JP2713870B2 - Automatic focusing device - Google Patents

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.
Signal to instruct the execution of the auto focus operation
While outputThe focus of the shooting lens on the subject
To detect the defocus amount (hereinafter referred to as defocus amount).
MeasurementBased on the distance operation and the distance measurement resultFocusing operationRepeat
The present invention relates to an automatic focusing device that is repeatedly executed. [0002] 2. Description of the Related Art Conventionally, photographingFor cameras that do shadowsYou
The subjectDetects the amount of defocus of the body and
Auto focus adjustment based on the amount of focusDynamic focus adjustment device
Having,IwayuAuto focus (AF) camera
It is generally put to practical use. [0003] Such an AF turtleTo laSo taking a pictureShadow
When shooting, the subject in the shooting environment
Because of theIn some cases. [0004]In such a case,For the photo
Auxiliary light means for projecting auxiliary illumination light for distance measurement
This auxiliarylight'sSubject's brightness by projectionDegreeImprove and measure
Distance movement possibleWhat isHas been used. [0005] By the way, the automatic focusing of the AF camera or the like is performed.
In the joint device, once the focusing operation is performed,
After focusing, the driving of the shooting optical system is prohibited
A mode for maintaining the focus state (hereinafter, one-shot AF mode)
It is called. )WhenTo detect the amount of defocus of the subject
MeasurementBased on the distance operation and the distance measurement resultFocus adjustment operation
Mode to execute repeatedlyCode (hereinafter referred to as “continue”)AF
Mode. ) Can be selectively switched between
I didAlsoIt has been more commonly used than before
You. [0006] SUMMARY OF THE INVENTION
Select between AF mode and Continuous AF mode.
In automatic focus adjustment device that can be switched selectively
When continuous AF mode is selected
When the subject in the shooting environment has low brightnessIf
The auxiliary light is projected repeatedly, and the power battery is turned off in a short time.
It will wear out. Also, if the subject has low brightness
To completely prohibit the projection of auxiliary light when
Then, the focusing operation is never performed and it is very difficult to use
It becomes an automatic focusing device. The object of the present invention is toConsidering the problemsource
Prevent battery drainStop even in low brightness conditions.
Perform the auto focus operation at least once.
Easy to useProviding a dynamic focusing deviceIs toYou. [0008] SUMMARY OF THE INVENTION An automatic focus adjustment according to the present invention.
The joint device performs the automatic focusing operation.During line command signal output
Ranging operation to detect the defocus amount of the subject and this ranging operation
Focus adjustment of the shooting optical system based on the distance measurement result
And can be repeatedly executed.Dynamic focus adjustment device
Synchronizes with the above distance measurement operation when the subject has low brightness
And the auxiliary illumination lightIrradiateAuxiliary light hand
And a step for determining whether or not the subject cannot measure distance.
Once the focus is setWhen the distance becomes
In operationProhibition means for prohibiting irradiation of auxiliary lighting
EquipIn a state where irradiation of the auxiliary illumination light is prohibited.
In the distance measurement operation, the above-described determination means cannot measure the distance.
Only when it is determined that there is no
Allow the focus adjustment operation of the shadow opticsSpecially
Sign. [0009] According to the structure described above,, Once, supplement
Judgment means cannot measure distance after irradiation of auxiliary illumination light is prohibited
If it is determined that the distance is not
The focus adjustment operation of the shadow optical system is performed. [0010] [0011] BRIEF DESCRIPTION OF THE DRAWINGS FIG.
The present invention will be described. FIG. 1 shows an embodiment of the present invention.
In a camera system to which a dynamic focus adjustment device is applied,
FIG. 3 is an overall block diagram when mainly viewed from power supply.
You. In this embodiment, for example, a lens
An example in which it is applied to an interchangeable AF camera, etc.
I do. As shown in FIG. 1, the voltage V
cc is a DC / DC converter when the power switch 12 is closed.
The voltage is increased by the data 13 and the lines l (ell) 0, l (d)
(1) The voltage between 1 is constant at the voltage VDD. Line l
The main CPU 14 and the bipolar II circuit (D
Driver) 15, bipolar I circuit (photometry) 16, stroboscope
Control circuit 17, lens data circuit 18, data back
The circuit 19 is connected to the power supply of the bipolar II circuit 15.
The power supply control is performed by the power control circuit of the main CPU 14.
Signal from the road, and the bipolar I circuit 16 to
Power supply control of the data back circuit 19 is bipolar II
Done by the power control signal from road 15.
You. A focus sensor 20, an A / D converter 21,
The AF block composed of the AF CPU 22 is a power control
It is connected between the lines l0 and l1 via the transistor 23.
Power supply control for this AF block
Signal from the AF power control circuit of the CPU 14
ON / OFF of the transistor 23 by the signal
(OFF) control. The AF CPU 22
A circuit for performing the AF algorithm operation.
It is also a determining means for determining whether the object cannot be measured.
The camera is in focus once, or
If the step determines that the distance cannot be measured,
It is also a prohibition measure to prohibit the subsequent illumination of auxiliary lighting.
The AF CPU 22 displays an indication of in-focus / out-of-focus.
The AF display circuit 24 is connected. The main CPU 14 winds, rewinds, and exposes
Controls the sequence of the entire camera, such as the sequence
Display for displaying other than the above focus display
The circuit 25 is connected. The bipolar II circuit 15 is for winding and rewinding.
Cameras such as motor control, lens drive and shutter control
Circuit that includes various drivers necessary for the
Motor drive circuit 26 and AF auxiliary light circuit 27 are connected
Have been. In the AF auxiliary light circuit 27, the subject has low brightness.
The subject is synchronized with the distance measurement operation.
Auxiliary light means for projecting bright light. Bipolar I circuit 1
Reference numeral 6 denotes a circuit which mainly performs photometry.
Eight. The strobe control circuit 17 is built in or outside.
To control the light emission of the attached strobe 29
belongs to. The lens data circuit 18 is provided for each interchangeable lens.
Required for AF, metering, and other camera controls.
This is a circuit that stores unique lens data. This lens
Of the lens data stored in the data circuit 18,
Necessary data include the lens magnification factor (zoom factor).
Number), macro identification signal, absolute distance coefficients a and b, AF accuracy
Threshold ETh, lens movement direction, open F-number, etc.
is there. In the bipolar II circuit 15, the power supply voltage V
The status of DD is monitored and the power supply voltage is lower than the specified voltage.
System reset signal to the main CPU 14 when
Of the bipolar II circuit 15 to the data back circuit 19
Power supply, focus sensor 20, A / D converter
21 and an AF block composed of an AF CPU 22.
We are trying to cut off the power supply. Power to main CPU 14
The power supply is performed even at a specified voltage or less. FIG. 2 shows a signal centered on the AF block.
FIG. 3 is a system diagram showing transfer of a signal, and shows an AF CPU 22 and a main unit.
CPU 14 is a serial communication line
Data transfer, and the communication direction is serial control.
Controlled by the rule line. This communication
The contents of the line are unique in the lens data circuit 18.
Lens data and absolute distance information. Also the main
The CPU 14 sends the camera mode (W) to the AF CPU 22.
One-shot AF mode / Continuous AF mode /
Other information in each mode)
Loaded. Further, the main CPU 14 sends an AF CP
The AFENA (AF enable) signal to U22 is
This signal controls start and stop.
EOF from the AF CPU 22 to the main CPU 14
The AF (end of AF) signal is issued at the end of the AF operation.
Is a signal for permitting the shift to the exposure sequence. The bipolar II circuit 15 has an AF CP.
The signal of the AF motor control line from U22 is
Code and drive the AF motor drive circuit 26. A
The AF motor (lens) is output by the output of the F motor drive circuit 26.
When the drive motor 31 rotates, the rotating member of the lens barrel is rotated.
The slits 32 provided at equal intervals rotate, and
The light emitting portion 33a and the light receiving portion 33b are
The photo-interrupter 33, which is arranged oppositely, has a slit
Count 32. That is, the slit 32 and the photo-in
The taper 33 constitutes an address generator 34,
The address signal (slot) generated from the address generation unit 34
The waveform of the count signal of the unit 32) is shaped and the AF CP
It is taken in by U22. From the AF CPU 22 to the bipolar II circuit 1
5 (hereinafter abbreviated as S lamp)
You. ) The signal controls the AF auxiliary light circuit 27
In the signal, when the subject is low light (low brightness) LL, the S
The lamp 27a is turned on. The number of AF display operations connected to the AF CPU 22
The road 24 is a focus OK display LED (light emitting
Diode) 24a and non-focusable that lights up when focus is not possible
It has a display LED 24b. The AF C
The PU 22 has a clock oscillator 35 and a reset capacitor.
The sensor 36 is connected. The AF CPU 22 and the A / D converter
The barter 21 transmits and receives data via a bus line.
The transmission direction is controlled by the bus line control signal
Is done. Then, an A / D converter is sent from the AF CPU 22.
Sensor switching signal and system clock signal
It is supposed to be. And the A / D converter 21
Is a CCD for a focus sensor 20 composed of, for example, a CCD.
Sends drive clock signal and CCD control signal, and focus sensor
20 is read out from the CCD output, and the read out analog is read out.
The CPU output of the AF 22
Send to Next, a distance information output device according to the present invention is provided.
The camera centered on the AF block shown in FIG.
Flowchart of program operation of microcomputer
Will be described below. The AF block, as shown in FIG.
Operate AF power control circuit of CPU14
The transistor 23 is turned on.
The power supply voltage VDD is supplied.
The execution of the power-on reset routine shown in
It is. As shown in FIG. 3, the power-on reset
When the reset routine is started, first, the <I / O initializer
Rise> subroutine of the AF block drive circuit
Initialization is performed. Specifically, the AF display circuit
24, AF motor drive circuit 26 and AF auxiliary light circuit 2
7 and the serial communication with the main CPU 14.
Initialization of the communication line is performed. Next, a lens reset operation is performed. Len
The lens reset forces the lens to infinity (∞).
To the relative distance signal, ie,
Infinity distance output signal output from focus sensor 20
(∞) Absolute distance by replacing the number of pulse movements from the position
Initialization operation to convert to a signal
That is, the clear operation of the absolute distance counter. Following the lens reset operation, the low light
Lag (hereinafter abbreviated as LL flag) is “L”, LS
The TOP flag and the LDIR flag are set to “H”. L
The STOP flag indicates that the distance ring of the lens is on the infinity side.
"H" when touched, "L" when approached
Become. The LDIR flag is used to set the movement direction of the lens.
This flag is set to “H” for infinity,
Are “L”. Then, the AF CPU 22 executes the AF display
Focusing OK display LED 24a for road 24 and inability to focus indication LE
D24b is turned off, and the EOFAF signal
“H” is transmitted to the main CPU 14. Next, the AF CPU 22 is a main CPU.
Wait for the AFENA signal from 14 to go to "H". Me
The CPU 14 monitors the shooting mode set by the user.
After output to the load line, the user presses the release button.
Wait for the first stage to operate. AFENA signal
When the state changes from “L” to “H”, the AF CPU 22 immediately
Go to read the state of the mode line. State of this mode
<AF single (hereinafter AFSIN)>, <A
F sequence (hereinafter, AFSEQ)>
Select and execute a routine. The operation in the <AFSIN> mode is as follows.
One-shot AF operation, AF operation on the subject
The focus is locked later. Also, <AFS
The EQ> mode is a continuous AF operation.
In the mode, the first step of the release button continues to operate
The AF operation is performed continuously as long as possible. Next, the operation in each lens drive mode
This will be described with reference to the flowcharts of FIGS. First, referring to the flowchart shown in FIG.
If the <AFSIN> mode is selected,
The <AFSIN> routine shown in FIG.
FSIN2> is called. However,
The second stage operation of the release button is accepted
Indicates that the AF operation is completed and the
It is when the service starts. In <AFSIN2>, as described later,
Computation of CCD integration, distance measurement output and focusing of focus sensor 20
The driving of the lens is performed. And the main CPU 14
The AFENA signal from is monitored and the AFENA signal is
Wait until the “H” level (active) is reached,
The status flag is monitored, and <AFSIN2>
Of in-focus and out-of-focus as a result of the AF operation of
You. On the other hand, AFENA from the main CPU 14
When the signal is at “L” level (inactive),
AFENA of the power-on reset flow shown in FIG.
Return to signal test. <AFSIN2> is a result of the AF operation.
As described above, the indication of in-focus and out-of-focus is <AFSIN
After the operation of 2>, the AF status flag is monitored and
However, here, the AF status flag is
Lag (when the subject has low brightness (low contrast)
Flag set to "1", hereinafter abbreviated as LC flag
I do. ), Move flag (when the subject is moving
Flag set to "1", hereinafter abbreviated as M flag
You. ) And closest flag (lens more than closest distance)
A flag that is set to "1" when trying to advance,
Hereinafter, it is abbreviated as N flag. ), Over flag (for example
If the lens is not focused even after driving the lens eight times, it is set to “1”
The flag to be set, hereafter abbreviated as OV flag. )
And any of these flags is 0
When focusing is possible, any of the above flags
If a lag occurs, it is impossible to focus, so the AF status flag
If the AF status flag is 0 as a result of monitoring
The indication of in-focus OK is indicated by the LED 24a of the AF display circuit 24.
AF status flag must be 0
If the focus cannot be displayed, the LED 24b indicates
You. That is, if in-focus, the EOFAF signal
(“L”) is issued, the AF operation ends, and the main CP
The operation of the second step of the release button, that is, the exposure
It is in a state of waiting for the start of the sequence. In other words, once
When the focusing is completed, the AFENA signal becomes “H” level (active).
), The subsequent lens movement is prohibited.
The LED 24a of the focus OK display remains lit,
The focus is locked. From the main CPU 14
The AFENA signal becomes “L” level (inactive).
The power-on reset flow shown in FIG.
Returns to the test of the AFENA signal. During the operation of the <AFSIN> mode, <AFSIN>
The program operation of the subroutine FSIN2> is shown in FIG.
This is performed as shown in FIG. First, it is used as a flag for controlling the AF operation.
Clear the LL flag, and then count the number of AF operations.
Clear the counter AFCNT to be reset. Next, 1 is added to AFCNT, and the first time
The AF operation starts. First, all AF stators
Clear the slag and autofocus for ranging <
AF> routine is called. This <AF> routine
Within, subjectThe amount of defocus in the bodyDetect and output AF calculation
Calculate force value (ERROR) and move lens
Set the power direction to the DIR flag.
"H", and "L" for the closest direction). However, the subject
If the body is low brightness, set the LL flag to “H”
In both cases, the distance is measured while turning on the S lamp 27a. Also,
Set LC flag to “H” if subject is low contrast
I do. Subsequently, the lens lead <LENSRD>
Calls a routine and enters the lens data circuit 18
Read the data for each lens. Loaded lens
Of the data, the lens's open F number (No.)
<ERROR> subroutine using the information
Then, the AF accuracy threshold (ETh) is determined.
Thereafter, the LC flag is determined. The subject is low
If not last, LC flag remains cleared
Therefore, if the LC flag is “L”, the pulse <PU
Call the LSE> routine to calculate the lens drive amount
I do. That is, in the <PULSE> routine,
The AF (ranging) calculation output value obtained by the <AF> operation is
In order to convert the distance movement amount for each interchangeable lens,
The information such as the scaling factor is read from the
The focal length is determined by the obtained zoom factor and AF calculation output value.
The number of pulses (address signals) corresponding to the movement amount is calculated.
You. Thereafter, the AF calculation output value (ERROR)
R) and the above AF accuracy threshold (ETh)
The AF calculation output value (ERROR) is
If it is less than the threshold (ETh), it is determined to be in focus and <CA
LDIST>. Otherwise, AFCNT
Proceed to check. If the value of AFCNT is 8, already 8
This indicates that the AF operation has been performed twice.
Considering that focusing is impossible even if AF operation is continued,
Set to "H" and proceed to <CALDIST>. If the value of AFCNT is not 8, then 1
Check if there is. If 1, LSTOP
Proceed to lag check. LSTOP flag is “H”
If the lens is already at the end,
LDIR flag indicating the direction you got, and move from now
Compare the DIR flag indicating the direction to be
If so, proceed to check the DIR flag. here
If the DIR flag is "H", the moving direction of the lens
Indicates the infinity side of the lens at the infinity end.
Therefore, in this case, it is considered that the lens is focused and <CALDI
ST>. On the other hand, if the DIR flag is "L",
The object must be closer than the nearest end of the lens.
In this case, it is considered out of focus and the N flag is set to “H”.
Then, proceed to <CALDIST>. If they do not match, LSTOP
The flag is cleared, and then the AF calculation output value (ERROR
R) is the previous ERROR storage register (LERROR)
DIR flag to indicate the direction of movement
To the LDIR flag that indicates the end-addressing direction of. Returning to the previous state, when the LSTOP flag is "H"
If not, proceed to LERROR and LDIR flag setting
No. Subsequently, the <MDRIVAF> routine is called,
D for the number of pulses calculated in the <PULSE> routine
The lens is moved in the direction indicated by the IR flag. Also
If the lens touches the end of the lens while
Power supply to the laser drive motor 31 is stopped, and the LSTOP
To "H" and return. Also, <MDRIVA
During the execution of the routine of F>, the AFENA signal is checked at any time.
Click. Therefore, if the user releases the lens while driving the lens,
When the operation of the first stage of the close button is stopped
The main CPU 14 changes the AFENA signal from “H”
Since it is changed to “L”, the AF CPU 22
As soon as the "L" of the A signal is detected, the lens drive is stopped.
To return. Return from the routine of <MDRIVAF>
After checking the AFENA signal,
If the ENA signal is "L", proceed to <CALDIST>
No. If it is “H”, the process proceeds to “1” and the second AF operation is performed.
start. The second and subsequent AF operations are the same as the first AF operation.
However, when judging whether AFCNT is 1 or not, A
Since FCNT ≠ 1, AF calculation output value (ERROR)
Is not less than 4 times the AF accuracy threshold (ETh)
Check if. If less than 4 times, the first time
Proceed to check the LSTOP flag. 4 times or more
Next, the current AF calculation output value (ERROR)
Is compared with the AF calculation output value (LERROR) of the
If OR ≧ LERROR, LSTOP of the same as the first time
Proceed to check. If ERROR ≧ LERROR
Then, the M flag is set to “H” and <CALDIST>
Proceed to. This is more than four times the AF accuracy threshold
AF calculation output value in the large range of the defocus amount
Being larger than the number of times means that the subject
Because it is moving, even if the AF operation is continued further
This is because it was determined to be useless. Next, since the object has a low contrast,
In the AF> routine, the LC flag is set to “H”.
The following describes the case in which it is performed. <LENSRD>, <ER
RORTH> routine is executed in the same manner, but the LC flag
If the LC flag is "H" in the determination of <
OCUS> is called. <PANFOCUS
The routine of <> changes the taking lens to the focal length of the taking lens.
Subroutine for moving to the normal focus position determined
This will be described with reference to FIG. First, in the <LENSRD> routine, the lens
Focal length of the photographic lens read from the zoom data circuit 18
From information, the constant focus position or pin at that focal length
Position where the matching range is the widest (hereinafter these positions
Is called a pan focus position. ) Of the AF CPU 22
Determined from the conversion table in the internal ROM. Where, for example,
If the pan focus position is Xm, then shoot
When the lens is moved to the position of Xm, the absolute distance
Calculate the number of counters. Subsequently, the position at which the photographing lens is currently stopped
And the pan focus position
The value of the absolute distance counter at
Calculate the number of dynamic pulses. Next, the moving direction of the lens is set, and <M
DRIVAF> is called and the shooting lens is
Move to pan focus position and return. Returning to FIG. 5, the <PANFOCUS> rule
After returning from the routine, clear the AF status flag.
A and proceed to <CALDIST>. This is Panforca
This is because the focusing is performed at the pseudo position. Therefore, <C
ALTIST> routine is terminated, and <AFSIN>
When returning to the routine, an in-focus display is displayed. Here, the routine of <CALDIST> is
The distance to the subject is determined by the value of the absolute distance
Determined from the absolute distance coefficients a and b in the road 18, the main CPU
14 is a subroutine to be sent. The <AFSIN2> routine ends here.
Then, the process returns to the <AFSIN> routine. Next, referring to the flowchart shown in FIG.
And if the <AFSEQ> mode is selected,
The <AFSEQ> routine shown in FIG. 7 is called.
In this <AFSEQ>, the first stage of the release button
When the operation is performed, the EOFAF signal is thereafter activated.
The first AF operation until the active state
The same operation as in the case of SIN> is performed. That is, <
AFSIN> and <AFSEQ> are both <AFSIN2>
When the lens is in focus and it is impossible to focus,
Drive and inform the user. By the way, in <AFSIN2>,
As described above, at low light (low brightness), the S lamp 27 is used.
Using a to assist distance measurement for AF operation
But the AF operation is continued in the <AFSEQ> mode.
Also use the S lamp 27a
Lamp 27a is a CCD integration operation in <AF>
It emits light continuously during the time of
Increase and decrease in efficiency due to heat generation of S lamp 27a
And abnormal driving of the lens when focusing is impossible
Is performed continuously, giving anxiety to the user
It will be. Therefore, in the <AFSEQ>, the AF operation
After executing once and setting the EOFAF signal, A
Determine the FENA signal, and if the signal is active,
The first-step operation of the release button is continued
And the <AFSEQ2> routine is called.
If the AFENA signal is non-active, the release button
The first stage operation of the button is off, or the second stage operation
Will return as if it was turned on. One
In other words, once in focus, or for AF
When the CPU 22 determines that the distance cannot be measured
A is also a means for prohibiting the subsequent irradiation of auxiliary illumination light.
Prohibited by the F CPU 22. In <AFSEQ2>, as described later,
CCD integration of focus sensor 20, AF calculation and lens
Drive, etc., but aggressive due to abnormal drive of the lens
Point of S lamp 27a for in-focus inability display and distance measurement
There is no lighting. Then, the operation of <AFSEQ2>
As a result of the operation, the AF status flag is determined.
If the lag is 0, the display shows that the focus is OK.
Then, an indication that focusing is impossible is performed. In-focus OK display
Means that the EOFAF signal is emitted and the release button
Exposure sequence can be started by second stage operation
You. After this EOFAF signal is issued, or
After the indication of impossibility is made, the AFENA signal is
The first step of the release button
As long as you keep turning on, focus on <AFSEQ2>
The AF operation is performed continuously. And the AFENA signal
When the signal becomes inactive, the power
Return to reset flow. The flow of the <AFSEQ> mode shown in FIG.
In the chart, <AFSEQ2> subroutine
Is performed as shown in FIG. First, once in the <AFSEQ> mode, E
When the OFAF signal is set to “L”,
To prevent the S lamp 27a from being turned on.
At the beginning of the FSEQ2> routine, the AF CPU 2
2, the use of the S lamp 27a is prohibited,
Clear the status flag. Then, the <AF>
The AF calculation output value (ERROR) is calculated by the
Is set in the DIR flag. However,
As described above, even if the subject has low brightness, the S lamp
27a does not light. Next, in the routine <LENSRD>,
The data for each lens in the lens data circuit 18.
And then the AF in the <ERROR> routine
Determine the accuracy threshold (ETh). Next, AF
Double the accuracy threshold (ETh). This is <
In the <AFSEQ> mode, the <AFSIN2
AF accuracy threshold
When the subject moves slightly in the range of about twice the field (ETh)
The camera lens moves and the release is disabled.
That's because I did. Next, the LC flag is determined, and the LC flag is determined.
If the lag is "H" (distance measurement impossible due to low contrast)
If not, go to <CALDIST> without driving the lens
move on. If the LC flag is "L", the LSTOP flag
And the LSTOP flag is "H", that is,
When the lens is on the infinity or near side
Is an LDIR flag indicating the assigned direction, and
Compare DIR flags indicating the direction to move,
If not, the process proceeds to the <PULSE> routine. Conversely, one
If so, proceed to check the DIR flag. Here, if the DIR flag is "H",
The direction of movement of the lens is even less than the infinity end of the lens.
Since this indicates the telephoto side, in this case,
Think and proceed to <CALDIST>. On the other hand, if the DIR flag is "L",
The object must be closer than the nearest end of the lens.
In this case, the N flag is set to "H"
And proceed to <CALDIST>. Returning to the previous step, when the LSTOP flag is "H"
If there is not, in the <PULSE> routine,
After calculating the number of target movement pulses, the AF calculation output value (E
RROR) and the AF accuracy threshold doubled
(ETh), ERROR ≧ ETh holds
If not, it is determined that the focus is in the in-focus area and <CALDI
ST>, and returns. ERROR
If ≧ ETh, set the EOFAF signal to “H”.
Out of focus with respect to the main CPU 14
Let them know Next, the in-focus OK display LED 24a and the out-of-focus
The function display LED 24b is turned off, and the lens is moved in the moving direction.
DIR flag indicating the previous moving direction
Transfer to IR flag. Next, the <MDRIVAF>
And calculate with the <PULSE> routine
Lens in the direction indicated by the DIR flag
To move. From the <MDRIVAF> routine,
First, check the AFENA signal and set it to “H”.
If so, return to "1" and repeat the same. "H"
If not, execute <CALDIST> and return. Next, a method of calculating the absolute distance will be described.
You. The absolute distance counter contains the infinity (∞) position of the lens.
The number of pulses (address signals) corresponding to the amount of movement from
So the lens movement can be approximated as a linear function.
If you can, you can get the absolute distance by calculation. Where
Lens movement amount (absolute distance counter) as Y and absolute distance as X
Then, the relationship between the two can be approximated as in the following equation (1).
You. Y = b / (X−a) (1) Here, a and b are absolute distance coefficients unique to the lens. Obedience
Thus, a and b are determined for each lens, and the lens
If it is stored as information of the data circuit 18, the lens movement
The absolute distance can be determined from the quantity. In the above-described embodiment, the lens
The focal length information is read from the data circuit 18 and the AF CP
From the conversion table stored in the internal ROM of U22,
Focus position.
A method of calculating the position of the scum as a function of the focal length,
The pan focus position information is stored in advance in the focus data circuit 18.
The effect is the same even if the method of storing information is used.
You. Also, when the pan focus position is
Exposure aperture can be set when release is possible as a focus
If you only squeeze it, the range of focus will be wider, so pan
Only during pseudo-focusing at the focus position, the shutter
Slow down the speed so that camera shake does not occur.
A method of controlling so as to narrow down as much as possible is also possible. [0071] As described above, according to the present invention,,N
Tinus AF modeAuxiliary light irradiation when necessary
Regulations can prevent power battery drain.
You. In addition, continuous AF mode is selected at low brightness.
Auto focus at least once, even if selected
Since the knot operation is performed,Dynamic focus
An adjustment device can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of an electric circuit mainly for supplying power to an interchangeable lens AF camera to which an automatic focusing apparatus according to an embodiment of the present invention is applied. FIG. 2 is a block diagram showing transmission and reception of signals centering on an AF block in the camera of FIG. 1; FIG. 3 is a flowchart showing a program operation centering on the AF CPU shown in FIG. 2 and showing a power-on / reset routine; FIG. 4 is a single AF mode <AFIN> in FIG. 3;
5 is a flowchart showing the operation of the embodiment. FIG. 5 is a flowchart showing an operation in the single AF mode in FIG. 3, showing a subroutine of <AFSIN2>; FIG. 6 is a flowchart showing the operation of the single AF mode in FIG. 3, showing a subroutine <PANFOCUS>; FIG. 7 shows a continuous AF mode <A in FIG.
8 is a flowchart showing the operation of the continuous AF mode in FIG. 3 and shows a subroutine of <AFSEQ2>. [Description of Signs] 14 Main CPU 15 Bipolar II circuit (driver) 16 Bipolar I circuit (photometry) 17 Flash control circuit 18 Lens data circuit 20 Focus sensor 22 AF CPU (determination means, prohibition means) 24 AF display circuit 27 AF auxiliary light circuit (auxiliary light means) 28 AF motor drive circuit

Claims (1)

(57) [Claims] The execution instruction signal in the output of the automatic focusing operation, the
Ranging operation to detect the defocus amount of the subject and this ranging operation
Focus adjustment of the shooting optical system based on the distance measurement result
In Nau operation and executable with the automatic focusing device repeatedly, when the object is low luminance, and an auxiliary light means you irradiating auxiliary illumination light to the subject in synchronism with the distance measuring operation, Determining means for determining whether or not the subject is incapable of distance measurement; and
There comprising a prohibiting means for prohibiting irradiation of the auxiliary illumination light, a, the measuring radiation of the auxiliary illumination light is performed in a state of being banned
In the distance operation, it is determined that the determination means is not incapable of distance measurement.
Only when specified, the shooting optical system based on the distance measurement result
An automatic focus adjustment device , wherein the focus adjustment operation is allowed .