JPH01287612A - Automatic focus adjusting device - Google Patents

Abstract

PURPOSE:To make automatic focus adjustment to a moving body even when a one-shot AF system is adopted by performing the correction of an out-of-focus quantity and lens drive to the movement of the moving body after shutter release is manually performed. CONSTITUTION:A control circuit 31 constituted of a microcomputer starts focus detecting operations when a shutter release button is pressed by one step in a state where a focus detecting mode switch is turned on. The circuit 31 successively stores picture element signal data in its memory, but, when the storage of the data is completed, calculates a de-focusing quantity and direction. Upon calculating the quantity and direction, the circuit 31 causes a display circuit 38 to display the calculated quantity and direction and, at the same time, drives a lens driving device 40 so as to perform automatic focus adjustment on a photographing lens LZ. In other words, correction and lens drive to the movement of the moving object are performed in response to the shutter releasing operation until the exposure is actually started. Therefore, the photographing lens LZ can be caused to sufficiently follow and focused at the time of exposure even by the automatic focus adjusting device of the one-shot AF system.

Description

Detailed Description of the Invention The present invention is an automatic focus adjustment device that adjusts the focus by detecting the focal layer of the photographic lens by receiving the subject light that has passed through the photographic lens of the camera. Regarding.

1 of the photographing lenses, which are symmetrical to each other with respect to the optical axis of the lens.
The subject light beams that have passed through the and second regions are respectively re-imaged to create two images, and the mutual positional relationship of these two images is determined to determine the amount of deviation of the imaging position from the expected focal position and its deviation. A focus detection device has already been proposed that obtains the direction (whether the imaging position is in front of or behind the expected focus position, that is, in the front bin or the back bin). The optical system of such a focus detection device has a configuration as shown in FIG.
This optical system has a planned focal plane (4) behind the photographic lens (2).
) or a condenser lens (6) further rearward from this surface, and a reimaging lens (8) further rearward thereof.
), (10), and each reimaging lens <8), (10)
Image sensors (12) and (14) each having, for example, a CCD as a light-receiving element are disposed on the imaging plane. As shown in FIG. 12, the image on each image sensor (12), (14) is the optical axis (18
), they become close to each other, and conversely, in the case of the rear bin, they become far from the optical axis (18). If the focus is correct, 2
The distance between two corresponding points of the two images is a specific distance defined by the configuration of the optical system of the focus detection device. Therefore, in principle, the focus state can be determined by detecting the distance between two corresponding points of the two images.

In an automatic focus adjustment device for a camera that has this kind of focus detection optical system, it integrates the amount of light from a subject using a CCD image sensor, performs focus state detection calculation (defocus amount calculation) using the CCD image sensor output, and calculates the amount of defocus. Lens drive accordingly.

The sequence of stopping at the in-focus position (shutter release...when the shutter button is pressed) is program-controlled by a control circuit made up of a microcomputer.

This automatic focus adjustment device continuously performs the above-mentioned sequential automatic focus adjustment control even when the subject image comes close to being in focus, so that the final focus position can be set accurately. Continuous AP (Auto Focus Adjustment) is performed.

By the way, with an automatic focus adjustment device such as the one described above, when the subject approaches or moves away from the camera, the amount of defocus is detected by one distance measurement, and the amount of defocus is detected based on this amount of defocus. When the photographic lens is moved to the in-focus position, the subject is moving during that time, so
In reality, the subject is no longer in focus.

The situation is shown in Figure 13.The horizontal axis is the time axis, and the vertical axis is the amount of defocus on the film plane. indicates the degree to which the amount of defocus increases, and the linear theory tracks the position where the photographic lens is about to focus its image.

The subject data is captured at the center A and B of the integration time.
, C, . . . are represented by T in Fig. 13. Let be the first integration center point. The defocus amount at this time is Do, and T0 to T1 are the time required from the center to the end of the integration time and the distance measurement calculation. T1 to T2 are lens drive times. When the lens driving is finished, the lens is stopped and the next integration (T2 to T,) and calculation (T, to T<) are started again. The subject has already moved when the lens stops, and when compared to the T0 point, the data of the 0th-order subject that has already produced a defocus amount of (DI-DO>) is captured at T, and this defocus The time to find the amount (Di Do) and finish driving the lens is T. At this time, the subject image has already moved, and even after driving the lens (
T5) The amount of defocus further occurs (D3 D2), and the amount of defocus becomes even larger compared to the point T2. Similarly, point T8 (D5-D,), point TI, point (D
2D, ) and instead of getting closer to the in-focus state, it spreads out, and A
Even though I'm at FL, the lag keeps getting worse, and I can't release the camera when it's in focus.

Such tracking lag accompanying AF sub-control is particularly problematic when using a long-focus interchangeable lens such as a telephoto lens with a slow focusing speed.

Also, when trying to focus on a moving object, since lens drive is stopped (AF lock) after focusing with Funshot AF, the moving object will move until the shutter release (this period is undefined). Automatic focus adjustment for moving objects was not possible because the focus would gradually shift.

SUMMARY OF THE INVENTION An object of the present invention is to enable automatic focus adjustment for a moving object even with such a one-shot AF type automatic focus adjustment device.

The present invention focuses on the fact that even if a manual operation for shirt release is performed, there is a release time lag from when the film is actually exposed, and the release time lag is caused by the movement of a moving object. The present invention is characterized in that correction of the amount of defocus and lens driving are performed after manual operation.

1-History In other words, if the subject is a moving object, even if the lens is once stopped by the one-shot AP, the correction and lens drive due to the moving object will continue until exposure actually starts in response to the shirt release operation. It is done for a period of .

(The following is a blank space) Example Embodiments of the present invention will be specifically described below with reference to the accompanying drawings.

■ System configuration of automatic focus adjustment device No. 9 (2I) - The left side of the dashed line is the interchangeable lens (L
Z), the camera body (BD) is on the right side, and both are mechanically connected via clutches (106) and <107>, respectively, to connecting terminals (J L 1 ) to (J L 5), (J
B 1 ) to (JB5) are electrically connected.

In this camera system, the subject light that has passed through the lens system of the interchangeable lens (LZ) is transmitted through the central semi-transparent part of the reflective mirror (108) of the camera body (BD), is reflected by the sub-mirror (109), and is transmitted to the CCD. Image sensor (F
The optical system is configured so that the light is received by the LM.

The interface circuit (112) drives the CCD image sensor (FLM) in the focus detection module (AFM), takes in subject data from the CCD image sensor (FLM), and sends this data to the AP controller (113). or

(115) attached to (113) is E2PROM,
Memory that retains data even when the power is turned off.

The AF controller (113) is a CCD image sensor (
Based on the signal from FLM), the defocus amount 1ΔLl indicating the amount of deviation from the in-focus position and the signal in the defocus direction (front bin, f&bin) are calculated. Motor (Mo
1) is driven based on these signals, and its rotation is transmitted to the interchangeable lens (LZ) via the slip mechanism (SLP), drive fin (LDR), and camera body side clutch (1o7). The slip machine 1 (SLP) slips when a torque exceeding a predetermined value is applied to the driven part of the interchangeable lens (LZ) to prevent the motor (Mol) from being subjected to the load.

A transmission device i (105) is connected to the lens-side clutch (106), and focus adjustment is performed by moving the lens system in the optical axis direction via this transmission mechanism (105). In addition, an encoder (ENC) for monitoring the drive amount of the motor (Mol) that drives the interchangeable lens (LZ) is connected to the drive unit t# (LDR) of the camera body (BD), and this encoder (ENC) is connected to the drive unit t# (LDR) of the camera body (BD). ) outputs a number of pulses corresponding to the drive amount of the motor (Mol) that drives the interchangeable lens (LZ).

Here, the rotation speed of the motor (Mol) is NM (rot),
The number of pulses from the encoder (E N C) is N, the resolution of the encoder (E N C) is p (1/ rot),
From the rotating shaft of the motor (Mol) to the encoder (ENC
) is the reduction ratio of the mechanical transmission system up to the mounting shaft of the motor (
From the rotating shaft of the MOl) to the camera body side clutch (107)
The deceleration of the mechanical transmission system up to μB, the lens side clutch (
μ is the reduction ratio of the mechanical transmission system from 106) to the lens system, and the helicoidal lead of the focus adjustment member (102) is LH.
(mm/rot), and the amount of movement of the focusing lens (FL) is Δd (m), then N=ρ・μP−NM △d=NM・μB・μL−LH That is, △cl=N・μB・μL-LH/(ρ・μP)・・・・
・・・・・・・・・・・・・・・・・・・・・・・・
- The relational expression (1) is obtained.

Also, when the lens is moved by △d (IIm), the ratio of the amount of movement △L (mm) of the imaging plane to the above △d is Ko
p=Δd/ΔL・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・・・・
・When expressed as (2), from equations (1) and (2>), N-Koρ・△L・ρ・μP/ (μB・μL−LH) ・・・・・・・・・・・・・・・
......The relational expression (3) is obtained. Here, KL=Kop/(μL-LH)...
・・・・・・・・・・・・・・・(4) KB=ρ・μP/
μB ・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・ Assuming (5), N=KB −KL・ΔL ・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・The relational expression (6) is obtained.

In addition, in equation (6), △L is the AP controller (11
3) as signals in the defocus direction and the defocus JiltΔL1.

Further, KB in equation (5) is data that is fixedly determined according to the reduction ratio μB in the camera body (BD), and this data KB is held by the camera controller (111).

Here, the camera body (BD) [tl! From the reading circuit (LDC) of I to the lens circuit (LEC) on the lens side, power is supplied via terminals (JBI) and (JLI), and synchronization clock pulses are supplied via terminals (JB2) and (JL2). However, reading start signals are sent via terminals (JB3) and (JL3), respectively. In addition, from the lens circuit (LEC) to the reading circuit (LDC), terminals (JL4>, (JB4)
Data KL is output in series through the .

Note that the terminals (JB5) and (JL5) are a common ground terminal. The lens circuit (LEC) is connected to the terminal (J B 3
>.

When the reading start signal is input via (JL3), ■(L
data from the camera body (BD) terminal (JB2),
(JL2), it is serially outputted to the reading circuit (LDC) in synchronization with the clock pulse inputted via JL2. Then, the reading circuit (LDC) reads the terminal (J B
4) Read the serial data from and convert it to parallel data.

The camera controller (111) is a reading circuit (LDC)
The AF controller (
113) uses the subject image data from the interface circuit (112) to find the defocus amount 1ΔL1, and based on this defocus amount 1ΔL1 and the data from the camera controller (111), K・1ΔLl=N The number of pulses to be detected by the encoder (ENC) is calculated. The AF controller (113) controls the motor (
(Mo2) clockwise or counterclockwise, and connect the encoder (ENC) to the AF controller (113).
When the number of pulses equal to the calculated value N is input, it is determined that the interchangeable lens (LZ) has moved by the amount of movement Δd to the in-focus position, and the rotation of the motor (Mo2) is stopped.

In the above explanation, data K B is stored on the camera body (BD) side.
is fixedly memorized, and the interchangeable lens (LZ) is stored in this data KB.
The value = KL - KB was calculated by multiplying the data KL from , but the calculation of the K value is not limited to the above method. For example, if there are multiple types of camera bodies with different KB values. If an interchangeable lens can be attached to any of the lenses, the lens circuit (LZ) of the interchangeable lens (LZ)
EC), data of 1=KL-KBI corresponding to a camera body having a specific KB value is output according to the set focal length.

On the other hand, in this particular model of camera body, data KB in the camera controller (111) and calculation of KL and KB are unnecessary, and 1 is set to the data from the read rotation (LDC).
When the above-mentioned lens is attached to another camera body having a value KB2 (≠KB 1) different from the above-mentioned specific KB value, the above-mentioned lens is inputted into the camera controller (111). It is also possible to have the data KL=KB2/KBI, and then perform the calculation of 1·KB2/KB1=KL-KB2 on 2=to obtain the value KL-KB2.

In particular, in the case of a front group extension type zoom lens in which the focus lens is placed in front of the zoom lens as described above, the value of Kop is KOp=([1/f)2
・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・(7)fl
: This is the focal length of the focusing lens, and the KL value or value for one zoom lens changes over a very wide range. In this case, the data KL or K stored in the lens is divided into exponent data and significant figure data (for example, in the case of 8-bit data, the top 4
The bits are divided into an exponent part and the lower 4 bits are a significant figure part), and the lower 4 bits of the data read by the reading circuit (LDC) of the camera body are shifted by the data of the exponent part and sent to the camera controller (111 ), even if the value of KL or K changes significantly, it can be handled satisfactorily. Note that the switch S2 connected to (111) is a release request switch.

In the explanation regarding FIG. 9 above, in order to make it easier to understand the overall function and operation of the present invention, the device of the present invention was shown to be constructed by a combination of circuit blocks, but in reality, Most of the functions of these circuit blocks are accomplished by a microcomputer, as described below.

Next, a block diagram of the entire focus detection control circuit according to the present invention is shown in FIG.

In FIG. 10, when a focus detection mode switch (not shown) is on, a control circuit (31) constituted by a microcomputer starts a focus detection operation by pressing a shirt release button (not shown) one step.

First, a pulsed integral clear signal IC is sent from the control circuit (31) to the CCD image sensor as the first and second photoelectric conversion element arrays provided in the photoelectric conversion circuit (2o).
G5 is output, which causes C of the photoelectric conversion circuit (20) to
Each pixel of the CD image sensor is reset to its initial state, and the output AGCO3 of a brightness monitor circuit (not shown) built into the CCD image sensor is set to the power supply voltage level. At the same time, the control circuit (31) outputs a shift pulse generation permission signal 5H at a "High" level.
Output EN. Then, at the same time as the integration clear signal ICG5 disappears, each pixel in the CCD image sensor of the photoelectric conversion circuit (20) starts integrating the photocurrent, and at the same time, the output AGCO of the brightness monitor circuit of the photoelectric conversion circuit (20)
Although S begins to decrease at a rate corresponding to the subject brightness, the reference signal generation circuit built into the photoelectric conversion circuit (20) continues to output a reference signal.

S is kept at a constant reference level. Gain control circuit (32
) compares AGCO3 with DOS and controls the gain of the variable gain differential amplifier (26) depending on how much AGCO3 decreases with respect to DOS within a predetermined time (100 m5ec during focus detection). Also, gain control circuit 32)
If it is detected that AGCO3 has decreased by a predetermined level or more with respect to DOS within a predetermined time after the disappearance of the integral clear signal I CGS, then the TI at the “HiFih” level
Outputs NT signal.

This TINT signal is input to a shift pulse generation circuit (34) through an AND circuit (AN) and an OR circuit (OR), and in response, a shift pulse SH is output from this circuit (34). When this shift pulse SH is input to the photoelectric conversion circuit (20), the photocurrent integration by each pixel of the CCD image sensor is completed, and a charge corresponding to this integral value is transferred from the CCD image sensor to the shift register in the photoelectric conversion circuit 20. are transferred in parallel to corresponding cells.

On the other hand, based on the clock pulse CL from the control circuit (31), the phase is 18 from the transfer pulse generation circuit (36).
Two sensor drive pulses φ1. shifted by 0°. φ2 is output and input to the photoelectric conversion circuit (20).

The CCD image sensor of the photoelectric conversion circuit (20) receives these sensor drive pulses φ1. Of φ2, the charges of each pixel of the CCD shift register are serially discharged one by one from the end in synchronization with the rising edge of φ1, and an O8 signal forming an image signal is sequentially output. This ○S signal has a higher voltage as the incident intensity to the corresponding pixel is lower, and the subtraction circuit (2
2) is subtracted from the reference signal DO3 mentioned above to obtain (
DO3-○S) is output as a pixel signal. Furthermore, if a predetermined time elapses without the TINT signal being output after the disappearance of the integral clear signal ICG, the control circuit (31) becomes High'h''.
A level shift pulse generation command signal SHM is output.

Therefore, if the gain control circuit (32) does not output the "High" level TINT signal even after a predetermined period of time has passed after the integral clear signal ICG disappears, the shift pulse is generated in response to the shift pulse generation command signal SHM. A circuit (34) generates a shift pulse SH.

On the other hand, in the above operation, the control circuit (31) receives the sample hold signal S when pixel signals corresponding to the 7th to 10th pixels of the CCD image sensor of the photoelectric conversion circuit (20) are output. / Outputs H.

This part of the CCD image sensor is covered with an aluminum mask for the purpose of removing dark output components, and is a part that is in a light-shielded state as a light receiving pixel of the CCD image sensor.

On the other hand, in response to the sample hold signal, the peak hold circuit (24) holds the difference between the outputs O8 and DO8 corresponding to the aluminum mask portion of the CCD image sensor of the photoelectric conversion circuit (20), and from now on, this difference output ■P and the pixel Signal DO3'
is input to the variable gain amplifier (26). The variable gain amplifier (26) amplifies the difference between the pixel signal and its differential output with a gain controlled by the gain control circuit (32), and the amplified output DOS'' is sent to the A/D converter (28).
After being A/D converted by , it is taken into the control circuit (31) as pixel signal data. A/D conversion circuit (28)
A/D conversion is performed with 8 bits, but the control circuit (31
), the upper and lower 4 bits are transferred.

Thereafter, the control circuit (31) sequentially stores this pixel signal data in an internal memory, but when the data corresponding to all pixels of the CCD image sensor is completed, the control circuit (31) processes the data according to a predetermined program. , calculates the defocus amount and its direction, displays them on the display circuit (38), and drives the lens drive device (40) according to the defocus amount and its direction, and controls the photographing lens (LZ). Perform automatic focus adjustment.

(2) Automatic focus adjustment method <ll-1> Overall automatic focus adjustment flow The flow of the main routine of automatic focus adjustment is shown in FIG.

The overall flow will be explained below with reference to FIG.

Step #1 integrates the CCD image sensor (FLM) and stores the subject data in the CCD image sensor. Step #2 (hereinafter "step" is omitted) converts each pixel data from the CCD image sensor into A/D. The amount of defocus is calculated in #3. A method of calculating the defocus amount will be exemplified later. In #4, it is determined whether the defocus amount can be detected. If the subject is largely blurred or has low contrast, it is determined that it cannot be detected and the process proceeds to #5.

#5. #6. #7 is low contrast processing, which scans the lens if a low contrast lens scan has not yet been performed and searches for a contrasting area while repeating distance measurement (low contrast scan, hereinafter referred to as low contrast scan). If the contrast is still low even after the contrast is finished, a blinking display is performed in step #7 to indicate that the focus cannot be detected.

If it is determined that the defocus amount can be detected from the defocus amount calculation result in #3, the process proceeds from #4 to #8.
Calculate the lens drive amount. In #9, it is determined whether the lens is stopped, and if it is stopped, a focus judgment is made in #10, and if it is in focus, the process proceeds to #103, where the focus is displayed and a release request is waited for.

If it is out of focus in #10, then in #12, if the lens drive direction in the previous AF and the defocus direction (lens drive direction) obtained in the current AF are different directions, that is, reversed. Proceeding to #13, the amount of backlash in the lens drive system, which causes an error during reversal, is corrected. If the lens driving direction is not reversed, the process proceeds to #14. In #14, as will be described in detail later, it is determined whether the AP drive mode for performing tracking correction, that is, the AP state requires the tracking mode. If the tracking mode is necessary, the conditions or timing for performing tracking correction are determined in #15 (this determination will be described in detail later), and if the conditions are met, the lens drive amount is corrected in #16. This drive amount correction will be explained in detail later.

If the lens is in the process of being driven, proceed from #9 to #21 to find the amount of lens overdrive from the time of capturing the subject data to the end of calculation (see Japanese Patent Application Laid-Open No. 78823/1982). The moving bones of the lens are corrected. Here, only the moving bones of the lens are corrected, but it is also possible to correct the moving bones of the subject. In #23,
Compare the previous lens drive direction and the defocus direction found this time (this includes the correction in #22), and if it is determined that the direction is reversed, proceed to #24 and move the lens. Stop it, return to #1, and start the next distance measurement. The reason why the lens is stopped here is because the accuracy of the distance measurement result will be low if the distance measurement calculation is performed while moving the lens.If it is not inverted to 0, proceed to #17 and return to the same flow as when the lens was stopped. .

In #17, it is determined whether the determined defocus amount is near the in-focus area, and if it is in the vicinity, it is the near zone, so proceed to #19, set the lens to drive at low speed, and set the lens to drive at a low speed. If not, it is outside the near zone, so set the lens to drive at high speed in #18. Then, in #20, lens driving is started. If the lens is being driven, the lens will continue to be driven.

In #101, check the focus non-confirmation flag, and if there is no flag, return to #1 again, calculate the defocus amount at a predetermined timing #3), and calculate the current lens drive amount corresponding to this # 8) The above-described flow is executed again.

If the non-confirmation flag is set in #101, wait for the lens to stop in #1゜2, display focus in #1o3, and then focus on #1.
Wait for the release to go in at 04.

<ll-2> Defocus amount calculation The defocus amount calculation performed in #3 of FIG. 1 is shown in FIG.

The principle of the defocus amount calculation performed here is based on the principle of the defocus amount calculation performed by the applicant of the present application as disclosed in Japanese Patent Application Laid-open No. 59-126517 and No. 60-49.
Since this process is disclosed in detail in Publication No. 14, specific processing will be described below.

Before moving on to the explanation of the specific flow, the configuration of the CCD image sensor will be explained. As shown in Figure 3, the CCD image sensor has pixels separated by an intermediate separation band. ,~l,
. A reference portion consisting of a pixel r.

It is divided into a reference part R consisting of ~r4B. The reference part is the first block I1 pixel from 11 to 12 degrees! ■〜
l. The blocks are divided into overlapping blocks, such as the second block (1) up to 1 pixel L+ and the third block (3) up to 14 degrees. The correlation calculation is first performed on the second block H located in the center of the reference section, and then
If an effective minimum value cannot be found as a result of the correlation calculation, the correlation calculation is performed in the order of the first block I and the third block (2). In this case, as shown in FIGS. 4 and 5, the amount of image interval deviation detected for each block is
The requirements overlap in some areas.

Next, a method for calculating the defocus amount will be explained according to the flowchart shown in FIG. As shown in Figure 2,
First step #25. In #26, the subject pixel data is pre-processed, and every third pixel difference data NSk and rsk are created from the pixel data of the standard part and the reference part R, respectively. This data processing is aimed at a kind of low-pass filter effect, and is effective in removing focus detection errors caused by imbalance between two images due to manufacturing errors in the focus detection optical system. In step #27, the correlation between the reference section R and the reference section R is calculated in the second block (2). This range is ± from focus
The pitch is 8 pixels, and in terms of reference pixel position < rsk21), 1 = 6 to 22 (see Figure 5). A high function value H2 (ffiM2) is calculated.

In #29, it is determined whether the correlation calculation just obtained is highly reliable and it is possible to obtain the defocus amount. If it is determined that the defocus amount can be determined, the process proceeds to #3° and blocks #30. Perform interpolation calculation using the formula shown below to find the maximum phase open position XM2.

As a result, the maximum correlation position XM is determined with high accuracy.

In #31, the image interval deviation amount P is determined using the image interval deviation amount P, and in #32, the defocus amount DF is calculated using the image interval deviation amount P.

If it is determined in #29 that detection is not possible, the process proceeds to #33 and the correlation calculation in the first block (2) is performed.

The range of this first block (■) is -4 to +14 pitches, and in terms of reference area pixel positions, it is 1=0 to 18 (see Figure 5).Similar to the second block (■), the maximum is #34. The correlation position 1M is determined, and it is determined in #35 whether or not it is undetectable. If it can be detected, the process advances to #36 and the same interpolation calculation as #30 is performed.

However, in the formula #30, IM, becomes IM, XM2 becomes XM,
, H2 replaces Hl. Then, in #37, the image interval deviation iP is determined using the maximum correlation position XM, and the process proceeds to #32, in which the defocus iDF is determined.

If it cannot be detected in #35, proceed to #38 and perform correlation calculation in the third block (■).The range of the third block (■) is -1
From 4 pitches to +4 pitches, as shown in Figure 5,
At the reference pixel position! - 10-28. Below, Part 2.
Similar to the first blocks ① and ②, find the maximum correlation position XM, , image interval deviation IP, and defocus amount DF (#38.
#39° #40. #41. #42), if it is undetectable in #4o, it means that the defocus amount cannot be calculated by any block, so #4
At step 3, the undetectable flag is set and the process returns to #3 in FIG. This flag is used in #4 of the first [2I], and if the undetectable flag is set, low contrast processing starts in #5.

<ll-3> Tracking mode, tracking conditions, etc. Figure 6 is the same as Figure 1.
In this embodiment, which is a flowchart illustrating in detail the flow from #8 to #16 while the lens is stopped, the tracking mode is set on the assumption that the subject approaches. If it is determined that detection is possible at #4 in Figure 1, the process moves to #44 in Figure 6, where the determined defocus amount DF is multiplied by the conversion coefficient K (K = KL - KB) to obtain the lens drive amount. Number of driving pulses ER of the corresponding encoder (E N C)
Find R (hereinafter simply referred to as lens drive amount ERR) (
ERR=DFXK>, determine whether the lens is stopped at #45, and if it is not stopped, go to #21 in Figure 1.
If it is stopped, proceed to #46.

In #46, the lens drive JiERR is compared with the preset focusing area FZC, and if ERR<FZC and it is determined that the lens is in focus, the process proceeds to #47, where a green LED is displayed to indicate focus, and in #48 Lens drive ff1 which is the result of this calculation
ERR and current defocus direction are LAST, respectively.
Save it as the previous direction in preparation for the next distance measurement loop.

If it is determined in #46 that the lens is not in focus, the process proceeds to #5o, where it is determined whether the previous lens driving direction and the current defocus direction are reversed, and if so, the process proceeds to #51. The backlash jlcNV of the lens drive system is corrected for the current lens drive amount ERR. And #52
Now, similarly to #48, the corrected lens drive amount ERR and its defocus direction are saved, and the process proceeds to #17 in FIG.

If the direction has not been reversed at #50, proceed to #53.

In #53, it is determined whether the tracking mode is possible, and then, in steps #54 to #59, it is determined whether the subject is approaching and a tracking lag has occurred, and whether the tracking conditions are satisfied.

First, in #53, it is determined whether the number of times the lens was driven LNSCNT was 3 or more, and only when it is 3 or more times does the flow proceed to the moving object determination flow. This means that the cause of the driving up to 2 times was the amount of lens backlash. This means that it may be an error caused by the AP due to large defocus. In #54, the gain of the CCD image sensor is 4.
Tracking correction can be effective when the brightness is smaller than 4 times.
This is because if it is more than double, it will be dark and the noise will be large, making it impossible to correct the correction. This can also be determined by the sensor integration time. In #155, the current calculation result is determined and it is determined that the direction is 0, that is, the subject is approaching in the rear bin.

In #56, the defocus amount of the current calculation result is 300
It is determined whether or not it is less than 300 μm, and follow-up correction is performed only for 300 μm or less. This is to prevent false detection of moving object detection.
We assume that large defocus is due to other reasons such as camera shake or another object passing in front of the subject, and set a limit to which tracking correction can be performed.

At #57, the previous direction is checked to see if it is an approaching direction, and at #58 it is determined whether the previous calculation result is less than 300μ.... In step #59, a check is made to see if there is a release request, that is, if switch 82 in FIG. 15 is pressed.

If S is pressed, the process advances to #60 to proceed with the follow-up correction flow. If S2 is not pressed, proceed to #91,
Add 1 to the lens count LNSCNT and proceed to #52.

In the follow-up correction flow from #60, first, a non-confirmation flag is set. This detects a moving object, and if the release is released and tracking compensation is applied, the camera will display the focus display immediately after the lens drive is completed without checking the focus (proceeds to #102 instead of proceeding to #1 at #101). This is because it causes the camera to release the camera.

In #61, in order to correct the drive, the current defocus amount and the previous defocus amount are added, and in #62 the amount is multiplied by 4. In #63, the memory (
The value (determined when the camera is assembled and shipped) is returned to the counter.

In #64, the correction amount is halved again, but this number of times is repeated until the counter reaches 0. In #66, the tracking correction amount is determined in units of defocus (μm), so as in #44, K and By multiplying, the correction amount ΔERR in terms of lens drive amount is determined.

Lens drive amount ERR and △ERR found in #90
The current drive amount ERR is determined by:

Here, the tracking correction will be explained with reference to FIG.

This repeats CCD integration, distance measurement calculation, and lens drive, and the horizontal axis represents time, and the vertical axis represents defocus i (subject movement and lens movement) on the film surface. The subject is a moving object that approaches. As shown in the flowchart of FIG. 6, tracking correction is performed at distance measurement (2) after three integrations and three lens drives. I tried AF for each range measurement from ■ to ■, but when I checked it, it was out of focus, and I repeated the lens drive until it reached ■. The defocus in (2) is d. Even if the drive amount is set to d in (2), it will only move to point X. Still defocused. Therefore, if the integration, calculation, and lens drive are considered to be one cycle, the cycle A in (2) and the cycle B in (2) can be considered to be almost the same (if the movement of the subject on the film plane is considered to be a straight line). Therefore, anticipating the next cycle B and assuming that the subject is moving at the same speed, the defocus d′ after driving the lens with distance measurement ■
It can be predicted that d'''=d. If you drive this amount in anticipation, it will move to point Y. Therefore, if you want to focus here, you can add the current defocus d to the correction amount. However, since the aim is to be in focus when the shutter is released and the light is exposed, it is necessary to anticipate the release time lag due to mirror up, etc. This time is used as the AF cycle A#B# B'#
If designed as C, the defocus d'' which would shift during the release time lag can also be considered as d''#cl. Therefore, the correction amount is 2d. However, it is possible that d is not reliable data due to variations in distance measurement calculations. Therefore, the previous data C should also be used d+C
), if the average data is used as the tracking correction amount, the error will be reduced. Therefore, by combining the defocus from this time and the previous time,
#61 uses this as the correction amount.

By the way, the reason for multiplying by 4 in #62 and multiplying by 1/2 in #64 n times is to consider cameras with long or short release time lags, and also to increase the speed on the film surface if the speed of the subject is constant. This is because the correction coefficient is prepared so that it can be determined according to the camera, considering that the speed increases as a function of 1/X and that the speed of the moving object is not constant.

F! ! Ideally, n = 2 is fine, but for cameras that only take pictures of fast moving objects, n = 10. For subjects that move back and forth, you can use a smaller correction and a larger value such as n = 3 or 4. , this n can be written in the E2PROM.

Note that in this embodiment, a moving object is determined even if a release request does not come, and moving object correction is performed after a release request is received.
As shown in the figure, after receiving a release request, it determines whether there is a moving object.
Moving object correction may also be performed.

Also, 7th. In Figure 8, I was only considering the approaching subject, but
#55. If you change the direction check in #57 to simply check if the current and previous directions are the same, you can get closer to a moving object that is moving away (it can also handle moving objects).

Note that the flow after the release is omitted, but since it is a -eye reflex camera, the mirror is raised, the first curtain of the focal brain shutter is run to expose the camera, and the second curtain is run to complete the exposure. Also, do mirror down, mechanical charge, etc.
Shooting ends.

Shrine-1 As described above, according to the present invention, when the subject is a moving object, even if the subject is in focus and the AF is locked, the distance corresponding to the movement of the moving object is adjusted in response to the shirt release. Since correction and lens drive are performed until the exposure actually starts, even with a one-shot AF automatic focus adjustment device, it is difficult to sufficiently track a moving object and bring it into focus during exposure. can.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing the operation of an embodiment of the present invention, FIG. 2 is a flowchart showing the operation of the main part thereof,
3 through 5 are diagrams explaining the specific method shown in FIG. 2, FIGS. 6 through 8 are flowcharts showing the operation of the main parts of FIG. 1, and FIGS. 9 and 10 are A first block diagram showing the overall configuration of a camera system to which the present invention is applied.
1 to 13 are diagrams showing conventional examples. Applicant: Minolta Camera Co., Ltd. Figure 7 Figure 1/Figure 1? figure

Claims (1)

[Claims] a focus detection means for calculating the amount and direction of deviation of the subject image formed by the photographic lens from a planned focal position; and a determination for determining whether the photographic lens is at the in-focus position based on the output of the focus detection means. a driving means for moving the photographic lens to the in-focus position; and a drive control means for driving the lens when the determining means determines that the lens is out of focus, and stopping subsequent lens driving once it is determined that the lens is in focus. a moving object determining means for determining whether or not the subject is a moving object; a moving object correcting means for correcting a lens driving amount according to the calculated deviation amount when a moving object is determined; and a shutter. An automatic focus adjustment device comprising: a manual operation member that is manually operated for shutter release; and a correction control means that operates the moving object correction means only when shutter release is started by operating the manual operation member.