation between the trajectory of the focal position and the actual image plane position, and
According to the characteristics of the shadow lens and the driving means,
At a time interval shorter than the focus amount generation interval, the target drive
Driving speed correction means for correcting a dynamic speed;
The drive according to the target drive speed corrected by the corrector.
And a drive control means for controlling the moving means . 3. An automatic focusing device according to claim 1, wherein
In a camera system provided with an adjusting device, the in- focus position trajectory prediction information includes a defocus amount and an image plane shift.
A camera system comprising an automatic focusing device, comprising a set of dynamic velocities .