JPH1184220A - Automatic focusing device for camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To regard a shutter opportunity as important and to shorten a time lag in an automatic focusing device for a camera having a moving body predicting function. SOLUTION: This automatic focusing device for the camera having the moving body predicting function is focused on a moving subject by detecting the movement of the subject in the optical axis direction of a photographing lens 11, predicting the image surface position of the subject after a specified time, and driving the lens 11 to the predicted image surface position. Then, the device is provided with a focus calculation part 5 calculating the out-of-focus amount of the lens 11, a release switch 12 causing exposing operation by the operation of a photographer, and a sequence control part 6 which stops the calculation of the out-of-focus amount so as to immediately shifts to the exposing operation in the case of operating the switch 12 within a specified time after starting the calculation of the out-of-focus amount and deciding that the lens 11 is driven to a focusing position in driving the lens previous time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic focusing device for a camera.

[0002]

2. Description of the Related Art Conventionally, a movement of a photographic lens of a subject in the optical axis direction is detected, an image plane position of the subject is predicted after a predetermined time, and the photographic lens is moved to the predicted image plane position. Various techniques have been proposed for an automatic focusing device of a camera having a so-called moving object prediction function for focusing on a subject.

[0003] When such moving object prediction is performed,
Moving object prediction is generally performed in a so-called "continuous AF" in which focus detection and lens driving are repeatedly performed instead of a so-called "one-shot AF" in which focus locking is performed after the above-described photographing lens is driven to a focus position. I have.

[0004] For example, Japanese Patent Publication No. 8-27425 discloses a release time lag based on a change in the defocus amount, that is, a movement amount of a subject image which is predicted to move during a time lag due to lens driving or mirror up. Has been disclosed.

[0005]

However, in the automatic focusing device for a camera employing the continuous AF as described above, the timing at which the photographer presses the release button to cause the camera to perform an exposure operation is determined by the timing at which the lens is driven. If it is just before the completion, the camera shifts to the exposure operation after the lens driving is completed, so the photographer feels that the time lag is short and there is no problem, but if the release button is pressed immediately after the start of focus detection, Since the camera shifts to the exposure operation after completing the focus detection and completing the lens driving, there has been a problem that the photographer feels that the time lag is long.

As described above, when the release button is pressed immediately after the start of the focus detection, since the time has not passed much since the previous lens driving was completed, the lens is in the vicinity of focus. Therefore, even if the operation immediately shifts to the release operation, the focus shift is small. Rather, it is more effective to take a picture with an emphasis on the shutter chance than to perform the exposure operation after the completion of the next lens drive until the time lag is increased.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems and viewpoints, and has as its object to reduce the time lag in an automatic focusing device of a camera having a moving object predicting function, with an emphasis on a shutter chance. It is in.

[0008]

In order to achieve the above object,
An automatic focusing apparatus for a camera according to a first aspect of the present invention detects a movement of a subject in a direction of an optical axis of a taking lens, predicts an image plane position of a subject after a predetermined time, and reaches the predicted image plane position. In an automatic focusing apparatus for a camera having a moving object prediction function in which a moving object is focused by driving a photographing lens, a defocus amount calculating means for calculating a defocus amount of the photographing lens; Release means for causing an exposure operation by operation, lens driving means for driving the photographing lens to a focusing position, operation of the release means within a predetermined time from the start of the calculation of the defocus amount, and If it is determined that the taking lens has been driven to the in-focus position during driving,
First control means for stopping the calculation of the defocus amount and immediately shifting to the exposure operation.

The automatic focus adjusting device for a camera according to the second aspect detects the movement of the photographic lens of the subject in the optical axis direction, predicts the image plane position of the subject after a predetermined time, and calculates the predicted image plane. A defocus amount calculating means for calculating a defocus amount of the photographic lens in an automatic focusing apparatus for a camera having a moving object predicting function in which a photographic lens is driven to a position to focus on a moving subject; Release means for causing an exposure operation to be performed by a user, play back driving means for driving the photographing lens so as to close the play of the drive system of the photographing lens, and release means upon completion of the operation of the play back driving means If the operation of (2) is performed, the second operation immediately proceeds to the exposure operation.
Control means.

Further, the automatic focusing apparatus for a camera according to the third aspect detects the movement of the photographic lens of the subject in the optical axis direction, predicts the image plane position of the subject after a predetermined time, and calculates the predicted image plane. A defocus amount calculating means for calculating a defocus amount of the photographic lens in an automatic focusing apparatus for a camera having a moving object predicting function in which a photographic lens is driven to a position to focus on a moving subject; Release means for causing an exposure operation by an operator's operation, lens driving means for driving the photographing lens, and determining means for determining whether the photographing lens is in focus before driving the lens by the lens driving means, Even if it is determined by the determining means that the lens is out of focus, the release hand is moved after the photographing lens is driven by the lens driving means. If the operation has been performed is provided with a third control means to immediately shift to the exposure operation, the.

According to the above-described first to third aspects, the following operations are provided.

That is, in the automatic focus adjusting device for a camera according to the first aspect of the present invention, the defocus amount of the photographing lens is calculated by the defocus amount calculating means, and the exposure operation is caused by the operation of the photographer by the release means. The photographing lens is driven to the in-focus position by the lens driving means, the release means is operated within a predetermined time from the start of the calculation of the defocus amount by the first control means, and the photographing lens is driven in the previous lens driving. Is determined to have been driven to the in-focus position, the calculation of the defocus amount is stopped, and the process immediately shifts to the exposure operation.

In the automatic focusing apparatus for a camera according to the second aspect, the defocus amount of the photographing lens is calculated by the defocus amount calculating means, and the exposure operation is performed by the photographer's operation by the release means, and the backlash is reduced. In the case where the photographing lens is driven by the driving means so as to reduce the play of the driving system of the photographing lens, and the release means is operated by the second control means when the operation of the play reducing driving means is completed. , The operation immediately shifts to the exposure operation.

Further, in the automatic focus adjusting device for a camera according to the third aspect, the defocus amount of the photographing lens is calculated by the defocus amount calculating means, and the exposure means is operated by the photographer's operation by the release means, thereby driving the lens. The photographing lens is driven by the means, the determining means determines whether the photographing lens is in focus before the lens is driven by the lens driving means, and the third control means determines that the photographing lens is out of focus. Even when it is determined that the photographing lens is operated by the lens driving unit, the operation immediately shifts to the exposure operation when the release unit is operated.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram of an automatic focusing apparatus for a camera according to a first embodiment of the present invention. As shown in the figure, the automatic focusing device of the camera includes an AF unit 21 including an AFIC 240, which will be described in detail later.
A focus detection unit 1 having 0 is provided, and a focus calculation unit 5 is connected to the focus detection unit 1.

The focus calculation unit 5 calculates the amount of movement of the subject in the optical axis direction based on the focus detection signal output from the focus detection unit 1 to predict and calculate the amount of image movement during exposure. A unit 2, a defocus amount calculating unit 3 for calculating a defocus amount of the photographing lens 11, and a lens driving amount calculating unit 4 for calculating a driving amount of the photographing lens 11 based on a defocus amount as a result of the calculation. Includes two components.

Further, the focus calculation section 5 is connected to a sequence control section 6. This sequence control unit 6
Is a controller for controlling the sequence of the entire camera, and corresponds to a CPU 201 in FIG. 3 described later.

In addition, an optical system such as a zoom 7, an aperture 8, a mirror 9, a shutter 10, and a photographing lens 11 is connected to the sequence controller 6. Further, the release switch 12 is provided to both the focus detection unit 5 and the sequence control unit 6.
Are electrically connected. This release switch 12
Has a two-stage configuration in which the first release is input by half-pressing and the second release is input by full-pressing, and is for instructing the exposure operation of the camera based on an operation according to the photographer's will. .

Next, an example of a camera system to which the automatic focusing device for a camera according to the first embodiment is applied will be described in detail.

FIG. 2 is a diagram showing in detail the configuration of a camera system to which the automatic focusing apparatus for a camera according to the first embodiment is applied. It should be noted that FIG. 2 mainly shows a detailed configuration of an optical system of the system having a built-in zoom lens mechanism.

In FIG. 1, a subject light beam is incident on a main mirror 102 via a photographic lens 101 including a first to fifth lens groups and a photographic stop. The photographing lens 101 performs a focusing action in the first and second groups, performs a zoom action in the third and fourth groups, and the fifth group is fixed. With this configuration, at the time of actual zooming, the first and second units are driven by the cam structure at the same time as the third and fourth units are driven, thereby preventing defocus during zooming.

The main mirror 102 has a half mirror structure. Two-thirds of the incident light amount enters the finder optical system 103, and the remaining one-third of the incident light amount is
After passing through the main mirror and being reflected by the sub-mirror 104, the light is guided to the AF optical system 105 in the subsequent stage. The AF optical system 105 includes a field stop 106 and an infrared cut filter 1.
07, a condenser lens 108, a mirror 109, a re-imaging stop 110, a re-imaging lens 111, and an AFIC 112.

The field stop 106 is set to A
This is for determining the field of view for F detection and preventing two light images split by the re-imaging lens 111 from interfering with each other. The infrared cut filter 107 is for removing infrared light unnecessary for AF detection and preventing aberration shift due to the infrared light. The condenser lens 108 is provided in the vicinity of the image plane of the subject light image formed by the photographing lens 101, that is, in the vicinity of the film equivalent plane.
12 is re-imaged. Also, the re-imaging aperture 11
0 is symmetrical with respect to the optical axis and forms a pair. Two light beams that have passed through the condenser lens 108 are AFIC1
The image is re-imaged on the two photoelectric conversion element arrays 12.

The finder optical system 103 includes a focusing screen 113, a condenser lens 114, a prism 115, and a mold roof mirror 11 in detail.
6 and an eyepiece 117. Then, the subject light image that has passed through the photographing lens 101 is formed on a focusing screen 113, and the formed image is guided to be observed by a photographer via a condenser lens 114 and an eyepiece 117. The main mirror 102 and the sub-mirror 104 are retracted to the position indicated by the dotted line in the drawing (corresponding to the direction of the arrow G6 in the drawing) during film exposure. Then, the subject light that has passed through the photographing lens 101 is exposed to the film 119 between the time when the front curtain of the shutter 118 opens and the time when the rear curtain closes.

Next, FIG. 3 is a block diagram showing in detail a control system of a camera system to which the automatic focusing apparatus according to the first embodiment is applied.

As shown in the figure, the camera system to which the automatic focusing device of the first embodiment is applied is C
PU 201, interface IC 202, power supply unit 203, strobe unit 204, mirror shutter unit 205, winding unit 206, lens unit 207, finder unit 208, display unit 2
09, each unit of the AF unit 210, and the like.

The CPU 201 controls the entire camera system. The CPU 201 controls the interface IC 202 and the LCD IC 23 via a serial communication line 211.
5. Data is transmitted / received to / from the AFIC 240 and the EEPROM 237. This CPU 201 and interface IC
There is another communication line between the input and output terminals 202 and 202 for inputting various analog signals and inputting signals after waveform shaping of PI.
The analog signal is input to an A / D conversion input terminal of the CPU 201 and is converted into a digital signal. In addition, the CPU 201
Has various arithmetic units, a data storage unit, and a time measurement unit.

Then, the interface IC 202
Is a Bi-CMOS IC with digital and analog circuits
Analog processing units such as motor and magnet drive, photometry, battery check, backlight LED, auxiliary light LED lighting circuit, photo interrupter waveform shaping circuit, and input serial communication data conversion of switch (SW), etc. Digital processing unit.

The power supply unit 203 supplies two systems of power. In the power supply unit 203, one is a power supply used for a driver requiring power such as a motor or a magnet, and the voltage of the battery 212 is always supplied. The other one is a DC / DC converter 2
13 is a power source for small signals stabilized by CP
It is controlled by the U201 through the interface IC202.

The strobe unit 204 includes a strobe charging circuit 214, a main capacitor 215, a strobe light emitting circuit 216, a strobe light emitting tube 217, and the like. When the strobe light needs to be emitted in a low-luminance or backlight state, the interface I
Via C202, the flash charging circuit 214 boosts the battery voltage and charges the main capacitor 215. At the same time, the divided charging voltage from the flash charging circuit 214 is input to the A / D conversion input terminal of the CPU 201.
Thereby, the CPU 201 controls the charging voltage.

When the charging voltage reaches a predetermined level, a charging stop signal is transmitted from the CPU 201 to the flash charging circuit 214 via the interface IC 202, and the charging of the main capacitor 215 is stopped. CP
U201 controls the start and stop of light emission of the flash light emitting tube 217 via the flash light emitting circuit 216 at a predetermined timing during film exposure.

The mirror shutter unit 205 includes a mirror shutter motor 218, two shutter magnets 219 for controlling the traveling of the front curtain and the rear curtain, a front curtain traveling completion switch included in the sequence switch group 244, and the like. I have. This mirror shutter motor 218 is
Controlled by the CPU 201 via the interface IC 202 and the motor driver 241, the forward rotation of the main mirror 102 causes the main mirror 102 to be moved up and down, the shooting aperture to be reduced, and the open shutter to be charged (the front curtain is closed and the rear curtain is opened). is there.

The shutter magnet 219 is controlled by the CPU 201 via the interface IC 202. At the start of exposure, first, the mirror shutter motor 218 retracts the main mirror and narrows the photographing aperture immediately before the start. Next, the shutter curtain 219 is energized, and simultaneously with the start of exposure for attracting the magnet, the front curtain is opened by releasing the suction of the shutter magnet 219 of the front curtain. After the desired exposure time has elapsed from the input of the front curtain advance completion switch 244, the suction of the shutter magnet 219 of the rear curtain is released, and the rear curtain is closed. Thus, the film is exposed between the opening of the front curtain and the closing of the rear curtain. Next, the mirror is lowered by the forward rotation of the shutter motor 218, and the photographing aperture is opened. At the same time, the shutter is charged. still,
The shutter motor 218 reverses the film to rewind the film.

The winding unit 206 includes a winding motor 220 and a film detection photointerrupter 221.
And so on. The hoist motor 220 is controlled by the CPU 201 via the interface IC 202 and the motor driver 241. The output of the film detection PI 221 is
, And is transmitted to the CPU 201 to generate a winding amount feedback pulse. The CPU 201
By counting the number of pulses, 1
Controls the amount of winding for a piece.

The lens unit 207 includes a photographing lens 222, a zoom motor 223, a zoom gear train 224,
F motor 225, AF gear train 226, AFPI 227,
It comprises a zoom encoder 228, an aperture PI 229, an aperture magnet 230 and the like. This zoom motor 22
3. The AF motor 225 is an interface IC 20
2. Controlled by the CPU 201 via the motor driver 241. The rotation of the zoom motor 223 is reduced by the zoom gear train 224, thereby
The second zoom system is driven. Also, the zoom encoder 2
Reference numeral 28 denotes an encoder including six switches provided around a lens frame that supports the photographing lens 222. Six switch ON / OFF data are input to the CPU 201, and the absolute position of the zoom lens is detected. It has become.

The CPU 201 obtains the focal length from the absolute position of the zoom lens and stores it in the focal length storage unit 247. The rotation of the AF motor 225 is controlled by the AF gear train 226.
As a result, the focusing lens of the photographing lens 222 is driven. On the other hand, the output of the AF photointerrupter 227 is extracted from the middle of the AF gear train 226. The output of AFPI 227 is waveform-shaped by interface IC 202 and transmitted to CPU 201,
An AF lens drive amount feedback pulse is generated. C
The PU 201 counts the number of pulses so that A
The driving amount of the F lens is controlled. The protrusion amount of the AF lens from the mechanical stopper or the infinite reference position is AFPI2
The pulse amount is 27 and is stored in the lens ejection amount storage unit 246 in the CPU 201.

The aperture magnet 230 is controlled by the CPU 201 via the interface IC 202. At the same time as the mirror-up operation is started, a magnet to which a current is supplied is attracted. At the same time as the above-described mirror-up operation of the mirror shutter motor 218 of the mirror shutter unit 205, the aperture of the shooting aperture is mechanically started by a spring. Then, when the desired aperture value is reached, the attraction of the aperture magnet 230 is released and the aperture operation is stopped to set. Aperture PI229
Is shaped by the interface IC 202 and transmitted to the CPU 201 to generate a narrowing-down amount feedback pulse. The CPU 201 controls the stop-down amount of the shooting aperture by counting the number of pulses.

The finder unit 208 includes an in-finder LCD panel 231 and a backlight LED 23.
1 and an eight-segment photodiode element 233 for photometry. The LCD panel 231 in the finder is made of transmissive liquid crystal, and the display is controlled by the LCD IC 235 in accordance with the display content sent from the CPU 201 to the LCD IC 235. And the backlight LED 232 is
Lighting is controlled by the CPU 201 via the interface IC 202 to illuminate the LCD panel 231 in the finder. The photometric element 233 is controlled by the CPU 201 via the interface IC 202. The photocurrent generated by the photometric element 233 is sent to the interface IC 202 every eight elements, and is subjected to current / voltage conversion therein. Only the output of the element specified by the CPU 201 is transmitted from the interface IC 202 to the CPU 201.
Is sent to an A / D input conversion terminal, and is converted into a digital signal and used for photometric calculation.

The display unit 209 includes an external LCD panel 234, an LCD IC 235, and a key switch (SW).
Group (1) 236 and the like. And the LCD panel 23
Reference numeral 4 denotes a reflective liquid crystal, which is transmitted from the CPU 201 to the LCD IC 2.
The display is controlled by the LCD IC 235 according to the display content sent to the LCD 35. Key switch group (1) 236
Is mainly for setting the mode of the camera.
Mode selection switch, camera exposure mode selection switch,
Switches such as a strobe mode selection switch, an AF / PF switch, and a micro mode switch are included.
The states of these switches are read into the CPU 201 via the LCD IC 235, and the respective modes are set.

The AF unit 210 has an EFPROM 23
7, condenser lens 238, separator lens 239,
It is composed of an AFIC 240 and the like.

A part of the subject light image is
38, divided into two images by the re-imaging lens 239,
The light is received by two rows of photoelectric conversion elements on the FIC 240.
The AFIC 240 generates an analog output corresponding to the light intensity for each element. The analog output is sent to an A / D conversion input terminal of the CPU 201 and converted into a digital signal.
It is stored in the element output storage unit 245 in U201.

The CPU 201 calculates an image interval between two divided images or a moving amount of each image after a predetermined time by an internal correlation operation circuit 248 based on the stored element outputs. Further, the CPU 201 controls the photoelectric conversion operation of the AFIC 240. In the EEPROM 237, non-uniformity correction data of the photoelectric conversion element output, which will be described later, and various adjustment data such as the interval between two images at the time of focusing are written, for example, at the time of shipment from a factory. Even if the power is turned off, data that needs to be stored is written.

The motor driver 241 is a driver for controlling a large current of the mirror shutter motor 218, the winding motor 220, the zoom motor 223, the AF motor 225 and the like.

The auxiliary light LED 242 is an LED for illuminating the subject at low luminance. This auxiliary light LED 24
Reference numeral 2 indicates that the AFIC 240 is turned on when the photoelectric conversion is not completed within a predetermined time and the image interval between the two images cannot be detected, so that the AFIC 240 can perform the photoelectric conversion of the subject image by the illumination light.

The key switch (SW) group (2) 243
This is a group of switches for controlling the operation of the camera. This includes
Release switch first stroke signal (1R), second stroke signal
It includes a stroke signal (2R), a switch for driving the zoom lens to the long focal length side, a switch for driving the short focal length side, a switch for storing the spot photometric value, and the like. The states of these switches are read into the CPU 201 via the interface IC 202 to control the camera operation. The sequence switch (SW) group 244 detects the state of the camera. This includes a switch for detecting a mirror raised position, a switch for detecting completion of shutter charge, a switch for detecting completion of running of a shutter front curtain, a power switch, a switch for detecting a strobe pop-up state, and the like. Also, the buzzer 245
The sound is displayed when F is in focus, out of focus, when the power is turned on, or when a camera shake warning occurs.

Hereinafter, the correlation operation between the two subject image signals will be described in detail.

In the apparatus according to the first embodiment,
The following two types of correlation calculations are performed.

That is, one of them is to perform a correlation operation between the first subject image and the second subject image divided by the re-imaging lens 111 by the same method as that of the conventional automatic focusing device. The defocus amount is obtained from the shift amount between the two images. The other is to calculate the amount of movement of the subject image by performing a correlation operation between the subject image at time t0 and the subject image at time t1.

First, the calculation of the correlation between the first subject image and the second subject image will be described. In the following description, for convenience, the first subject image is referred to as an image L, the first subject image signal is referred to as L (I), the second subject image is referred to as an image R, and the second subject image signal is referred to as R (I). I do. This I is an element number, and in this embodiment, since each element row has 64 elements, it is assumed that they are 1, 2, 3, ..., 64 in order from the left.

Hereinafter, referring to the flowchart of FIG.
The above-described correlation calculation will be described.

First, 1, 20, and 8 are set to variables SL, SR, and J as initial values (step A1, step A2). Here, SL is a variable that stores the head number of the small block element row for which the correlation is detected from the subject image signal L (I), and similarly, SR is the variable for which the correlation is detected from the subject image signal R (I). This is a variable that stores the head number of the block element row, and J is a variable that counts the number of small block movements in the subject image signal L (I). Next, the correlation output F (s) is calculated by the following equation (step A3).

[0053]

(Equation 1)

Here, the number of elements of the small block is 44, and the number of elements is determined by the size of the distance measurement frame displayed on the finder and the magnification of the detection optical system.

Next, the minimum value of the correlation output F (s) is detected (step A4). That is, F (s) is compared with FMIN,
If F (s) is smaller than FMIN, F (s) is substituted for FMIN, SL and SR at that time are stored in SLM and SRM (step A5), and the process proceeds to step A6. On the other hand, in step A4, if F (s) is larger than FMIN,
The process proceeds to step A6 without performing any processing.

In step A6, 1 is subtracted from SR, and 1 is subtracted from J. If J is not 0 (step A7), the calculation by the correlation equation of the above equation (1) is repeated. In other words, the small blocks in the image L are fixed, and the small blocks in the image R are correlated while being shifted by one element. When J becomes 0, 4 is added to SL, and 3 is added to SR to continue the correlation (step A8). That is,
The correlation is repeated while shifting the small block in the image L by four elements. Thus, when the value of SL becomes 17, the correlation operation is completed (step A9). As described above, the correlation operation can be performed efficiently, and the minimum value of the correlation output can be detected.
The position of the small block indicating the minimum value of the correlation output is
This shows the positional relationship between the image signals having the highest correlation.

Next, the correlation of the detected image signal of the block having the highest correlation is determined. That is, first, at step A10, the values of FM and FP are calculated by the following equations.

[0058]

(Equation 2)

That is, for the subject image R, the correlation output when the block position showing the minimum correlation output is shifted by ± 1 element is calculated. At this time, FM, FMIN,
FP has a relationship as shown in FIG.

If the detected image interval has a high correlation, the correlation output F (s) is obtained as shown in FIG.
Becomes zero at the point S0, but does not become zero as shown in FIG. 5B if the correlation is low.

Here, the correlation index Sk is obtained by the following equation (step A11).

When FM ≧ FP, Sk = (FP + FMIN) / (FM−FMIN) (4) When FM <FP Sk = (FM + FMIN) / (FP−FMIN) (5) This correlation index Sk As can be seen from FIG. 5, Sk = 1 when the correlation is high, and Sk> when the correlation is low.
It becomes 1. Therefore, it can be determined from the value of the correlation index Sk whether or not the detected image shift amount is reliable (step A12). Actually, the images L and L are caused by variations in the optical system, noise of the photoelectric conversion element, conversion errors, and the like.
Since a mismatch component of the image R subject image occurs, the correlation index S
k does not equal 1. Therefore, when Sk ≦ α, it is determined that there is a correlation, and the image shift amount is obtained (steps A13 and A1).
5). On the other hand, when Sk> α, the CPU 201 determines that there is no correlation and determines that AF detection is not possible (step A1).
4). The value of the determination value α is about 2 to 3. In addition, when the auxiliary light is turned on, the relativity deteriorates due to the influence of the color, aberration, and the like of the auxiliary light. Therefore, the determination value is increased so that the AF detection becomes difficult. If there is a correlation, the two image interval S0 between the image L and the image R is obtained from the relationship shown in FIG.

When FM ≧ FP S0 = SRM−SLM + (1/2) · {(FM−FP) / (FM−FMIN)} (6) When FM <FP S0 = SRM−SLM + (1/2) ) · {(FP−FM) / (FP−FMIN)} (7) The image shift amount ΔZd from the in-focus state is obtained by the following equation.

ΔZd = S0−ΔZ0 (8) where ΔZ0 is the image shift amount at the time of focusing, which is measured for each product and stored in the storage device. Note that the first S0 at time t0 is ΔZ1 and the second S0 at time t2 is ΔZ2.
, The future predicted S0 at time t2 is denoted by ΔZ '. The defocus amount ΔD on the optical axis from the image shift amount ΔZd can be obtained by the following equation.

ΔD = B / (A−ΔZd) −C (9) (A, B, and C are constants determined by the optical system.) The method of obtaining the lens drive amount from the defocus amount ΔD on the optical axis is as follows. Since various techniques have been conventionally proposed, a detailed description thereof will be omitted here.
In the method disclosed in Japanese Patent Application Laid-Open No. 4-54409, it can be obtained as in the following equation.

ΔL = b− (a × b) / (a + ΔD) + c × ΔD (10) (where a, b, and c are constants obtained for each focal length) By driving only the photographing lens ΔL, a focused state can be obtained. In this embodiment, the movement of the subject image is obtained by the method disclosed in Japanese Patent Laid-Open No. 5-93850.

Here, a correlation calculation for obtaining the movement of the subject image will be described.

Subject images L '(I) and R' (I) at time t0
And the correlation block positions SLM 'and SRM', the correlation coefficient Sk ', and the image shift .DELTA.Z obtained by the above-described correlation operation between the two images are temporarily stored in a storage area in the CPU.
Next, at time t1, subject image signals L (I) and R (I) are detected. First, for the signal of the image L, a correlation operation is performed between the subject image signal L '(I) at time t0 and the subject image signal L (I) at time t1.

The manner in which the correlation is obtained will be described below with reference to FIGS. Here, only the method of calculating the movement amount of the image L will be described.

First, SLSTR-10 is substituted for a variable SL (step B1). This SLSTR is an element number for starting the correlation operation, and will be described later in detail. The variable J is
This is the variable that the correlation range counts, here the initial value 2
0 is substituted (step B2). Then, step B
At 3, the correlation output F (s) is output by the following correlation equation.

[0071]

(Equation 3)

Next, similarly to the above-described correlation calculation, F (s)
And FMIN are compared (step B4), and if smaller than F (s), F (s) is substituted for FMIN and the SL at that time is stored in the SLM (step B5). In this case, the number of elements of the block to be correlated Is 12, which is smaller than the number of block elements 44 when the above-described image shift amount is obtained. Next, 1 is added to SL and 1 is subtracted from J (step B6). The correlation equation F (s) is repeated until J becomes a negative number (step B7).
In this case, the correlation was obtained by changing to ± 10 elements.
This correlation range is determined by the movement amount range to be detected.

Therefore, when the focal length is short, that is, when the brightness of the subject is bright, the moving amount of the subject image is expected to be small, so that the correlation range is reduced. The calculation time can be shortened by reducing the correlation range. Conversely, if the moving amount of the subject image is expected to be large, the correlation range is increased.

Next, the correlation is determined. Time t described above
In the same manner as when the image interval of 0 is obtained, it is obtained by the following equation (step B8).

[0075]

(Equation 4)

The correlation coefficient Sk is obtained by the above equations (4) and (5) (step B9). And
If Sk≤β, it is determined that there is a correlation, and the movement amount is obtained (step B10). This determination value β is set to a value larger than the determination value α used for obtaining the image interval at time t0 (β becomes about 7). This is because the waveform often changes when the subject is moving, so that there is a high possibility that the correlation will deteriorate. Also, since the correlation becomes worse as the moving amount of the subject image becomes larger, a lens with a longer focal length, a shorter subject distance, a longer time interval from time t0 to t1, that is, a darker subject brightness, etc. Increase the judgment value.

Next, the moving amount ΔXL of the image is obtained (step B11). It is obtained by the following equation in the same manner as when the image interval at time t0 is obtained.

When FM ≧ FP ΔXL = SLM−SLSTR + (() · {(FM−FP) / (FM−FMIN)} (14) When FM <FP ΔXL = SLM−SLSTR + (1/2) ) · {(FM−FP) / (FP−FMIN}... (15) Then, the undetectable flag is cleared (step B1).
3) Return.

Similarly, a correlation operation is performed on the image R to obtain a correlation block position SRM and a movement amount ΔXR.

The moving amounts ΔX R and Δ of the subject images of the images L and R
Once XL has been obtained, the two-image interval .DELTA.Z2 at time t1 can be obtained from the two-image interval .DELTA.Z1 at time t0 as follows.

ΔZ2 = ΔZ1 + ΔXR−ΔXL (16) In order to further reduce the calculation error, the image L at time t1
Alternatively, the correlation calculation shown in FIG. 4 may be performed again on the basis of the signal of the image R to obtain the interval between the two images and calculate ΔZ2. The amount of image movement between times t0 and t1 is obtained by the following equation.

ΔZ01 = | ΔXR−ΔXL | (17) The interval ΔZ 'between two images at the time t2 is predicted by the following equation as described above.

ΔZ ′ = ΔZ1 + {(t2−t1) / (t1−t0)} · (ΔXR−ΔXL) (18) The lens is moved at time t2 by driving the lens by an amount based on ΔZ ′. You can focus on the subject you are doing.

On the other hand, in step B10, Sk ≦ β
If not, the process proceeds to step B12, where the undetectable flag is set.

If the moving amount ΔXR or ΔXL of the subject image is too large, it is determined that focusing is impossible, and the image shift amount is not predicted. On the other hand, when the moving amount of the subject image is small and is regarded as a detection error, the moving amount is set to zero. This determination value is increased in accordance with the focal length, the subject distance, and the subject brightness when the movement amount of the subject image is predicted to be larger than the movement amount of the subject.

FIG. 8 shows the subject image signals L '(I) and R' (I) at time t0 and the subject image signals L (I) and R 'at time t1 for a moving subject. An example of (I) is shown.

As shown in the figure, SLM 'and SR
M ′ is the object images L ′ (I) and R ′ (I) as described above.
Is the head number of the block element row (44 elements) that has the smallest FMIN when detecting the amount of image shift of.

As described above with reference to FIG. 6, when the correlation operation between the subject image signals at time t0 and time t1 is performed to calculate the image movement amounts of the images L and R, 44
An image moving amount is calculated by dividing a block row composed of elements into, for example, three.

Here, as shown in FIG.
It is divided into third blocks, each having 20 elements. The head element numbers of the small blocks are SLM1 (= SLM ') for the first block, SLM'2 (= SLM'1 +12) for the second block, and S for the third block.
LM'3 (= SLM'1 +24).

That is, when calculating the image movement amount of each block, first, SLSTR = SLM'1 in FIG.
To determine the image movement amount of the first block, and then SLS
The image movement amount of the second block is obtained by setting TR = SLM'2, and finally, the image movement amount of the third block is obtained by setting SLSTR = SLM'3.

The image R is similarly treated in the same manner as the first to third images.
And the image movement amount ΔZ01 between the time t1 and the time t0 is obtained by Expression (17). Since the signal of the portion denoted by A is substantially the same at time t0 and time t1, the first block has high reliability. On the other hand, the second and third blocks have different object image signals, so the reliability is high. Sex is reduced. Therefore, in this case, the moving object prediction is performed using the calculation result of the first block.

The reason why it is extremely unlikely that high reliability is obtained in all blocks when the subject is moving is as follows. That is, the time interval between the time t0 and the time t1 is generally several tens of ms, and the subject is moving during this time. Because they are at least partially different. That is, even if the image movement amount of the subject image signal portion that is different between the time t0 and the time t1 is calculated, the reliability becomes low, and the time t
This is because if the image movement amount calculation of the substantially same subject image signal portion is performed at 0 and at time t1, the reliability is improved.

Hereinafter, referring to the flowchart of FIG.
The operation of the entire camera employing the automatic focusing device for a camera according to the first embodiment of the present invention will be described.

The CPU 201 is a microcomputer that performs sequence control of the entire camera and various operations. When the main switch of the camera is turned on by the photographer, C
PU 201 is power-on reset and starts operation,
First, the initialization of the I / O port, the initialization of the RAM, and the like are performed (step C1).

Then, the output of the photometric element 233 is computed by the photometric circuit in the interface IC 202, and the computation of the shutter speed and the aperture value, that is, the apex computation is performed (step C2). Subsequently, the output of the AFIC 240 is calculated as described above, and an AF calculation including a moving object prediction function is performed (step C3). This step C3 will be described later. The release button of the camera according to the present invention has two stages, performs photometry and AF with a half-pressed first stroke (hereinafter referred to as 1R), and performs exposure with a fully-pressed second stroke (hereinafter referred to as 2R). Has been reached.

Then, the release flag output from step C3 is determined (step C15). If the output is 0, the process proceeds to step C4. If the output is 1, the process proceeds to step C8.
And the operation proceeds to the exposure operation. This release flag is set so that 2R is turned on within a certain period of time from the start of focus detection when moving object prediction is performed, and is set to 1 when focusing is performed by the previous lens drive.

Subsequently, it is determined whether or not 1R is on (step C4). If 1R is off, step C2 is performed.
Return to On the other hand, if 1R is on in step C4, the lens is driven by the lens drive amount calculated in step C3 (step C5). This will be described later.
Then, it is determined whether the lens is in focus (step C6). This determines a focus flag described later. When it is determined that the subject is out of focus, the process returns to step C2. When it is determined that the subject is focused, it is determined whether or not 2R is on (step C7). Return to C3. If 2R is on, the diaphragm is driven to the value calculated in step C2 (step C2).
8) The mirror 102 is moved up (step C9).

Then, the shutter 118 is controlled to open at the shutter speed calculated in step C2 (step C10). Next, when the shutter 118 is opened for a predetermined time, the mirror 102 is lowered (step C11), and the aperture is set to open (step C12).
8 is charged to the initial position (step C13), one frame is wound up (step C14), and the process returns to step C2 to repeat the above operation.

Next, referring to the flowchart of FIG.
The operation of the AF subroutine of step C3 in FIG. 9 will be described.

First, in step D1, a subroutine for AF detection described later is executed. This subroutine is a subroutine from the start of integration to the calculation of the defocus amount ΔZ, and includes a moving object prediction calculation.

Then, it is determined whether or not the detection is impossible by a detection impossible flag (step D2). Here, if it is determined that detection is impossible, the focus flag is cleared (step D3), and the routine returns. On the other hand, if it is determined that detection is possible, it is next determined whether or not the continuous AF mode is set by the continuous AF flag (step D4). Here, if it is determined that the AF is not the continuous AF, it is not necessary to determine whether or not the first distance measurement is performed, and the process proceeds to step D6. If it is determined that the AF is the continuous AF, , The release flag output from the AF detection subroutine is determined, and
If it is, the process proceeds to step D5, but if it is 1, the process returns and shifts to the exposure operation in the main routine described above.

Next, it is determined whether or not the first distance measurement has been performed by using the first calculation completion flag (step D5). If it is determined that the distance measurement is the first distance measurement, step D
The process proceeds to step 3, but if it is determined that the distance measurement is the second distance measurement, the process proceeds to step D6 to calculate the defocus amount. Here, the first time and the second time mean the calculations at the times t0 and t1, respectively, as described with reference to FIG. 7, and the first and second calculations are repeated during one RON.

In step D6, a defocus amount is calculated from the defocus amount calculated in step D1 based on equations (8) and (9). Subsequently, the calculated defocus amount is compared with the focus determination value (step D7). This determination value is a value obtained based on the permissible circle of confusion. If it is within the determination value, it is already in focus.

If it is determined in step D8 that the defocus amount is within the allowable focus range, it is not necessary to drive the lens, so that a focus flag is set (step D9), and the process returns. On the other hand, if it is determined that the in-focus range is not within the allowable focus range, the in-focus flag is cleared (step D10), the driving amount of the lens necessary for focusing is calculated (step D11), and the process returns.

Next, the operation of the subroutine for AF detection will be described with reference to the flowcharts of FIGS.

First, the process waits until the integration of the AFIC 240 is completed (step E1). Next, data of all elements (pixels) is read out for each pixel (step E2). AFIC2
The output of the pixel 40 is an analog value.
The signal is converted into a digital signal by an A / D converter in U201 and stored in a predetermined storage area. Then, the integration operation is reset (step E3).

Next, non-uniformity correction is performed on the obtained subject image signal (step E4). This is for correcting subtle variations in sensitivity for each pixel that occur during manufacturing, and unevenness in illuminance of the re-imaging optical system in the AF unit 210.
Correction is made so that the output of another pixel is matched with the pixel with the lowest sensitivity among all the pixels. The correction coefficient is adjusted for each product and stored in the EEPROM 237. The details are described in Japanese Patent Application Laid-Open No. 5-93850, and the description is omitted here.

Next, the release flag is cleared to 0 (step E41).

Subsequently, it is determined whether the moving object mode (mode for performing moving object prediction) is selected (step E5), whether the self-timer shooting mode is selected (step E6), and the remote control shooting mode is shot. Is determined (step E7), it is determined whether the landscape photographing mode is selected (step E8), it is determined whether the night scene photographing mode is selected (step E9), and it is determined whether the person photographing mode is selected. Determine (step E10)
It is determined whether the camera shake prevention mode has been selected (step E11), and it is determined whether the auxiliary light LED 242 has been turned on during the current integration operation (step E12).

In the above eight determination items, the continuous AF flag is set only when it is determined that the moving object mode is selected, all the other shooting modes are not selected, and the auxiliary light is also turned off. (Step E1)
3). If this flag is set, moving object prediction AF is performed hereinafter. On the other hand, if the determination result is other than that, the continuous AF flag is cleared (step E1).
4) The process moves to step E17 via step E16, and the moving object prediction AF is not performed thereafter.

The reason why the auxiliary light is determined in step E12 is that, when the auxiliary light LED 242 is on, the subject is darker, so that the AF detection accuracy is lower than when the subject is brighter, and the error in the moving object prediction calculation becomes larger. Because. Basically, in a dark situation, the shutter speed is slow, and thus it is not suitable for capturing a moving object.

Subsequently, it is determined whether the first image shift calculation has been completed (step E15). This is to determine the first calculation completion flag that is set and cleared in steps E18 and E10 described later. This flag indicates whether or not the first image shift amount has been calculated, and the initial value has been cleared in advance in step C1 in FIG. If the first image shift calculation has not been completed, the correlation operation described with reference to FIG. 4 is performed to calculate the image shift amount ΔZ1 (step E16).

Subsequently, it is determined whether the 2R is on (step E42). If the 2R is not turned on, the process proceeds to step E17. If the 2R is turned on, subsequently, it is determined whether or not the lens is in focus in the previous lens drive (step E43). As will be described later in detail, a focus flag which is an output of a lens driving subroutine is determined. If it is determined that the subject is not in focus, the process proceeds to step E17 to start the exposure operation after the next focusing, but if it is determined that the subject is in focus, the release flag is set to 1 (step E44). ), Return.

With this configuration, when the continuous AF moving object prediction is performed by repeatedly executing steps C3 to C7 in the main loop of FIG. Is turned on, and when it is determined that the lens is in focus in the previous lens drive, the operation can immediately shift to the exposure operation.

Subsequently, it is determined whether or not the image shift amount ΔZ1 has been calculated. (Step E17). That is, a detection impossible flag that is set and cleared in steps A14 and A15 in FIG. 4 is determined. If it is determined in step E17 that detection is impossible, the first calculation completion flag is cleared (step E18), the detection impossible flag is set (step E19), and the routine returns. On the other hand, step E17
If it is determined that the detection is possible, the first calculation completion flag is set (step E20), and the routine returns. still,
If it is determined that the lens cannot be detected, the process proceeds to a lens scan in a lens driving subroutine to be described later, and a position of a detectable lens is searched for.

On the other hand, if it is determined in step E15 that the first image shift amount calculation has been completed, a second image shift amount calculation is performed. First, the first calculation completion flag is cleared for the next time (step E21). Then, as in the first time, the correlation calculation is performed to calculate the image shift ΔZ2 (step E22).

Subsequently, as in the first case of step E17, it is determined whether the image shift amount ΔZ2 has been calculated (step E23). If the calculation has not been performed, the process proceeds to step E40, and the calculated .DELTA.Z1 is calculated at time t2.
Is the image shift amount ΔZ ′. If you can calculate,
The amount of movement of the image L of the first block is calculated according to the flowchart of FIG. 6 by performing the correlation calculation of the image L of the first block described in FIG. 8 (step E24).

Subsequently, the correlation between the images L of the second and third blocks is calculated to calculate the movement amounts of the images L of the second and third blocks (steps E25 and E26). continue,
It is determined whether the calculated amount of movement of the image L of the three blocks is larger than a predetermined first determination value (step E27).
This first determination value is a relatively large value,
Reference numeral 27 is provided to detect a case where the subject deviates from the distance measurement area in the viewfinder and the distance cannot be measured, or a case where the moving speed of the subject is too high to achieve the focus even if the moving object is predicted. If the calculated amount of movement of the image L is larger than the predetermined first determination value, it is determined that the moving object is unpredictable, and the process shifts to step E38 to be described later.

Similarly, the movement amount of the image R is calculated (steps E28, E29, E30) and the calculated movement amount is determined (step E31). If the calculated moving amount of the image R is larger than the first predetermined determination value, the process proceeds to step E38 as a moving object cannot be predicted. The first calculated above
Based on the reliability index of the third block, a block having the highest correlation is selected. That is, a block having the smallest reliability index Sk is selected (step E32).

Next, in the selected correlation block, a detection impossible flag is determined (step E33). If the selected block cannot be detected, the process shifts to step E38 to perform a non-detection process. Then, if the selected block can be detected, the image movement amount ΔZ01 moved during the first and second integrations is obtained based on equation (17) (step E34). Then, it is determined whether the subject is moving by comparing the calculated ΔZ01 with a predetermined image moving amount (step E35).

The moving object flag output from step E35 is determined (step E36). If it is determined that the subject is moving, a future image shift amount ΔZ 'is predicted based on equation (18). (Step E37). And
The undetectable flag is cleared (step E39), and the routine returns. On the other hand, if it is determined that the subject is stationary, it is not necessary to predict the moving object, so that ΔZ ′ is set to the image shift amount ΔZ2 calculated in step E22 (step E22).
38), return.

Here, the time required from the second calculation to the actual exposure, that is, t2-t1 in the equation (18) will be described. Hereinafter, this time is referred to as an estimated time. The prediction time is a fixed time in the present invention for simplifying the control. The breakdown of the prediction time is mainly based on the CPU 20 related to the moving body prediction.
1 is a calculation time, a lens driving time, and a time from 2R, which is a required time for driving the mirror and the aperture, to an actual exposure start. Among these, the lens drive time has the largest variation in the required time, the operation time of the CPU 201 is substantially constant, and the actual exposure start from 2R
As long as 2 is not extremely worn, it takes a substantially constant value. The driving time of the lens is different between the case of driving only a few pulses and the case of driving several hundred pulses. Since the distance measurement is performed again, the dispersion of the driving time can be minimized. That is, the prediction time can be a fixed value.

The operation of the subroutine integral reset executed in step E3 in FIG. 11 will be described below with reference to the flowchart in FIG.

First, the value of the integration time timer is read as the current integration time (step F1). This timer may be configured to stop counting of the timer, for example, in synchronization with the integration end signal of the AFIC 240. Next, the value of the integration interval timer is read as the previous and current integration intervals (step F2). Next, the integration time timer and the integration interval timer are reset (steps F3 and F4). Finally,
At the same time as starting the next integration of the AFIC 240, the integration time timer and the integration interval timer are started (step F5), and the process returns.

Next, referring to the flowchart of FIG.
The operation of the lens driving subroutine executed in step C5 of FIG. 9 will be described.

First, the play reduction flag is cleared to 0 (step G16). This is a flag indicating whether or not the drive for reducing the backlash of the drive system gear was performed in the current lens drive, and is cleared to 0 as an initial value. Then, it is determined whether or not detection is possible by a detection impossible flag (step G).
1). Here, if it is determined that detection is not possible, the process shifts to lens scan for searching for a detectable state.
On the other hand, if it is determined that detection is possible, it is next determined whether or not the current mode is continuous AF (step G2). If it is determined that the current mode is not continuous AF, the process proceeds to step G4.

If it is determined that continuous AF has been performed, it is determined whether or not the first distance measurement has been performed (step G3). If it is determined that this is the first distance measurement, the process returns because the lens cannot be driven. If it is determined that the distance measurement is the second distance measurement, initialization for driving the lens is performed (step G4).

Next, it is determined whether or not the camera is already in focus (step G5). This is based on the determination result of step D7 in FIG. 10. When it is determined that the lens is in focus, it is not necessary to drive the lens, so that the focus flag is set (step G18), and the process returns. When it is determined that the lens is not in focus, the following three types of lens driving are performed based on the driving amount calculated in step D11 in FIG.

That is, first, it is determined whether the drive amount is larger than the drive amount determination value (step G6). Here, if it is determined that the distance is larger than the determination value, the distance is measured again after driving by a predetermined drive amount. For example, if the predetermined drive amount determination value is 150 pulses and the calculated drive amount is 250 pulses, the lens drive subroutine is first performed after driving the predetermined drive amount 150 pulses, and the distance measurement is performed again.
In step G7, the drive amount is set to a predetermined drive amount. Then, after clearing the focusing flag (step G8), the process proceeds to step G14.

On the other hand, if it is determined in step G6 that the drive amount is smaller than the drive amount determination value, then it is determined whether the current drive direction (retracting direction or extending direction) is the same as the previous driving direction. (Step G9). This step G
The judgment of No. 9 is, in other words, a judgment of whether or not the backlash of the gear of the drive system is blocked.

If it is determined in step G9 that the current driving direction is the same as the previous driving direction, the driving amount calculated in step D11 in FIG. 10 is set (step G9).
10) Set the focus flag (step G11),
Move to step G14. On the other hand, if it is determined in step G9 that the current driving direction is different from the previous driving direction,
The drive amount corresponding to the play amount stored in the EEPROM 237 is set (step G12), the play reduction flag is set to 1 (step G17), the focus flag is cleared (step G13), and the process proceeds to step G14. I do.

That is, if there is any play in the gear, the distance is measured again after driving to reduce the play, and the play is reduced in the next distance measurement. You will be scorched. Finally, the current drive direction is stored in the drive direction flag (step G14), and the drive amount set in steps G7, G10, and G12 is driven in the drive direction of step G14 (step G15), and the process returns. .

As described above, in the first embodiment of the present invention, the determination of 2R after the start of focus detection and the focus determination (steps E42 to E44) are performed immediately after the calculation of the image shift amount ΔZ1 (step E16). Put in. The reason is that about 30 ms elapses from the start of the integration to the end of the ΔZ1 calculation, which is appropriate in terms of time. Step E
If 42 to E44 are put in the first half too much, there is no time lag reduction effect, and if they are put in the second half too much, the focus will be completely out of focus. It is to be noted that a timer may be started from the start of integration, and if the timer overflows, the process may proceed to steps E42 to E44 depending on the processing time of the CPU. is there.

Next, a second embodiment of the present invention will be described.
A description will be given focusing on differences between the second embodiment and the above-described first embodiment.

As described above with reference to FIG. 15, the lens driving in the present invention is roughly classified into three driving methods. First, when focusing is performed through steps G10 to G15, 2
First, when the lens drive amount is larger than the determination value, and the lens is once driven near the in-focus state through steps G7 to G15, the third is step G1 in order to reduce backlash in the drive system.
This is a case in which the drive is performed to reduce the play through 2 to G15.

The second embodiment is different from the first embodiment in that if 2R is turned on immediately after the backlash drive, the exposure operation is performed immediately to reduce the time lag. Step C3 as described in the main flow of FIG.
Since the continuous AF is repeatedly performed on the loop of C7 to C7, the driving amount until focusing per one loop is relatively small, and the backlash driving is to drive a small amount toward the focusing direction. It is often driven near the focal point only by the shifting drive. If the second embodiment is not adopted, the photographer waits while pressing 2R for the time lag from backlash driving to recalculation to focusing on the route of step G10. It becomes a big camera. Rather, it is often better to shift to the exposure operation after the completion of the backlash drive, with a focus on the photo opportunity.

Since the second embodiment differs from the first embodiment only in the main flow, the second embodiment differs from the first embodiment in FIG.
Only such a sequence will be described with reference to FIG.

Since steps C1 to C15 are the same as those in FIG. 9, the description is omitted, and new steps C16 and C15 are added.
The description will be focused on C17.

The case where it is determined in step C6 that the subject is out of focus is the case where the lens has passed steps G7 to G15 as understood from the lens driving subroutine of FIG.
In this case, the vehicle travels through 2 to 15 backlash driving routes.

If it is determined in step C6 that the subject is not focused, it is determined whether or not 2R is turned on (step C16).
If the 2R is not turned on, the process returns to the step C2. If the 2R is turned on, it is determined whether the play reduction flag is set (step C17). If it is set to 1, it is immediately after the backlash drive has been performed in step C5, and the process moves to the subsequent step C8 to perform the exposure operation. It returns to step C2. Thus, by configuring the main flow, if the 2R is turned on after the completion of the play for reducing the play, the operation can shift to the exposure operation.

Next, a third embodiment of the present invention will be described.

The third embodiment is an example in which, since the lens drive amount is larger than the determination value, even if the lens is once driven before the focal point, if 2R is turned on after the lens is driven, the operation shifts to the exposure operation. is there. Such a situation in which the driving amount is larger than the determination value indicates that the subject is very fast, it is difficult to predict the moving object, and it is difficult to obtain a focused photograph. In such a situation, considering that the subject is fast, it is desirable to reduce the time lag and attach importance to the photo opportunity.

The third embodiment differs from the first embodiment only in the main flow, and is different from the second embodiment in that step C17 is omitted from the main flow (see FIG. 17). ). The description of each step is the same as that of the above-described first and second embodiments, so that the description is omitted here. By configuring the main flow in this way, when the driving amount is larger than the determination value, and once driving is performed before the focal point, and the 2R is turned on, the exposure operation can be immediately shifted to.

Although the first to third embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various improvements and modifications can be made without departing from the gist of the present invention. Of course. For example, the first to third embodiments may be implemented independently of each other to obtain a certain effect, or may be implemented in combination. Further, the moving object detection method is not limited to the method disclosed in Japanese Patent Application Laid-Open No. 5-93850, and it goes without saying that another method can be adopted.

The above embodiments of the present invention also include the following inventions.

(1) The movement of the photographic lens of the subject in the optical axis direction is detected, and the image plane position of the subject after a predetermined time is predicted.
In the automatic focus adjustment device for a camera having a moving object prediction function in which a photographing lens is driven to the predicted image plane position to focus on a moving object, a defocus amount calculation for calculating the defocus amount of the object is performed. Means, release means for causing an exposure operation by an operation of a photographer, lens driving means for driving the photographing lens, operation of the release means within a predetermined time from the start of the defocus amount calculation, and When it is determined that the photographing lens has been driven to the in-focus position in the lens driving of (1), first control means for stopping the defocus amount calculation and immediately shifting to an exposure operation is provided. Automatic focus adjustment device for the camera.

According to the automatic focus adjusting device for a camera described in (1), the shutter time lag can be sufficiently reduced.

(2) The automatic focus adjustment device has a pupil division type focus detection device, and the pupil division type focus detection device starts the charge accumulation of the charge accumulation type photoelectric conversion element for focus detection from the time when the charge accumulation starts. (1) The automatic focusing apparatus for a camera according to (1), wherein the time is a time required for calculating an image shift amount of the two divided images.

The time required for calculating the amount of image shift is usually about 30 msec. Even when the subject is moving, it is almost in focus. According to the focus adjustment device, the shutter time lag can be reduced as compared with the case where the distance is measured again and the focus is driven. Needless to say, the timer may be used to measure the time.

(3) The first control means, when performing the image movement amount calculation by the defocus amount calculation means, prohibits the shift to the exposure operation immediately after the release operation is performed. (1) An automatic focusing device for a camera according to (1).

According to the automatic focusing device for a camera described in the above (3), since the moving amount of the image is calculated and the moving object prediction function is operated, it is possible to perform in-focus shooting. (4) The automatic focusing device of the camera according to (1), wherein the automatic focusing device of the camera inhibits the operation of the first control unit when the moving object prediction function is not operating. Adjustment device.

According to the automatic focusing device for a camera described in the above (4), when the moving object predicting function is not operating, there is a possibility that the photographing lens is not in the vicinity of the focal point and the photograph is out of focus. In this case, since the exposure operation is performed after the focus driving, the image is not out of focus.

(5) The determination by the first control means compares the result of the detection by the detection means or the result of the prediction calculation by the moving body prediction calculation means with a first determination value.
Alternatively, a driving amount of the photographing lens obtained based on the detection result or the prediction calculation result is compared with a second determination value, and when the driving amount is smaller than the first or second determination value,
The automatic focusing apparatus for a camera according to (1), wherein the focusing is determined, and then the photographing lens is driven by the lens driving unit in accordance with the defocus amount.

According to the automatic focus adjusting device for a camera described in the above (5), the exposure operation is performed after the photographing lens is driven toward the in-focus position, so that the exposure operation is sufficiently close to the in-focus position.
Even if the shutter time lag is shortened, a focused photograph can be taken.

(6) The camera further comprises a backlash driving unit for driving the photographing lens so as to close the backlash of the driving system of the photographing lens, and the release unit when the operation of the backlash driving unit is completed. A second control unit that immediately shifts to an exposure operation when an operation is performed;
The automatic focusing device for a camera according to (1), further comprising:

According to the automatic focus adjusting device for a camera described in (6), the exposure operation can be started immediately by the second control means in addition to the case where the exposure operation is immediately executed by the first control means. Therefore, the chance of missing a shutter chance is further reduced.

(7) The camera further includes a judging means for judging whether or not the photographing lens is in focus as a result of the driving of the lens, and the release means even if the judging means judges that the photographing lens is out of focus. (3) The automatic focus adjusting device for a camera according to (1) or (6), further comprising: third control means for immediately shifting to an exposure operation when the means is operated.

According to the automatic focusing device for a camera described in the above (7), in addition to the case where the exposure operation is immediately executed by the first control means and / or the second control means, the exposure is also immediately executed by the third control means. Since the operation can be started, the chance of missing a photo opportunity is further reduced.

(8) Detecting means for repeating and detecting information relating to the distance of the subject in the optical axis direction of the photographing lens, and information relating to the movement of the subject based on the information from the detecting means at different times. Moving object prediction calculating means for calculating the focus position of the subject at the time of exposure; driving means for driving the photographing lens based on the result of the prediction calculation by the moving object prediction calculating means; and driving of the photographing lens by the driving means As a result, determining means for determining whether the focus position or the vicinity thereof has been reached, a release button for outputting a release signal for instructing start of an exposure operation, and calculation of a predicted focus position by the moving object prediction calculating means. Therefore, during the operation, the release signal is input, and it is determined by the determination means that the in-focus position or the vicinity thereof is reached. Case, immediately a camera autofocus system that is characterized in that comprising a first control means for starting the exposure operation, the.

According to the automatic focus adjusting device for a camera described in the above (8), even if the moving object prediction calculation is being performed, the moving object prediction is performed if the in-focus position was at or near the in-focus position before that. Instead, the operation immediately shifts to the exposure operation, so that the shutter time lag can be shortened and a photograph in focus can be taken. In the embodiment, the focus shift of the photographing lens is calculated by using a focus detection method based on a so-called pupil division method. However, the present invention is not limited to this, and the subject distance is directly calculated as in an external light passive AF or an active AF. Of course, the moving object prediction may be performed by a method for obtaining the moving object.

(9) The movement of the photographic lens of the subject in the optical axis direction is detected, and the image plane position of the subject after a predetermined time is predicted.
In the automatic focus adjustment device for a camera having a moving object prediction function in which a photographing lens is driven to the predicted image plane position to focus on a moving subject, a defocus amount calculation for calculating a defocus of the subject is performed. Means, release means for causing an exposure operation by a photographer's operation, play back driving means for driving the photographing lens so as to close the play of the drive system of the photographing lens, and completion of operation of the play back driving means If the release means is operated in the second step, the operation immediately shifts to the exposure operation.
An automatic focus adjusting device comprising:

(10) The automatic focusing device for a camera according to (9), wherein the driving amount by the backlash driving means is a constant driving amount.

According to the automatic focusing device for a camera described in the above (10), since it is only necessary to drive backlash, it is simple and sufficient AF accuracy can be ensured.
It should be noted that the accuracy can be further improved by taking into account the amount of displacement of the photographing lens when the backlash is reduced.

(11) The camera further includes a judging means for judging whether or not the photographing lens is in focus as a result of the lens driving, and the release means even if the judging means judges that the photographing lens is out of focus. (9) The automatic focus adjusting device for a camera according to (9), further including a third control unit that immediately shifts to an exposure operation when the operation of the unit is performed.

According to the automatic focus adjusting device for a camera described in (11), the exposure operation can be started immediately by the third control means in addition to the case where the exposure operation is immediately executed by the second control means. Therefore, the chance of missing a shutter chance is further reduced.

(12) Detecting means for repeating and detecting information relating to the distance of the photographic lens of the subject in the optical axis direction;
Based on the information from the detection means at different times, information on the movement of the subject is obtained, and a moving body prediction calculation means for calculating a focus position of the subject at the time of exposure, and a result of the prediction calculation by the moving body prediction calculation means. A driving unit for driving the photographing lens, a judging unit for judging whether or not the driving direction of the photographing lens by the driving unit is the same direction in the previous time and this time, and instructing a start of an exposure operation. A release button for outputting a release signal, and a photographic lens for removing backlash of the photographic lens when the determination unit determines that the direction is different even if the photographic lens has not reached the focused state. Is driven and when the release signal is input,
An automatic focusing device for a camera, comprising: a second control means for immediately starting the exposure operation.

According to the automatic focusing device for a camera described in the above (12), when a moving object is predicted, the subject is sufficiently in the vicinity of focus, and immediately after the backlash is absorbed, the exposure operation is started. By doing so, it is possible to shorten the shutter time lag and take a photograph in focus.
In the embodiment, the focus shift amount of the photographing lens is calculated by using a focus detection method based on a so-called pupil division method. However, the present invention is not limited to this. Of course, the moving object prediction may be performed by a method for obtaining the moving object.

(13) The movement of the photographic lens in the direction of the optical axis of the subject is detected, the image plane position of the subject after a predetermined time is predicted, and the photographic lens is driven to the predicted image plane position. In an automatic focusing device for a camera having a moving object prediction function that also focuses, a defocus amount calculating means for calculating the defocus amount of the subject,
Release means for causing an exposure operation by an operation of a photographer, lens driving means for driving the photographing lens, judgment means for judging whether the photographing lens is in focus as a result of driving the lens, An automatic focus adjustment device for a camera, comprising: third control means for immediately shifting to an exposure operation if the release means is operated even when it is determined that the image is out of focus.

(14) The determining means compares the result of the detection by the detecting means or the result of the prediction operation by the moving object prediction calculating means with the first determination value, or obtains the value based on the detection result or the prediction operation result. The driving amount of the photographing lens is compared with a second determination value. If the driving amount is larger than the first or second determination value, a determination of out-of-focus is made, and then the photographing lens is driven by a predetermined amount by lens driving means. (12) The automatic focusing apparatus for a camera according to (12).

According to the automatic focusing apparatus for a camera described in (14), the exposure operation is performed after the photographing lens is driven toward the in-focus position. Even if you shorten the, you can take a focused photo.

(15) Detecting means for repeating and detecting information relating to the distance of the photographic lens of the subject in the optical axis direction;
Based on the information from the detecting means at different times, obtaining information on the movement of the subject, and calculating a focus position of the subject at the time of exposure; and a detection result by the detecting means or the moving object prediction calculation. Comparing the result of the prediction calculation by the means with the first determination value,
Or a determination unit that compares the driving amount of the photographing lens obtained based on the detection result or the prediction calculation result with a second determination value to determine whether the photographing lens is already at or near the in-focus position. A driving unit for driving the photographing lens, a release button for outputting a release signal for instructing a start of an exposure operation, based on a result of the prediction calculation by the moving body prediction calculation unit, after the determination, and Even if a signal is input and the determining means determines that the focus position or the vicinity thereof has not been reached, the third exposure operation is started immediately.
An automatic focusing device for a camera, comprising: a control unit.

According to the automatic focusing device for a camera described in (15), when the photographing lens is driven based on the prediction of the moving object, even if it is out of focus, it is extremely out of focus. Therefore, if the photographing lens is driven by a predetermined amount after the focus detection, even if the operation immediately shifts to the exposure operation, the focus is not extremely out of focus, and the shutter time lag can be shortened. In the embodiment, the focus shift amount of the photographing lens is calculated by using a focus detection method based on a so-called pupil division method. However, the present invention is not limited to this. Of course, the moving object prediction may be performed by a method for obtaining the moving object.

(16) The movement of the photographing lens of the subject in the optical axis direction is detected, the image plane position of the subject after a predetermined time is predicted, and the photographing lens is driven up to the predicted image plane position, so that the moving subject can be detected. An automatic focus adjustment device for a camera having a moving object predicting function that also focuses on the subject, wherein a defocus amount calculating means for calculating a defocus amount of the photographing lens, and a release means for causing an exposure operation by a photographer's operation. A lens driving means for driving the photographing lens, and before driving the lens by the lens driving means,
Determining means for determining whether the photographing lens is in focus,
Even if it is determined by the determining means that the lens is out of focus, the operation immediately shifts to the exposure operation when the release means is operated after the taking lens is driven by the lens driving means. An automatic focusing device for a camera, comprising: a control unit.

The automatic focusing apparatus for a camera described in the above (16) is capable of achieving an in-focus state before the photographing lens is driven.
After driving toward the in-focus position, the large blur state is resolved,
This is an invention in which a release is permitted from the viewpoint of giving priority to a photo opportunity because a certain focus state is obtained. Here, in the embodiment, the determination by the determination unit is performed by comparing the drive amount of the photographing lens based on the defocus amount with the determination value. However, the present invention is not limited to this. Of course, the amount may be compared with the moving object prediction value itself, the driving amount based on the moving object prediction value, or the like. This determination is the same for any of the additional notes described above. In the embodiment, the timing of the determination is performed before the driving of the photographing lens. However, the present invention is not limited to this. The state before the driving of the photographing lens may be determined.

[0175]

As described in detail above, according to the present invention,
In an automatic focusing device for a camera having a moving object predicting function, it is possible to provide an automatic focusing device for a camera that emphasizes a photo opportunity and reduces a time lag.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an automatic focusing apparatus for a camera according to a first embodiment of the present invention.

FIG. 2 is a diagram showing in detail a configuration of an optical system of a camera system to which the automatic focusing apparatus for a camera according to the first embodiment is applied.

FIG. 3 is a diagram illustrating in detail a configuration of a control system of a camera system to which the automatic focusing apparatus according to the first embodiment is applied.

FIG. 4 is a flowchart illustrating a sequence of a correlation operation according to the first embodiment.

FIG. 5 is a diagram illustrating a relationship between FM, FMIN, and FP when calculating a correlation output when the block position showing the minimum correlation output is shifted by ± 1 element with respect to the subject image R;

FIG. 6 is a flowchart illustrating a sequence of calculating a moving amount of the image L;

FIG. 7 is a diagram for explaining a method of calculating a movement amount of an image L;

FIG. 8 shows examples of subject image signals L '(I) and R' (I) at time t0 and subject image signals L (I) and R (I) at time t1 for a moving subject. FIG.

FIG. 9 is a flowchart showing a main operation of the camera employing the camera automatic focusing apparatus according to the first embodiment.

FIG. 10 is a flowchart showing an operation of a subroutine AF executed in step C3 of FIG. 9;

FIG. 11 is a flowchart showing an operation of subroutine AF detection.

FIG. 12 is a flowchart illustrating an operation of subroutine AF detection.

FIG. 13 is a flowchart illustrating an operation of subroutine AF detection.

FIG. 14 is a flowchart showing an operation of a subroutine integral reset executed in step E3 of FIG. 11;

FIG. 15 is a flowchart showing a subroutine lens driving operation executed in step C5 of FIG. 9;

FIG. 16 is a flowchart showing a main sequence performed by a camera employing the camera automatic focusing apparatus according to the second embodiment.

FIG. 17 is a flowchart showing a main sequence performed by a camera employing the camera automatic focusing apparatus according to the third embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Focus detection part 2 Moving body prediction calculation part 3 Defocus amount calculation part 4 Lens drive amount calculation part 5 Focus calculation part 6 Sequence control part 7 Zoom part 8 Aperture 9 Mirror 10 Shutter 11 Lens 12 Release switch

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[Procedure amendment]

[Submission date] October 7, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0089

[Correction method] Change

[Correction contents]

Here, as shown in FIG.
It is divided into third blocks, each having 20 elements. The head element numbers of the small blocks are SLM'1 (= SLM ') for the first block, SLM'2 (= SLM'1 +12) for the second block, and SLM'3 (= SLM') for the third block. '1 +24).

Claims (3)

[Claims] 1. A moving object is detected by detecting movement of the photographing lens in the optical axis direction of the object, predicting the image plane position of the object after a predetermined time, and driving the photographing lens to the predicted image plane position. In an automatic focusing device for a camera having a moving object predicting function that is in focus, a defocus amount calculating unit that calculates a defocus amount of the photographing lens, a release unit that causes an exposure operation by an operation of a photographer, Lens driving means for driving the photographing lens to a focus position; operating the release means within a predetermined time from the start of the defocus amount calculation; and driving the photographing lens to the focus position in the previous lens drive. A first control means for stopping the calculation of the amount of defocus and immediately shifting to the exposure operation when it is determined that Dynamic focusing device. 2. A moving object is detected by detecting movement of the photographing lens in the optical axis direction of the object, predicting the image plane position of the object after a predetermined time, and driving the photographing lens to the predicted image plane position. In an automatic focusing device for a camera having a moving object predicting function that is in focus, a defocus amount calculating unit that calculates a defocus amount of the photographing lens, a release unit that causes an exposure operation by an operation of a photographer, Backlash driving means for driving the photographing lens so as to close the play of the drive system of the photographing lens; and if the release means has been operated when the operation of the backlash driving means is completed, the exposure operation is immediately performed. And a second control means for shifting to (a). 3. A moving object is detected by detecting movement of the photographing lens in the optical axis direction of the object, predicting the image plane position of the object after a predetermined time, and driving the photographing lens to the predicted image plane position. In an automatic focusing device for a camera having a moving object predicting function that is in focus, a defocus amount calculating unit that calculates a defocus amount of the photographing lens, a release unit that causes an exposure operation by an operation of a photographer, Lens driving means for driving the taking lens; determining means for determining whether the taking lens is in focus before driving the lens by the lens driving means; and determining that the taking lens is out of focus by the determining means Even in this case, if the release means is operated after the taking lens is driven by the lens driving means, the operation immediately shifts to the exposure operation. Third automatic focusing device of a camera, characterized by comprising control means, the.