JPH04256914A - Automatic focus adjustor - Google Patents

Abstract

PURPOSE:To obtain a photograph of an in-focus moving object by driving a focusing lens to a position where focusing is obtained at a position where the object is to move a specific time later. CONSTITUTION:A CPU 3 calculates a defocusing quantity from range finding data obtained by a range finding sensor 1 and calculates the relative moving direction and moving speed of the object in the direction of the optical axis from the defocusing quantity. Then the range finding operation of the range finding sensor 1 is repeated at specific intervals of time and it is decided whether or not the moving speed of the object calculated in each range finding operation is larger than a specific value. When it is decided that the moving speed of the CPU 3 is larger than the specific value continuously a specific number of times, a lens driving circuit 4 is controlled according to the calculation result of the CPU 3 to drive the focusing lens 100 to the position where focusing is obtained at the position where the object is to move a specific time later.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention provides an automatic focusing function (AF).
AF (AUTOMATIC function), for example, an AF (AUTOMATIC
This invention relates to a device for accurately moving a focusing lens of a camera to a focusing position.

0002

2. Description of the Related Art In recent years, the number of cameras equipped with an AF function has increased significantly, and the AF function is becoming essential even in single-lens reflex cameras with interchangeable lenses. Single-lens reflex cameras generally employ AF using a phase difference method. AF using the phase difference method is performed in the following procedure. First, a subject image is projected onto a detection element (such as a CCD) having two light receiving sections, and the amount of light is integrated over time. Next, based on the phase difference between the two subject images on each light receiving section, the distance difference between the detection element (film equivalent surface) and the imaging plane formed by the photographing lens facing the subject and its direction (defocus amount /defocus direction) is calculated. The amount of motor drive required to drive the lens to the in-focus position is determined from the calculated defocus amount/direction, and the lens is driven along its optical axis so that the image plane matches the film equivalent plane. Ru. The number of pulses applied to the motor at this time is determined by the following equation. P=Kv×D Here, P is the number of drive pulses applied to the motor,
D is the amount of defocus. Kv is called the lens movement amount conversion coefficient (K value), and is a coefficient for calculating the number of pulses to drive the motor by the amount necessary to move the lens to the in-focus position from the above defocus amount and direction. , is a value specific to the lens.

FIGS. 30 to 31 are diagrams illustrating a conventional AF system configured as described above, and the subject image position in each diagram refers to the focus of the subject image with respect to the position of the focusing lens. This is the image position, and the focus position indicates the position of the film equivalent plane with respect to the position of the focusing lens. In FIG. 30, assume that as a result of distance measurement at time t0, the distance difference between the focus position and the subject image position, that is, the defocus amount, is D0. Then, the lens is driven to make this defocus amount D0 zero. Since the subject is stationary, the focus position and the subject image position match as a result of lens driving. In this state, if the release ON interrupt processing is performed at time t1, and exposure is actually started at time t2 after the release time lag, that is, the time required for mechanical drive to raise the mirror and stop the aperture, has elapsed, then the exposure is actually started at time t2. As shown, the focus position and the subject image position at the start of exposure t2 always match. However, if the subject is a moving object (moving in the direction in which the lens is driven), integration and calculations are performed, and based on the results, the subject continues to move even while the lens is being driven to focus. Therefore, it is necessary to repeat the integration, calculation, and lens driving processes.

FIG. 31 shows a case where a subject is moving from a far place to a near place at a constant speed, and the amount of change in the subject image position increases as the subject approaches the photographic lens. In this case, it is assumed that the distance difference between the subject image position and the focus position at point 2, that is, the defocus amount, is D1. The lens is driven by the amount corresponding to this D1, and the time t
It is assumed that when the defocus amount is calculated at point ■ after one elapse, D2 is obtained. Similarly, the lens is driven by an amount corresponding to D2, and the defocus amount D3 is determined at the next point (■) after time t2 has elapsed. Here, the focus position when calculating the amount of defocus at point ■corresponds to the subject image position at point ■, and since the subject is moving during time t1, the subject moves from far to near When the subject is moving at a constant speed, the amount of defocus will gradually increase each time the distance is measured, as D1<D2<D3, and the lens drive will not be able to sufficiently follow changes in the position of the subject image. The problem of putting it away arises.

[0005] In order to solve this problem, it is necessary to predict the distance that the subject will move during the time from the start of integration to the time when the lens drive is completed by performing calculations, and to drive the lens by taking this amount into account. Therefore, various methods have been considered to solve the problem of tracking delay as described above. In such a method, it is determined whether the image plane speed of the subject image measured during distance measurement operation is greater than or equal to a predetermined value, and if the image plane speed is greater than or equal to the predetermined value, the image plane speed of the subject image is determined based on the image plane speed. It is configured to predict the moving distance of the robot and perform a follow-up operation.

[0006]

[Problems to be Solved by the Invention] However, with this method, it is determined whether or not to perform a tracking operation based only on the image plane speed of the subject image, and therefore the subject image may move when the speed is just below a predetermined value. However, there is a problem in that the decision to perform a follow-up operation becomes unstable due to variations in distance measurement data. Furthermore, even though the subject is actually stationary and there is no need to perform a tracking operation, there is a problem in that if the subject moves momentarily for some reason, the tracking operation starts. Furthermore, even when a moving object crosses in front of a stationary subject, unnecessary tracking operations are likely to be performed, making it impossible to quickly measure the distance.

[0007] The present invention has been made to solve these problems, and is configured to be able to obtain a photograph with a moving object in focus, and also to be able to make decisions regarding lens drive. It is an object of the present invention to provide an automatic focusing device configured to avoid unnecessary lens driving by performing continuous movement of a subject.

[0008]

[Means for Solving the Problem] In order to solve this problem, the automatic focusing device of the present invention includes a focusing lens that is movable in the optical axis direction, and a focusing lens that focuses on a specific object using the focusing lens. a distance measuring means for determining a focus amount; a calculation means for calculating a relative moving direction and a moving speed of the object in the optical axis direction based on a defocus amount determined by the distance measuring means; control means for controlling the distance measuring means to repeat the distance measuring operation of the means at predetermined time intervals; and a control means for controlling the distance measuring means to repeat the distance measuring operation of the means at predetermined time intervals; a determining means for determining whether the moving speed of the object is equal to or higher than a predetermined value; and a determining means for determining whether the moving speed of the object is equal to or higher than a predetermined value for a predetermined number of consecutive times based on the calculation result of the calculating means. , further comprising a drive control means for driving the focusing lens to a position where the object is in focus at a position where the object moves after a predetermined period of time has elapsed from the current time. Furthermore, it is preferable that the calculation means is configured to calculate the direction and amount of movement of the object image by the focusing lens. Further, the drive control means is configured to follow the object when the moving direction of the object is moving away from the camera, and to move ahead by a release time lag when the moving direction of the object is moving toward the camera. In order to determine the amount of lens drive to achieve focus,
Preferably, the calculation means is configured to be controlled.

[0009]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the main parts of an AF camera in which an automatic focus adjustment device of the present invention is implemented. AF
When the switch S1 is turned on and the potential of the port P71 of the CPU 3 becomes LOW, the operation of the AF system is started. Via the interface 2, a distance measurement sensor consisting of a detection element such as a CCD measures the distance, and the obtained distance measurement data is input to the CPU 3 through the port 1, where calculations are performed and the amount of defocus is determined. is calculated. Next, the lens driving amount is calculated from the K value stored in the lens ROM 9 mounted in the lens 100 and the defocus amount calculated above. In addition, if the defocus amount cannot be determined, check whether the distance measurement data is invalid or not. If the data is invalid, perform NG processing such as displaying that the distance measurement was not performed correctly. configured to do so. At this time, distance measurement is performed again. Next, it is determined whether the defocus amount is within a predetermined focusing width, and if it is determined that the defocus amount is within a predetermined focusing width, the port P7 of the CPU 3 is
4, controls the LED drive circuit 10 and controls the focusing LED
Focusing processing such as lighting is performed, and release ON interrupts are permitted. Note that if it is determined that it is not within the in-focus width, the release interrupt is prohibited, the lens drive amount is set in the counter 6, and the lens drive circuit 4 is controlled to start lens drive. AF rotated by lens drive circuit 4
The rotation speed of the motor is monitored by an encoder 5,
When the counter 6 is decremented and the content of the counter 6 becomes 0, the rotation of the AF motor is stopped and lens driving is stopped.

[0010] When the release switch SWR is turned on, the release ON interrupt processing is executed by the port Por of the CPU3.
After t5, the release control circuit 8 performs a series of release control processes including mirror raising, exposure, and mirror lowering. When you turn on the release as soon as the autofocus function focuses, in reality, the shutter does not open the moment the release ON signal is read, but the shutter actually opens after the release ON signal is read. Before exposure starts, there is a time lag corresponding to the time required to narrow down the aperture to the aperture value set in advance manually or by exposure control calculation, and to drive the mirror up (hereinafter referred to as This time difference is called the release time lag). When photographing a stationary subject, the subject's position will not change during this release time lag, so once focus is achieved, defocus will no longer occur regardless of the length of the release time lag. ,
The actual exposure is performed with the subject in focus. In this embodiment, the time point when exposure actually starts after the release ON interruption (that is, after the release time lag has elapsed)
In order to match the subject image position and the focus position, the following method is used.

In FIG. 2, solid lines indicate movement of the subject image position. If you control the lens drive so that the focus position is located on the solid line after the release time lag has elapsed,
No matter when the release is turned on, exposure will be performed in the focused state. The curve indicated by the broken line in the figure is obtained by translating the solid line graph indicating the actual movement of the subject image to the left by the release time lag. If the lens is driven so that the focus position follows this broken line, no matter when the release is turned on, the release control process will always start at the focus position that is ahead by the release time lag, and the subject image will be at the focus position after the release time lag has elapsed. Upon arrival, exposure will be performed in a focused state.

FIG. 3 is a flowchart showing the main processing of the AF system of this embodiment. In this embodiment, the processing procedure is changed depending on the number of AF distance measurements, so first, in S1, a flag AlS indicating the number of AF distance measurements is cleared. At S2, a distance measuring sensor 1 consisting of a detection element such as a CCD is connected via an interface 2.
Distance measurement is carried out using the sensor, and the amount of received light is integrated over time to obtain distance measurement data. The distance measurement data is sent to the CP via port 1.
The signal is input to U3, and the CPU 3 performs calculations to calculate the defocus amount. In S3, the lens driving amount (the number of AF pulses) is calculated from the K value stored in the lens ROM 9 mounted in the lens 100 and the defocus amount calculated in S2 using the above formula. This lens drive amount is set in the counter 6. In S4, a moving object prediction calculation (described later) is performed.

[0013] Next, in S5, if the defocus amount cannot be determined, etc., a check is made to see if the distance measurement data is invalid, and if the data is invalid, a message indicating that the distance measurement was not performed correctly is displayed. After performing NG processing such as
Returning to S2, distance measurement is performed again. In S6, it is determined whether the defocus amount is within a predetermined focusing width, and if it is determined that the defocus amount is within a predetermined focusing width, in S7
, the LED drive circuit 10 is controlled to perform focusing processing such as lighting up a focusing LED. In the next step S8, the release ON interrupt is permitted, and the release operation becomes possible. S9
This is a so-called one-shot process, in which the focusing process is stopped once focus is achieved.

Next, in S10, it is determined whether the correction is ON, that is, whether the tracking mode is in effect. S if not in tracking mode
Returning to step 2, the CCD integration process is restarted. In the case of tracking mode, it is determined in S11 whether the subject is moving towards the lens 100 or away from the camera based on the contents of the flag FFN, and if the subject is moving in the direction away from the camera, the process proceeds to S2. return. Here, the case where the subject is moving away from the lens is shown as FFN=1. When it is determined in S10 that the subject is moving in the tracking mode and that the subject is moving toward the camera in S11, it is determined in S12 whether or not the current number of lens drive pulses (AFP) is 0. If the number of lens drive pulses is 0, the process returns to step 2, but if it is not 0, the lens drive flag BFM is set to 1. This is a flag indicating whether the lens has been driven.

If it is determined in S6 that the defocus amount is not within the predetermined focus width (that is, if the defocus amount is not within the predetermined focus width), after taking steps to prohibit the release operation in S6-1, It is determined in S6-2 whether the correction ON mode is in effect, that is, whether the tracking mode is in effect, and if it is ON, it is determined in S12 whether the lens drive pulse number AFP is 0 or not. AFP=
If it is 0, lens driving is not performed, and the process returns to distance measurement processing in S2. If AFP is not 0 and the lens is being driven, or if it is determined in S6-2 that the tracking mode is not in effect, the lens drive flag BFM is set to 1 in S13 as described above. Then, lens drive processing from S14 onwards is performed.

In this lens driving process, first, S1
4, the lens drive amount is set in the counter 6, and the lens drive circuit 4 is controlled to start lens drive. In addition,
The rotation speed of the AF motor rotated by the lens drive circuit 4 is monitored by the encoder 5, and when the counter 6 is decremented and the content of the counter 6 becomes 0, A
The rotation of the F motor is stopped and lens driving is stopped. After lens driving is started in S14 in this manner, in S15, interrupt processing is permitted when the lens is driven to the end point of its driving range during lens driving. This interrupt processing will be described later.

[0017] In S16, the value of counter 6 is exactly 0.
The motor's PWM (Pulse Width Modular) controls the AF motor so that the lens drive speed is gradually slowed just before the lens drive ends, so that the lens stops accurately at the in-focus position.
tion) It is determined from the number of pulses remaining until focusing whether or not control is required, and when it is not required yet, that is,
When the lens is being driven, it is determined in S17 whether correction is ON. And when the correction is not ON,
At S18, overlap processing is performed, that is, distance measurement, calculation, etc. are further performed while the lens is being driven, and processing for updating the value of the counter 6 is performed, and the determination at S16 is performed, that is, it is determined whether or not PWM control of the motor is required. repeat. However, if the correction is ON in S17, the process returns to S16 without performing the overlap process. Note that the relationship between this correction ON and overlap processing will be described later. When PWM control becomes necessary in S16, that is, immediately before the end of lens driving, PWM control is performed in S16-1, and it is determined in S16-2 whether or not driving is completed. When lens driving is completed, S1
In step 6-3, interrupt processing at the time of endpoint detection is prohibited, and the process returns to step S2 to continue distance measurement processing.

The follow-up mode when the correction is ON in this embodiment will be explained below. First, an explanation will be given of the algorithm at the time when the camera enters the anticipatory tracking mode, which moves ahead by the release time lag from normal tracking focusing. In FIG. 4, the number of motor drive pulses obtained at point ■ is assumed to be A1 (the image plane defocus amount is calculated by multiplying it by the K value, which is the pulse applied to the motor to drive the lens 100 to the in-focus position. Since it can be converted into a number, in the following explanation, the number of pulses applied to the motor to eliminate the amount of defocus will be simply referred to as the number of pulses or the amount of lens drive.) It is assumed that after this, a pulse A1 is applied to the motor to drive the lens, and after a time t1 has elapsed, the number of pulses A2 at point ■ is determined. The amount of movement of the subject image from point (2) to point (2) becomes A2 when converted into the number of pulses. Therefore, the object image movement speed OBJsp between the points ■ and ■ points is OBJsp=A2/t1. Here, the subject image position at point ■ after time t2 has elapsed from point ■ based on the subject image position at point ■ is expressed as A2+t2×OBJsp, assuming that the subject image speed is constant. Let P2 be the amount of movement of the subject during time t2, and P
2=t2×OBJsp, the driving amount is calculated as A2+P2. In other words, the point where the motor is driven by A2+P2 at point ■ coincides with the subject image position after time t2 has elapsed. Note that this P2 must be calculated in advance at the time of calculating the lens drive amount. The time required to calculate the lens driving amount after obtaining the distance measurement data is always constant, and it can be considered that the time including the driving time does not differ much each time. Therefore, the current calculation time and drive time, ie, time t2, are the previous calculation time and drive time, ie, time t2.
1, time t2 is obtained by actually measuring time t1, and P2 is calculated.

As described above, even if the motor is driven by A2+P2 at point (2) to match the focus position and the subject image position, and the release is interrupted at that point, exposure will actually start only at the release. Since this is after the time lag has elapsed, it is necessary to move the lens to advance the focus position by the amount of movement of the subject image during that time. If the release time lag is RLt, the number of advance pulses TXP2 required to advance the focus position by the release time lag from the subject image position is calculated as TXP2 = RLt x OBJsp, and it is sufficient to drive the motor by that number of pulses. . It should be noted that the release time lag RLt is from the end of lens driving to the start of exposure in each period from ■ to ■ in FIG. As shown in FIG. 6, in order to measure the amount of defocus, integration is performed during the time interval Tint, and each data is obtained based on the integrated value, but the actual amount of defocus is The obtained position is not the position at the start of the integration, but can be considered to be the measured distance value at a time point Pi that has elapsed by Tint/2 (ie, the midpoint of the integration time). Therefore, the above release time lag R
If Lt is configured to be corrected and calculated as RLt-Tint/2, more precise tracking will be possible. Therefore, the formula for calculating TXP2 above is TXP2
A correction is added as follows: =(RLt-Tint/2)×OBJsp. From the above, the lens drive amount AF at point ■
By setting P2 to AFP2=A2+P2+Txp2, the lens drive changes from so-called trailing tracking, which only adds correction for the amount of subject image movement to the defocus amount, to proactive tracking, which drives the lens in anticipation of the release time lag. The number of driving pulses A3 actually obtained at the point where time t2 has elapsed from the point is the above Txp2.
If it matches, it means that the release time lag has been taken in advance. (Actually, since the moving speed of the subject image is not constant, A3=Txp2 is not necessarily the case.)

0020
] Next, in FIG. 5, it is assumed that the number of pulses A3 is obtained at point ■ as a result of integration and calculation. Then, from the figure, the difference between the subject image position corresponding to the ■ point and the subject image position corresponding to the ■ point (
The amount of movement of the subject image) corresponds to the time from point ■ to point ■, assuming that the time from point ■ to point ■ is the same as t2, and assuming that the movement of the subject image is linear. It is considered to be equal to the amount of movement to the subject image position, so
The amount of movement of the subject P3 from the position corresponding to the point (2) to the position corresponding to the point (2) is determined as P3=P2+Txp2-A3. Therefore, the lens driving amount AFP3 from the point ■ to the point ■ becomes AFP3=P3+Txp3-A3. Based on the same idea, the following formula can be obtained as a general formula for determining the amount of movement of the subject image and the amount of lens drive during proactive tracking. Pn=Pn-1+(Txpn-1-An)Txpn=f
(Pn) AFPn=Txpn+Pn-An Here, Txpn is a function f(Pn) of the subject image movement amount Pn
It is required as. In principle, Txp = (P
n/t)×RLt. However, as mentioned above, as shown in FIG. 6, in order to measure the defocus amount, integration is performed during the time interval Tint, and each data is obtained based on the integrated value, so the actual defocus amount is The position from which the amount can be obtained is not the position at the start of the integration, but can be considered to be the measured distance value at the time point Pi after Tint/2 (that is, the midpoint of the integration time). Therefore, if the above-mentioned release time lag RLt is corrected by this amount and calculated as RLt-Tint/2, more precise tracking becomes possible. Therefore, the above Txp can be expressed as Txp=(Pn/t)×(RLt-Tint/2).

[0021] Furthermore, since Txp is obtained from distance measurement data, and variations in the distance measurement data have a large effect, in this embodiment, the immediately preceding four data are It is averaged and used according to the formula. Txpn=(Txp+Txpn-1+
Txp
n-2+Txpn-3)/4 Note that calculations are performed by substituting 0 for those for which there is no past data.

FIG. 7 is a flowchart of the subroutine of the moving object prediction calculation performed in S4 of FIG. The distance measurement data is checked in S201, and if the distance measurement data is not OK, the flag AS for counting the number of distance measurements is set in S226.
is set to 0, indicating the first time, and returns to the main processing. Examples of such cases include a subject with very low contrast, or a case where the amount of defocus is so large that distance measurement data cannot be obtained. In addition, if you set the AF one-shot mode as described above, that is, if you perform control to stop the focusing process once the object is in focus, the focusing process will continue to follow the subject even once the object is in focus. There is no need to switch to continuous tracking mode, so S201-1
If it is determined that the AF one-shot mode is selected, the process directly returns to the main processing. If it is not AF one-shot, and the process comes to this routine for the first time after entering AF mode, and it is determined that the distance measurement data is OK in S201, it is determined that AlS=0 in S202, and S
The process moves to S218 via S224 and S225, and returns to the main process. At this time, in S224, the flag AlS for counting the number of distance measurements is set from 0 indicating the first time to 1, and after that, AlS=1 indicates that the process is the second time or more, and the time interval of distance measurement is set. A timer 7 for measurement is started, and each data for calculation is sent to S22.
It is initialized at 5.

[0023] When the number of distance measurements is the second or more, S202
The process then proceeds to S203, and in S203, the timer 7 measures the time interval t from the previous distance measurement. Next, S204
Then, it is determined whether the correction is ON, that is, the tracking mode is in effect, but in the initial state, the correction is ON, that is, the tracking mode is not in the mode, so the process advances to S205. S205 to S21
In routine 1, it is determined whether the subject image is to be treated as a moving object. In S205, the current and previous defocus directions are compared, and if they are different, it is considered that the subject image has changed its moving direction, and the calculation data is cleared in S225 without determining whether to treat it as a moving object. , S2
18 and returns to the main processing. If the defocus directions are the same, it can be considered that they are moving in the same direction, and the process advances to S206. In S206, it is determined based on the flag BFM whether the lens was driven during the previous distance measurement. If the lens was driven in the previous distance measurement, that is, if BFM=1, the process advances to S209 and the current subject image movement amount XX=
An, if the lens was not driven last time, that is, BF
If M=0, the process advances to S207 and compares the previous defocus amount An-1 and the current defocus amount An,
It is determined whether the subject image is approaching the focus position. If the subject image is approaching the focus position, the process will return to the main process via S218 because it will eventually become in focus even if it does not enter the tracking mode. On the other hand, in S207, if it is determined that the subject image is moving away from the focus position or if it is determined that the subject image is at the same distance, in S208, the previous defocus amount An-1 is calculated from the current defocus amount An. Subtract the current subject image movement amount XX = A
As n-An-1, in S210, from t obtained in S203, the object image speed OBJSP during one cycle from distance measurement to distance measurement, that is, XX/(Kva
lue x t) and determine whether this is larger than a predetermined value. Here, the predetermined value is, for example, the amount that the subject image moves within the time period t from distance measurement to distance measurement plus the release time lag RLt, which is expressed by the formula, focusing width / (t + RLt). The speed matches the width. In other words, if the object image speed OBJSP is smaller than this value, if you drive the lens based on the current distance measurement and then perform the release ON interrupt processing, the moving object image will be displayed at the start of exposure after the release time lag has elapsed. This means that the subject is within the focusing range, so there is no particular need to track the moving object. However, in order to reliably identify a moving object, the predetermined value may be set to a smaller value with a margin. Further, although the judgment is somewhat rough, the predetermined value may be set to a speed at which the amount by which the subject moves during the release time lag matches the focusing width. As described above, when the object speed OBJSP is determined to be smaller than the predetermined value,
The process moves to S225, and after clearing the calculation data,
The process passes through S218 and returns to the main process. On the other hand, if the object image speed OBJSP is greater than the predetermined value, S2
In step 11, it is determined whether or not this is the first time that the above speed determination has been made. If it is the first time, it cannot be determined with certainty that the object is a moving object, so
and return to main processing. If the object image speed OBJSP is determined to be larger than a predetermined value in two or more distance measurement calculations, it is determined that the object is definitely moving, and the correction is turned on for the first time, and the lens drive based on the moving object tracking algorithm in this case is activated. It will be done. S21
2. In S213, each correction is turned on, flag C10 = 0
(Indicates that this is the first time the correction has been turned on. From the second time onward, set C10=1). In S214, the current defocus direction is determined, and based on this, the moving direction of the subject image is determined. That is, if the defocus direction is rear focus (+), it is determined that the subject is moving closer to the camera, and advance tracking processing is entered in S222. On the other hand, if the defocus direction is the front focus (-), it is determined that the moving direction of the subject is moving away from the camera, and a tracking process is entered in S223. Further, in S215, a flag FFN indicating the relative positional relationship between the subject and the camera is set to 0, indicating that the subject is moving closer to the camera. Further, in S216, the flag FFN is set to 1 to indicate that the subject is moving away from the camera. Thereafter, the process returns to main processing via S218.

When the process reaches this routine after the correction is turned ON, the process moves from S204 to S219, and if the subject is moving closer to the camera according to the moving direction of the subject, the process proceeds to S220. Process and S2
In step 17, the defocus amount for focusing is recalculated using the routine of FIG. 23, and if the subject is moving away from the camera, the process of S221 is performed,
18 and returns to the main processing.

[0025] In S218, for the next calculation,
An is set to An-1, AFPn is set to AFPn-1, each data is stored, and the flag BFM is reset to 0. FIG. 8 shows a subroutine in S222 of FIG. 7 when the mode shifts from follow-up mode to anticipatory mode. XX
is the object movement amount (number of pulses), and is set to Pn in order to use it in the current calculation (S261). As described above, the drive amount for the release time lag is calculated as a function of the subject movement amount Pn (S262), and in S263 the current lens drive amount (the drive amount for switching from trailing tracking to anticipatory tracking) AFP is calculated. The details are as already described in the explanation of the basic calculation.

In the second and subsequent moving object prediction calculations after the correction is turned on, different processing is performed depending on the moving direction of the object based on the FFN value set in S215 and S216 in FIG. FIG. 9 shows the processing in S220 when the subject approaches the camera from a distance. When this routine is passed for the first time after the correction is turned on, the flag C10 is determined to be 0 in S301, and it is determined in S303 whether or not proactive tracking has started beyond the movement of the subject. If the defocus directions this time and the previous time are different, it is determined that proactive tracking has started, the flag C10 is set to 1 in S304, and the process moves to S305. If the previous and current defocus directions are the same, it is determined that trailing tracking remains the same, and the process moves to S323. If this routine is entered for the second time or later after entering proactive tracking after correction is turned on, it is determined in S301 that flag C10 is not 0, and it is determined in S302 whether the defocus direction of the previous time and this time are the same. . In this case, since the previous process has already been in the proactive tracking state, if the defocusing direction is different between the previous time and this time, the process has changed from proactive tracking to trailing tracking, and the process moves to S323. If the defocus direction this time and the previous time are the same, it means that proactive tracking is continued, and the process is performed in S305.
Move to.

In S305, the defocus amount An obtained by the current distance measurement is compared with the lens drive amount Txpn-1 corresponding to the previous release time lag. As mentioned above, assuming that the speed of the subject image is constant, Pn
This is a measure to correct errors caused by calculating . If An>Txpn-1, this means that the actual movement amount of the subject image is smaller than Pn, and it is determined that the previous lens drive amount was too large, and the process moves to the case where the advance amount is too large (step S314 onwards). Further, if NO in S305, this means that the actual moving amount of the subject image is equal to or larger than Pn, and the process is performed when the previous lens driving amount was insufficient or appropriate. The flag BOV in the next steps S306 and 314 is a flag that indicates what the judgment result of the previous step (S305) was last time.If BOV=1, it is too proactive, and if BOV=0, it is insufficiently proactive. This indicates that the amount was appropriate, and when this routine first comes, it is always processed as BOV=0.

[0028] S307 shows the calculation in the case where An>Txpn-1 is not satisfied both this time and the previous time, as shown in FIG.
The calculations are performed as already explained with respect to the same figure. S310
is shown in FIG. 10, the previous time An>Txpn-1,
Moreover, this time we show the calculation formula for a case where this is not the case. In FIG. 10, the correction amount (subject image movement amount) P2 is P
2=|A2-A1|, Txp2=f(P2), and the driving amount AFP is AFP=Txp
2+(P2-A2). The above can be summarized as follows. Pn=|An-An-1| Txpn=f(Pn) AFP=Txpn+Pn-An In any case where the above steps S307 and S310 are performed, in the subsequent S308 or S311, it is checked whether AFP<0, and AFP< If it is 0, the process moves to S312 and Pn=0.
, AFP=0, and lens drive is not performed (lens drive in the opposite direction is not performed). In either case, the subsequent S30
9 or 313, the BOV is reset based on the current calculated value.

If An>Txpn-1 this time, the process moves to a loop starting from S314. In this case, An is T
Since it is larger than xpn-1, the subject image is in advance by more than the release time lag, and the lens is not driven, so both the correction amount and AFP are set to 0 in any process and used for the next calculation. , Txp is only calculated. In S314, the same case classification as in S306 is performed.

S315 is shown in FIGS. 11 and 12. Previously, An>Txpn-1 was not satisfied, but this time An>Tx
In the calculation when pn-1, the correction amount P2 is P2=
It is represented by P1-(A2-Txp1). Therefore, Txp2=f(P2) In summary, Pn=Pn-1-(An-Txpn-1)Txpn=f
(Pn) Pn=0 AFP=0.

[0031] For S317 and below, An>Txp both this time and last time.
The processing when the number is n-1 is shown. In S317,
Whether or not the amount by which An exceeds Txpn-1 is within the predetermined focusing width used to determine focus in S6 in FIG. In order to determine whether it is within the focal width, An is compared with Txp-1 plus the number of pulses corresponding to the focal width.

The next step S318 is when the amount by which An exceeds Txpn-1 is smaller, that is, when the subject image position after the raise time lag has elapsed is within the focusing width, as shown in FIG. This is the calculation. From the same figure, P
2=|A2-A1| Therefore, Txpn=f(Pn) To summarize, Pn=|An-An-1| Txp2=f(P2) Pn=0 AFP=0 Amount by which An exceeds Txpn-1 in S317 If it is determined that is not within the in-focus width, the process moves to S319. In S319, if it is determined that the state in which An exceeds Txpn-1 and does not fall within the predetermined focusing width continues three or more times, it is determined that the subject image position has deviated significantly from the focus position or that the subject image has moved. S
At step 322, the correction is turned off and all calculation data is cleared. Then, the moving object prediction calculation is performed again using the current data as the data for the first AF. S320 is the calculation for the case shown in FIG. 14, and the content is the same as S318.

[0033] If it is determined in S302 or S303 that proactive tracking is not being performed this time, the flag BOV is checked in S323 to determine whether An>Txpn-1 last time.
It is judged by. Previous An>Txpn-1 in S323
If it is determined that it is, the process moves to S324. This is the case shown in FIG. 15, where the previous tracking was performed in advance and the current focus position is after the subject image. At this time, the correction amount P2 is expressed as P2=A2+A1. Therefore, Txp2=f(P2). The driving amount AFP is AFP=Txp2+P2+A2 To summarize the above, Pn=An+An-1 Txpn=f(Pn)AFP=Txp
It becomes n+Pn+An.

[0034] If it is determined in S323 that the previous time An>Txpn-1 is not satisfied, the process moves to S327. FIG. 16 shows a case in which the transition from trailing tracking to anticipatory tracking was performed, but it was not possible to move ahead, and FIG. 17 shows a case where it became impossible to move ahead during anticipatory tracking. In either case, the correction amount P2 is as follows: P2=Txp1+P1+A2. Therefore, Txp2=f(P2), and the drive amount AFP becomes AFP=Txp2+P2+A2 (S327). To summarize the above, Pn=Txp
n-1+Pn-1+An Txpn=f(Pn) AFP=Txpn+Pn+An.

After performing the calculation in S324 or 327, in S325, the flag C10 is set to 0,
In the next distance measurement, this calculation will be treated as the first calculation after correction. Further, in S326, the flag BOV=
Set to 0.

In FIG. 7, S221 and S223 are both cases where the subject is moving from near to far. When the subject moves away from the camera at a constant speed, the subject image speed gradually slows down.
The amount of lens drive decreases accordingly. In this case, if correction is performed in advance by the release time lag, as in the case where the subject is approaching the camera, there is a high possibility that over-correction will occur. If over-correction occurs, it will result in so-called back focus, which is not very desirable when considering the quality of the photo. Therefore, when the subject moves in a direction away from the camera, the camera basically follows the subject without moving in advance by the release time lag.

FIG. 18 is a graph showing the relationship between the subject image position of a subject moving away from the camera and the lens drive pulse. In FIG. 18, the number of motor drive pulses obtained at point ■ is assumed to be A1. It is assumed that after this, a pulse A1 is applied to the motor to drive the lens, and after a time t1 has elapsed, the number of pulses A2 at point ■ is determined. The amount of movement of the subject image from point (2) to point (2) becomes A2 when converted into the number of pulses. Therefore, the object image movement speed OBJsp between the points ■ and ■ points is OBJsp=A2/t1. Here, the subject image position at point ■ after time t2 has elapsed from point ■ based on the subject image position at point ■ is expressed as A2+t2×OBJsp, assuming that the subject image speed is constant. Here, time t2 is considered to be the same as t1 as explained in the proactive tracking section, so t
The amount of movement of the subject image between A2 and A2 is considered to be the same. Therefore, the drive amount is calculated to be 2×A2. That is,
The point where the motor is driven by 2xA2 at point (2) coincides with the subject image position after time t2 has elapsed. In this case, even if you interrupt the release ON after the lens drive ends and start exposure after the release time lag has elapsed, the focus position is in front of the subject image position at that point and is not in the rear focus state, so do not calculate TXP. Perform follow-up. As a result of driving the lens by 2×A2 based on the defocus amount A2 obtained at point ■, the result is A at point ■.
Assuming that a defocus amount of 3 is obtained, the next drive amount is simply set to A3×2 as in the previous drive without performing any correction as in proactive tracking. That is, the following formula can be obtained as a general formula for determining the amount of lens drive during rear tracking. Lens drive amount AFP = 2 x An (assuming that t1 = t2 and the lens was driven last time)

[
FIGS. 19 and 20 show S223 and S in FIG. 7, respectively.
221 subroutines. In FIG. 19, S2
In step 71, the sum of the moving amount (number of pulses) XX of the subject image and the amount of defocus (number of pulses) is determined as the lens driving amount. The amount of movement XX of this subject image is determined by S206 in FIG.
~ In S209, it is calculated based on whether or not the lens was driven last time, and if the lens was driven last time, XX=An
, if it was not driven last time, XX=An-An-1
Therefore, the lens drive amount AFP calculated in S271 of FIG. 19 does not exceed 2×An.

In FIG. 20, the current defocus direction is checked in S272. This is because even though the subject is moving away, if the defocus direction after driving the lens is positive, that is, if the rear focus is on, over-compensation is being performed, so we check to avoid this. It is something. In case of over correction, S2
At step 77, the correction is turned off, the calculation data is cleared, and the current data is recalculated as the first AF data. If the check to see if over-correction is passed, in the next S273 to S275, S206-20 in FIG.
9, the amount of subject movement is calculated based on the presence or absence of the previous lens drive, and the lens drive amount AF is calculated in S276.
Set P. This is similar to the case in FIG.

Here, the determination of focus in S6 in FIG. 3 will be explained. This determination is made based on whether the defocus amount obtained in S2 is within the aforementioned predetermined focusing width. However, in advance tracking mode, control is always performed to advance by the amount of the release time lag, so even if it is possible to focus after the release time lag has elapsed, the defocus amount may not be within the focus range when measuring distance. do not have. Furthermore, even if the object is within the focus range during distance measurement, it does not necessarily mean that the object will be within the focus range after the release time lag has elapsed. Therefore, from the obtained defocus amount itself, focus cannot be detected even if it is in a focusable state. Therefore, in S217 of FIG. 7, the defocus amount for focus check is calculated. This recalculation in S217 will be explained with reference to FIG. 23. First, in S51, the drive amount T corresponding to the release time lag in the previous AF process is
Convert xpn-1 from the number of pulses to the image plane defocus amount DD. Next, in S52, the image plane defocus amount DD is added to the defocus amount Defocus obtained by the current distance measurement, regardless of whether it is positive or negative, thereby obtaining the defocus amount for focus check. Note that in the case of trailing tracking, the lens is not driven extra by the release time lag, so such calculation of the defocus amount for focus check is not performed.

With the above operation, when the subject is moving toward the camera, the lens is driven in advance by the release time lag, so it is difficult to know when to turn on the release.
However, the focus will not be too far behind, and you can always take pictures with the camera in focus. Furthermore, if the subject is moving away from the camera, the algorithm follows the subject, so it is possible to take a photograph in focus without over-compensating and getting the subject behind the camera.

[0042] In distance measurement, if the integration time is shortened, the sampling interval of the distance measurement data can be shortened, and it becomes easier to follow the subject, so a limit may be set on the integration time. FIG. 21 is a flowchart in the case of setting a limit on the integration time. Usually, the maximum value of integration time: T
intMAX = normal maximum integration time NORMAX, but when the correction is ON, as shown in Figure 21, by using the maximum integration time CONMAX when the correction is ON, which is smaller than the normal maximum integration time NORMAX, as the maximum value of the integration time, the Distance measurement can be performed with a short integration time.

Furthermore, as described above, there may be cases where the lens is driven to an end point during tracking. When driving the lens, the end point detection circuit 11 (FIG. 1) is reset in S15 of FIG. 3, and the INT2 interrupt is enabled. The end point detection circuit 11 generates an interrupt at INT2 of the CPU 3 when no pulse is received from the encoder for a certain period of time. That is, when the lens is driven to the end point while the lens is being driven, the encoder 5 no longer outputs pulses, so the end point detection circuit 11 is turned on and an INT2 interrupt occurs. FIG. 22 is a flowchart of this interrupt processing. When an interrupt occurs, lens driving is stopped, subsequent end point detection interrupts are prohibited, and then correction is turned OFF (
S501-503). If no interrupt occurs and lens driving is completed, the INT2 interrupt is prohibited in S16-3 of FIG.

FIG. 24 is a subroutine showing an example of the focusing process shown in S7 of FIG. 3. By lighting the focusing LED by the LED drive circuit 10 of FIG. This is to let you know that you are in a state of focus. This focusing LED is preferably provided within the viewfinder of the camera. Here, if C10 is not 1, the process simply displays the focus and returns.

Further, when C10=1, that is, when proactive tracking is performed, MAXAFPspeed/Kvalue≧OBJSP(
mm/s) MAXAFPspeed: Maximum driveable speed (pulse/
s) OBJSP: When the object image speed is (mm/s), in-focus display is always performed. In other words, you can confirm that you can always take in-focus photos when the focus is displayed during proactive tracking (MAXS = MAXAFPspeed in the flowchart).
/Kvalue, OBJ=OBJSP). If the subject speed exceeds the tracking limit speed, that is, MAXAF
When Pspeed/Kvalue<OBJSP (mm/s) holds, it is not possible to anticipate the release time lag, and even if you release the camera, you will not be able to take a photo in focus, so in this case, the focus will not be displayed. .

In the case of advance tracking mode, the AF switch S is set in advance by the release time lag.
If only 1 is turned on to bring the camera into focus, and then the release switch SWR is turned on at the end of lens driving, the subject image position and the focus position will always match at the start of exposure. However, if you turn on the release switch at other times, or if you set the release switch SWR to AF in advance.
When the switch SW1 is turned on at the same time and the release ON interrupt is permitted after a predetermined processing time has elapsed after the lens is driven, the pre-assumed starting point of the release time lag does not match the actual release ON interrupt timing. Further, in the case of tracking, the release time lag is not taken into consideration. Therefore, in these cases, the subject image position and the focus position do not necessarily coincide at the start of exposure. Therefore, if the lens is configured to be driven as much as possible during the release time lag, more precise focusing can be achieved. Also, when shooting several pictures in a row in advance tracking mode, the mirror may be lowered or lowered after the exposure is completed.
If the AF is restarted after film winding is completed, tracking ability cannot be improved. Since distance measurement is possible after the mirror is lowered, distance measurement is started immediately after the mirror is lowered, and regardless of whether winding is completed or not, the number of drive pulses based on the distance measurement data and the measurement obtained before the release are The tracking ability can be improved by driving the lens by adding the number of driving pulses depending on the distance.

FIG. 25 is a flowchart of the release interrupt processing taking these cases into consideration.
is a diagram showing the state of lens driving controlled by this flowchart. Figure 26 shows the release O when the lens is stopped.
FIG. 27 shows a state in which an interruption of N occurs, and FIG. 27 shows a state in which a release ON interruption occurs during lens drive. The release ON interrupt is enabled in S8 of FIG.
This process is started by an interruption of the release ON signal from the release switch SWR. First, S60
In step 1, control the mirror up and lens aperture,
In S602, it is determined whether correction is ON. When the correction is OFF, normal release control in S603-S605 is performed via S602. That is, the shutter is controlled in S603, and after waiting for the mirror to complete lowering in S604, the S
Winding is performed in step 605, and the interrupt processing is ended. On the other hand, when the correction is ON, it is determined in S607 whether or not the lens is being driven, and based on the result, S608 or
In S609, the lens drive amount AFP is reset. If the lens is not being driven, in step S608, the amount of movement of the subject since the end of the previous lens drive is calculated using the elapsed time tt since the end of the previous lens drive, as shown in FIG.
Calculate using the formula OBJSPx KVALUExtt and set the new value in AFP. On the other hand, if the lens is being driven, in S609
The elapsed time t from the end of the previous lens drive, shown in
Drive amount to be driven during t (same as S608 above) OB
J×Kvalue×tt This is the amount of the current lens drive setting value AFP that has already been driven (AFP-Dar). However, Dar: Calculated by subtracting the remaining lens drive amount, and the new lens drive Amount AFP
shall be. A reset in S608 or S609
If FP exceeds the maximum number of AF pulses MXM that can be driven in the release time lag time, AFP=MX in S611.
Let it be M. The lens is driven by the set AFP and exposure is performed (S612, S613).

When it is determined in S614 that the mirror has finished lowering, the next distance measurement, that is, the integration and
Input and calculation are performed in S615, and the number of drive pulses An is calculated in S616.

Referring now to FIG. 28, a function for increasing the tracking ability by starting the next tracking operation as soon as distance measurement becomes possible after the shutter release is completed will be described. In other words, in tracking mode, if the next distance measurement calculation etc. is started after the film winding is completed after the release is completed,
I can't improve my tracking ability. Since it is possible to measure the distance when the mirror is lowered, the distance measurement is started after the time t0 when the mirror was raised last time, the release operation is started at t1, and the distance measurement is started at the time t11 when the mirror has finished lowering. Then, the number of driving pulses An is determined. Then, the number An-1 of drive pulses determined before the previous distance measurement, that is, the start of the release operation, is added to the number An of drive pulses to obtain a new number of drive pulses. By configuring in this way, it is possible to start the next distance measurement and drive the lens after waiting until t2 after the mirror has descended to complete winding of the film (in the case represented by the dotted line in Fig. 28). The follow-up operation can be continued earlier by the time t2-t11 (in the case represented by the solid line in FIG. 28). And S6
17, the previous defocus amount An-1 + the current defocus amount An = AFP, and in S618,
The flag AlS is cleared, the correction is turned OFF, and the release interrupt processing is ended. After the interrupt ends, L in Figure 3
Moving to MOV, the lens is driven by the above drive amount AFP.

FIG. 29 is a flowchart showing a series of so-called overlap processes in this embodiment. The overlap process further performs a distance measurement operation while the lens is being driven to more accurately determine the position of the focusing lens. When distance measurement is performed on a subject that is significantly deviated from the focus position at the time of initial distance measurement, the obtained defocus amount itself contains a large error, so the determined lens drive amount may not be an accurate value. Therefore, the focusing operation will not be satisfactory. Therefore, by configuring the camera to further calculate the drive amount while the lens is being driven, overlap processing is performed in order to perform accurate focusing operation.

First, CCD integration is started while the lens is being driven. The lens drive amount is set in the counter 6,
In S701, the number of lens drive pulses at the start of integration is set to C1, and the number of lens drive pulses at the end of integration is set to C3. In S702, the CCD integral data is input, and in S70
In step 3, the amount of defocus is calculated. S7
In step 04, based on the obtained defocus amount, the number of AF pulses is calculated in the same manner as in the process of S3 in FIG. 3, and the calculated value is set as Cx. The number of lens drive pulses in the counter 6 at the time of Cx calculation is assumed to be C4. In S705, the number of lens drive pulses required to update the lens drive amount is calculated using the following equation. C2=(C1+C3)/2 A=Cx-(C4-C2) The above A is the updated number of lens drive pulses. This is set in counter 6 in S706, and the process ends.

Note that, as is clear from S17 and S18 in FIG. 3, overlap processing is not performed when the correction is ON, that is, in the tracking mode. As mentioned above, overlap processing is necessary when the amount of defocus is large, but when the correction is ON, the focusing lens is tracking the subject, so it is difficult to imagine that the amount of defocus is that large. This is because it is unthinkable. Additionally, the AFP value obtained for tracking is updated by AFP calculation for overlap processing, which is performed in a routine different from the main routine, resulting in the problem that the tracking operation itself becomes impossible. It is.

In the automatic focus adjustment device installed in the camera configured as detailed in the above embodiment,
The tracking mode is entered only when it is determined that the subject on the imaging plane is moving at a predetermined speed or higher for a predetermined number of consecutive distance measurement operations. In other words, since you can enter tracking mode after knowing for sure that the subject is moving at a speed higher than a predetermined value, you can avoid unnecessarily driving the lens when a stationary subject moves momentarily. What you do can be avoided.

Furthermore, even if the focusing lens is already within the focusing range and the focus is displayed, if the tracking mode is in effect, the lens will be driven further to follow the movement of the subject. It is also possible to configure the camera to focus completely.

The release time lag used in calculations for tracking may not be used as is, but a value that takes into account the integration time for distance measurement may be used, thereby allowing smoother tracking.

Furthermore, if the release is turned on not immediately after the lens drive ends, the amount of defocus can be reduced by configuring the focusing lens to be driven by the amount that can be driven within the release time lag. It is also possible to make it smaller.

Furthermore, when transitioning to the next tracking mode after the release, it is not necessary to start distance measurement for the next tracking mode after all release operations are completed, but at a certain point during the release operation, for example, By configuring the camera to measure the distance when the mirror has finished lowering and use that data for the next calculation, it becomes possible to continuously perform appropriate tracking during continuous shooting mode.

In the tracking mode, the object is in focus;
In addition, it is also possible to configure so that a focus display such as turning on an LED is performed only when tracking is possible. in this case,
It is preferable to make the lighting of the LED visible in the viewfinder of the camera. With this configuration, the camera has an indicator function that notifies the operator that the camera is in focus.

In this embodiment, the tracking mode is entered when it is determined in two distance measurements that the moving speed of the image plane of the object is equal to or higher than a predetermined speed. However, the configuration may be such that the tracking mode is entered when the determination is made a predetermined number of times or more. Additionally, if the amount of lens drive during tracking is equal to or greater than a predetermined value three or more times, it is determined that tracking is not being performed correctly and tracking is turned off. It is possible to set.

Furthermore, if the integration/calculation time becomes long, there is a possibility that the lens drive will not be able to follow the moving speed of the object, so by setting an upper limit on the integration time in the tracking mode, the distance measurement time can be shortened. , it can be followed smoothly.

[0061] Overlap processing may be necessary when the moving speed of the subject is high and the amount of lens drive is relatively large accordingly, but normally during the tracking mode,
The amount of lens drive is relatively small, and if the amount of lens drive becomes relatively large even though it is in tracking mode, it is considered that the moving speed of the subject is close to the limit value that can be tracked. Therefore, by configuring so that overlap processing is not performed during the follow-up mode, appropriate follow-up driving can be realized.

Furthermore, although this embodiment has been described only in the so-called focus priority mode in which the release operation is performed after the in-focus state is achieved, the so-called release priority mode in which the release operation is performed regardless of the in-focus state is described. It is also applicable to cases where That is, the configuration is such that either focus priority or release priority can be selected using a switch (not shown), and in the case of release priority, S6-1 and S in FIG.
If the shutter speed is set to jump 8 and the release ON interrupt is always enabled, the release operation will be performed regardless of the in-focus state.

[0063]

As described above, in the automatic focusing device according to the present invention, the focusing lens is movable in the optical axis direction, and the amount of defocus for a specific object is determined by the focusing lens. a distance measuring means; a calculating means for calculating a relative movement direction and a moving speed of the object in the optical axis direction based on the defocus amount determined by the distance measuring means; and a distance measuring means for the distance measuring means. a control means for controlling the distance measuring means to repeat the operation at predetermined time intervals, and a moving speed of the object calculated by the calculating means for each distance measuring operation by the distance measuring means is equal to or higher than a predetermined value. a discriminating means for discriminating whether the moving speed of the object is equal to or higher than a predetermined value for a predetermined number of consecutive times by the discriminating means; Since the configuration includes a drive control means for driving the focusing lens at a position where the object is in focus at a position where the object moves after a lapse of time, appropriate focusing processing can be performed for the moving object. In addition, by measuring the speed of the subject image more than a predetermined number of times to determine whether to enter tracking mode, it is possible to enter tracking mode after accurately grasping that the subject is moving. can.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the main parts of the AF system of the automatic focus adjustment device of the present invention;

[Figure 2] Graph explaining the basic principle of the tracking method in this case,

[Fig. 3] Flowchart showing the processing of the AF system that adopts the tracking method of the present case,

[Fig. 4] A graph explaining the principle of changing the mode from trailing tracking to proactive tracking,

[Figure 5] A graph explaining the calculation method during proactive tracking,

[
Figure 6: Graph explaining the principle of moving object prediction calculation when considering integration time,

[Figure 7] Main flowchart of moving object prediction calculation,

[Figure 8
] A flowchart explaining the calculation when the subject approaches the camera immediately after the correction is turned on.

[Figure 9] Correction ON
A flowchart explaining the calculation when the subject approaches the camera from the second time onwards.

FIG. 10 is a graph illustrating moving object prediction calculation based on the movement status of the subject and the driving results of the lens;

FIG. 11 is a graph illustrating moving object prediction calculation based on the movement status of the subject and the driving results of the lens;

FIG. 12 is a graph illustrating moving object prediction calculation based on the movement status of the subject and the driving results of the lens;

FIG. 13 is a graph illustrating moving object prediction calculation based on the movement status of the subject and the driving results of the lens;

FIG. 14 is a graph illustrating moving object prediction calculation based on the movement status of the subject and the driving results of the lens;

FIG. 15 is a graph illustrating moving object prediction calculation based on the movement status of the subject and the driving results of the lens;

FIG. 16 is a graph illustrating moving object prediction calculation based on the movement status of the subject and the driving results of the lens;

FIG. 17 is a graph illustrating a moving object prediction calculation based on the movement status of the subject and the driving results of the lens;

FIG. 18 is a graph explaining the algorithm when the subject moves away from the camera;

FIG. 19 is a flowchart illustrating calculations when the subject moves away from the camera immediately after correction is turned on;

FIG. 20 is a flowchart illustrating calculations when the subject moves away from the camera from the second time onwards after correction is turned on;

FIG. 21 is a flowchart showing processing when setting a limit on integration time;

FIG. 22 is a flowchart showing processing when an end point of the lens is detected during tracking;

FIG. 23 is a flowchart representing a focus check defocus amount recalculation subroutine for checking whether the position where the lens is driven based on the moving object prediction calculation is the in-focus position;

FIG. 24 is a flowchart illustrating focus display during tracking;

FIG. 25 is a flowchart illustrating processing when distance measurement is performed immediately after the mirror is lowered in the case of continuous shooting;

26 is a diagram showing the state when the release is turned on when the lens is stopped during the operation shown in FIG. 25,

27 is a diagram showing a state when the release is turned on while driving the lens during the operation shown in FIG. 25,

FIG. 28 is a diagram showing the lens operation when the next distance measurement operation is performed immediately after the mirror is lowered;

FIG. 29 is a flowchart illustrating overlap processing in this case;

FIG. 30 is a diagram showing the state of lens drive in a conventional AF system;

FIG. 31 is a diagram showing a lens driving state in a conventional AF system.

[Explanation of symbols]

100... Lens 1... Distance sensor (distance measuring means) 3...
CPU (calculation means)

Claims (3)

[Claims] 1. A focusing lens movable in an optical axis direction, a distance measuring means for determining a defocus amount of a specific object by the focusing lens, and a defocus amount determined by the distance measuring means. calculation means for calculating the relative moving direction and moving speed of the object in the optical axis direction based on the above, and controlling the distance measuring means to repeat the distance measuring operation of the distance measuring means at predetermined time intervals. a control means for determining whether the moving speed of the object calculated by the calculation means is equal to or higher than a predetermined value for each distance measurement operation by the distance measurement means; When the moving speed of the object is determined to be equal to or higher than a predetermined value for a predetermined number of consecutive times, the object is brought into focus at a position where the object will move after a predetermined period of time has elapsed from the current time based on the calculation result of the calculation means. , and drive control means for driving the focusing lens. 2. The calculation means calculates the direction and amount of movement of the object image by the focusing lens.
automatic focusing device. 3. The drive control means follows the object when the moving direction of the object is moving away from the camera, and moves ahead by a release time lag when the moving direction of the object is moving toward the camera. The automatic focusing device according to claim 1 or 2, wherein the focusing lens is driven to the point.