JPS632013A - Automatic focusing device - Google Patents

Abstract

PURPOSE:To obtain a desired focused state in a short time by calculating a defocus amount in the present time point, which follows a movement of an object, setting this defocus amount as a target value, and correcting a lens. CONSTITUTION:At present, the device is in the time point TM3 when an arithmetic operation C3 has been ended, and a defocus amount DFc in the center point TMI of an integration I3 is also derived, but in the present time point TM3, an object moves already. When a moving extent of the object extending from the time point TMIL to TMI is denoted as WR, and a moving extent of the object in the present time point TM3 is denoted as X, {(TMI-TM 3)/(TMIL-TMI)}XWR is formed, and by this corrected value WR, a lens driving amount ERR is corrected. This lens driving amount ERR shows a distance to the object in the present time point by a pulse count number unit. In this way, by setting the corrected target value as the present time point, a distance to the object can be displayed by a real time to match an arithmetic operation timing.

Description

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

[Prior art and its problems 1] In a camera equipped with an automatic focus adjustment ffIJ (auto 7 orcus, hereinafter abbreviated as AF) device, first, the integration of the light receiving element is performed to perform focus detection, and this element The data is A/D converted and input to a microcomputer, and the microcomputer calculates the amount of defocus of the photographic lens for 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 the focus detection calculation is started until the S shadow lens reaches its focused state, a time lag occurs. At this time, if the amount of defocus of the [75 lens from the camera to the subject changes due to the movement of the subject, the subject will be out of focus due to the time lag at the time when the movement of the photographic lens is completed.

Therefore, it is necessary to enable AF even for moving subjects. For example, according to the AP 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. However, here we are simply discussing what happens after the subject is captured. In other words, the prerequisite is to initially focus on a stationary or slow-moving subject, and then control to drive the lens so that it can focus on a moving subject. However, there is no discussion of how to bring a subject moving at high speed into focus from the beginning.

(Objective of the Invention 1) This invention has been made to solve the above-mentioned problems, and its purpose is to provide an automatic focus adjustment device that can quickly obtain an in-focus state for a moving subject. shall be.

[Structure 1 of the Invention The automatic focus adjustment device of the present invention includes a focus detection means for detecting a state of focus on a solid subject of a photographic lens;
Defocus amount calculation means for calculating the amount of defocus of the photographing lens based on the data from the focus detection means; Subject speed movement means for calculating the moving speed of the subject based on the data from the focus detection means; Defocus amount Based on the defocus amount obtained by the calculation means and the moving speed of the object obtained by the object speed calculation means, the amount of defocus of the lens accompanying the movement of the object at the end of the calculation related to focus detection is calculated. A defocus amount calculation means is provided, and the photographing lens is driven by using the defocus amount at the end of the calculation as a target value.

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

Figure 1 shows the block configuration of the camera. The left side of the straight line AA' in the figure shows the interchangeable lens LZ, and the right side shows the force/
It shows the main body BD. Both have clutch 1
The clutch 1 (11, 102) allows the clutch 1 (11, 102 to connect the lens circuit 103 of the interchangeable lens LZflll to the camera body Bl when the interchangeable lens LZ is mounted on the camera body BD. )
The side reading circuit 1()4 is connected to the connection terminals JLI to JL5. J
They are electrically connected by BI to JBS.

In this camera system, the manuscript 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 and 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
CD image.

The sensor 107 is used as a focus detection means for measuring the amount of defocus for the subject.
It is possible to use a known device in which a plurality of photoelectric conversion elements are arranged in seven layers and signals are sequentially extracted from each photoelectric conversion element.

The interface circuit 108 drives the COD image sensor 107, takes in object data from the COD image sensor 107, and sends the collected data to the controller 109. The controller 109 determines a defocus amount 1Δ1 indicating the amount of deviation of the lens from the in-focus position based on subject data from the COD image sensor 107, and whether the lens position is shifted forward (front focus) or backward (front focus). A signal with respect to the defocus direction indicating the direction of deviation of the rear focus (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 driving rock 111 and the clutches 102, 101, the lens system of the interchangeable lens LZ is moved back and forth in the optical axis direction to perform focus and α adjustment. At this time, in order to monitor the amount of movement of the lens system, an encoder 113 is connected to the drive mechanism 111 of the camera body BD, and the encoder 113 outputs a number of pulses corresponding to the amount of movement 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. ing.

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 A read start signal for starting data reading is sent via terminals JB3 to 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 KLl based on the same clock pulse as the clock pulse outputted to the terminal and lens circuit 103:
It is converted and sent to the controller 109.

The controller 109 calculates the defocus amount lΔ1 from the subject image data from the interface circuit 108 based on the data from the reading circuit 104, and calculates the number N of pulses to be detected by the encoder 113 by calculating K·1Δ1. . 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 changes the encoder 113 to the output value N. When a pulse equal to is input 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 micro combinator (hereinafter referred to as a microcomputer) 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 performs mirror-up of the reflecting mirror 105 and aperture control 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. 124 is a one-frame winding circuit that drives the motor MO2 to wind the film one frame in response to a signal from the microcomputer 109, and 125 is an exposure setting circuit that sets the shutter speed and aperture value, and the set values are determined by the microcomputer. 109.

Reference numeral 107 is the COD 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 M○1, and 113 is an encoder that outputs the drive amount of the motor Mol as the number of pulses. 103 and 104 are lens circuits and reading circuits, and 1''15-1 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 at the first step of pressing a release button (not shown). When this switch Sl is turned on, the microcomputer 109 is turned on, and the AF flow described later is executed. 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 fully raised, and when a release member (not shown) is charged, switch S is turned off. sS4 is for switching between continuous i-motion mode and single-frame shooting mode. S is a switch for changing the shooting mode, 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 switches 81 to S is grounded, and the secondary side connected to the microcomputer 109 is pulled up to voltage V 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 S1 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 single microcomputer 109 is started in order to know the time in 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. Lens open F value A. . , data such as data Dk+ for converting the amount of lens extension and actual distance are stored in the microcomputer 109.
be taken in. 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 is performed as described later, and the lens is driven to the in-focus position based on the result of this calculation. An AF operation is performed to 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, after an exposure calculation for exposure is performed based on the above input data, the process returns to step S3 and performs a loop operation.

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

First, in step 3401, 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 a data gump), an interface. After being A/D converted by the circuit 108, it is taken into the microcomputer 109. In step 5403, calculations for focus detection 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 follow-up correction are performed as will be described later. In step 5405,
The amount of defocus and its direction are calculated from the data from the CCD image sensor 107, and el+ is determined from the calculation result as to whether or not the amount of defocus can be detected. If the subject image is significantly off by 1r or has low contrast, it is determined that detection is not possible and the process proceeds to step 8406. In step 5406, when the 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 a loaf scan) has been completed. If the loaf scan is not being performed, the loaf scan is started in step 5407. If this low-contrast scan is repeated and the focus is still undetectable even after the low-contrast scan is finished,
In step 8408, a blinking display is performed on the display circuit 115-1 to indicate that focus detection is not possible, and after that, the third
The process returns to step S6 in the figure.

- On the other hand, if it is determined in step 5405 that the defocus amount can be detected, the process proceeds to step 5409;
Calculated defocus amount DF and step S in FIG.
The lens drive amount ERR (in pulse count units) is calculated from the lens extension amount conversion coefficient, which is one of the lens data taken in step 3.

ERR=DF x K At step 5410, it is determined whether the lens is stopped. For example, in step 5412, the display circuit 115-
After the focus is displayed on point 1, 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 proceeds 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 obtained in the previous routine execution is determined. If the focus 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 the process proceeds to step 5424. If the lens drive directions are the same, the process proceeds to step 5414, where it is determined whether an AF drive mode that performs tracking correction (described later) is necessary; if it is determined that the tracking correction mode is selected, step 541
In step 5, the driving amount of the lens is corrected as follow-up correction.

In the next step 8416, focus determination in the tracking mode is performed, 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 requested 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 determined focus amount, and if it is not in the near zone, the process proceeds to step.

The lens is set to be driven at high speed in step 5425, and if it is a near zone, the lens is set to be driven at low speed in step 5426. 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.

In FIG. 5, steps 83 to S6 in FIG. 3 are described in more detail to explain the tracking correction. In step $501, the time TMI of the 7 rerun timer at the time of starting the 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 time of starting this integration is read. It will be done. In step 5503, integration of the CCD image sensor 107 is performed. In step 5504, the integration end time T M 2 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. After that, in step 5506.5SO7, as described above, data dump of the CCD image sensor 107,
A focus detection calculation is performed. Of the time required for one execution of this routine, most of the time is spent in steps 5501 to 555 above.
It will be spent on 07 r. 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 sequence is stored in register R, and in step 5508, The event count value MI is stored as MIL in the register R' that stores the previous calculated value. In step 5509, similarly, the time TMI at the center point of integration is stored in the register that stores the previous calculated value.
is stored as. In step 5510, the count value (T1 + 72)/2 of the event counter EVTCNT at the start and end of the integration obtained by the current routine execution is calculated from the count value Tl and T2 of the event counter EVTCNT at the time of the start and end of the integration, and is stored in the register R. It is stored as a new MI. In step 5511, similarly, from the time TMI and TM2 at the start and end of integration to the time at the center point of integration (TM
1+TM2)/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 line is time, and the vertical line is the value of the event counter EVTCNT. T 1 , , T 1 □ are integral 1, , respectively
At the start of I2 TM1. ．． I21°T22 is the count value of the event counter EVTCNT at TM12, and I21°T22 is the count value of the event counter EVTCNT at the same integration end time TM21-TM2□, respectively.I), T3,
, T 3 are the operations g, c, and c, respectively, performed after the same integration.
, c2 end time TM3. , 7M32 is the count value of the event counter EV T CNT.

Moreover, MIt and MI are each T1. and T2. , T12 and T2□. Here, TM3. =TM'12. register R,
The value of the event counter EVTCNT stored in R' is rewritten at the end of each calculation. The end time TM321 of it-C2 (the count value T3□ of the event counter EVTCNT stores the event count value MI in the register R, and the event count value MIL obtained by the previous calculation C1 is stored in the register R. This event count value is a value obtained by converting the amount of defocus obtained by calculation into the amount of movement of the encoder. However, as shown in FIG. 14, a discontinuity occurs in the event count value when the calculation C1 ends and the next integration I2 starts.
．． This is because the event count value is rewritten based on the end detection result of the integral I, and is due to a focus detection error. MIL
The value of -Ml does not indicate the exact amount of lens movement in one period of integration. If the gap of this discontinuous part is DT, this value DT is the value 5ERR, which is set as the number of lens movements in the encoder as a result of the calculation at the end of calculation CI, and the event counter EVTCNT which indicates the lens position at this time. The difference between the value T3 (=T3.) and the value 5ER
R-T3 loses 4. As a result, the lens movement amount ITI within one period of focus detection time can be obtained by subtracting (MI-DT) the value (MI-DT) obtained by subtracting \II from the above DT'c from the MIL. That is, ITI=MIL-(Ml-DT).

After the above DT and ITI calculations are performed in steps 5512 and 5S13, 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 the process then proceeds to step S7 in the @3 diagram.

Now, Figures 6 and 1 and 7 show step 5 of the above-mentioned second figure.
7 after determining whether the lens is stopped or being driven in 410
This is a flow that describes 0- in detail.

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 currently calculated lens drive amount ERR for the next correction, the previous lens drive amount LER is used.
The lens drive set value EVTCNT obtained this time is similarly set to 5EER. In step 5603, the defocus direction found this time is similarly overwritten with the previous result, and in step 5604, as will be described later, in addition to displaying the focus, the distance to the subject is displayed on the display circuit 115-2 (see below for details). (to be described later) is performed, and then the process returns to step S6 in FIG. 3, 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 advances to step 5605, where it is determined whether this is the first execution of the flow, and if it is the first execution, the process advances to step 8606, where the tracking flag is reset. Ru. 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. .

During the next 70-execution, steps 5605 to 5610. Proceeding to S611 and S5612, the defocus direction based on the previous calculation result and the current defocus direction are compared. If the direction is reversed, step 5
At step 613, the lens drive M (1> backlash is corrected, and then the process proceeds to step 8606, where the tracking flag is reset as an initial setting. This means that if it is in tracking mode, this mode will be exited. - direction, if the defocus direction is the same direction, step 5614
The process proceeds to step 21, where the amount of movement WR of the subject is calculated. This calculation method will be explained with reference to FIG.

The vertical axis indicates the focal position of the lens, and the horizontal axis indicates time. In the figure, A indicates a moving subject, B indicates a lens driven to follow the subject, and the distance between them at the same time indicates the amount of defocus. Currently, it is at T\13 when the performance EC1 ended,
Integral center point TMI between previous integral ■2 and current integral ■
The movement amount WR of the object for one cycle between L and TMI has already been determined, and it has also been determined from the focus amount DFc at the center point TMI of integration (3). The converted values of the lens at this time are LERR and ERR, respectively. The defocus amount WR caused by the movement of the subject during this period is defined as one period between the center point TMI L of the integral 2 and the center point TMI of the integral I, as shown in the figure, WR = ERR + ITI - LERR. It is required as. 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 following flag is reset by the first execution of this flow, so this time we will move to step 561.
Proceed to step 5, step 2, step 5616. Here, it is determined whether the movement amount WR of the subject is greater than or equal to a predetermined value A2. The predetermined value AB mentioned here refers to a range that is considered to be the in-focus zone even if no follow-up correction is performed in consideration of variations in calculation results and the width of the in-focus zone. This predetermined value AB may be a fixed value, but may also be changed in accordance with one period of focus detection time as shown below. Since one cycle of the subject's movement changes depending on the integration time, it may be expressed as AB=AB,X(TMIL-TMI). ABo is a constant, TMIL-TM
I is the value obtained in steps 5508 and 5510 in FIG. 5, and TMTL-TMI is the time of one cycle from one center of integration to the next center of integration. WR/(TMIL-
Since TMI) is the slope of the subject's movement, it is nothing more than incorporating the denominator value into AB.

Now, if the movement amount WR of the subject is less than the predetermined value AB, the process proceeds to step 5607, but if the movement amount WR is less than the predetermined value A2.
In the above case, the following mode is set by setting the following flag, so the following mode is set by setting the following flag in step S607.
01. S614. The process passes through S615 and proceeds to 8618. Here, similarly to step 8616, the moving amount WR of the subject is compared with the predetermined value AB, and if the moving amount WR of the subject is less than the predetermined value AB, no tracking correction is performed and step 56
The process proceeds to step 07, but if the movement amount WR is equal to or greater than the predetermined value A2, the process proceeds to step 5619. Here, the amount of movement 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 70- is 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 katsunta EVTCN
T is not updated, the previous counter value remains as is, and follow-up correction is prohibited, and 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 amount of defocus 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
In this case, the annual 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 7 lags, then in step 5627, tracking correction is calculated, which will be described in detail later, 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, in step 3628, the tracking flag is set to 1.
If it is set to , it is determined in step 5629 whether the tracking focus zone is within the tracking focus zone (described later), and if it is within the focus zone, focus display and distance display are performed in step 5630. , and then proceeds to step 5424 in FIG. - On the other hand, if the tracking flag is reset in step 8628 and if it is outside the in-focus zone in step 5629, the process advances to step 5424. The above-mentioned tracking focusing zone refers to a zone that may not be within the focusing zone at the end of the current calculation, but will become within the focusing zone as the effect of tracking correction appears at a future timing. In some cases, 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 ■2 and the current integral.

The center point of integration with T\=11. The amount of movement WR of the object for one period between TMr has already been determined, and the integral I
The defocus amount DFc at the center point TMI of , has also been determined. This item 7 orcus amount DFc is corrected, but this value is data obtained at time TMI, and at the present time TM3, the subject has already moved.

WR is the amount of movement of the subject from time TMTL to TMI.
Then, the slope a indicating the moving speed of the subject at this opening is THIL-TMI. Therefore, if the moving amount of the subject at the current time TM3 is X, then X = aX(TMI-TM3) The obtained movement amount X of the subject is determined in step 5627-
1, it is corrected as WR, and the next step 5627-2
Now, the lens drive amount ERR is corrected using this correction value WR.

This lens drive amount ERR represents the current distance to the subject in units of pulse counts. Therefore, by setting the correction target value to the current time, it becomes possible to display the distance to the subject in real time in accordance with the calculation timing.

Although the case where the lens catches up with the moving subject is discussed here, the same control as described above is performed even when the subject moves in the direction of movement of the lens. .

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

DF=DF1+DF2-ITJ=DF1+(v+-v2), where: DFI: Defocus point of the photographing lens at the center of integration performed before focus detection calculation; DF2: From the center of integration. The amount of movement of the subject on the focal plane of the photographing lens until the end of the focus detection calculation, ITI: The 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 : moving speed of the subject, v2: moving speed of the photographing lens, L: time from the center of integration to 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 photographic lens is retracted. The count value is stored in the counter (LNSC).

In step 5901, the sum of the count value by the lens extension 1 absolute counter LNSC obtained as described above and the lens drive amount ERR is calculated as the distance counter DS.
Set to CH. This lens extension 1 absolute counter LNSC is O 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 DSCN. be done. Step 5902
Now, the count value by the distance counter DSCN,
Lens-specific distance conversion data D input from the lens
kl is multiplied and converted into data called display parameter DSPS. 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 3701 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 the vJ3 diagram, 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 5706, and as described above, the movement amount WR of the subject is ERR+I T I-L
It is determined by ERR. In the next step 3707,
Based on the determination of the flag, it is determined whether the tracking mode is in progress, and if the tracking mode is in progress, the process proceeds to steps 8703 to 5714.
This part corresponds to step 8 in the stopped mode in Fig. 6.
Since it is the same as 618 and later, the explanation will be omitted. - On the other hand, if it is not the tracking mode, the process proceeds to step 5715, and it is determined whether the movement defocus jt'vVR of the subject is larger than the predetermined value AA, which is slightly smaller than the predetermined value AB, and if it is smaller, the process proceeds to step 5712.3714. The non-updating flag and the tracking correction flag are reset, and if the moving defocus jtWR of the subject is equal to or greater than the predetermined value AA, the tracking flag is set in step 8716, and then in step S711. In S713, the non-update flag is reset and the follow-up correction flag is set.

This point is different from the stopping mode, and since high-speed control is required in the lens moving mode, a tracking correction flag is set so that tracking correction is performed immediately. After step 5713 and step 5714, the process proceeds to step 5624 in FIG. 6. FIG. 10 shows steps 8424 to 5427 in FIG. 4 in detail.

First, the state of the non-update flag is determined in step 5100I, and if the flag has been reset, step 5100I determines the state of the non-update flag.
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.
(=Mr-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 51005.

If the lens is not being driven, step 51002.5
1003 is skipped. In step 5IO05, it is determined whether the lens drive count value ERR is within the near zone NZC. If it is within the near zone NZC, the lens drive is set to low speed in step 51006 to improve focusing accuracy. , the newly determined lens drive count value ERR is the event counter EV.
Set to TCNT. - the near zone NZC
If outside, high speed is set in step 51007, and lens drive count value ERR is set in event counter EVTCNT. Step 5100
8, the count value of the event counter EVTCNT is set as the lens drive amount 5ERR for the offset calculation of the next event count. Next step 51
After the AF drive motor is energized in step 009, the process returns to step S6 in FIG.

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 5IIOI, an event count value indicating the amount of lens drive is subtracted. 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 again 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 switch S2 is turned on by pressing the release button during execution of the AF sequence shown in FIG.

Step 51201 determines whether it is in tracking mode,
When the follow flag is set, the balance wheel 512
At step 02, a follow-up correction for the lens drive amount is calculated, and the lens is rAased based on the correction result until the start of exposure. This correction is to correct the event force sensor 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 S1203. This is because during tracking mode, the lens is relatively close to the subject, so it is controlled at low speed, but in normal mode52, which is not tracking mode, it can be controlled at high speed, and in this case, the lens is controlled at low speed. Even if a stop signal is issued, it takes a while for the lens to completely stop, and the maximum delay is about the same as the release time lag, so the lens is stopped unless it is in tracking mode.

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

In step 51301, RT is a camera-specific correction time lag time, and is a constant value. WR
/(TMI L-TMI) is the amount of defocus the subject moves per unit time, and therefore WR/(TMI
IL-T\iN•RT represents the tracking delay amount during the release time lag, and this value is taken as the object movement defocus amount WR. In the next step 51302, the determined 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 512
At step 05, the reflection mirror 105 starts to rise, and at the next step 31206, aperture control is performed via the exposure control circuit 121. Step 5120? Then, it is determined whether the raising of the reflecting mirror 105 is completed, and if it is completed, the process proceeds to step 51208, and the driving of the lens is stopped.

In this way, until the reflective mirror 105 rises, that is,
Lens driving continues in the tracking mode until exposure starts. Exposure is started in step 51209, and in the next step 51210, switch S is turned on and it is determined whether exposure is completed. When the exposure is completed, automatic winding of the film is started using the switch 1211, and then the reflecting mirror 105 is lowered at step 51212. In step 51212, it is determined whether the continuous shooting mode is selected depending on the state of the switch S4. If the continuous shooting mode is Y, the process returns to step S3 in FIG. 3, and the same control is performed thereafter. -On the other hand, in single shot mode,
Proceeds to a loop that repeats only the photometry of the stems 51214 and 51215, and then performs the next release operation or switch S1
wait for it to turn off.

As explained above, the current amount of defocus that occurs as the subject moves is calculated, and the lens is corrected using this amount of defocus as the target value. This makes it possible to achieve a desired focused state. Furthermore, it is also possible to display the distance to the subject based on the currently obtained defocus amount.

[Advantageous Effects of the Invention 1] In the present invention, since correction is performed using the calculated current defocus amount as a target value, a focused state can be obtained in a short time.

[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.
FIG. 3 is a flowchart showing the control operation in FIG. 1, and FIGS. 14 and 15 are diagrams used to explain the control operation in an easy-to-understand manner. 101.102...Clutch, 103...Lens circuit, 104...Reading circuit, 105...Reflection mirror,
107... CCD image sensor, 108... Interface circuit, 109... Microcomputer, 110... Slip mechanism, 111... Drive mechanism,
112...Transmission mechanism, 113...Encoder, 11
4...Motor driver, 115...Display circuit, 12
1... Exposure control circuit, 122... Photometry circuit, 124
...-piece winding circuit, 125...exposure setting circuit,
N101. Mo2...Motor, S1~S,...Switch. Patent Applicant Minolta Camera Co., Ltd. Agent Patent Attorney Seihaku Ao and two others Figure 1 Tototo '138, L City - Procedural Amendment (Voluntary) August 14, 1985

Claims (2)

[Claims] (1) Focus detection means for detecting the in-focus state of the photographic lens on the subject to be photographed; Defocus amount calculation means for calculating the defocus amount of the photographic lens based on data from the focus detection means; Focus detection means a subject speed moving unit that calculates the moving speed of the subject based on data from the subject; and a defocus amount calculation means for calculating the defocus amount of the lens due to the movement of the subject at the end of the calculation related to detection, and the photographing lens is driven with the defocus amount at the end of the calculation as a target value. automatic focusing device. (2) The automatic focus adjustment device according to claim 1, further comprising distance display means for displaying the distance to the subject using the calculated defocus amount.