JP2727548B2 - Camera with auto focus function - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial applications)   The present invention relates to a camera with an automatic focusing function.
It is particularly suitable for AF single-lens reflex cameras. (Conventional technology)   Conventionally, automatic focus adjustment based on multiple focus detection results
Cameras have been proposed. For example, JP-A-56-78
No. 811 and JP-A-57-128307,
The focus detection is performed several times, and the data obtained by each focus detection is obtained.
Drive the lens based on the average value of the focus amount
Has been proposed. Also, Japanese Patent Application Laid-Open No. Sho 62-12531 discloses
If the direction of the defocus is the same as the previous one,
When the subject is moving,
Select the tracking mode that drives the lens in accordance with
In the case of it is suggested to select the normal focus adjustment mode
Have been. However, these prior arts are not
The adjustment mode is not switched between before focusing and after focusing.
No. (Problems to be solved by the invention)   Cameras with autofocus are basically the first
Once the focus is adjusted, the focus adjustment is locked.
Equipped with a shot AF mode. This one-shot AF mode
If you are using a card, the shutter will stay
The focus priority release mode, which cannot be
And many. By the way, focus on one shot AF mode
Even when using the priority release mode,
In some cases, the subject may not be in focus. This is an example
For example, if the subject is moving
This is because the subject deviates from the in-focus position by the time it is performed. Ma
If the focus detection is not reliable, one focus detection
Even if the lens is driven based on the
In some cases, it may not be inside the enclosure.   Therefore, as in the prior art described above, focus detection is performed a plurality of times.
Follow the lens drive according to the speed of the subject
Lens drive based on the mode and the average defocus amount.
It is conceivable to use the averaging mode in which
Focusing with small amount of tefocus in both mode and average mode
If it is not in the vicinity, the tracking processing and averaging with sufficiently high accuracy
There is a problem that processing cannot be performed. In addition, following mode and
If the average mode was always active, the
And then the averaging process is performed even if the composition changes.
So that the focus lock
This is not convenient.   The present invention has been made in view of such a point,
The goal is to achieve more accurate
A camera with automatic focus adjustment that enables high focus adjustment
To provide mela. (Means to solve the problem)   In a camera with an automatic focusing function according to the present invention
In order to achieve the above object, as shown in FIG.
The focus of the lens on the subject to be focused
Signal DF indicating the amount and direction of defocus.
Focus detecting means (1) for applying force and a signal indicating a defocus amount.
Focus determination means (2) for determining the focus state based on the signal DF
Is determined to be out of focus by the focus determination means (2).
Sometimes based on the signal DF indicating the defocus amount and direction
A lens driving means (3) for driving a lens,
When focusing is determined by step (2), after focusing
Focus adjustment mode before focusing based on the results of multiple focus detections
Control to execute a specific focus adjustment different from the mode
Means (4).
You.   However, FIG. 1 functionally blocks the configuration of the present invention.
FIG.
All or part of steps (1) to (4)
Data program. (Action)   Hereinafter, the operation of the present invention will be described with reference to FIG. Focus examination
In the output means (1), the object to be focused
Detects the focus state of the lens and adjusts the defocus amount and direction.
And outputs a signal DF. The focus judging means (2) includes a focus detection
Each time focus detection is performed by the output means (1), each defocus
Focus determination is performed based on the focus amount DF. Lens driving means
(3) is determined by the focus determination means (2) not to be in focus
Signal DF indicating the defocus amount and direction when
Drive the lens. Further, the control means (4)
When it is determined by the focus determining means (2) that the subject is in focus,
Focus before focusing based on multiple focus detection results after focusing
Perform a specific focus adjustment mode different from the adjustment mode
You. Here, as the specific focus adjustment mode, for example,
The amount of defocus may decrease due to the movement of the subject after focusing.
When the direction changes, the subject
A tracking mode in which the focus is adjusted to focus on the body,
Defocus when the amount of defocus varies after focusing
Average mode for driving the lens according to the average value of the amount, after focusing
Defocus amount is completely different by changing composition
Focus lens to stop driving the lens if
Lock mode.   For more detailed configuration and operation of the present invention,
Will be further clarified in the description of the embodiment described below. (Example)   FIG. 2 shows a camera hardware according to one embodiment of the present invention.
FIG. In the figure, (21) is a turtle
Microcomputer for AF control
). (22) is a CCD image sensor for AF
Yes, integration start signal φ from microcomputer (21)_ICGReceive
Integration starts, and after the integration is completed, the output of each pixel is A / D converted.
And sends it to the microcomputer (21). Microcomputer (21) is CC
The output of each pixel transmitted from the D image sensor (22)
Calculation based on the amount of defocus of the subject image (defocus
Amount). The microcomputer (21) is the default
After calculating the amount of scum, the lens should be set to zero.
Drive. Here, the lens drive amount and the defocus amount
Is different for each lens.
Therefore, the conversion coefficient k is equal to the number of times of the lens incorporated in each lens.
It is stored in the road (25). Microcomputer (21) is lens rotation
The value of the conversion coefficient k is read from the road (25), and the calculated
By multiplying the focus amount by the conversion coefficient k, the lens
The number of pulses required for driving is calculated. The microcomputer (21)
Calculated by the AF motor control unit (23)
The number of pulses is transmitted, and the AF motor controller (23) drives the lens
Transmitted from the microcomputer (21) to the AF motor (24) for
Drive for the number of pulses obtained.   (26) is a display unit for displaying figures shown in FIG.
Is made. In Fig. 3, the LED (26A) is focused and focused
Indication of impossibility. That is, the defocus amount is calculated.
If the lens is in focus after driving, the LED (26A)
Lights in green to notify the photographer of in-focus. Also described below
If the defocus amount is not calculated for the reason
The LED (26A) flashes red, indicating to the photographer
Notice. Furthermore, LEDs (26B) and (26C)
Is a display showing the switching of the camera shooting mode in
You. If the subject is stationary, the focus position after focusing
Fixed, focus lock mode shooting, LED
(26B) lights up. On the other hand, if the subject is moving
Follows the movement of the subject and keeps the subject in focus.
The LED (26C) lights up.   In FIG. 2, (S1) is a relay button (not shown).
This switch turns ON when pressed down to the first stroke.
You. When the switch (S1) is turned ON, the interrupt port described later
(INT1) interrupt processing is executed and AF operation is performed.
Will be (S2) indicates that the release button is the first stroke
Turns on when pressed down to the second stroke deeper than
It is a switch. When the switch (S2) is turned on,
Interrupt processing by the interrupt port (INT2),
A release operation is performed. This interrupt port (INT
When interrupts due to 2) are prohibited by the program
There is. Therefore, the switch (S2) is turned on for the microcomputer (1).
Port (IP2), and an interrupt port
Even if interrupts are disabled by (INT2),
Con (21) scans input port (IP2)
Determines whether the photographer has made a release request
It is possible. (S3) is a mirror up switch
This switch controls the light passing through the lens
Inside the camera body so that
The mirror (not shown) located on the
When the light passes through the lens, the light reaches the film surface.
ON when completely retracted from the shooting optical path to reach
Switch, and a shutter mechanism (see
Is reset to the OFF state by charging.   (27) irradiates the subject when the brightness of the subject is low
LED that emits infrared light (auxiliary light).
Controlled by (28). The microcomputer (21)
When it is determined that the brightness is low, the auxiliary light control unit (28) is
Output the auxiliary light emission signal, and
Integration start signal φ for sensor (22)_ICGAnd output
At the end of the minute, output to the auxiliary light controller (28)
The emission signal of the auxiliary light is stopped. This allows CC
The D image sensor (22) uses the auxiliary light at low
Perform CD integration. (29) focuses on dynamic subjects described later
This is a timer for calculating the change speed of the position.
Clear to zero when AF is started by turning on the switch (S1).
After that, the timer value TM constantly increases and the AF
It is possible to monitor the time after the start
You. This concludes the description of the hardware.   Subsequently, the algorithm of the present embodiment will be described.
In the present embodiment, the distinction between a still subject and a dynamic subject is performed.
Perform “Focus lock mode” and “Follow mode”
Automatically switch between these two shooting modes
I have. Hereinafter, each shooting mode will be outlined.   First, select the focus mode
If you set
Grasp at a predetermined place (hereinafter referred to as focus frame)
Of the subject image in this focus frame.
Find the amount of focus and drive the lens so that the subject image is in focus
Is performed. In general shooting, the photographer
The subject to be adjusted is
Frame the frame so that it is located in a different location
There are many cases in which you want to use In such a case,
The photographer focuses on the subject to be focused.
Shake the lens so that it is within the frame,
Do not change this focus position after performing AF operation.
Framing is required. "Foca
In such a case, the "slock mode"
This is a mode in which the release is performed without changing the position.   In this embodiment, another shooting mode is
It has a “follow mode”. This is the photographer
Shooting mode corresponding to the moving subject
It is. If the subject is moving, focus
The amount of defocus of the subject detected on the
Become This change is within the depth of field on the film surface
There is no problem if it is small enough to fit, but the scene
If there is a change in the defocus amount beyond the depth,
The focus position is changed every moment according to the changing defocus amount.
It is necessary to follow the subject to change. This implementation
In the example, if such an object moves,
Mode), and the image formation position of the subject image that changes every moment
And always keep focus on
You. In the “follow mode”, the photographer presses the release button.
When you press, the release button
The shutter curtain actually travels and is exposed on the film surface.
Considering the time lag (time delay) until the timing
The subject image is focused at the timing of exposure on the film surface
Predicts the amount of defocus as
A predictive control method for performing motion is also included. This "follow
The camera is equipped with a
Can always obtain a focused photograph.   Hereinafter, a detailed flowchart will be described in detail. Lerry
Button is pressed down to the first stroke, and the switch (S1) is
When turned ON, the AF start flow shown in Fig. 4 is executed.
It is. In the following description, the symbol "#"
Shall mean step. In # 1, interrupt
By disabling the interrupt from the port (INT2)
The release button is pressed down to the second stroke,
Release routine is not called even if release request is issued
Like that. Then, in # 2, the microcomputer (21)
When converting the amount of focus to the number of pulses for driving the lens
Of the lens circuit (25) shown in FIG.
Input from Subsequently, the distance measurement time described later is monitored in # 3.
Reset the timer (29) Further
Then, a focus detection calculation is performed in # 4.   FIG. 11 shows a subroutine of the focus detection calculation. #Ten
8 reads the timer value TM, and # 109 reads the memory value TM '
The start time of the CCD integration described later is stored in the microcomputer (21).
Store in memory. Subsequently, in step # 110, the low-luminance flag is determined.
It is carried out. If the brightness of the subject is low, the CCD image
Because the light sensor (22) is not illuminated enough
Illuminates the subject with the auxiliary light
Is determined by the low luminance flag. Low brightness immediately after AF start
Since the flag is cleared, the auxiliary light emission of # 111
Skipped, CCD integration of # 112 is performed. CCD image cell
The sensor (22) is the information of the subject for performing the focus detection calculation.
Is an image sensor for obtaining
The luminance information of the subject is stored in each pixel. CCD at # 113
The data of each pixel in the image sensor (22) is
A data dump process to be taken into the server (21) is performed. Less than
Below, correlation calculation, interpolation calculation, defocus
Switch calculation shows the flow of the well-known focus detection calculation
It is. The above processing is the focus detection calculation subroutine of # 4
Done in   When focus detection calculation was performed in # 4, the reliability of the result
If the distance is insufficient, the focus cannot be detected. In # 5 that
Make a decision. If focus detection is not possible here
Proceeds to # 501, otherwise proceeds to # 11. #Five
If you proceed to 01, check here whether the brightness is low.
U. First, if CCD integration is performed prior to the focus detection calculation
In this case, since the auxiliary light is not emitted, the subject brightness is low.
In some cases, focus detection cannot be performed. # 501 low brightness
And the low luminance flag is set in # 6.
If not, proceed to # 7, set the low luminance flag and #
Returning to step 4, the auxiliary light is emitted and CCD integration is performed. one
On the other hand, if the low brightness is not determined in # 501, or
In # 6, the low brightness flag is set, and CC is
If D integration has been performed, the contrast of the subject image
Is determined to be in a low contrast state. in this case#
Proceed to 8. In # 8, focus while scanning the lens position
A low contrast scan that repeats point detection calculations was performed in the past.
To determine whether or not
If entered, NO is determined in # 8, and low contrast is determined in # 9.
Start scanning. # 8 already low contrast scan
If it has been finished, the low contrast display is displayed in # 10 and the
Notify the shadow person that focus detection is not possible. This is
The LED (26A) shown in Fig. 3 is displayed by blinking red.   If it is determined in # 5 that focus detection is possible, proceed to # 11
No. In # 11, the low-luminance flag is determined. Auxiliary light
The above CCD integration time is used with and without
The defocus amount is repeated as described later.
Sampling period T when calculating₀Need to change
You. Therefore, the respective sampling periods T in # 12 and # 13₀
Is set. In # 14, the differential from the result of the focus detection calculation
The amount of focus is calculated. This defocus amount at # 15
Is within the focusing range or not.
For example, proceed to AF mode determination routine after # 441,
If the scum amount is out of the focusing range, the flow proceeds to the flow after # 16.
Usually, the position of the lens is not fixed at the start of AF
Therefore, it is rare if it is within the focusing range, and proceed to # 16 or later.
No.   In # 16, the defocus amount calculated in # 14 and the input in # 2
Calculate the number of pulses for driving the lens from the input conversion coefficient k
Put out. Subsequently, the lens is driven in # 17, and the calculated value is calculated in # 16.
Lens driving is performed for the number of pulses obtained. After this, the subject
The routine enters a routine for detecting the state of the body. In # 18
Is the counter CN₁Is cleared to zero. This counter C
N₁Indicates how many times the focus determination has been performed in the routine after # 19.
This is a counter for counting.   The focus detection calculation is performed again in the subroutine # 19.
You. If the focus cannot be detected in # 20, the focus is detected.
Repeat # 19 with. If focus detection is performed,
Calculate the focus amount, and in # 22, counter CN₁One value of
The focus is determined at # 23. At this time, the subject
The focal position, whether stationary or moving
If the change is slow, the defocus amount calculated in # 21 is
It is within the focus range, and proceeds to # 24. Where the counter CN₁The value of the
Is 1, that is, with one lens drive in # 17
If in focus, go to AF mode determination routine after # 441
move on. However, if the focus was not determined in the focus determination of # 23,
If the focus position of the subject image has changed while driving the lens
Or the focus detection accuracy is low and the defocus amount
It is considered that there is variation and proceed to the routine after # 30
No.   Counter CN by # 30 and # 31₁If the value of
Lens drive has been performed once in the past.
After calculating the number of pulses, the lens is driven in # 42.
Then, after waiting for the time in # 43, the operation after # 19 is performed.
repeat. The reason for waiting here is that the focal position of the image is
For a subject that changes over time, the moving speed is described below.
When the focus detection time interval is short when detecting by the method
This is because speed detection is not accurately performed. # 19 of
In the subroutine, the CCD integration start time TM '
1) Timer is set in # 43 because it is stored in the memory inside
-Value TM is TM ≧ T₀Wait until time reaches + TM '.
After repeating the calculations of # 19 to # 22, focus determination is again made at # 23
I do.   If the focus is determined in # 23, the counter CN₁Is 2
Therefore, in # 24, CN₁= 1
And # 25 scans the input port (IP2) of the microcomputer (21).
Is performed to determine whether or not there is a release request. here,
If there is no relays request, the AF mode judgment routine
Proceed to If there is a release request,
After performing the process of # 26 ~ # 29 for quick response
Proceed to the release routine. In # 26, the last defoca we got
The sign of the defocus amount DFb and the sign of the defocus amount DFa obtained this time are
Determine if they are equal. Mark of defocus amount DFA, DFb
Equal sign means that the focus positions of the subject images are the same
The focus amount DFb and the
If the defocus amount DFA or the same sign, the subject moves
Is determined and the speed V is calculated in # 27.
Set the tracking mode flag to follow the movement of the subject with
Then, release the shutter at # 29 and enter the relays routine
You. In the calculation of the subject speed of # 27, the default
The focus amount DFa is set to the time interval between the current and previous focus detection (ta−t
b) and then multiply that value by (1/2). this is
If there is a variation in the calculated defocus amount,
The estimated subject speed V is estimated faster than it is.
Calculate subject speed with 1/2 weight to avoid
That's why. Actually, this time the defocus amount DFA is in focus
Within the range, the moving speed of the subject is not so fast
No, the following speed is enough. Meanwhile, in # 26 now
Times the defocus amount DFa and the sign of the previous defocus amount DFb
In the opposite case, the focal position of the subject image has shifted in the opposite direction.
The subject is considered to be moving in the same direction.
The relays operation is performed without following.   Next, in the focusing judgment of # 23, the counter CN₁Is 2
If out of focus, proceed to # 37 by the determination of # 30
Moves. In # 37, the current defocus amount DFA and the previous default
The sign of the focus amount DFb is compared. Where the same
If it is a sign, it is determined that the subject is moving in the same direction.
And proceed to # 38 and thereafter. If the sign is reversed, the subject is the same.
Since it is not determined that the lens is moving in one direction, the lens drive
Without performing the process, proceed to # 43. In # 38, if there is a release request
And if there is a release request, the object speed V
Calculates, sets the flag of the following shade in # 40, and follows
Proceed to the mode routine. In the speed calculation of # 39, this time
The focus amount DFA is divided by the focus detection time interval (ta-tb).
And (1/2) times more. This is the same as
However, here, the defocus amount DFA is focused
Because it is out of the range and the speed V of the subject is large,
Do not move to the lasing operation, but temporarily follow-up mode
Enter the speed V of the subject accurately, and then
To enter the routine.   On the other hand, if there is no release request in # 38, proceed to # 41,
The number of pulses for driving the lens is calculated, and the lens
And go to # 43. # 43 to # 22 were repeated
After that, the focus is determined again at # 23. The place where I was focused here
If it is out of focus, the process proceeds to # 24 and below.
Unta CN₁Is 3, so # 30 and # 31 are not
The deviation is also determined as NO, and the flow proceeds to the determination of # 32. # 32 three times
If the signs of the defocus amounts are the same, # 33
Whether the absolute values of the three defocus amounts are all within 1 mm
Has been determined. Absolute value of defocus amount is 1mm
If anything exceeds, measure the distance of another subject
Because it is highly probable, proceed to # 41 and after and focus detection again
repeat. If both # 32 and # 33 are YES,
Focus detection is normal three times and the subject is in the same direction
It is determined that the vehicle is moving, and the speed V = (DFa−DF
b) After calculating / (ta−tb), the flow of the tracking mode is performed at # 35.
Set the lag and shift to follow mode. Also in # 32
If the three defocus amounts are not the same, # 36
Is the sign of the current defocus amount DFA and the previous defocus amount DFb.
Judge whether the numbers are the same.
When the sign of DFa and the previous defocus amount DFb match
Starts the lens drive again in # 41 and # 42, and after # 43
And the determination of the subject is repeated. Also, this time at # 36
The sign of the focus amount DFa matches the sign of the previous defocus amount DFb
If not, focus detection accuracy is low and defocus
Is determined to be uneven, and the vehicle enters average mode II.
I do.   FIG. 10 shows a flow of the average mode II. # 99
In this example, the defocus amount
DFa, previous defocus amount DFb, and defocus before last time
Average value DF = (DFa + DFb + DFc) / 3
You. This defocus amount DF is within the focusing range at # 100
It is determined whether or not the camera is in focus.
After the release is permitted in # 102, the average mode I
Move to In the average mode I, # 66 of FIG.
After setting the average correction flag as shown in FIG.
The focus lock is displayed and the camera waits for release. one
On the other hand, # 100 has large variation in the amount of defocus
Average defocus amount may exceed the focusing range.
You. In this case, the number of pulses for driving the lens is
After calculating and driving the lens to the predetermined position in # 104,
At 05, the focus detection calculation is performed again. Focus detection at # 106
If it is not possible, # 105 until focus is detected
The focus detection calculation is repeated. # 10 if focus is detected
Calculate the defocus amount at 7, return to # 99, and
The processes of # 99 to # 107 are repeated until the focus amount falls within the focusing range.
Return.   As described above, after calculating the defocus amount,
If the lens is driven and out of focus,
The moving speed of the imaging position is fast, and the lens drive cannot keep up
Or the accuracy of defocus amount calculation is low,
If the amount of defocus varies
Deemed to be a method to determine whether to follow mode or average mode
I mentioned. At the same time, the release request is being determined.
The sequence in the case where the error occurs is also described.   If the moving speed of the subject is fast, follow-up
Mode can be determined, but the speed of the subject is slow.
Has a time lag caused by driving the lens to the expected focal position.
Even if there is, it does not fall out of the focusing zone, and it is determined that focusing is in # 23
Sometimes. For this reason, even after the focus determination of # 23,
Follow mode determination in AF mode determination routine after # 441
It is carried out. Hereinafter, this AF mode determination will be described.
You.   In # 441, we have entered the AF mode judgment routine
Flag (AFMF) is set. In # 44, focus indication
And notify the photographer of the in-focus condition. Also, when in focus
Disables interrupts by interrupt port (INT2)
Release, always accept the release, there was a relays request
Sometimes, the relays operation is performed immediately.
I have. Then, in # 46, the counter CN_TwoHas been cleared.
Counter CN_TwoIndicates the number of focus detections for AF mode determination.
Show. Focus detection calculation is performed in # 47, and focus detection is not possible in # 48
The contrast of the original subject is low.
What is the subject you want to shoot after focusing
Performs focus detection calculation for another subject with a significantly different focus position.
It is considered possible to proceed to # 55. Focus is normal at # 48
, The defocus amount DF is calculated in # 481.
I do. If | DF |> 1mm in # 49, focus and shoot
Another subject with a different focus position than the subject to be shadowed
Since it is considered that the focus detection has been performed, the process proceeds to # 55. # 55
~ # 57 such an irregular focus detection calculation was performed
Perform the processing for the case. In # 55, first,
Perform a check. Last ignore flag is not regular
This flag is used to determine whether focus detection has been performed.
Yes, this flag is reset at first,
If the determination is no, the process proceeds to # 56. In # 56, next is regular
If the focus is detected, the answer is YES in # 55
, Set the previous ignore flag. YES at # 55
In this case, two consecutive non-regular focus detections
In this case, the AF mode determination routine is performed at # 571.
Reset flag (AFMF) as escaped from #
Press 57 to display focus lock and wait for relays.
You.   Here, if the non-regular focus detection is performed twice consecutively,
The reason is limited to the following reasons. Moving subject
When shooting a subject in follow-up mode, always keep the subject
It is necessary to follow the focus frame,
Subject deviates from focus frame due to camera shake
In some cases. For this reason, once non-regular focus detection is performed.
If this is done, ignore it. However, this is twice consecutive
The photographer intentionally focuses the subject
It is determined that he has deviated outside the frame. This is because the photographer
Camera to determine the composition after focusing on the subject
This is because the focus is locked. For this reason,
If the camera detects incorrect focus detection twice in a row, the AF mode
The focus lock mode is determined as the mode and the
Displays the focus lock and waits for release.   If NO is determined in both # 48 and # 49, the subject is
It has not changed, and the defocus amount has been reliably calculated.
And it proceeds to # 50. # 50: last ignore flag
Is checked. Here, the last ignore flag is set
If so, the normal focus detection calculation was not performed last time
The defocus amount DFc two times before in # 51
And the average of the defocus amount DFA this time
The focus amount DFb is calculated by interpolation. Then, # 5
In 2, the previous time ignore flag is cleared, and the process proceeds to # 53. Meanwhile, # 5
If 0 and the ignore flag was not set previously, interpolation is required.
Since there is no need, the process proceeds directly to # 53. # 53 in the counter
CN_TwoIs counted up and the counter CN at # 54._TwoIs 4
Steps # 47 to # 54 are repeated until it becomes. Counter CN_TwoIs the value of
If it is 3 or less, the timer value TM is set to the memory value T at # 541.
M ′ to T₀Wait until the number increases.   After completion of the four focus detection calculations, AF mode determination at # 581
Resets the flag (AFMF) indicating
No. In # 58, the signs of the four defocus amounts are all the same,
In addition, the defocus amount changes monotonically, and
The difference between the two consecutive defocus amounts between 59 and 61
When all the absolute values are determined to be equal to or greater than the predetermined determination threshold a
Assumes that the subject is moving and moves to the tracking mode.
Run. At this time, V = (DF
a-DFc) / (ta-tc) and follow mode flag at # 63.
And set it to follow mode. At this time, the speed V
Calculated from the defocus amount DFA and the defocus amount DFc two times before
The reason is that the focus detection time interval (ta-tc) is long.
Is more accurate, and the newer the data, the better
The initial speed V at the time of mode entry is calculated more accurately.
It is.   On the other hand, in # 58, all four defocus amounts have the same sign.
Or if the change is not monotonic,
Defocus of focus detection twice for stability of focus amount
It is determined whether the sign of the amount difference has changed alternately, and
In such a case, it is considered that the calculation of the defocus amount DF is unstable.
Then, the averaging process of # 65 and below is performed. # 65 defocused
Defocus amount DFA this time, and defocus amount D last time
Fb, 3 times defocus amount before 2nd time defocus amount DFc
Is the true defocus amount, and the average correction
The focus lock display at step # 67.
Waiting for the laze. On the other hand, the defocus amount alternates at # 64
If not, or # 59 to # 61
The absolute value of the difference between successive defocus amounts is determined as
When the subject is smaller than the threshold a, the subject moves.
And the defocus amount was calculated with high accuracy.
No, averaging is not performed, and
It displays a waste lock and waits for release.   With the above, the AF mote judgment is completed from the start of AF
The description of the routine up to this point is ended.   Next, about the sequence after entering the following mode
explain. In FIG. 8, first, the following mode table is set in # 68.
And notify the photographer that the tracking mode has been entered.
You. Next, at # 69, the counter CN_ThreeIs substituted for 2. Mosquito
Unta CN_ThreeIs used to determine when to escape from the following mode.
It is. Counter CN at # 70_Four, CN_FiveHas been cleared. Mosquito
Unta CN_FourIs the normal focus detection calculation after entering tracking mode.
A key for counting the number of times that focus detection was not performed.
Counter CN_FiveIs the time when regular focus detection was performed
This is a counter for counting the number. # 71 is the subject
Body moving speed V and focus detection calculation period T₀Multiplied by
In addition to the new defocus amount DFA,
Defocus amount when the lens drive is not performed
DF 'is calculated. Based on this planned defocus amount DF ′
Calculates the number of pulses for driving the lens by # 72
Then, the lens is driven in # 73. Timer value TM reaches the maximum at # 74
The focus detection cycle T is added to the memory value TM 'for the new focus detection calculation.₀
Wait until it reaches the value plus. Originally # 71
Period T at₀Is the prediction period T including the lens driving time₀′
Should be used, but here for simplicity of discussion
T₀≒ T₀′, And there is almost no lens driving time.
Keep it. In the lens drive of # 73, do not drive the lens
Lens drive by the planned defocus amount DF '
Therefore, when the focus detection calculation is performed in # 75, the differential
The focus amount is calculated as approximately zero. #
At 76, it is determined whether or not focus detection was impossible.
You. As described above, regular focus inspection is required due to camera shake etc.
If not, go to # 89. Also # 76
If normal focus detection is performed in
Calculate the scum amount DF, but calculate the absolute value of the obtained defocus amount.
If the value | DF | is judged to be 1 mm or more in # 77,
As described above, it is determined that normal focus detection was not performed.
And proceed to # 89. In # 89 now as a result of focus detection calculation
Has set the defocus amount DFA to zero
You. This is the difference during the focus detection calculation this time, as described above.
The lens is driven so that the amount of focus is approximately zero.
Because it is. In addition, irregular focus detection at # 90
Counter CN that counts the number of operations_FourIncrease the value of
ing. This is often due to non-regular focus detection as described below.
If the calculation is performed, exit from this tracking mode in # 87.
This is to get out. Judged as | DF | <1mm at # 77
If so, proceed to # 78. In # 78, the position of the subject
The difference from the previous subject position is defined as the defocus amount difference ΔDF.
It has been calculated.   FIG. 13 illustrates a method of calculating the defocus amount difference ΔDF.
FIG. In Fig. 13, the origin of DFA is
This is the lens position at the time of focus detection, and the DFb origin is the previous focus
This is the lens position at the time of detection. At the previous focus detection time tb
Since the lens was located at the DFb origin,
The focus amount DFb is generated. Previous lens
The driving defocus amount DFb ′ is determined by the previous focus detection time t.
Elapsed time from b to the current focus detection time ta (ta-tb)
Of the predicted movement amount of the subject obtained by multiplying the
It is obtained by adding the defocus amount DFb. Therefore,
At the current focus detection time ta, the lens position is
Point, but the subject is actually outside the predicted position
And the defocus amount DFA is generated this time. this
In this case, the position of the subject at the previous focus detection time tb
Defocus to subject position at focus detection time ta
As is clear from the figure, the amount difference ΔDF
Add the previous lens drive defocus amount DFb ′ to the amount DFa.
In addition, by reducing the previous defocus amount DFb
Obtained.   In # 79, the difference between the defocus amount difference ΔDF and the moving speed V
Sign comparison is performed. If the sign is different, move speed
The subject is moving in the direction opposite to the direction calculated as the degree V.
The focus was not detected properly
Considered as # 88 counter CN_FourIs increased by one.
You. In step # 80, the absolute value of the defocus amount is determined to be a predetermined value.
Defocus actually measured even when it is equal to or greater than the threshold b.
Is much different from the expected defocus amount
That is, as in the case described above,
No, it is considered to have not been performed, and the process proceeds to # 88. # 79, # 80
If the deviation is also determined to be YES, proceed to # 81, and the normal focus
Counter CN indicating the number of detections_FiveIncrease the value of
You.   Counter CN at # 82_FiveIf the value of is not 5, # 87
Proceed to. In # 87, counter CN_ThreeAnd CN_FourComparing
You. Initially the counter CN is set by the initial setting of # 69_ThreeThe value of
2 and this counter CN_ThreeThe value of
Counter CN indicating the number of focus detection_FourCompared to the value of
You. That is, here, the counter CN_FourIs greater than or equal to 2
In this case, it is determined as YES, and release is prohibited in # 871 again.
Return to AF mode determination and repeat. This is accidentally added
When entering any mode, the counter CN_FourValue and counter C
N_ThreeIt is possible to compare the values of
To do that.   On the other hand, the counter CN at # 82_FiveIf the value of becomes 5,
At step # 83, the low luminance flag is checked. As aforementioned,
When the low-brightness flag is set, an auxiliary light is emitted.
CCD integration is performed, but the power consumption is large when auxiliary light is used.
It is not advisable to perform unlimited focus detection
I don't. Therefore, the counter CN_FiveWhen the value of reaches 5
It comes out of following mode. Low brightness hula
If the focus is set, focus determination is made in # 91,
If the camera is in focus, release the camera in step # 92, then release it in step # 94.
The focus lock is displayed, the tracking mode ends, and focus
The photographer is notified that the focus lock mode has been set.   If the camera is not in focus, the relays are prohibited in # 93.
To return to AF mode determination again. On the other hand, do not use auxiliary light
In this case, follow-up mode is continued because there is no worry about power consumption
I do. Counter CN at # 84_ThreeIs increased by one. Further
And counter CN at # 85, # 86_Four, CN_FiveHas been cleared.
Counter CN_ThreeIs to escape from the # 87 following mode
Parameters. This counter CN_ThreeIs in follow mode
Increases according to the elapsed time since the entry (number of focus detections)
Therefore, the conditions for getting out of the # 87 following mode are gradually becoming stricter.
It becomes difficult. That is, the elapsed time since entering the following mode
Is longer, it means that the subject is moving,
Irregular focus detection due to camera shake
Even after that, the control that keeps following is performed.   In # 87, it was determined that the player could not exit the following mode
In this case, the following speed V is newly calculated in # 95. #
In 95, to improve the calculation accuracy of the following speed V,
Difference between the subject position two times before and the subject position two times before (defocus
差 DF) divided by the focus detection time interval (ta-tc)
The moving speed is V.   FIG. 14 illustrates a method of calculating the defocus amount difference ΔDF.
It is a figure for clarification. In Fig. 14, the origin of DFA is now
Is the lens position at the time of focus detection, and the DFb origin is
This is the lens position when focus is detected, and the DFc origin is
This is the lens position at the time of point detection. Focus detection time tc before last time
In, since the lens was located at the DFc origin,
The defocus amount DFc is generated every time. Before
The lens drive defocus amount DFc 'is
Elapsed time from detection time tc to previous focus detection time tb
(Tb−tc) multiplied by subject speed Vc
The moving amount is obtained by adding the moving amount to the defocus amount DFc two times before.
Therefore, at the previous focus detection time tb, the lens
The position has reached the DFb origin, but the subject is actually predicted
Out of the position, causing the previous defocus amount DFb.
ing. The previous lens drive defocus amount DFb ′ is
From the previous focus detection time tb to the current focus detection time ta
The subject obtained by multiplying the elapsed time (ta-tb) by the subject speed Vb
Is calculated by adding the predicted movement amount of
It is. Therefore, at the current focus detection time ta,
The lens position has reached the DFA origin, but the subject is actually
Is out of the predicted position, and the defocus amount DFA
Has occurred. In this case, the focus detection time tc
Object position at the current focus detection time ta from the object position
The defocus amount difference ΔDF up to
In this case, the defocus amount
Focus amount DFb 'and defocus for driving the lens two times before
Add the amount DFc ′ and reduce the defocus amount DFc two times before
It is obtained by doing. That is, the defocus amount difference Δ
DF is ΔDF = DFa−DFc + DFb ′ + DFc ′ Becomes When the defocus amount difference ΔDF in the above formula is used for focus detection
Calculate the following speed V by dividing by the interval (ta-tc)
doing. After that, the focus is determined at # 96, and the
If it is, the relays are permitted at # 97, and if it is not focused, it is # 98.
To prohibit relays and repeat the process from # 71. Reli
Release permission, if there is a release request, release
The chin is called and a relays operation is performed.   Finally, the release routine will be described. First,
At # 117 in FIG. 12, the average correction flag is set.
Or not. Here the average correction flag is set
If so, proceed to # 121 and calculate the default
The number of pulses for driving the lens is calculated from the amount of scum, and # 12
Use 2 to drive the lens and use # 123 to monitor the input port (IP3).
After checking the mirror up and the lens in # 124
After stopping the driving, the shutter travels. #
If the average correction flag is not set in 117, # 1
Determines whether the following mode flag is set at 18
doing. Here, the tracking mode flag is set.
If not, the relays will be performed during AF mode judgment in # 125
It is determined by a flag (AFMF). This flag
If (AFMF) is set, the above judgment mode is executed at # 126.
The subject may be moving during the
To correct, average the defocus amount obtained during the above determination
Then, the process proceeds to step # 121 to drive this amount.
For example, focus detection is performed twice, and defocus amount is calculated twice.
If (DF1, DF2) is obtained, set DF = (DF1 + DF2) / 2.
You. If the above flag (AFMF) is not set,
No lens drive is performed, and the process proceeds to # 123 and thereafter. Follower in # 118
If the mode flag has been set, the process proceeds to # 119.
In # 119, the time lag τ is calculated. Time lag τ
Indicates that the shutter travel has actually started since the latest focus detection calculation.
It is time to be performed. Subject moving speed V at # 120
Multiplied by the time lag τ and the latest defocus amount DFA
In addition to the defocus amount DF '
It has been calculated. In # 121, the number of pulses for driving the lens
Calculate and drive the lens in # 122, when running the shutter
Is driven to the expected focal position. Below, # 123, #
After performing the processing of 124, the shutter travels. to this
Control that focuses when the shutter is running
You. Exposure control is not related to the present invention, so it is explained
Is omitted. (The invention's effect)   As described above, according to the present invention, the focus adjustment mode
It is possible to switch between after focus, so once focus is achieved,
It is possible to perform highly accurate focus adjustment, for example,
Averaging when focus detection is not reliable
To perform the follow-up processing when the
Even in the case where the defocus amount is small and in the vicinity of focus
To execute processing based on the results of focus detection multiple times
, So that highly accurate processing can be performed.
This has the effect.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a basic configuration of the present invention, FIG. 2 is a block circuit diagram of one embodiment of the present invention, FIG. 4 to 12 are flow charts for explaining the operation of the above, and FIGS. 13 and 14 are operation explanatory diagrams of the same. (1) is focus detection means, (2) is focus determination means, (3)
Denotes lens driving means, and (4) denotes control means.

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Jun Hasegawa               2-30 Azuchicho, Higashi-ku, Osaka-shi, Osaka               Osaka International Building Minolta Camera Co., Ltd.               Inside (72) Inventor Kenji Ishibashi               2-30 Azuchicho, Higashi-ku, Osaka-shi, Osaka               Osaka International Building Minolta Camera Co., Ltd.               Inside (72) Inventor Toshio Kaida               2-30 Azuchicho, Higashi-ku, Osaka-shi, Osaka               Osaka International Building Minolta Camera Co., Ltd.               Inside (72) Inventor Hiroshi Otsuka               2-30 Azuchicho, Higashi-ku, Osaka-shi, Osaka               Osaka International Building Minolta Camera Co., Ltd.               Inside                (56) References JP-A-60-188935 (JP, A)                 JP-A-59-121322 (JP, A)                 JP-A-63-304232 (JP, A)

Claims (1)

(57) [Claims] Focus detection means for detecting the focus state of the lens with respect to the subject to be focused and outputting a signal indicating the defocus amount and direction; and focus determination means for determining the focus state based on the signal indicating the defocus amount. A lens drive unit that drives a lens based on a signal indicating a defocus amount and a direction when the focus determination unit determines that the image is out of focus; Control means for executing a specific focus adjustment mode different from the focus adjustment mode before focusing based on a plurality of focus detection results after focusing. Camera. 2. 2. A camera with an automatic focus adjustment function according to claim 1, wherein said focus determination means includes means for performing a focus display when focus is determined. 3. The focus adjustment mode before focusing is a one-shot AF mode in which focus adjustment is locked when focus is first achieved, and the focus determination unit prohibits an exposure operation due to a release request before focusing and focuses. 3. A camera with an automatic focusing function according to claim 2, further comprising means for permitting a release after focusing. 4. The control means includes moving body detection means for determining whether or not the subject is moving based on the focus detection result.When the moving body is detected, the lens driving is performed as a specific focus adjustment mode so as to focus on the moving subject. Claim 1 characterized by means for selecting a following mode to be performed.
Camera with automatic focus adjustment function described in section. 5. 5. The control unit according to claim 4, wherein the control unit selects a focus lock mode in which the lens is not driven as the specific focus adjustment mode when the moving object detection unit determines that the subject is not moving. Camera with automatic focus adjustment function described in section. 6. The moving object detecting means is means for determining that the subject is moving when the defocus direction is the same a plurality of times and the defocus amount is monotonically changing. A camera with an automatic focusing function according to claim 4. 7. 5. The moving object detecting means according to claim 4, wherein the moving object detecting means is means for judging that the subject is moving when a difference between defocus amounts in two consecutive focus detections is equal to or more than a predetermined value. Camera with automatic focus adjustment function as described. 8. The moving object detecting means is means for determining that the subject is not moving when the defocus direction is not the same for a plurality of times or when the defocus amount does not change monotonically. A camera with an automatic focusing function according to claim 5. 9. 6. The moving object detecting means according to claim 5, wherein the moving object detecting means is means for judging that the subject is not moving when a difference between defocus amounts in two consecutive focus detections is smaller than a predetermined value. Camera with automatic focus adjustment function as described. 10. When the defocus direction is not the same or does not change monotonically, the control unit performs three
When the relative defocus directions of the defocus amounts of more than two times are alternately reversed, the average value of the defocus amounts of a plurality of times equal to or less than the number of times of focus detection is calculated as a specific focus adjustment mode. 2. A camera with an automatic focusing function according to claim 1, wherein the camera is a means for selecting an average mode to perform. 11. 11. The average mode according to claim 10, wherein the lens driving is stopped after calculating the average value, and the lens is driven based on the average value of the defocus amount after the release request is issued. Camera with automatic focus adjustment function. 12. The control means is means for selecting a focus lock mode in which lens driving is stopped when the relative defocus directions of the defocus amounts are not alternately changed. A camera with an automatic focusing function according to item 10. 13. When the tracking mode is selected, the control means repeatedly detects the subject speed, drives the lens based on the subject speed, and when a release request is issued after the subject speed is detected, the release until the start of exposure. 5. A device with an automatic focus adjustment function according to claim 4, wherein said means performs prediction control for driving a lens by a defocus amount predicted to move a subject during a time lag before exposure starts. camera. 14． The control means according to claim 4, wherein the control means is means for prohibiting the release when it is determined that the subject cannot be focused when the tracking mode is selected. camera. 15. When the tracking mode is selected, the control unit calculates the speed of the subject based on the focus detection result, and cannot focus on the subject when the calculated speed of the subject differs from the actual speed of the subject by a predetermined value or more. 15. The camera with an automatic focus adjustment function according to claim 14, wherein the camera is a means for determining. 16. The control means selects the focus lock mode in which the lens is not driven as a specific focus adjustment mode when the defocus amount is large or the focus detection becomes impossible as a result of focus detection after focusing. 2. A camera with an automatic focusing function according to claim 1, wherein: 17． The control means has a large defocus amount, or
17. The camera with an automatic focus function according to claim 16, wherein the camera is a means for selecting a focus lock mode when any state in which focus detection cannot be performed occurs twice in succession. 18. The control means is means for performing focus lock display when the focus lock mode is selected, wherein the control means performs focus lock display.
Item 18. The camera with an automatic focusing function according to any one of Items 12, 16, and 17.