JP3081013B2 - Automatic focusing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an automatic focusing function (AF)
Device, for example, AF (AUTOMATIC)
FOCUSING) The present 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 been remarkably increased, and the AF function is becoming undecidable even in single-lens reflex cameras with interchangeable lenses. In a single-lens reflex camera, AF by a phase difference method is generally adopted. AF by the phase difference method is performed in the following procedure. First, a subject image is projected on a detection element (CCD or the like) 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 the respective light receiving units, the distance difference between the detection element (film equivalent surface) and the image forming surface of the photographing lens facing the subject and the direction (defocus amount) And the defocus direction) are calculated. The amount of motor drive necessary to drive the lens to the in-focus position is determined from the calculated defocus amount and its direction, and the lens is driven along its optical axis so that the image plane matches the film equivalent plane. Is done. The number of pulses applied to the motor at this time is obtained by the following equation. P = Kv × D

Here, P is the number of drive pulses applied to the motor, and D is the defocus amount. Kv is called a lens moving amount conversion coefficient (K value), and is a coefficient for calculating the number of pulses for driving the motor as necessary for moving the lens to the in-focus position from the above defocus amount and direction. , A lens-specific value.

FIGS. 30 to 32 are diagrams for explaining a conventional AF system configured as described above. The subject image position in each figure is defined as the subject image position with reference to the position of the focusing lens. This is an image forming position, and the focus position indicates the position of the film equivalent surface with reference to the position of the focusing lens. In FIG. 30, it is assumed 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 set the defocus amount D0 to O. Since the subject is stationary, the focus position and the subject image position match as a result of the lens drive. In this state, it is assumed that the release ON interrupt process is performed at time t1 and that the exposure is actually started at time t2 after the release time lag, that is, the time required for mechanical drive for raising the mirror and stopping down the aperture, as shown in FIG. As described above, the focus position at the exposure start time t1 always coincides with the subject image position.

However, when the subject is a moving body (moving in the lens driving direction), integration and calculation are performed, and based on the result, the subject is not driven while the lens is driven for focusing. In order to keep moving, it is necessary to repeat the processes of integration, calculation, and lens driving.

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 taking lens. In this case, it is assumed that the distance difference between the subject image position and the focus position at a point, that is, the defocus amount is D1. The lens is driven by an amount corresponding to D1 and the time t
When the defocus amount is obtained at a point after one elapse, it is assumed that D2 is obtained. Similarly, the lens is driven by an amount corresponding to D2, and the defocus amount D3 is obtained at the next point after the lapse of time t2. Here, the focus position when the defocus amount at the point is obtained corresponds to the object image position of the point, and the object moves even during the time t1, so that the object moves from far to near. When moving at a speed, the defocus amount gradually increases with each distance measurement, such as D1 <D2 <D3, and the lens drive cannot sufficiently follow the change in the position of the subject image. The problem arises.

In order to solve this problem, it is necessary to predict the distance the subject will move in the time from the start of integration to the completion of lens driving after calculation, and to drive the lens taking that into account. Accordingly, various methods for solving the above-described problem of the following delay have been considered. In such a case, it is conceivable to indicate to the operator that the subject is in the in-focus range by following a predetermined method, for example, an LED or the like. Thus, the operator can recognize that the in-focus photograph can be taken.

However, even if the in-focus display is performed in such a manner, when the moving speed of the subject is extremely high, for example, when the driving speed of the lens is higher, the in-focus state is obtained for a moment. Since the focus is out of the focus width and tracking is impossible, the focus display cannot be said to be meaningful. Therefore, in such a case, it is conceivable that the operator may make an erroneous determination due to the in-focus display even though a photograph in focus cannot be taken.

Further, in the conventional automatic focusing apparatus, since the in-focus display is performed when the defocus amount based on the distance measurement data for a specific object (an object in the distance measurement zone) becomes almost zero, the forward follow-up is performed. The defocus amount based on the distance measurement data does not become 0 in the forward movement state,
Does not display focus. For this reason, there is a problem that the photographer does not know whether the exposure can be performed in a focused state and feels uneasy.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to solve such a problem, and when a specific object moves, when it comes into focus at the start of exposure, it indicates that it is in focus. It is an object of the present invention to provide an automatic focus adjustment device capable of performing such operations.

[0011]

SUMMARY OF THE INVENTION In order to solve this problem, the present invention repeatedly finds a photographing lens provided with a focusing lens movable in the optical axis direction and a defocus amount for a specific subject formed by the photographing lens. A distance measuring unit, and calculates a relative moving direction and a moving speed in the optical axis direction in which the image of the specific subject moves based on the defocus amount obtained by the distance measuring unit, and further, based on the calculation result. Calculating means for calculating a moving direction and a moving amount of moving the focusing lens; a driving control means for moving the focusing lens based on a calculation result of the calculating means; and a display means for displaying a display related to focusing And a calculating unit that moves the focusing lens to a position where an image plane moves by an amount equivalent to a multiple of the defocus amount obtained via the distance measuring unit. Zum and always switched in response to the preemptive tracking algorithm an image of the object after the release time lag can move the focusing lens to the amount preemptive position will move in the direction of movement of the specific subject,
When the moving direction of the specific subject is away from the photographing lens, the moving amount of the focusing lens is calculated by the backward tracking algorithm, and when the moving direction of the specific subject is closer to the photographing lens, the forward-looking follow-up is performed. Calculating an amount of movement of the focusing lens by an algorithm, and calculating a defocus amount for focus determination based on a defocus amount corresponding to a release time lag; the display means includes: the drive control means An image plane moving speed at the maximum drivable speed of the focusing lens drivable by the camera is equal to or higher than the moving speed of the image of the specific subject calculated by the calculating means, and the calculating means calculates the forward-looking algorithm When the defocus amount for focusing determination is within the focusing range, To a focus display, a has a feature. According to the configuration of the present invention, the amount of movement of the focusing lens is calculated by a different algorithm when the subject approaches and separates from each other, so that an appropriate algorithm for the focusing according to the moving state of the subject is calculated. Since the focusing lens is driven by determining the amount of movement of the lens, it is possible to perform in-focus exposure on the moving subject. In addition, when the focusing lens is capable of following movement, and when the calculation is performed by a forward-looking follow-up algorithm, a defocus amount for focus determination is further calculated based on the defocus amount corresponding to the release time lag, and Since the in-focus display is performed when the in-focus amount for focus determination is within the in-focus range, the user can move the desired subject to be moved.
It is possible to follow while always recognizing whether or not the subject is in focus during shooting.

In the case where the calculating means is calculating by the following-follow-up tracking algorithm, it is preferable to display the focus when the defocus amount is within the focus range. According to this configuration, even when the subject is approaching or moving away from the subject, it is possible to perform focusing display with high accuracy, and the user does not miss the focused state.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a main part of an AF camera on which the automatic focusing device of the present invention is mounted. 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. Distance measurement is performed by a distance measurement sensor 1 including a detection element such as a CCD via an interface 2, and the obtained distance measurement data is input to a CPU 3 via a port 1. The amount is calculated. Next, a lens drive amount is calculated from the K value stored in the lens ROM 9 mounted in the lens 100 and the calculated defocus amount. It should be noted that if the defocus amount is not obtained or the like, it is checked whether or not the distance measurement data is invalid. If the data is invalid, an NG process such as displaying that the distance measurement was not correctly performed is performed. Configured to do so. At this time, the distance measurement is performed again. Then
It is determined whether the defocus amount is within a predetermined focus width. If it is determined that the defocus amount is within the focus width, the port P of the CPU 3 is determined.
74, the LED drive circuit 10 is controlled to
Focusing processing such as turning on D is performed, and a release interrupt is permitted.

If it is determined that the distance is not within the in-focus range, the release interrupt is inhibited and the lens drive amount is reduced by the counter 6.
And the lens driving circuit 4 is controlled to start lens driving. The number of rotations of the AF motor rotated by the lens driving circuit 4 is monitored by the encoder 5, and when the content of the counter 6 is decremented to 0, the rotation of the AF motor is stopped and the lens driving is stopped.

When the release switch SWR is turned ON, the release process of the release ON interrupts the port Por of the CPU 3.
After t5, the release control circuit 8 performs a series of release control processes of mirror raising, exposure, and mirror lowering.

If the release is turned on at the time of focusing by the automatic focusing function, actually, the shutter is not opened at the moment when the release ON signal is read, but is actually released after the release ON signal is read. Is opened and the exposure is started, there is a time difference by the time required for the aperture-down operation and the mirror raising drive for narrowing the aperture down to the aperture value set in advance manually or by the exposure control calculation (hereinafter, this time difference is referred to as the time difference). "Release time lag"
Call. ). When photographing an object in a stationary state, the position of the object does not change during this release time lag, so once in focus, defocus no longer occurs regardless of the length of the release time lag. The actual exposure is performed in a state where the subject is in focus. However, when the subject moves, since the subject has moved from the in-focus position during the release time lag, defocus occurs when actual exposure is performed.

Therefore, in this embodiment, the release is ON.
After the interruption, the following method is used in order to match the subject image position with the focus position at the time when the exposure is actually started (that is, after the release time lag has elapsed).

In FIG. 2, the solid line indicates the movement of the subject image position. If the lens drive is controlled so that the focus position is on the solid line after the release time lag has elapsed,
Whenever the release is turned on, exposure is performed in a focused state. The curve shown 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, the release control process will always start at the focus position that is ahead of the release time lag regardless of the release ON, and the subject image will be in focus after the release time lag has elapsed. And exposure is performed in a focused state.

FIG. 3 is a flowchart showing the main processing of the AF system according to the present embodiment. In the present embodiment, since the processing procedure is changed depending on the number of times the AF distance measurement is performed, first, step S (hereinafter, referred to as “S”)
In step 1, the flag A1S indicating the number of times of AF distance measurement is cleared. In S2, distance measurement is performed by the distance measurement sensor 1 including a detection element such as a CCD via the interface 2, and the amount of received light is integrated with respect to time to obtain distance measurement data. The distance measurement data is input to the CPU 3 via the port 1 and the
In U3, a predetermined calculation is performed to calculate the defocus amount. In S3, the lens drive amount (the number of AF pulses) is calculated from the K value stored in the lens ROM 9 mounted in the photographing lens 100 and the defocus amount calculated in S2 by the above expression. This lens drive amount is set in the counter 6. In S4, a moving object prediction calculation (described later) is performed.

Next, in S5, it is checked whether the distance measurement data is invalid, for example, when the defocus amount is not obtained, and when the data is invalid, it is displayed that the distance measurement was not correctly performed. After performing NG processing such as performing in S5-1,
Returning to S2, distance measurement is performed again.

In S6, it is determined whether or not the defocus amount is within a predetermined focus width. If it is determined that the defocus amount is within the focus width, the LED drive circuit 10 is controlled via the port P74 of the CPU 3 in S7. Then, a focusing process such as turning on a focusing LED is performed. In the next S8, the release ON interrupt is permitted, and the release operation becomes possible.

Step S9 is a so-called one-shot process, which is a process for stopping the focusing process once the image is focused.

Next, in S10, it is determined whether or not the correction is ON, that is, whether or not the tracking mode is set. S if not in tracking mode
Returning to step 2, the CCD integration process is restarted.

In the case of the tracking mode, whether the subject is moving in the direction approaching the lens 100 (camera) in S11
Alternatively, it is determined whether or not the camera is moving away from the lens 100 (camera) based on the content of the flag FFN. If the camera is moving in the direction moving away from the camera, the process returns to S2. Here, the case where the subject moves in the direction away from the lens is indicated by FFN = 1. Follow mode in S10, S11
When it is determined in step S12 that the subject is moving in the direction approaching the camera, in step S12, the current lens drive pulse number (AF
It is determined whether or not P) is 0. If the number of lens drive pulses is 0, the process returns to step 2. If not, the lens drive flag BFM = 1 is set. This is a flag indicating whether or not the lens has been driven.

If it is determined in step S6 that the defocus amount is not within the in-focus range (that is, if the defocus amount is not within the predetermined in-focus range), after performing a process of inhibiting the release operation in S6-1, It is determined in S6-2 whether or not the correction ON mode, that is, whether or not the tracking mode, and if it is ON, it is determined in S12 whether or not the lens drive pulse number AFP is 0. AFP
If = 0, the lens drive is not performed, and the process returns to the distance measuring process in S2.

If AFP is not 0 and the lens is driven, and if it is determined in S6-2 that the camera is not in the following mode, the lens drive flag BFM is set in S13 as described above.
Set to 1. Then, the lens driving process after S14 is performed.

In this lens driving process, first, S1
In step 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 number of rotations of the AF motor rotated by the lens drive circuit 4 is monitored by the encoder 5, and the counter 6 is decremented. When the content of the counter 6 becomes 0, A
The rotation of the F motor is stopped, and the lens driving is stopped.

After the driving of the lens is started in S14 in this way, in S15, an interruption process when the focusing lens is driven to the end point of the driving range during the driving of the lens is permitted. This interrupt processing will be described later.

In S16, the value of the counter 6 is exactly 0
, That is, the AF motor is controlled so that the lens driving speed gradually decreases immediately before the end of the lens driving so that the lens stops accurately at the in-focus position, and the PWM (Pulse Width Modulation) of the motor is controlled.
on) It is determined from the number of pulses remaining before focusing whether or not control is necessary. If it is not necessary yet, that is, if the lens is being driven, it is determined in step S17 whether or not the correction is ON. When the correction is not ON, S1
In step 8, the overlap processing, that is, the distance measurement, calculation, and the like are further performed while the lens is being driven, and the processing of updating the value of the counter 6 is performed. In step S16, that is, whether the PWM control of the AF motor is necessary is determined. repeat. However, if the correction is ON in S17, the process returns to S16 without performing the overlap processing. The relationship between the correction ON and the overlap processing will be described later.

If PWM control is required in S16,
That is, immediately before the end of the lens driving, PWM control is performed in S16-1 and it is determined in S16-2 whether the driving is completed.

When the driving of the lens is completed, the interrupt process at the time of detecting the end point is prohibited in S16-3, and the process returns to S2 to continue the distance measuring process.

The following describes the follow-up mode when the correction is ON in the present embodiment. First, a description will be given of an algorithm at the time of entering the advanced follow-up mode, which is advanced by the release time lag from the normal backward-tracking in-focus.

In FIG. 4, the number of motor drive pulses obtained at the point is denoted by A1. The image plane defocus amount is K
By multiplying the value, the number of pulses applied to the motor to drive the focusing lens to the in-focus position can be converted to the number of pulses applied to the motor in order to eliminate the defocus amount. It is simply referred to as the “number of pulses” or the lens drive amount. Thereafter, it is assumed that the pulse A1 is applied to the motor to drive the lens, and after the lapse of time t1, the pulse number A2 at the point is obtained.
The amount of movement of the subject image from point to point becomes A2 when converted into the number of pulses. Therefore, the object image moving speed OBJsp between the two points is OBJsp = A2 / t1. Here, the subject image position at a point after a lapse of time t2 from the point based on the subject image position is represented by A2 + t2 * OBJsp, assuming that the subject image speed is constant. If the amount of movement of the subject image during the time t2 is P2 and P2 = t2 * OBJsp is replaced, the driving amount is calculated as A2 + P2.
That is, the point at which the motor is driven by A2 + P2 coincides with the position of the subject image after the lapse of time t2.

Note that this P2 must be calculated in advance when calculating the lens drive amount. Here, the time required for calculating the lens drive amount after obtaining the distance measurement data is always constant, and the time including the drive time may be considered to be substantially the same every time. Therefore, assuming that the present calculation time and drive time, that is, time t2, is the same as the previous calculation time and drive time, that is, time t1, actual measurement of time t1 obtains time t2, and calculates P2. I do.

As described above, even when the motor is driven by A2 + P2 at the point to make the focus position coincide with the object image position and the release ON is interrupted at that time, the exposure actually starts because of the release time lag. After the lapse of time, it is necessary to move the focusing lens in order to further advance the focus position by the moving amount of the subject image during that time.

Assuming that the release time lag is RLt, the number of advance pulses TXP2 required to further advance the focus position from the object image position by the release time lag
Is obtained by the following equation: TXP2 = RLt × OBJsp, and it is sufficient to drive the motor by the number of pulses. In FIG. 4, the release time lag RLt is a period from the end of lens driving to the start of exposure in each period. Here, as shown in FIG. 6, in order to measure the defocus amount, the time interval Tint
Is performed, and each data is obtained based on the integrated value. However, the position at which the actual defocus amount is obtained is not the position at the start of integration, but the time when Tint / 2 has passed therefrom It can be considered as the distance measurement value at Pi (that is, the midpoint of the integration time) Pi. Therefore, if the release time lag RLt is corrected so as to be calculated as RLt-Tint / 2, more precise tracking is possible. Therefore, the above TXP2 calculation formula is corrected as follows: TXP2 = (RLt−Tint / 2) × OBJsp. As described above, by setting the lens driving amount AFP2 at the point as AFP2 = A2 + P2 + Txp2, the so-called follow-up following, in which correction of the object image moving amount is simply added to the defocus amount, and the lens driving amount in anticipation of the release time lag. You will follow. If the number of drive pulses A3 actually obtained at the point when the time t2 elapses from the point coincides with the above-mentioned Txp2, it means that it has advanced by the release time lag. Actually, since the moving speed of the subject image is not constant, A3 = Txp2 is not always satisfied.

Next, in FIG. 5, it is assumed that the pulse number A3 is obtained at the result of the integration and calculation. Then, from the figure,
The difference between the subject image position and the subject image position corresponding to (the amount of movement of the subject image) is considered to be the same as t2 as described above, and the movement of the subject image is linear. assuming that, since it is considered to be equal to the amount of movement from the point to the subject image position corresponding to the point, the up position corresponding to the position corresponding to the point
The object image movement amount P3 is obtained as P3 = P2 + Txp2-A3. Therefore, the lens driving amount AFP3 from point to point is AFP3 = P3 + Txp3-A3.

With the same concept, the following equation is obtained as a general equation for obtaining the moving amount of the subject image and the lens driving amount during follow-up. Pn = Pn-1 + (Txpn-1-An) Txpn = f (Pn) AFPn = Txpn + Pn-An where Txpn is a function f (P
n). Txp is theoretically obtained by Txp = (Pn / t) × RLt. However, as described above, as shown in FIG. 6, the integration is performed during the time interval Tint to measure the defocus amount, and each data is obtained based on the integration value. The position at which the amount is obtained is not the position at the start of the integration, but can be considered as the distance measurement value at the point Pi after a lapse of Tint / 2 (that is, the middle point of the integration time). Therefore, if the release time lag RLt is corrected so as to be calculated as RLt-Tint / 2, more precise tracking is possible. Therefore, the above Txp can be expressed as Txp = (Pn / t) × (RLt−Tint / 2).

Further, Txp is obtained from the distance measurement data, and since the dispersion of the distance measurement data has a great effect, in the present embodiment, the immediately preceding four data are averaged according to the following equation. Txpn = (Txp + Txpn-1 + Txpn-2 + T
xpn-3) / 4 For data for which there is no data in the past, 0 is substituted for the calculation.

FIG. 7 is a flowchart of a subroutine of the moving object prediction calculation performed in S4 of FIG. In step S201, the distance measurement data is checked. If the distance measurement data is not OK, a flag A1 for counting the number of times of distance measurement is determined in step S226.
S is set to 0 indicating the first time, and the process returns to the main processing.
Examples of such cases include, for example, a subject having a very low contrast, and a case where distance measurement data cannot be obtained due to a very large defocus amount. Also, when the AF one-shot mode is set as described above, that is, when control is performed to stop the focus processing once the focus is achieved, the focus processing is performed by following the subject even if the focus is achieved once. Since it is not necessary to set the tracking mode to be continued,
If it is determined that the current mode is the AF one-shot mode in the determination of 1, the process returns to the main process. If it is not the AF one-shot, the process comes to this routine only after the AF mode is entered, and if the distance measurement data is determined to be OK in S201, it is determined that A1S = 0 in S202,
The process proceeds to S218 via S224 and S225, and returns to the main process. At this time, in S224, the flag A1S for counting the number of times of distance measurement is set from 0 indicating the first time to 1 indicating the second and subsequent times, and thereafter A1S =
1 indicates that the processing is the second or more processing,
The timer 7 for measuring the time interval of distance measurement is started, and each data for calculation is initialized in S225.

When the number of times of distance measurement becomes the second time or more, S202
The process proceeds from step S203 to step S203, and the time interval t from the previous distance measurement is measured by the timer 7 in step S203. In S204, it is determined whether the correction is ON, that is, whether or not the camera is in the following mode. However, since the correction is OFF in the initial state, that is, the camera is not in the following mode, the process proceeds to S205. S205 to S
In the routine 211, it is determined whether or not the subject image is handled as a moving object. In S205, the current defocus direction is compared with the previous defocus direction. If the defocus directions are different, it is considered that the subject image has changed the moving direction, and it is not determined whether to treat the subject image as a moving object. The calculation data is cleared in S225, S218
And returns to the main processing. If the defocus direction is the same, it can be regarded as moving in the same direction,
Proceed to S206. In S206, it is determined by the flag BFM whether the lens was driven in the previous distance measurement. If the lens was driven in the previous distance measurement, that is, if BFM = 1, the process proceeds to S209, and the current subject image movement amount XX = An
And when the lens was not driven last time, that is, BFM =
If it is 0, the process proceeds to S207, where the previous defocus amount An-1 is compared with the current defocus amount An, and it is determined whether or not the subject image is approaching the focus position. If the subject image is approaching the focus position, the subject will be in focus even if not in the following mode.
The process returns to the main processing via 18.

On the other hand, if it is determined in S207 that the subject image moves away from the focus position and if it is determined that the subject images are equidistant, in S208, the current defocus amount An is compared with the previous defocus amount An. In step S210, the object image movement amount OBJSP in one cycle from the distance measurement to the distance measurement is calculated from the value t obtained in step S203 in step S210 by subtracting -1 to obtain the current object image movement amount XX = An-An-1. That is, XX / (Kvalue × t) is obtained and it is determined whether or not XX / (Kvalue × t) is larger than a predetermined value. Here, the predetermined value is, for example, a formula, focusing width / (t + RL)
The amount by which the subject image moves within a time period obtained by adding the release time lag RLt to the period t from the distance measurement to the distance measurement represented by t) is the speed at which the focus width is matched. That is, if the object image speed OBJSP is smaller than this value, the lens is driven based on the current distance measurement, and then the release is turned on.
Is performed, the moving subject image is within the in-focus range even at the start of exposure after the elapse of the release time lag, and there is no need to particularly follow the moving object. However, the predetermined value may be set to a smaller value with a margin in order to reliably determine the moving object.
Although the judgment is somewhat rough, the predetermined value may be set to a speed at which the moving amount of the subject during the release time lag matches the focusing width.

As described above, when the object image speed OBJSP is smaller than the predetermined value, the processing shifts to S225, where the calculation data is cleared, and the processing returns to S218 and returns to the main processing. Conversely, object image speed OBJSP
Is larger than the predetermined value, in S211, it is determined whether or not the determination regarding the speed is made for the first time. If it is the first time, the process returns to the main process through S218. When it is determined that the object image speed OBJSP is larger than the predetermined value in the two or more distance measurement calculations, the correction is turned ON for the first time, and the lens is driven by the moving object tracking algorithm of the present case. S2
12, S213: correction ON, flag C10 =
0 (indicating that this is the first time since the correction is turned on. C10 = 1 is set for the second and subsequent times. In S214, the current defocus direction is determined, and thereby the moving direction of the subject image is determined. That is, when the defocus direction is the back focus (+), it is determined that the subject is moving so as to approach the camera, and the process proceeds to the forward follow-up in S222.

On the other hand, when the defocus direction is the front focus (-), it is determined that the moving direction of the subject is away from the camera, and the process proceeds to the follow-up following process in S223. In S215, the flag FFN indicating the relative positional relationship between the subject and the camera is set to 0, indicating that the subject is moving so as to approach the camera. In S216, the flag FFN is set to 1
To indicate that the subject is moving away from the camera. Thereafter, the processing returns to the main processing via S218.

When the process comes to this routine after the correction is turned on, the process proceeds to S219 in S204. If the subject is moving in the direction approaching the camera according to the moving direction of the subject, the process proceeds to S220. Processing is performed, and S2
In step 17, the defocus amount for focusing is recalculated according to the routine in FIG. 23. If the subject is moving in a direction away from the camera, the processing in S221 is performed, and the processing in S2 is performed.
Then, the process returns to the main process through the step 18.

In S218, for the next calculation,
Each data is stored with An being An-1 and AFPn being AFPn-1, and the flag BFM is reset to 0.

FIG. 8 is a subroutine in S222 of FIG. 7 for shifting from the follow-up mode to the advance mode. XX
Is the object movement amount (number of pulses), which is set to Pn for use in the current calculation (S261). As described above, the drive amount corresponding to the release time lag is calculated as a function of the object movement amount Pn (S262), and the current lens drive amount (the drive amount for entering the forward follow-up from the backward follow-up) AFP is calculated in S263. The details are as already described in the description of the basic calculation.

In the moving body prediction calculation for the second and subsequent times after the correction is turned ON, different processing is performed according to the moving direction of the subject based on the FFN value set in S215 and S216 in FIG. FIG. 9 shows the processing of S220 when the subject comes closer to 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 step S303 whether or not the movement of the subject has been advanced and the forward movement has been started.
Is determined. If the defocus direction is different from the previous defocus direction, it is determined that follow-up tracking has been entered, the flag C10 is set to 1 in S304, and the process proceeds to S305.
If the previous and current defocus directions are the same, it is determined that the rearward follow-up is still being performed, and the process proceeds to S323.
If this routine is entered for the second time or later after entering the follow-up following correction ON, the flag C10 = 0 in S301.
It is determined in step S302 whether the previous and current defocus directions are the same. In this case, since the previous process is already in the forward-tracking state, if the defocus direction is different from the previous and current defocus directions, it is changed from the forward-tracking to the backward-tracking, and the process proceeds to S323. If the current and previous defocus directions are the same, it means that the forward follow-up is continued as it is, and the process proceeds to S3.
Move to 05.

In step S305, the defocus amount An based on the current distance measurement is compared with the lens drive amount Txpn-1 corresponding to the previous release time lag. As described above, this is a process for correcting an error caused by calculating Pn assuming that the moving speed of the subject image is constant. If An> Txpn-1, it is a case where the actual movement amount of the subject image is smaller than Pn.
It is determined that the previous lens drive amount was too large, and the process proceeds to a case where the advance amount is too large (S314 and thereafter). On the other hand, if the determination in S305 is NO, it 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 is insufficient or appropriate. The BOV flag in the next S306 and S314 is a flag indicating how the result of the determination in the previous step (S305) was the last time. The case of BOV = 1 is too advanced, and the case of BOV = 0 is insufficient or This indicates that the amount was appropriate, and when the routine first comes to this routine, it is always processed as BOV = 0.

Step S307 shows the calculation shown in FIG. 5 when An> Txpn-1 is not satisfied in both the current and previous times, and the calculation is performed as already described with reference to FIG. In step S310, the previous An> Txpn shown in FIG.
This is a calculation formula in the case of -1 and not this time. In FIG. 10, the correction amount (subject image movement amount) P2 is P2 = | A2-A1 |, and Txp2 =
f (P2) and the driving amount AFP are AFP = Txp2 + (P
2-A2). The above is summarized as follows. Pn = | An-An-1 | Txpn = f (Pn) AFP = Txpn + Pn-An

In both cases where the processing of S307 and S310 was performed, AFP <
If AFP <0, it proceeds to S312 and sets Pn = 0 and AFP = 0 to perform no lens driving (no lens driving in the reverse direction). In either case, the BOV is reset in the subsequent step S309 or S313 based on the current calculation value.

If An> Txpn-1 this time, the processing shifts to the loop from S314. In this case, An is T
Since it is larger than xpn-1, it is in a state in which it has advanced more than the release time lag, and the lens is not driven.
In both processes, the correction amount Pn and the drive amount AFP are both set to 0 and used for the next calculation.
Only the calculation of is performed. In S314, the same case classification as S306 is performed.

In step S315, as shown in FIGS. 11 and 12, it was not An> Txpn-1 the previous time, but this time An> Txpn.
In the calculation in the case of xpn-1, the correction amount P2 is represented by P2 = | P1- (A2-Txp1) | Therefore, Txp2 = f (P2), and collectively, Pn = │Pn-1- (An-Txpn-1) │ Txpn = f (Pn) Pn = 0 AFP = 0.

In step S317 and subsequent steps, An> Txp
The processing when n-1 is shown. In S317,
Whether the amount of An exceeding Txpn-1 is within a predetermined focus width used for the focus determination in S6 of FIG. 3, that is, the position of the subject image after the release time lag elapses from the focus position. In order to determine whether or not the focus is within the focus width, the number of pulses corresponding to the focus width is added to Txp and Ax
Compare n.

The next step S318 is the case where the amount of An exceeding Txpn-1 is smaller, that is, the position of the subject image after the release time lag has elapsed is within the focusing width, as shown in FIG. Is calculated. From the figure,
P2 = | A2-A1 |, and therefore Txp2 = f
(P2). In summary, Pn = │An-An-1│ Txpn = f (Pn) Pn = 0 AFP = 0.

If it is determined in S317 that the amount of An exceeding Txpn-1 is not within the focus width, the process proceeds to S319. In S319, when it is determined that the state in which the amount of An exceeding Txpn-1 does not fall within the predetermined focus width has been continued three times or more, if the subject image position largely deviates from the focus position, or if the subject image It is determined that the moving direction or the moving speed has greatly changed, and the tracking mode is stopped because it is unlikely that the subject image comes within the focus width. Therefore, the correction is turned off in S322, and all the calculation data is cleared. . Then, the moving object prediction calculation is performed again using the current data as the first AF data.
S320 is a calculation in the case shown in FIG.
318.

If it is determined in S302 or S303 that the vehicle does not follow the advance this time, it is determined in S323 whether or not An> Txpn-1 last time by using the flag BOV.
Is determined by In S323, the last time An> Txpn-1
If it is determined that the process has been completed, the process proceeds to S324. This is the case shown in FIG. 15 in which the previous follow-up was performed and the current focus position was after the subject image.
The correction amount P2 at this time is represented by P2 = A2 + A1.
Therefore, Txp2 = f (P2), and the driving amount AFP
Is AFP = Txp2 + P2 + A2. To summarize the above, Pn = An + An-1 Txpn = f (Pn) AFP = Txpn + Pn + An

If it is determined in S323 that An> Txpn-1 was not satisfied last time, the process proceeds to S327. FIG. 16 shows a case in which the processing for entering the forward-looking follow-up from the backward-follow-up follow-up is performed. However, FIG. 16 shows a case where the forward-looking follow-up cannot be performed. In any case, the correction amount P2 is P2 = Txp1 + P
1 + A2. Therefore, Txp2 = f (P2), and the driving amount AFP is AFP = Txp2 + P2 + A2 (S327). To summarize the above, Pn = Txpn-1 + Pn-1 + An Txpn = f (Pn) AFP = Txpn + Pn + An

After the calculation in S324 or S327, the flag C10 is set to 0 in S325, and in the next distance measurement, the current calculation is handled as the first calculation after correction. In S326, the flag BO
Set V = 0.

In FIG. 7, S221 and S223 are cases where the subject is moving from near to far.
If the subject moves away from the camera at a constant speed, the subject image speed gradually decreases,
The lens driving amount decreases accordingly. In this case, if the correction is made ahead of the release time lag as in the case where the subject is approaching the camera, there is a high possibility that overcorrection will occur. In the case of overcorrection, a so-called rear focus is obtained, but this is not so preferable in consideration of the finished image. Therefore, when the subject moves in the direction away from the camera, it is based on the follow-up following, which does not advance by the release time lag.

FIG. 18 is a graph showing the relationship between the position of the subject image of the subject moving away from the camera and the lens drive pulse. In FIG. 18, the number of motor drive pulses obtained at the point is denoted by A1. Thereafter, it is assumed that the pulse A1 is applied to the motor to drive the lens, and the pulse number A2 at the point is obtained after the lapse of time t1. The amount of movement of the subject image from the point to the point becomes A2 when converted into the number of pulses. Therefore, the object image moving speed OBJsp between the point and the point is OBJsp = A2 / t1. Here, the subject image position at a point after a lapse of time t2 from the point based on the subject image position of the point is represented by A2 + t2 × OBJsp, assuming that the subject image speed is constant. Here, the time t2 is considered to be the same as the time t1, as described in the case of the advanced follow-up.
It is considered that the object image movement amount between the two is the same as A2. Therefore, the driving amount is calculated to be 2 × A2. That is, the point where the motor is driven by 2 × A2 at the point is
This corresponds to the position of the subject image after the lapse of time t2.
In this case, even if the release ON is interrupted after the lens driving is completed and the exposure is started after the lapse of the release time lag, the focus position is in front of the subject image position at that time and is not in the rear focus state, so that the TXP calculation is not performed. Follow-up is performed. As a result of driving the lens by 2 × A2 based on the defocus amount A2 obtained at the point as described above, A
Assuming that the defocus amount of 3 is obtained, the next drive amount is simply set to A3 × 2 as in the previous drive without performing the correction as in the follow-up follow-up. That is,
The following equation is obtained as a general equation for calculating the lens drive amount during the follow-up following. Lens drive amount AFP = 2 × An (provided that t1 = t2 and the lens was driven last time)

FIGS. 19 and 20 show S22 of FIG. 7, respectively.
3, a subroutine of S221.

In FIG. 19, in step S271, the movement amount (pulse number) XX and the defocus amount (pulse number) of the subject image
The lens drive amount is obtained by adding. This movement amount XX of the subject image is calculated in S206 to S209 in FIG. 7 based on the presence or absence of the previous lens driving. XX = An when the lens is driven last time, and XX when the lens is not driven last time. = An−An−1, and the lens driving amount AFP calculated in S271 of FIG. 19 does not exceed 2 × An.

In FIG. 20, in S272, the current defocus direction is checked. This is a case in which the defocus direction after driving the lens is positive, that is, when the subject is away from the camera. Things. S2 for over correction
The correction is turned off at 77, the calculation data is cleared, and the current data is recalculated as the first AF data. If the overcorrection check is passed, in the next S273 to S275, S206 to S20 in FIG.
As in the case of 9, the photographic by the presence or absence of the previous lens drive
The body image movement amount is calculated, and in S276, the lens drive amount A is calculated.
Set the FP. This is the same as in FIG.

Here, the determination of the focus in S6 of FIG. 3 will be described. This determination is made based on whether or not the defocus amount obtained in S2 is within the above-described predetermined focusing width. However, in the case of the forward-looking follow-up mode, the camera is always controlled to advance ahead by the release time lag, so even if focus is possible after the release time lag has elapsed, the defocus amount is not always in the focusing range during distance measurement. Absent. Also,
Even if it is in the focusing range at the time of distance measurement, it is not always within the focusing range after the release time lag has elapsed. Therefore, the in-focus state cannot be detected based on the obtained defocus amount itself even in a state where focusing is possible. Therefore, in S217 of FIG. 7, the defocus amount for focusing check is calculated. The recalculation in S217 will be described with reference to FIG. First, in S51, the previous A
Movement amount Txpn for release time lag in F processing
-1 is converted from the pulse number 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 the sign, to obtain a defocus amount for focusing check. In the case of following-up tracking, since the lens is not driven any more than the release time lag, such calculation of the defocus amount for focusing check is not performed.

According to the above operation, when the subject is moving in the direction approaching the camera, the lens is driven ahead of the release time lag, so that the release is always turned on.
Even if you do not have a big back focus, you can always shoot in focus. When the subject is moving in the direction away from the camera, the algorithm is to follow-up and follow, so that overcorrection can be performed to achieve in-focus photographing without focusing on the back.

In the distance measurement, if the integration time is shortened, the sampling interval of the distance measurement data can be shortened, and it becomes easy to follow the subject. Therefore, the integration time may be limited. FIG. 21 is a flowchart in the case where the integration time is limited. Normally, the maximum integration time Ti
Although ntMAX = normal maximum integration time NORMAX, when the correction is ON, as shown in FIG. 21, the correction ON maximum integration time CONMAX having a value smaller than the normal maximum integration time NORMAX is used as the maximum value of the integration time. Distance measurement can be performed in a shorter integration time.

Further, as described above, the lens may be driven to the end point at the time of following. At the time of driving the lens, the end point detection circuit 11 (FIG. 1) is reset in S15 of FIG. 3 and the INT2 interrupt is permitted. The end point detection circuit 11 generates an INT2 interrupt 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 during the driving of the lens, no pulse is output from the encoder 5, so that the end point detection circuit 11 is turned on, and an INT2 interrupt occurs. FIG. 22 is a flowchart of this interrupt processing. When the interruption occurs, the lens driving is stopped, the subsequent end point detection interruption is prohibited, and the correction is turned off (S501-503).

When the interruption has not occurred and the lens driving has been completed, the INT2 interruption 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 turning on the focusing LED by the LED driving circuit 10 of FIG. 1, the camera is focused on the operator. This signal indicates that the camera is in a focus state. This focusing LED is preferably provided in the viewfinder of the camera. Here, when C10 is not 1, the in-focus display is simply performed and the process returns.

When C10 = 1, that is, when the vehicle is in the forward-looking state, MAX AFPspeed / Kvalue ≧ OBJSP
(Mm / s) MAX AFPspeed: maximum drivable speed (pulse / s) OBJSP: subject image speed (mm / s) When in this case, in-focus display is always performed. In other words, it is possible to confirm that an in-focus photograph can be taken at all times when the in-focus state is displayed during the approaching ahead (MAXS = MAX A in the flowchart).
FPspeed / Kvalue, OBJ = OBJS
P).

When the subject image speed exceeds the following limit speed, that is, when MAX AFPspeed / Kvalue <OBJSP (mm / s) is satisfied, it is not possible to advance ahead by the release time lag, and the photograph is in focus even when released. Cannot be photographed, so that in-focus display is not performed in this case. that's all

In the forward follow-up mode, the advance is performed by the release time lag.
If the release switch SWR is turned on at the time when the lens drive is completed after only 1 is turned on to bring into the focused state, the subject image position always coincides with the focus position at the start of exposure.
However, release the switch at other times
N, or when the release switch SWR is turned on at the same time as the AF switch SW1 and the release ON interrupt is permitted after a predetermined processing time has elapsed after driving the lens, the start point of the release time lag assumed in advance and the actual The release ON interrupt timing does not match. Also, in the case of following-up, the release time lag is not considered. Therefore, in these cases, the subject image position and the focus position do not always match at the start of exposure.
Therefore, if the lens is driven by a further possible amount even during the release time lag, focusing can be performed more precisely. Further, in the case where several pictures are continuously taken in the forward-looking follow-up mode, if the AF is restarted after completion of the lowering of the mirror and the winding of the film after the end of the exposure, the following ability cannot be improved. Since the distance measurement becomes possible after the mirror descends, the distance measurement starts immediately after the mirror descends, and regardless of whether the winding is completed or not, the number of drive pulses based on the distance measurement data and the measurement By driving the lens by adding the number of drive pulses depending on the distance, the following ability can be improved.

FIG. 25 is a flowchart of a release interrupt process in which these cases are also taken into consideration.
FIG. 4 is a diagram showing a state of lens driving controlled by this flowchart. Fig. 26 shows release ON when lens is stopped
FIG. 27 shows a state in which a release ON interrupt has occurred during lens driving. The release ON interrupt is permitted in S8 of FIG. 3, and this processing is started when the release ON signal by the release switch SWR is interrupted. First, S601
In step, mirror up and lens aperture control are performed, and S
At 602, it is determined whether the correction is ON. Correction O
In the case of the FF, the normal release control of S603 to S605 is performed via S602. That is, in step S603, the shutter is controlled.
At 05, the film is wound up and the interrupt processing is terminated. On the other hand, when the correction is ON, it is determined whether or not the lens is being driven in S607, and based on the result, S608 or
In step S609, the lens drive amount AFP is reset. If the lens is not being driven, in S608, the moving amount of the subject from the end of the previous lens drive is calculated based on the elapsed time tt from the end of the previous lens drive shown in FIG.
It is calculated by the formula, OBJSP × KVALUE × tt, and the value is newly set in the AFP. On the other hand, when the lens is being driven, in S609, the driving amount to be driven during the elapsed time tt from the end of the previous lens driving (similar to S608) shown in FIG. 27, OBJ × Kvalue
A new lens driving amount is calculated by subtracting AFP-Dar (where Dar is the remaining lens driving amount), which is the already driven amount of the current lens driving set value AFP, from ext × tt. AFP
And A reset in S608 or S609
If FP exceeds the maximum number MXF of drivable AF pulses in the release time lag time, AFP = MXM is set in S611. The lens is driven by the set AFP, and exposure is performed (S612, S613).

If it is determined in S614 that the lowering of the mirror has been completed, the next distance measurement, ie, 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 description will be given of a function of increasing the following ability by starting the next following operation at the same time as the distance measurement becomes possible after the release is completed. That is, in the following mode, if the next distance measurement, calculation, or the like is started after the winding of the film is completed after the release is completed, the following capability cannot be improved. Since the distance measurement can be performed at the time of the mirror lowering, the time point of time t0 when the mirror was last raised has elapsed, the release operation is started at t1, and the distance measurement is started at the time point t11 when the mirror lowering is completed. Then, the number of driving pulses An is obtained. Then, the previous distance measurement, that is, the driving pulse number An-1 obtained before the release operation is started is replaced with the driving pulse number An.
To the new driving pulse number. With such a configuration, the next distance measurement is started and the lens is driven after waiting for t2 when the winding of the film is completed after the mirror is lowered (in the case of the dotted line in FIG. 28).
The follow-up operation can be continued earlier than the time t2-t11 (in the case represented by the solid line in FIG. 28). Then, in S617, the previous defocus amount An-1 +
Assuming that the current defocus amount An = AFP, the flag A1S is cleared in S618, the correction is turned OFF, and the release interrupt processing is terminated. After the interrupt ends,
The process moves to the LMOV shown in FIG. 3, and the lens is driven by the above-described drive amount AFP.

FIG. 29 is a flowchart showing a series of so-called overlap processing in this embodiment.
In the overlap processing, the distance measurement operation is further performed during driving of the lens, and the position of the focusing lens is more accurately obtained. At the start of the first distance measurement, if the distance of a subject that is greatly deviated from the focus position is measured, the obtained defocus amount itself contains a large error. Therefore, the focusing operation is not satisfactory. Therefore, by configuring to further calculate the driving amount even during the lens driving, the overlap processing is performed to perform the accurate focusing operation.

First, CCD integration is started during driving of the lens. The lens drive amount is set in the counter 6,
In step S701, the number of lens drive pulses at the start of integration is C1, and the number of lens drive palaces at the end of integration is C3.
In step S702, the CCD integration data is input.
In 3, the defocus amount is obtained by calculation. S7
In 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.
Let the calculated value be Cx. The number of lens drive pulses in the counter 6 when calculating Cx is C4. In step S705, the number of lens drive pulses required to update the lens drive amount is obtained by 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 the counter 6 in S706, and the process ends.

As apparent from S17 and S18 in FIG. 3, the overlap processing is not performed when the correction is ON, that is, in the follow-up mode. As described above, the overlap process is necessary when the defocus amount is large, but when the correction is ON, the focusing lens follows the subject, and therefore, the defocus amount is not so large. Because it is not possible. Further, the value of the AFP obtained for the following operation is updated by the AFP calculation for the overlap processing performed in a routine different from the main routine, which causes a problem that the following operation itself cannot be performed. It is.

In the automatic focusing device mounted on the camera configured as described in detail in the above embodiment,
When the imaging surface of the subject is moving at a predetermined speed or more, the camera enters the following mode, and when the subject is approaching the camera, the subject follows the release time lag, and when the subject moves away, the subject follows. The focusing lens is controlled so as to follow back. When displaying that the subject is in focus, if the maximum drivable speed of the lens is lower than the moving speed of the subject image, that is, if it is certain that the subject will deviate from the focused state, the focused display is displayed. It is controlled not to be performed. Therefore, the operator
Thus, it is possible to reliably keep track of the in-focus state. The present invention can also be used as an optical device other than a camera, for example, an automatic focusing device for binoculars.

Further, by setting the number of times of measuring the speed of the subject image for determining whether to enter the following mode to a predetermined number or more, it is possible to surely grasp that the subject is moving and to enter the following mode. It is also possible to configure.

Further, even when the focusing lens is already within the focusing width and the focusing display is being performed, the lens is further driven in the following mode so that the focus is completely adjusted. Such a configuration is also possible.

The release time lag used for the calculation for following may not be used as it is, but may be a value in consideration of the integration time for distance measurement, whereby smoother following can be performed.

If the lens is not turned on immediately after the lens drive is completed when the release-on state is reached, the driving amount and the focusing lens can be further driven within the release time lag to reduce the defocus amount. It is also possible to make it smaller.

In this case, the LED in the finder of the camera
It is preferable that the lighting of can be recognized. With this configuration, an indicator function is provided for notifying the operator that the camera is in focus.

In the present embodiment, the tracking mode is set if the moving speed of the subject on the image plane is equal to or higher than the predetermined speed by the two distance measurements. The configuration may be such that the tracking mode is entered when the number of determinations is not less than a predetermined number. Further, if the lens drive amount during following is equal to or more than a predetermined value three times or more, it is determined that the following is not correctly performed, and the following is turned off. It is possible to set.

Also, if the integration / calculation time is long, the lens drive may not be able to follow the moving speed of the subject. Therefore, by setting an upper limit on the integration time in the following mode, the distance measurement time can be reduced. , Can smoothly follow.

When the moving speed of the subject is high and the lens driving amount is relatively large, it is considered that the overlap processing is necessary.
If the lens drive amount is relatively small and the lens drive amount is relatively large even in the following mode, it is considered that the moving speed of the subject is close to the limit value at which the subject can be followed. Therefore, by configuring the overlap processing not to be performed during the following mode, an appropriate following drive can be realized.

Further, in the present embodiment, the release operation is performed only after the in-focus state is reached, that is, only when the so-called release priority is given. However, the release operation is performed regardless of the in-focus state, that is, when the so-called shutter priority is given. The case is also applicable. That is, it is configured that either the shutter priority or the release priority can be selected by a switch (not shown) or the like. In the case of the shutter priority, step S in FIG.
If 6-1 and S8 are jumped, the release operation will be performed regardless of the in-focus state.

[0091]

In the automatic focusing apparatus according to the present invention, the distance measuring means for obtaining the defocus amount for the specific object by the focusing lens and the two or more defocus amounts obtained by the distance measuring means are used. Calculating means for calculating a relative moving direction and a moving speed of the specific object in the optical axis direction, and a focal point at a position where the specific object moves after a lapse of a predetermined time from the present based on the calculation result of the calculating means. Drive control means for driving the focusing lens to a matching position, and the focusing lens is in a focused state, and
A display means for performing a predetermined display when the moving speed of the subject image is equal to or less than a predetermined value. When the camera is in focus, a predetermined display is displayed. It can be visually recognized that the camera is in a focus state or an in-focus state.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a main part of an AF system of an automatic focusing apparatus according to the present invention.

FIG. 2 is a graph illustrating a basic principle of a tracking system according to the present invention.

FIG. 3 is a flowchart illustrating an example of processing of an AF system employing a tracking method according to the present invention.

FIG. 4 is a graph illustrating a principle of a mode transition from follow-up tracking to forward-looking tracking in the present embodiment.

FIG. 5 is a graph illustrating a calculation method during advance tracking according to the embodiment.

FIG. 6 is a graph illustrating the principle of a moving object prediction calculation in consideration of the integration time according to the present embodiment.

FIG. 7 is a main flowchart of a moving object prediction calculation of the embodiment.

FIG. 8 is a flowchart illustrating a calculation in a case where the subject approaches the camera immediately after the correction is turned on in the embodiment.

FIG. 9 is a view showing the second and subsequent times after the correction is turned on according to the embodiment;
9 is a flowchart illustrating a calculation when a subject approaches a camera.

FIG. 10 is a graph illustrating a moving object prediction calculation based on a moving state of a subject and a driving result of a lens in the present embodiment.

FIG. 11 is a graph illustrating a moving object prediction calculation based on a moving state of a subject and a driving result of a lens in the embodiment.

FIG. 12 is a graph illustrating a moving object prediction calculation based on a moving state of a subject and a driving result of a lens in the present embodiment.

FIG. 13 is a graph illustrating a moving object prediction calculation based on a moving state of a subject and a driving result of a lens in the present embodiment.

FIG. 14 is a graph illustrating a moving object prediction calculation based on a moving state of a subject and a driving result of a lens in the present embodiment.

FIG. 15 is a graph illustrating a moving object prediction calculation based on a moving state of a subject and a driving result of a lens in the present embodiment.

FIG. 16 is a graph illustrating a moving object prediction calculation based on a moving state of a subject and a driving result of a lens in the present embodiment.

FIG. 17 is a graph illustrating a moving object prediction calculation based on a moving state of a subject and a driving result of a lens in the present embodiment.

FIG. 18 is a graph illustrating an algorithm when a subject moves away from a camera according to the present embodiment.

FIG. 19 is a flowchart illustrating a calculation performed when the subject moves away from the camera immediately after the correction is turned on in the present embodiment.

FIG. 20 is a flowchart illustrating a second and subsequent calculations performed when correction is turned on and the subject moves away from the camera according to the present embodiment.

FIG. 21 is a flowchart illustrating an example of a process when a limit is set for an integration time.

FIG. 22 is a flowchart illustrating a process when an end point of a lens is detected during tracking according to the embodiment.

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

FIG. 24 is a flowchart illustrating an in-focus display during subject tracking according to the present embodiment.

FIG. 25 is a flowchart illustrating an example of a process for performing distance measurement immediately after the mirror descends in the case of continuous shooting.

FIG. 26 is a graph illustrating the operation of the flowchart shown in FIG. 25.

FIG. 27 is a graph illustrating the operation of the flowchart shown in FIG. 25.

FIG. 28 is a graph illustrating the operation of the flowchart shown in FIG. 25.

FIG. 29 is a flowchart illustrating an overlap process according to the present embodiment.

FIG. 30 is a graph illustrating a conventional AF system.

FIG. 31 is a graph illustrating a conventional AF system.

FIG. 32 is a graph illustrating a conventional AF system. 1 distance measuring sensor (ranging means) 3 CPU (calculating means)

Claims (3)

(57) [Claims] 1. A photographing lens having a focusing lens movable in an optical axis direction, a distance measuring means for repeatedly calculating a defocus amount for a specific subject formed by the photographing lens, and a distance measuring means for obtaining the defocus amount. Calculating a relative movement direction and a movement speed in the optical axis direction in which the image of the specific subject moves based on the obtained defocus amount, and further based on the calculation result, a movement direction of moving the focusing lens and Calculating means for calculating the amount of movement; drive control means for moving the focusing lens based on the calculation result of the calculating means; and display means for displaying a display related to focusing. A follow-up tracking algorithm for moving the focusing lens to a position where the image plane moves by an amount equivalent to a multiple of the defocus amount obtained via the distance measuring means; A forward tracking algorithm that moves the focusing lens to a position that is ahead of the amount by which the image of the subject will move later is switched according to the moving direction of the specific subject, and the moving direction of the specific subject is the photographing lens. When the moving direction of the focusing lens is away from the moving distance of the focusing lens, the moving amount of the focusing lens is calculated by the backward tracking algorithm. And calculating a defocus amount for focus determination based on a defocus amount corresponding to a release time lag. The display means comprises: a focusing lens which can be driven by the drive control means by the calculation means. The image plane moving speed at the maximum drivable speed is the movement of the image of the specific subject calculated by the calculating means. Degrees or more, and when the calculating means is calculating according to the advance tracking algorithm, further performing a predetermined focus display when the focus determination defocus amount is within a focus range, An automatic focus adjustment device. 2. The automatic focusing apparatus according to claim 1, wherein the display means is configured to display an image plane moving speed at a maximum drivable speed of the focusing lens which can be driven by the drive control means by the calculation means. If the moving speed of the image of the specific subject calculated by the calculating means is equal to or higher than the moving speed of the image of the specific subject and the calculating means is calculating by the follow-up tracking algorithm, the defocus amount calculated by the calculating means is within the focusing range An automatic focus adjustment device that displays a predetermined in-focus state when it is in the position. 3. The automatic focusing apparatus according to claim 1, wherein a position at which the focusing lens is moved in the rear-tracking algorithm corresponds to twice a defocus amount obtained via the distance measuring unit. Automatic focus adjustment device where the image plane moves.