JPS63100429A - Autofocusing device - Google Patents

Abstract

PURPOSE:To quickly decide an in-focus state by deciding the in-focus state even at the time of driving a lens if an object is a moving body. CONSTITUTION:An in-focus state deciding means devices the in-focus state only at the time of stopping a photographic lens if a moving body deciding means decides a still object, but the in-focus deciding means decides the in-focus state even at the time of driving the photographic lens if the moving body deciding means decides a moving object. Since the in-focus state deciding means decides the in-focus state even at the time of driving the lens if the moving body deciding means decides a moving object, the in-focus state is decided more quickly in comparison with the case where the in-focus state is decided only at the time of stopping the lens. Meanwhile, since the in-focus state deciding means decides the in-focus state only at the time of stopping the lens if the moving body deciding means decides that the object is stopped, the in-focus state is decided with the same high precision as conventional.

Description

[Detailed Description of the Invention] [Industrial Application Field 1] This invention relates to an automatic focus adjustment device in a camera,
In particular, the present invention relates to an automatic focus adjustment device that enables focus adjustment even for a moving subject.

[Prior art 1] In a camera equipped with an automatic focus adjustment ff1i (auto 7 orcus, hereinafter abbreviated as AF) device, first, the integration of a light receiving element is performed to perform focus detection, and the data from this element is is A/D converted and input to a microcomputer, and the microcomputer calculates the amount of defocus of the photographing lens with respect to the subject. The camera is configured to drive the photographic lens based on the result of this focus detection calculation, thereby moving the photographic lens to the in-focus position for the subject.

Therefore, since a predetermined time is required from the time when focus detection calculation is started until the photographing lens reaches its focused state, a time lag occurs. At this time, if the amount of defocus of the photographing lens from the camera to the subject changes due to the movement of the subject, the subject will be out of focus by the time the photographing lens has finished moving due to the time lag.

Therefore, it is necessary to enable AF even for moving subjects. For example, according to the AF sub-control disclosed in Japanese Patent Application Laid-Open No. 60-214325, the distance measurement calculation and lens drive control are repeated to position the lens in real time. We are trying to make corrections.

[Problem to be solved by the invention 1 However, this article merely discusses what happens after the subject is once captured. In other words, initially, when the subject is stationary or moving at low speed, it is difficult to focus on the subject. It is a prerequisite that the subject is moving at a high speed, and then the control to drive the lens to follow the moving subject is described, and how to control the subject to move at high speed from the beginning. There is no discussion on whether to bring the camera into focus.

The present invention has been made to eliminate the above-mentioned problems, and an object of the present invention is to provide an automatic focus adjustment device that can quickly bring a moving subject into focus.

[Configuration 1 of the Invention The autofocus 1llW1 device of the present invention includes a lens driving means for driving a photographing lens, a defocus amount detecting means for detecting a defocus amount of the photographing lens and outputting the defocus amount in time series, A moving object defocus amount detection means detects the amount of defocus change due to the movement of the object from the detection means, and a lens driving amount is detected from the defocus amount detection means and the moving object defocus amount detection means in order to follow the object. a lens drive amount calculation means for calculating the moving object defocus amount, a moving object determination means for determining whether the object is a moving object or a stopped object based on the output of the moving object defocus amount detection means, and a moving object determination means for determining whether the object is in focus or not. and a focus determining means for determining the object, and the focus determining means is configured to perform the following operations only when the photographic lens is stopped when the moving object determining means determines that the object is a stationary object, and also when the photographing lens is moved when the object is determined to be a moving object. It is characterized by performing focus determination.

[Effect 1] When the moving object determination means determines whether the subject is moving, the focus determination means also performs focus determination while the lens is being driven, which results in faster focusing compared to the case where focus determination is performed only when the lens is stopped. Can determine focus. On the other hand, when the moving object determination means determines that the subject has stopped, the focus determination means performs focus determination only when the lens is stopped, so that highly accurate focus determination can be obtained as in the conventional art.

[Embodiment 1] Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings.

The pttJ1 diagram shows the block configuration of the camera. The left side of A-A' shows the interchangeable lens LZ, and the right side shows the camera body BD. Both can be mechanically connected by clutches 101 and 102, respectively. When the interchangeable lens LZ is mounted on the camera body BD, the lens circuit 103 of the interchangeable lens LZll and the camera body BD
The reading circuit 104 on the side is connected to the connection terminals JLI to JL5. JB
They are electrically connected by I to JB5.

In this camera system, the subject light that has passed through the lens system of the interchangeable lens LZ is reflected by the reflection mirror 105 of the camera body BD.
It passes through the semi-transparent part of the middle man, is reflected by the sub-mirror 106, and is reflected by the CCD image sensor 1 in the focus detection module.
The optical system is configured so that the light is received at 07. This C
The CD image sensor 107 is used as a focus detection means for measuring the amount of defocus for a subject, and has a plurality of charging conversion elements arranged in a 7-ray pattern.
A known device that sequentially extracts signals from each photoelectric conversion element can be used.

The interface circuit 108 drives the CCD image sensor 107, captures object data from the CCD image sensor 107, and sends the captured data to the controller 109. The controller 109 calculates a defocus amount IΔ1 indicating the amount of lens deviation from the in-focus position based on object data from the CCD image sensor 107, and determines whether the lens position is shifted forward (front bin) or backward. A signal with respect to the defocus direction indicating the direction of deviation of the dolphin (rear focus) is calculated.

The motor Mol is driven based on these signals, and its rotation is caused by the slip mechanism 110. By being transmitted to the transmission mechanism 112 via the drive rock 111 and the clutches 102, 101, the lens system of the interchangeable lens L2 is moved back and forth in the optical axis direction to perform focus adjustment. At this time, in order to monitor the amount of movement of the lens system, the drive mechanism 1 of the camera body BD is
An encoder 113 is connected to 11, and the encoder 113 outputs a number of pulses corresponding to the amount of drive of the lens system.

The slip mechanism 110 is configured such that the power of the motor Mol slips when a torque exceeding a predetermined value is applied to the driven part of the interchangeable lens LZ, so that no unnecessary load is applied to the motor Mol. There is.

Here, from the reading circuit 104 on the camera body side to the lens circuit 103 on the interchangeable lens side, power is supplied via terminals JBI-JLI, clock pulses for synchronization during data transfer are supplied via terminals JB2-JL2, and terminals A read start signal to start reading data is sent via JB3-JL3, respectively. Further, from the lens circuit 103 to the reading circuit 1
Serial data is sent to 04 via terminals JL4-JB4. Note that terminals JB51-JL5 are common ground terminals.

First, when a reading start signal is sent to the lens circuit 103, data from the lens circuit 103 is sent to the reading circuit 104 in synchronization with a clock pulse.

The reading circuit 104 converts the input serial data into parallel data KL based on the same clock pulse as the clock pulse outputted to the terminal and lens circuit 103.
It is sent to the controller 109.

The controller 109 receives data K from the reading circuit 104.
Based on this, the defocus amount 1Δ1 is determined from the subject image data from the interface circuit 108, and the number N of pulses to be detected by the encoder 113 is calculated by calculating K·1Δl. Further, the controller 109 rotates the motor Mol clockwise or counterclockwise through the motor driver 114 in accordance with the signal in the defocus direction obtained from the data of the subject image, and a pulse equal to the calculated value N is sent from the encoder 113 to the controller. 109, it is determined that the focusing lens system has moved by the amount of movement Δd to the in-focus position, and the rotation of the motor Mol is stopped.

When the object is in focus through such focus adjustment, a predetermined signal is sent from the controller 109 to the display circuit 115, and the in-focus display and the distance to the subject are displayed.

The general operation of the camera has been described above, and next, the control operation in the controller 109 will be explained in more detail using FIG. Note that the same parts as in FIG. 1 are given the same reference numerals.

109 is a microcomputer (hereinafter referred to as "My Fun") that operates in the controller described above;
Reference numeral 21 denotes an exposure control circuit that opens and closes the shutter in response to the start and end of exposure, and also controls the mirror 7 of the reflection mirror 105 and aperture in response to a mirror-up signal. A photometric circuit 122 digitizes a signal corresponding to the brightness of the subject and sends it to the microcomputer 109.

Reference numeral 123 denotes a film sensitivity automatic reading circuit for reading the loaded film sensitivity, and the read film sensitivity is taken into the microcomputer 109. Reference numeral 124 is a one-shot winding circuit that drives the motor MO2 to wind the film one frame in response to a signal from the microcomputer 109. Reference numeral 125 is an exposure setting circuit that sets the shutter speed and aperture value, and the set values are set by the microcomputer 109. be taken in.

Reference numeral 107 is the CCD image sensor described above, and image information of the subject is taken into the microcomputer 109 via the interface circuit 108. 114 is a motor driver that controls the focus adjustment motor Mol, and 113 is an encoder that outputs the drive amount of the motor MOI as the number of pulses. 103 and 104 are lens circuits and reading circuits, and 115-1 and 115-2 are display circuits that display the focus detection state and the distance to the subject, respectively.

Sl is a switch that is turned on when the release button (not shown) is pressed in the first step, and when this switch S is turned on, the microcomputer 109 is turned on, and the AF70-, which will be described later, is turned on.
Execute. S2 is a switch that is turned on at the second stage of pressing the release button, and when this switch S2 is turned on, release 70-, which will be described later, is executed. S, is a switch that is turned on when the reflection mirror is raised up, and when a release member (not shown) is charged, switch S, is turned off. es4 is a switch that is used to switch between continuous shooting mode and single frame shooting mode. It is a photographing mode changeover switch, and S is a switch that is turned on when exposure is completed and turned off when winding of one frame of film is completed.

The primary side of each of the above-mentioned switches S: to S is grounded, and the secondary side connected to the microcomputer 109 is pulled up to a voltage (2) via a resistor R, respectively.

Next, the control operation of the camera with the above configuration will be explained according to chart 70.

When the switch S is turned on by the first step of pressing the release button, the microcomputer 109 executes the flowchart shown in FIG.

First, in step S1, various flags are reset,
In step S2, a 7-rerun timer in the microcomputer 109 is started in order to know the time of each operation. Then, in step S3, from the lens circuit 103 through the reading circuit 104, the extension amount conversion coefficient representing the amount of movement of the lens in the optical axis direction with respect to the focal length of the lens necessary for AF, the maximum aperture value, and the rotational speed given to the lens is input. The microcomputer 10 stores data such as lens aperture F value A vow and data Dk1 for converting the lens extension amount to the actual distance.
Incorporated into 9.

In the next step S4, the set aperture value, shutter speed, etc. are read from the exposure setting circuit 125, and in the next step S5, a focus detection calculation as described later is performed, and an AF that drives the lens to the in-focus position based on the calculation result. An action is taken. In step S6, the photometry result by the photometry circuit 122 is fetched, and in step S7, the film sensitivity is fetched by the film sensitivity reading circuit 123. In step S8, with the above input data,
After the exposure calculation for exposure is performed, the process returns to step S3 and a loop operation is performed.

FIG. 4 shows the AF operation routine in step S5.

First, in step 5401, the interface circuit 10
8, the object light is integrated by the CCD image sensor 107. In the 0th order step 5402, the object data integrated by the CCD image sensor 107 is extracted for each pixel (this operation is called data dump).
After being A/D converted by the interface circuit 108, it is taken into the microcomputer 109. In step 5403,
Focus detection calculations are performed using the data of the subject. A detailed explanation of the optical system into which the subject light is input and the focus detection calculation will be omitted here as it is not necessary, but details are described in Japanese Patent Application Laid-Open No. 126517/1983.

In the next step 5404, preliminary calculations for tracking correction are performed as will be described later. In step 5405,
The defocus amount and its direction are calculated based on the data from the COD image sensor 107, and it is determined from the calculation result whether the defocus amount can be detected. If the subject image is largely blurred or has low contrast, it is determined that detection is not possible and the process proceeds to step 8406.

In step 5406, when focus cannot be detected, it is determined whether the operation of moving the lens to search for a focus detectable area (hereinafter referred to as low contrast scan) has been completed. When low contrast scan is not running,
In step 5407, a low contrast scan is started. If this low-contrast scan is repeated and the focus is still undetectable even after the low-contrast scan is finished,
In step 5408, a blinking display is performed on the display circuit 11S-1 to indicate that focus detection is impossible, and then the process returns to step S6 in FIG. 3.

On the other hand, if it is determined in step 5405i that the defocus amount can be detected, the process proceeds to step 5409, where the calculated defocus amount DF and the lens data captured in step S3 in FIG. The lens drive amount ERR (in pulse count units) is calculated from the lens extension amount conversion coefficient.

ERR=DF For example, in step 5412, the display circuit 115-1
After the in-focus display is made, the process returns to 70- in FIG. 3 and proceeds to step S6.

On the other hand, if the lens is out of focus, the process advances to step 5413, where it is determined whether the defocus direction obtained in the current routine execution is the opposite direction to the defocus direction obtained in the previous routine execution, and the defocus direction is determined. If the direction is reversed, the amount of backlash in the lens drive system that causes an error when the lens drive is reversed is corrected, and step 54
Proceed to step 24. If the lens drive directions are in the same direction, the process proceeds to step 5414, where it is determined whether an AF drive mode that performs tracking correction, which will be described later, is necessary.If it is determined that it is the tracking correction mode, then in step 5415, the tracking correction is performed. The amount of lens drive is corrected.

In the next step 5416, focus determination is made in the tracking mode, and if the in-focus state is determined here, step 5417
After the focus is displayed at step 5424, the process proceeds to step 5424.

On the other hand, if the lens is being driven in step 5410,
Proceed to step 5421, and step 54, which was flooded this time
The defocus direction including the correction in step 5423 is compared with the previous defocus direction, and if it is determined that the direction is reversed, the lens drive is stopped in step 5423, and then the process returns. The reason why the lens is stopped at this point is that if the focus detection calculation is performed while moving the lens even though the defocus direction has been reversed, the reliability of the focus detection result will be low. If the defocus direction has not been reversed, the process proceeds to step 5422, where it is determined whether or not tracking correction similar to step 5414 is required. If tracking correction is necessary, the process proceeds to step 5415, but if it is unnecessary, step Proceed to 5424.

In step 5424, it is determined whether the lens is in the in-focus area (near zone) based on the obtained defocus amount, and if it is not in the near zone, the process continues.

At step 5425, the lens is set to be driven at high speed, and if it is a near zone, at step 8426, the lens is set to be driven at low speed. Then, in step 5427, after the lens is driven at the set drive speed, the process returns, and focusing calculations are performed in step S6 and thereafter.

FIG. 5 describes steps 83 to 86 in FIG. 3 in more detail to explain tracking correction. In step 5501, the time TMI of the free run timer at the start of integration of the CCD image sensor 107 is read, and in step 5502, the count value T1 of the event counter EVTCNT for monitoring the lens drive amount at the start of this integration is read. It will be done. In step 5SO3, integration of the CCD sensor 107 is performed. In step 5504, the integration end time TM2 of the CCD image sensor 107 is read from the 7 rerun timer, and in step 5505, the count value T2 of the event counter EVTCNT at this time is read. Thereafter, in steps 5506 and 8507, as described above, data acquisition of the CCD image sensor 107 and focus detection calculation are performed. Most of the time required to execute this routine is spent in steps 8501 to S507. As will be described later, the value MI of the lens driving event counter EVTCNT at the center point of integration obtained by executing the AF routine is stored in register R, and in step 5508, the event count stored in this register R is stored. The value MI is stored as MIL in the register R' that stores the previous calculated value. In step 8509, similarly, the time TMI at the center point of integration is
is stored as TMIL in the register that stores the previous calculated value. In step 5510, the count value (T1+72)/2, which is the central point of integration, is calculated from the count values TI and T2 of the event counter EVTCNT at the time of the start of integration and the time of the end of integration obtained by the current execution of the routine,
It is newly stored in register R as MI. Step 5
Similarly, in 511, the time TMI at the start of integration and the time at the end of integration, and the time at the center point of integration from TM2 (TM1+TM
2)/2 is calculated and stored in a register.

In the next step, the lens driving amount between the previous integration center and the current integration center is calculated.
This will be explained using figures.

The horizontal axis is time, and the vertical axis is the value of the event counter EVTCNT. T 1 , , T 1 □ are the integrals I, ,
At the start of I2 TM1. ．． The count value of the event counter EVTCNT at TMI□ is T21°T2. are the same integration end time T M 2 + and T M 22, respectively.
is the count value of the event counter EVTCNT of
T 3 , , T 32 are the end times TM3 . ．． This is the count value of the event counter EVTCNT of 7M32.

Also, M I L and M I are T11 and T2. , T
12 and T2□. Here, TM3. =TM1. It becomes. The value of the event counter EVTCNT stored in registers R and R' is rewritten at the end of each operation, and the count value T32 of the event counter EVTCNT at the end time of operation KC2 is 7M32+2. , the event count value MI is stored in the register R, and the event count value MIL obtained by the previous calculation C1 is stored in the register R'. is a value converted into the amount of movement of the encoder, and indicates the position indicating the amount of defocus from the subject image plane at each integration center point.

However, as shown in FIG. 14, discontinuity occurs in the event count value when the calculation CI ends and the next integration I2 starts. This is the time TM3. This is because the event count value is rewritten based on the focus detection result of the integral (■), and is due to the focus detection error. The value of MIL-MI does not indicate the exact amount of movement of the lens in one period of integration. If the gap of this discontinuity is DT, then
This value DT is the value 5ERR, which is the calculation result set as the number of lens movements in the encoder at the end of calculation gc.
Event counter EVTC indicating the lens position at this time
The value T3 (=T3.) of NT is given by l5ERR-T3. As a result, the movement TI of the lens' within one period of focus detection time can be obtained by subtracting the value (MI-DT) obtained by subtracting Ml by the DT from the MIL. That is, ITI=MIL-(MI-DT).

After the above DT and ITI calculations are performed in steps 5512 and 5513, the value T3 of the event counter EVTCNT at the end of the current calculation is read in step 5514. Then, in step 5515, the time T at the end of the calculation
M3 is read, and then step S in FIG.
Proceed to step 7.

Now, FIGS. 6 and 7 show step 54 in FIG.
This flowchart describes in detail the flow after determining whether the lens is stopped or being driven in step 10.

Figure 6 shows the 70-chart when the lens is stopped.
Executed when confirming focus or when focusing. In step 5601, it is determined whether the lens is currently within a predetermined focus zone, and if it is within the focus zone, step 56
Proceed to step 02, and in order to use the lens ffi movement amount ERR found this time for the next correction, the previous lens drive amount L is used.
The lens drive set value EVTCNT obtained this time is similarly set to 5ERR. In step 5603, the defocus direction obtained this time is similarly overwritten with the previous result, and in step 8604, as described later, the distance to the subject is displayed on the display circuit 11S-2 along with the in-focus display (details). will be described later), and then step S6 in FIG.
The camera returns to , and focus detection is repeated again.

On the other hand, if it is determined in step 5601 that it is outside the focus zone, the process proceeds to step 5605, where it is determined whether this flow is being executed for the first time, and if it is the first execution, the process proceeds to step 5606, where the tracking flag is reset. . This tracking flag is used to determine whether to enter a tracking mode in which correction is performed to improve tracking performance of focus detection. Then, in step 5607, a non-update flag that prohibits updating the count value of the event counter EVTCNT is reset, and in the next step 5608, a tracking correction flag that sequentially corrects the calculation results obtained in tracking mode is reset to O. .

The next time 70- is executed, the process proceeds from step 5605 to steps 5610, 5611, and 5612, where the defocus direction based on the previous calculation result and the current defocus direction are compared. If the direction is reversed, step 5
At 613, the backlash of the lens drive system is corrected, and then the process proceeds to step 5606, where the tracking flag is reset as an initial setting. This means that if it is in tracking mode, it will exit from this mode. On the other hand, if the defocus directions are the same, the process proceeds to step 5614 and the movement amount WR of the subject is calculated. This calculation method is explained in the 15th
This will be explained using figures.

The vertical axis shows the focal position of the lens, and the horizontal thin line shows time. 1 In the figure, A shows a moving subject, B shows a lens driven to follow the subject, and at the same time The mutual distance between points indicates the amount of defocus. Currently, it is at TM3 at the end of performance 1t Cs, and the center point TM of the previous integral I2 and the current integral I is
Object movement amount WR for one cycle when IL and TMI are open
has already been determined, and the defocus amount DFc at the center point TMI of the integral I has also been determined. The converted values of the lens at this time are LERR and ERR, respectively. The center point TMIL of the integral I2 and the center point T of the integral
The amount of defocus WR caused by the movement of the subject during this period is determined from the figure as follows: WR=ERR+IT I-LERR. ITI is the amount of movement of the lens during this period.

In the next step 5615, the state of the tracking flag is determined. To explain the operation according to the flow of this flow, as mentioned above, the follow flag is reset by the first execution of this flow, so this time we will move to step 561.
The process proceeds from step 5 to step 8616, where it is determined whether the movement amount WR of the subject is greater than or equal to a predetermined value AB.

The predetermined value AB mentioned here refers to the range that is considered to be the in-focus zone even without tracking correction in consideration of the variation in calculation results and the width of the in-focus zone.This predetermined value AB is a fixed value. However, it may also be changed in accordance with one period of focus detection time as shown below.To explain this, one period of the subject's movement changes depending on the integration time, so AB= AB, X(TMIL-TMI) may be expressed as
I is step 8508°5SI in tjIJ5 diagram
TMIL-TMI is the value obtained by O, and TMIL-TMI is the time of one cycle from the center of integration to the next center of integration. WR/(TM
Since IL-TMI) is the slope of the subject's movement, it is nothing more than taking the denominator value into AB.

Now, if the movement amount 1iVR of the subject is less than the predetermined value AB, the process proceeds to step 5607, but if the movement amount WR is greater than the predetermined value AB, the tracking flag is set to 1 in step 5617.
After this is set, the process advances to step 5607.

In this case, the next time 70- is executed, the following mode is set by setting the following 7, so step 5
Proceed to 8618 through 601, 5614, and 5615.

Here, as in step 8616, the movement iWR of the subject is
is compared with the predetermined value AB, and if the movement amount WR of the subject is less than the predetermined value AB, no follow-up correction is performed and step 56
The process proceeds to step 07, but when the movement amount WR is equal to or greater than the predetermined value AB, the process proceeds to step 5619. Here, the movement amount WR of the subject is set to another predetermined value A that is considerably larger than the predetermined value AB.
If the moving amount WR is less than AX, the non-update flag is reset in step 5621, and the follow-up correction flag is set in the next step 5622.

On the other hand, when the movement amount WR of the subject is equal to or greater than AX, a non-update flag is set in step 5623, and the process then proceeds to step 8608, where the tracking correction flag is reset. This flow occurs when the movement amount WR of the subject changes significantly due to a change in the direction of the camera during the tracking mode, and in this case, the event counter EVTCN
T is not updated and the previous counter value is left as is, follow-up correction is also prohibited, AF sub-control is performed using the previous count value, and for this reason follow-up correction is also prohibited. It has become. The next time 70- is executed, the value that has changed significantly is replaced as the lens drive amount LERR. At this time, if the camera orientation remains unchanged, the object movement amount WR will not change significantly this time, so step 5621 , 5622, the non-update flag is reset, and the follow-up correction flag is set.

In this way, when the defocus amount changes significantly, the calculation result at this time is ignored once, and AF sub-control is performed using the previous data, and the camera direction remains unchanged even after that. This time, the moving amount WR of the subject becomes less than AX, and the process proceeds to step 5621, whereby the AF sub-control is thereafter performed using the greatly changed lens driving amount LERR.

After step 8608 and step 5622, the process advances to step 5624, where the current lens drive amount ERR is replaced as the previous data LERR, and step 5625
Then, the current defocus direction is replaced as the previous direction. Then, in step 8626, the tracking correction flag is determined, and if the tracking correction flag is set to 1, tracking correction, which will be described in detail later, is calculated in step 5627, and the value of the lens drive amount ERR is corrected.

Therefore, in step 5624, the previous lens drive amount L
ERR stores a lens drive amount ERR that has not been subjected to follow-up correction. Next, if the tracking 7-lag bow is set in step 5628, it is determined in step 5629 whether the tracking focus zone is within the focus zone (described later), and if it is within the focus zone, the process proceeds to step 5630. After the focus display and distance display are performed, the process proceeds to step 5424 in FIG. 4. On the other hand, if the tracking flag is reset in step 5628 or if it is outside the focus zone in step 5629, the process proceeds to step 5424. The above-mentioned tracking focus zone refers to a zone that may not be within the focus zone at the end of the current calculation, but will become within the focus zone when the effect of tracking correction appears at a future timing. In this case, the focus is displayed even while the lens is being driven.

FIG. 8 shows the detailed calculation contents of the following correction in step 5627, and this correction method is described in the 15th step.
This will be explained using figures.

Currently, we are at the time TM3 when the calculation C1 has finished, and as mentioned above, the previous integral I2 and the current integral ■.

The movement amount WR of the subject for one cycle between the integral center point TMIL and TMI has already been found, and the integral I,
The defocus 1lDFc at the center point TMI has also been found. However, at this point in time TM3, the subject has already moved from the time TMI when the defocus amount DFc was calculated, and the subject will move further during the lens drive after this (7M3), so the lens drive Anticipating the camera's tracking lag, the camera aims to correct the lens at the point in time when it is expected to catch up, and the lens drive stops when the camera catches up with the subject during the time lag caused by integration and calculation. This eliminates this problem, making it possible to maintain the ability of the lens to follow the subject.

To do this, it is sufficient to correct the relative object movement amount until the lens catches up with the position at the center point TMI of the integral I as a reference point.

First, if the amount of movement of the object from time TMIL to TMI is WR, then the slope a indicating the movement speed of the object during this time is TMIL - TI4r.Also, the current lens driving speed is b=LSD, and this If the defocus amount at time (7M3) is X, then X = aX (TMI - 7M3) + ERRERR is the value obtained by converting the defocus amount DFc measured at time TMI into the lens drive amount value, and the time point at which the calculation result is obtained. This is a value obtained by correcting the lens movement amount up to TM3. The time t required for the lens to catch up with the subject is t = B-^, therefore, the amount by which the lens should be driven during this time ERR
' is ERR'=bXt=LSDX - B-^, and this value is used as the corrected lens drive amount ERR as shown in step 5627. In this way, we set a target point in time when we can catch up with the subject,
This target time point is reached at the end of driving the lens.

Note that although the case where the lens catches up with the moving subject is discussed here, the same control as described above can be performed even when the subject is moving in the direction of movement of the lens. Ru.

That is, in this embodiment, the calculated defocus amount D
F is expressed as shown below.

DF = DF1 + DF2 - ITI = DF 1 + (vl v2), where: DFI: Defocus amount of the photographing lens at the center of integration performed before the focus detection calculation, DF2: Defocus amount from the center of integration Amount of movement of the subject on the focal plane of the photographing lens until the end of the detection calculation, ITI: Amount of movement of the photographing lens on the focal plane of the photographing lens from the central point of integration until the end of the focus detection calculation, vl: The moving speed of the subject, v2: The moving speed of the photographing lens, and t: The time from the center of integration until the end of the focus detection calculation.

FIG. 9 shows steps 5604 and 563 in FIG.
0 display routine is shown.

In the above embodiment, the pulse count value corresponding to the amount of lens extension is obtained by counting up the pulses from the encoder when the photographic lens is extended and counting down when the lens is retracted. The count value is stored in the counter (LNSC).

In step 5901, the count value by the lens extension 1 absolute counter LNSC obtained as described above,
The added value with the lens drive amount ERR is the distance counter DSC.
Set to N. This lens extension 1 absolute counter LNSC is 0 when the lens is at position ■, and is a counter that counts in proportion to the amount of lens extension.Therefore, a count value corresponding to the distance to the subject is input to the distance counter DSCH. be done. In step 5902, the count value by the distance counter DSCN and the lens-specific distance conversion data Dk input from the lens are input.
f and is converted into data called display parameter DSPD. Although this data is not distance data, it becomes distance display data by being sent to the display device, and the distance is displayed in step 5903.

Returning to FIG. 4 again, the operation when it is determined in step 5410 that the lens is being driven will be described in detail with reference to FIG. 7.

In steps 8701 to 5703, the driving direction of the lens is compared with the defocus direction after movement amount correction, and if the direction is reversed, the process proceeds to step 5704, where the tracking flag is reset. This means that the lens caught up with the subject during the tracking operation and then overtook it, so the tracking mode was canceled.

After the driving of the lens is stopped in the next step 5705, the process returns to step S6 in FIG. 3, and the distance measurement calculation is performed again. On the other hand, if the driving direction of the lens is the same as the previous driving direction, the process advances to step 8706, and as described above, the movement amount WR of the subject is ERR+I TI-LER.
It is determined by R.

In the next step 5707, it is determined whether the tracking mode is in progress based on the determination of the flag, and if it is in the tracking mode, step 8
The process proceeds to steps 708 to 5714, but since this portion is the same as step 5618 and subsequent steps in the stopped mode in FIG. 16, the explanation will be omitted. On the other hand, if it is not the tracking mode, the process advances to step 5715, and the moving defocus amount WR of the subject is
It is determined whether the predetermined value AA is slightly smaller than the predetermined value AB, and if it is smaller than the predetermined value AB, the process proceeds to steps 8712 and 8714, where the non-update flag and the tracking correction flag are reset, while the movement defocus amount WR of the subject is set to the predetermined value AA.
If the above is the case, the RA flag is set in step 8716, and then in steps 5711 and 5713,
The non-update flag is reset and the follow-up correction flag is set. This point is different from the stopped mode, and in the lens moving mode, high-speed control is required.
A tracking correction flag is set so that tracking correction is performed immediately. After step 5713 and step 5714,
Proceed to step 5624 in FIG.

FIG. 10 shows steps 5424 to 542 in FIG.
7 is written in detail.

First, the state of the non-update flag is determined in step 51001, and if the flag has been reset, step 5100
Proceeding to step 2, it is determined whether the lens is currently being driven,
If driving is in progress, in step 51003, the lens movement amount CTC from the time when subject data is captured until the end of calculation is calculated.
(=MI-T3) is calculated, and step 51004
The lens drive amount ERR is corrected at . That is, the lens movement amount CTC, which is the count error between the time of data input and the time of calculation completion result, is corrected.
After that, the process advances to step 81005.

If the lens is not being driven, step 51002.5
1003 is skipped.

In step 5ioos, the lens drive count value ER
It is determined whether R is within the near zone NZC, and if it is within the near zone NZC, the lens drive is set to low speed r in order to improve focusing accuracy in step 51006, and the newly determined lens drive count value is set. E
RR is set in the event counter EVTCNT.

On the other hand, if it is outside the near zone NZC, step 51
At 007, high speed is set, and lens drive count value ERR is set in event counter EVTCNT. In step 81008, the event counter EVT is used to calculate the offset of the next event count.
After the AF drive motor is energized in the zero-order step 51009 in which the CNT count value is set as the lens drive amount 5ERR, the process returns to step S6 in FIG. 3.

FIG. 11 shows an interrupt routine for controlling the amount of lens drive, and this routine is executed every time a pulse is output from the encoder as the motor rotates.

First, in step 81101, an event count value indicating the amount of lens drive is subtracted by 1. Step Sl 102
Then, when the event count value becomes 0, it is determined whether or not driving by the target lens drive amount has been completed. If it becomes 0, the motor is stopped at step 51103, and thereafter, the process returns. After returning, if the calculation result during the stop is within the focus zone, an in-focus display is made.

FIG. 12 shows an interrupt routine that occurs when the release switch S2 is turned on when the release button is pressed during execution of the AF routine shown in FIG.

In step 51201, it is determined whether the mode is tracking mode,
If the follow flag is set, step 812
At step 02, a follow-up correction for the lens drive amount is calculated, and the lens is driven based on the correction result until the start of exposure. This correction is to correct the event counter EVTCNT by the amount that the subject moves during the release time lag from the input of the release signal to the start of exposure.

If the tracking correction flag has been reset, the driving of the lens is stopped in step 81203. this is,
During tracking mode, the lens is relatively close to the subject, so it is controlled at low speed, but in normal mode, which is not tracking mode, there may be high speed V, and in this case, the lens will send a signal to stop it. Even if the lens is released, it takes a while for it to completely stop, and the maximum delay is about the same as the release time lag, so unless it is in tracking mode, the lens is stopped.

Here, the tracking correction calculation during release in step 51202 will be explained using FIG. 13.

In step 31301, RT is a camera-specific correction time lag time and is a constant value. WR
/(TMIL-TMI) is the amount of defocus the subject moves per unit time, so WR/(TM
IL-TM I).RT represents the tracking delay amount during the release time lag, and this value is taken as the object movement defocus amount WR. Next step 5130
In step 2, the submerged defocus amount WR is added to the count value of the event counter EVTCNT for correction.

Now, returning to FIG. 12, in step 51204, the display indicating the in-focus state is turned off. Then step Sl
In step 205, the reflection mirror 105 starts to rise, and in the next step Sl 206, aperture control is performed via the exposure control circuit 121. Step Sl 20? Then, it is determined whether the raising of the reflecting mirror 105 is completed, and if it is completed, the process proceeds to step 3120B, and the driving of the lens is stopped.

In this way, until the reflection mirror 105 rises, immediately
Lens driving continues in the tracking mode until exposure starts. Exposure is started in step 51209, and the following:
At step 51210, the switch S is turned on and it is determined whether the exposure is complete. When the 6M light is completed, automatic winding of the film is started at step 1211.
In step 51212, the reflecting mirror 105
is lowered. In step 51213, switch S4
It is determined whether the quick shooting mode is selected based on the state of , and if it is the continuous shooting mode, the process returns to step S3 in FIG.
Similar control is performed thereafter. On the other hand, in single shooting mode, the process advances to steps 51214 and 51215, a loop that repeats only photometry, and the next release operation or switch S
, waits for it to turn off.

As explained above, the subject moves even while the lens is driving, so in anticipation of the tracking lag required for lens driving, I set the target for correction at the point when the lens would catch up, so I could make corrections for a short period of time. This makes it possible to achieve a desired focused state.

Next, a second embodiment of the present invention will be described using FIGS. 16 and 17. In this second embodiment, the lens driving speed is constant in the first embodiment described above, but the lens is controlled to be driven by switching between two different driving speeds. In this embodiment, the lens driving speed is configured to be switched depending on the amount of driving required for the hinge to reach the in-focus position, and if the remaining lens movement within the near zone is larger than a predetermined amount, In this case, the lens driving speed becomes LSD, and if it is less than a predetermined amount, the lens driving speed becomes LSD2, which is faster than LSD. In 22, the switching of the lens drive speed is controlled independently of the tracking mode, but if the lens drive speed becomes LSD2 during the tracking mode, the movement of the focus position of the photographing lens will catch up with the movement of the subject ( Until then, the lens is driven at a driving speed LSD2.

FIG. 16 shows changes in the focus position of the photographic lens when a subject approaches the camera in this embodiment. In FIG. 16, it is assumed that the following mode is determined in performance W and C4. Here, when calculating the tracking correction and finding the lens drive amount, the drive amount ERR was larger than NZC2 (here, NZC>NZC2), so the lens drive speed was switched from LSD to LSD2 and tracking started. showing something. by this,
If the lens is driven at a driving speed of LSD, the movement of the focus position of the photographing lens cannot keep up with the movement of the subject as shown by the dotted line in FIG. By switching to LSD2, the movement of the focus position of the photographing lens can catch up with the movement of the subject, as shown by the solid line.

A 70-chart for switching the lens drive speed is shown in FIG. 17. In FIG. 17, first, in step 51701, the magnitude of the lens movement amount ERR and NZC2 is determined, and if ERR>NZC2, step 51702 is performed.
Go to and set the lens drive speed to LSD2. Then, in step 51703, it is determined whether or not the following flag is set, and it is determined whether or not the following mode is in progress, and if it is not in the following mode (following F=O), step 51704
Proceed to step 51703 to reset the speed lock flag (speed lock F). Conversely, if it is the follow mode in step 51703 (follow flag = 1), proceed to step 517.
Proceed to step 05 and set the speed lock flag. This is to prevent the lens drive speed from returning to the low speed LSD once the lens movement amount becomes greater than a predetermined amount during the tracking mode and the lens drive speed is once switched to the high speed LSD 2. and step 5170
4 or from step 51705 to step 8170
Proceed to step 8 and set the lens movement amount ERR to the event counter E.
Set it to VTCNT and go to step 81008 in Figure 10.
Proceed to.

In the next focus detection calculation cycle, the lens movement amount ERR decreases, and in step 51701 of FIG. 16, ERR≦
If it becomes NZC2, proceed to step 51706 and determine whether or not the speed lock flag (speed lock F) is set. If the speed lock flag is set, the lens drive speed remains as it is. Therefore, the process directly advances to step 51008. On the other hand, if the speed lock flag is not set in step 51706, the lens drive speed is set to the low speed LSD in step 51707, and step 81708
Proceed to. In this way, the lens can be driven as shown in the wS16 diagram.

Furthermore, FIG. 18 is a flowchart showing the operation of the third embodiment of the present invention. 2 shown in FIGS. 16 and 17
In the embodiment described above, the lens drive speed was controlled independently of the tracking mode V, but it is also possible to configure the lens drive speed to be set to the higher speed side LSD2 whenever the tracking mode is entered without making this independent. The third embodiment shown in FIG. 18 is constructed in this way. That is, in FIG. 18, first, in step 81801, it is determined whether a tracking flag (following F) is set, and whether or not the tracking mode is set is checked. If the following flag is set and the following mode is entered, the process advances to step 81802 and the lens drive speed is set to the high speed side LSD 2, and conversely, if the following flag is not set and the following mode is entered, step 81802 is executed. Proceed to step 51803 and set the lens drive speed to the low speed LSD. Then, from step 51802 or 51803, the process proceeds to step Sl 804, where, similarly to step 51708 in FIG. 17, the lens movement amount ERR is set in the event counter EVTCNT, and the process proceeds to step 51008 in FIG.

[Advantageous Effects of the Invention 1] As explained above, in the case of a moving subject, this invention enables focus determination to be performed even when the lens is driven, which is compared to a case where focus determination is performed only when the lens is stopped. This allows quick focus determination. On the other hand, when the subject is stationary, focus is determined only when the lens is stationary, so
Highly accurate focus judgment can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing one embodiment of the block configuration of a camera to which the automatic focus adjustment device of the present invention is applied, Fig. 2 is a block diagram showing the control circuit in Fig. 1, and Figs.
3 is a flowchart showing the control operation in FIG. 1, FIGS. 14 and 15 are diagrams used to explain the control operation in an easy-to-understand manner, and FIG. 16 explains a second embodiment of the invention. FIG. 17 is a flowchart showing the control operation of the second embodiment of the invention, and FIG. 18 is a flowchart showing the control operation of the third embodiment of the invention. 101.102...Clutch, 103...Lens circuit, 104...Reading circuit, 105...Reflection mirror,
1O7... CC, D image sensor, 108... Interface circuit, 109... Microcomputer, 110... Slip mechanism, 111... Drive mechanism, 112... Transmission mechanism, 113... Encoder ,1
14...Motor V driver, 115...Display circuit, 1
21... Exposure control circuit, 122... Photometry circuit, 12
4...-piece winding circuit, 125... exposure setting circuit, MOl, MO2... motor %Sl~S,... switch. Patent Applicant Minolta Camera Co., Ltd. Agent Patent Attorney Blue and White 葆 外 28 1 fig.

Claims (2)

[Claims] (1) A lens driving means for driving the photographic lens, a defocus amount detecting means for detecting the defocus amount of the photographing lens and outputting it in time series, and a defocus amount detecting means for detecting the defocus amount as the subject moves from the defocus amount detecting means. A moving object defocus amount detecting means for detecting the amount of change; a lens driving amount calculating means for calculating a lens driving amount from the defocus amount detecting means and the moving object defocus amount detecting means to follow the subject; A moving object determining means for determining whether the subject is a moving object or a stationary object based on the output of the focus amount detecting means; and a focus determining means for determining whether the subject is in focus; The focus determination means performs focus determination only when the photographing lens is stopped when the moving object determination means determines that the subject is a stationary object, and also when the photographing lens is moved when the moving object determination means determines that the object is a moving object. Device. (2) Claim 1, further comprising display means for displaying in-focus or out-of-focus based on the output of the focus determining means.
The automatic focus adjustment device described in Section 1.