JPS6318315A - Focus detecting device - Google Patents

Abstract

PURPOSE:To obtain a focus detecting device which eliminates the need to adjust a photoelectric converting means mechanically by providing a storage means which stores an effective picture element range wherein an effective photoelectric conversion signal is generated in an arithmetic means, and performing focus detection on the basis of the stored effective picture element range. CONSTITUTION:The effective picture element range SA wherein the photoelectric conversion signal corresponding to a finder distance measurement frame FFRM is checked previously in an adjusting process and stored in an EEPROM. Consequently, the need for the mechanical adjustment is eliminated and operation efficiency is improved greatly; even when only the finder distance measurement frame is changed to a different frame in a camera of the same constitution, the change is easily made. Further, if it is found that sensor has an irregularity in sensitivity after assembly, or that an AF optical system has an aberration, the camera is easily used while the part is evaded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of the Invention) The present invention relates to an improvement in a focus detection device that detects a focus state from the relative positional relationship between two images of an object.

(Background of the Invention) Conventionally, as one type of focus detection device for a camera, the exit pupil of a photographic lens is divided and the relative positional displacement of a pair of images formed by a beam of light passing through each pupil area is observed. A so-called "image shift type" method that determines the in-focus state is known.

The signal processing method for detecting the amount of image shift from the image signal is as follows:
JP-A-58-142306, U.S. Patent No. 4333
No. 007 and the like are disclosed, but all of them perform focus detection processing using all or a fixed range of signals output from the sensor. For this reason, if the focus detection range provided in the finder, that is, the distance measurement frame, is smaller than the entire area of the sensor, and the sensor is misaligned in the row direction due to assembly, the subject may not be located within the distance measurement frame. However, there are disadvantages in that the focus cannot be detected even when the focus is detected, or the focus may be detected on objects outside the distance measurement frame. In other words,
In cases where the visual field of view and the field of view where the focus is actually detected are different, accurate focus detection cannot be performed.

In order to deal with the above-mentioned problems, in the past, the positioning of the sensor and the distance measuring frame was performed one by one using a mechanical method. For this reason, it was extremely time-consuming and inefficient. Further, for example, there may be a case where the user wants to change to a different distance measurement frame due to some circumstances, and in such a case, the above-mentioned problem is noticeable.

(Object of the Invention) An object of the present invention is to provide a focus detection device that solves the above-mentioned problems, eliminates the need for mechanical adjustment of photoelectric conversion means, and can accommodate design changes.

(Features of the invention@) In order to achieve the above object, the present invention provides the following features:
The present invention is characterized in that a storage means for storing an effective pixel range that generates an effective photoelectric conversion signal is provided, and focus detection processing is performed based on the effective pixel range stored in the storage means.

(Embodiment of the Invention) First, the focus detection principle in this type of device will be explained as follows.
This will be explained using Figure 5. A field lens FLD is placed on the same optical axis as the photographing lens FLNS whose focus is to be detected. Behind it, in a symmetrical position with respect to the optical axis,
Two secondary imaging lenses FCLA and FCLB are arranged. Further behind it are sensor rows SAA and SAB.
is placed. Secondary imaging lens FCLA, FC
A diaphragm orA and ora are provided near LB.

The field lens FLD has the exit pupil of the photographing lens FLNS 2 (secondary imaging lenses FCLA, FCL
The image is almost focused on the face of B. As a result, the secondary imaging lens F
The light beams incident on CLA and FCLB respectively correspond to the secondary imaging lenses FCLA and FCLB on the exit pupil plane of the photographing lens FLNS.

They are emitted from areas of equal area that do not overlap each other. The aerial image formed near the field lens FLD is the secondary imaging lens FCLA.

When the image is re-imaged on the surface of the sensor arrays SAA and SAB by FCLB, based on the displacement of the aerial image position in the optical axis direction,
The two images on the sensor arrays SAA and SAB will change their positions. Therefore, by detecting the displacement (shift) of the relative positions of the two images, the focal state of the photographing lens Ft, 83 can be known.

As a signal processing method for detecting the amount of image shift from the image signals output from the sensor arrays SAA and SAB, Japanese Patent Laid-Open No. 58-142306 and Japanese Patent Laid-Open No. 59-107313 are known.
No. 60-101513, etc. are disclosed by the applicant of the present invention.

Specifically, the number of pixels constituting the sensor array SAA or SAB is N, and the image signal from the i-th (i = O, ..., N-1) sensor array SAA, SAB is A(i),
When B(i), X(k)-II: wax (A(i), B(i+
tkl+1))−εwax (μ0
1 → A (++1
), B(i÷1kl)) (k<O
)−T:, mat(A(i+k), B(++1
)) -T, ll1ax (I@OI@.

A (+1 to i+), day (i))
(k≧0)・xl(k) X2(k)
' (L) or Y(k)-Σ: win (A(i),
B(i+Ikl+1)) -Σ:m1n(io

'→A(++1), B(i+1kl))
(k<O)−Z ll1n (A(
i+k), B(++1)) −! : min (
++6
1″A (+1 to i◆), 5(i)
) (k≧O)= Ys (k)
The formula Y2 (k) (2) is
Calculations are performed for k1≦≦2. Furthermore, M is (M = N
-1kl-1), or called the relative displacement amount, and kl*k2 is usually -N/
2. It is often taken as N/2, where wax(a
, b) represents the extraction of the positive effect of a, b, and the operator win(a, bl represents the extraction of the connotation of a, b). Therefore, the above (1 ),
Page X+ (k), x2(k) in equation (2)
+Y1 (k), Y2 (k) C can be considered as correlation amounts in a broad sense. Furthermore, (1) above.

Looking at formula (2) in detail, we find that X+ (k), Yr
In reality, (k) is the correlation amount for each of the above definitions at (k-1) displacement, X2 (k), Y2 (k)
represent the amount of correlation at the displacement (k+1), respectively.

Therefore, the evaluation amount X (k), which is the difference between Xs (k) and X2 (k), is the image signal A (
i), means the amount of change in the correlation amount of B(i).

As is clear from the above definition, the correlation amounts X+ (k) and X2 (k) are minimum when the correlation between the two images is highest. Therefore, the amount of change, X(k), should be "0" when the correlation is highest, and the slope should be negative. However, since X (k) is discrete data, in reality, the relative displacement interval [kp By assuming that the peak of the correlation amount exists at , kp+11 and performing the interpolation calculation, it is possible to detect the image shift amount PR on a pixel basis or less.

On the other hand, according to the above definition, when the correlation between the two images is highest, the correlation amounts Yl(k) and Y2(k) are XL(k)
.

In contrast to x2(k), it is the maximum. Therefore, the amount of change, Y (k), should be "0" when the correlation is at its highest, and the slope should be positive. Similarly to X (k), Y(k) also satisfies Y(kp)≦O, Y(kp◆1)>O(1), and Y(
By performing the interpolation calculation when kp) -YCkp◆1) is maximum, it is possible to detect the image shift amount PR in units of pixels or less.

Furthermore, although it is possible to detect the amount of image shift using either the focus evaluation amount of X(k) or Y(k),
-1x(kp)-
X (kp+1)l> l Y (kp+1) -Y
(kP) + (7) Time point evaluation amount X (k) wo, lx (kp) -X (kp+1)l>IY(k
p+1) -Y (kp)l, it is more accurate in terms of S/N to calculate the image shift amount PR using the focus evaluation amount Y (kp).

FIG. 1 is a block diagram showing one embodiment of the present invention.
PRS is a camera control circuit, for example, an internal CPU (
central processing unit), RAM, ROM, EEFROM
(Electrically erasable programmable ROM), an input/output board, an analog input port with an A/D conversion function, etc. are arranged, and the RO
Camera sequence, AF (auto focus), AE
(Automatic exposure) control software and parameters necessary for AF and AE control are stored in the EEPROM. SHT receives the control signal C5 from the control circuit PRS.
A shutter control circuit that accepts data input via the data bus DBUS while the H-block is input, and controls the travel of the shutter front curtain and rear curtain (not shown) based on the data; APR is a control signal CAPR. The aperture control circuit receives data input via the data bus DBUS while the data bus DBUS is being input, and controls an aperture mechanism (not shown) based on the data. A display circuit that accepts data input via DBUS and displays various photographic information based on the data, SW
S is a release switch (not shown).

This is a group of switches placed on the outside and inside of the camera, including switches for setting various information such as the shutter and aperture.

SPC is a photometry circuit, and its output analog photometry signal 5SPC is sent to the analog input port with A/D conversion function of the control circuit PRS, where it is A/D converted and sent to the above-mentioned shutter control circuit 5) IT and aperture. It is used as photometric data for controlling the control circuit APR. LCOM
is input to the control signal CLCO while the data bus DB is input to the control signal CLCO.
A lens communication circuit that receives data input via the US and performs serial communication with the lens unit described later based on the data, and moves the photographing lens FLNS in the optical axis direction in synchronization with the claw signal LCK. The data DCL for driving the lens indicating the amount is transmitted to the lens control circuit described later, and at the same time, the lens drive data DCL indicating the amount is transmitted to the lens control circuit described later.
Lens information DCL such as a coefficient of the amount of defocusing of the LNS versus the amount of lens movement is serially input. BSY is FL photography lens
This signal informs the camera side whether or not the NS is moving. When this signal is "'H" (high level), the serial communication is disabled.

LNSU is a lens unit, LPRS is a control circuit within the lens that drives the motor MTR based on serially input data DLC to move the photographing lens FLMS in the optical axis direction, and ENC is a lens barrel holding the photographing lens FLNS, for example. An encoder circuit that detects a pulse signal generated as the lens moves, and outputs an encoder pulse signal EPL to an in-lens control circuit LPRS as position information of the photographing lens FLNS at any given time.

SDR is each signal STR input from the control circuit PRS.
, GK, and has two sensor arrays SAA and SAB, and controls a line sensor SNS, such as a COD, for example.

Next, the operation will be explained using FIGS. 2 to 14. Note that the shutter control circuit SHT and the aperture control circuit AP
Since the operations of the display circuit DSP and the photometry circuit SPC are not directly related to the present invention, detailed explanations thereof will be omitted here. In the tree embodiment, r
The AFJ flow is called as a subroutine.

When the AF operation starts, first, two flags, the flag RCFLG and the flag NRSDFLG, are set to "N" (N.

(step 10 in FIG. 2), the functions of the flags RCFLG and NRSDFLG will be described later in the 0-order image signal reading subroutine r IMAG.
E" (step 11), here.

The line sensor SNS is driven via the sensor drive circuit SDR, and two image signals A(i) and B(i) are obtained. Sensor drive circuit SDR and line sensor SN at this time
The operations of S, etc. will be briefly explained using FIG. 1.3. When the control circuit PRS outputs the accumulation start signal STR of "H" (step 50 in FIG. 3), the sensor drive circuit SDR outputs the clear signal OL to the line sensor SNS, and each photoelectric conversion of the sensor arrays SAA and SAB is performed. The charge on the part is cleared. Then, the secondary imaging lens, etc. (not shown in Fig. 1) placed in the front stage of the line sensor SNS,
(arranged as shown in FIG. 15), photoelectric conversion and charge accumulation operations of the optical images formed on the sensor arrays SAA and SAB are started. When a predetermined period of time has elapsed after the start of the above operation, a transfer signal SH is outputted from the sensor drive circuit SDR to the line sensor SNS, and the charges accumulated in the photoelectric conversion section are transferred to the CCD section. At the same time, the sensor drive circuit SDR receives an H= accumulation end signal IEN.
II is generated, and the signal is input to the control circuit PRS (
In step 51), when the CCD drive clock GK is then output from the control circuit PRS, the CCD drive signals φ1 and φ2 are output from the sensor drive circuit SDR. As a result, the analog image signal 5SNS is output from the line sensor SNS to the control circuit PR3 in accordance with this signal, and in response to this, the control circuit PRS A/D converts the analog image signal 5SNS in synchronization with the CCD drive clock GK. The image signals A(i) and B(i) of the image are stored at predetermined addresses in the RAM (steps 52 to 55).
It is assumed that the number of pixels in AA and SAB is 40.

Returning to FIG. 2 again, in step 12, focus detection calculation is performed with all pixels as the processing target range depending on the out-of-focus state, or
Flag VSN that determines whether focus detection calculation is to be performed using some pixels as the processing target range, that is, setting the processing target pixel range in which focus detection calculation is performed. is the focus detection subroutine rWPRED”
When the value is "NR" (meaning near focus), the focus detection subroutine r NRPREDJ is called (step 12). For example, when the image signal is significantly out of focus as shown in Figure 4, is subroutine rWPRED
'' is adopted, and when the focus is near as shown in FIG. 5, the subroutine rNRPREDJ is adopted. Note that the power-on flag MSN is set to "WD" (because it is the first time and the out-of-focus state is unknown), and when the AF operation starts, the flag MSN is set to "WD" depending on the focus state at that time.
Or it is reset to "NR". This resetting will be described later.

The focus detection process when the subroutine rWPRED J is called will be described according to the flowchart in FIG.

In steps 100 to 105, the relative displacement amount k is set to "-20".
The focus evaluation amount X (k) is calculated when the focus is changed within the range of .about.20''. Here, the reason why the relative displacement k is in the range of -20 to 20 is because the sensor arrays SAA and SAB
This is because the number of pixels is assumed to be "40", but this processing target pixel range may be variable depending on the focal length of the photographing lens FLNS used.

First, in step 101, the number M of pixels to be operated is calculated using the formula M=39-1kl. The number of calculated pixels M is the relative displacement amount k
It is variable depending on k, and the larger the absolute value of k, the smaller it becomes. This is because as the relative displacement amount k increases, the output of the corresponding sensor is missing from the end.In step 102, the sign (positive or negative) of the relative displacement amount is checked, and then Step 103 or 104 selects the first pixel positions FA and FB at which to start calculation of images A and B.
Calculate with. In step 105, focus evaluation amount X (k)
Perform the calculation.

Here, the processing steps in steps 100 to 105 are explained in the seventh step.
This will be explained using figures. FIG. 7(a) shows two image signals A(
i) represents B(i). FIG. 7(b) shows the correspondence of sensor arrays in the correlation calculation when 2=-20, where M=39-1201=19, FA is rOJ, and FB is "20".

In other words, since the relative displacement amount is a negative value, the B-image crab pixel (-
It is relatively displaced to the left by 200 pixels. From this correspondence relationship, the first term of the equation when calculating X (-20) is calculated using the correspondence relationship in which the B image is further shifted to the left by one pixel, and conversely, the correspondence is calculated by displacing the A image to the left by one pixel. The calculations based on the relationships correspond to the first term. In the first and second terms, the A image and B image are each shifted to the left by one pixel for calculation, so when calculating the number of calculation pixels M, M = 40-1kl.
M = 39-1 kl instead of . Figure 7 (c
) represents the correspondence when ni=0. Figure 7(d)
It represents the correspondence of correlation calculations in Hani:20,
Contrary to FIG. 7(b), the A image is displaced to the left by 200 pixels.

FIG. 8 shows an example of a plot of the focus evaluation amount X (k) calculated as described above.

Returning to the flow shown in FIG. 6, the step 110 detects the peak value kp of the image shift amount in pixel units of the two images A and H from the focus evaluation amount X (k). Below, steps 120-14
In step 6, the image shift amount PR of less than a pixel unit is determined. Based on the peak value kp determined in step 110, in steps 120 to 135, two focus evaluation amounts X(k
), recalculate Y(k). There are two reasons for this.

One is that in the previous step of calculating kp, the number of calculated pixels M is variable according to the phase change position k, and the focus evaluation amount X (k) calculated in this variable calculation range is interpolated. If the image shift amount PR is calculated in units of pixels or less, there is a risk that it will include an error due to the fact that the number of calculated pixels M does not match.

Another point is that it is better to use a combination of X(k) and Y(k) than to calculate the image shift amount PR using only the focus evaluation amount As mentioned above, depending on the signal pattern of the subject, the S/
Since it is superior in terms of N, which is greater than 0, in steps 120 to 135, the number of pixels M to be calculated is made constant based on kp (step 120), and the focus evaluation amount x(k),
Y(k) is calculated at the same time.

First, in step 120, M = 38-1k pi is calculated to determine the number of pixels M to be calculated.
For 30 to 135, centering on kP obtained earlier, k=k
Focus evaluation amount x(k) at three points p-1, kp, kp+1
, Y(k) are calculated in the same way as before. In addition, when calculating the number of calculation pixels M, M=38-Ikpl is set because k=
This is to fix the number of calculation pixels M at the relative displacement amount with the largest absolute value among the three points kp-1, kp, and kp+1.0 Next, the focus evaluation amount X(k) obtained as described above is
, Y(k) to detect image shift amounts kpm and kpy in pixel units based on each focus evaluation amount (step 14).
0゜141),,m(71:00 last winter point evaluation amount X(k),
XD (X
D −X(kpm) −X(kpx+1) ) and Y D
(YD = Y(kpx+1) −Y(kpx) )
This is because in this embodiment, the magnitude of the image signal at the end is not compared for each relative displacement according to the calculation method disclosed in the previous application (because the calculation process becomes complicated).
, When the amount of out-of-focus is large, by looking at the contrast evaluation amounts XD and YD, which also take into account the information of the image signal at the edge, it is possible to obtain information as if you were looking at the image signal at the edge for each relative displacement. This is to focus on and use this information, and the larger the contrast evaluation amounts XD and YD, the better the S/N. Therefore, in step 142, two contrast evaluation quantities XD are calculated.

Compare YD and when XD≧YD, focus evaluation amount X(k)
wo is adopted L (step 143), and when XD<YD (7), the focus evaluation amount Y (k) is adopted (step 144).
In steps 145 and 146, the adopted ZD (Z I
Z2), PR using kz +lz
, /201 is performed to obtain the image shift amount PR in pixel units or less. This process is shown in FIG. In the example shown in this figure, since there is a relationship of XD<YD, the focus evaluation amount Y(k) is adopted, and when the image shift amount PR@'j1 is less than the pixel unit, kz = kpy, Zs = Y(kp).

Z2=Y(kp+1) is used.

Steps 150 to 158 are processes for determining the focus state. First, in step 150, four flags LCFLG,
5DFLG, NJFFLG, JFFLG“
To describe the meaning of each flag qualitatively, rLCFLGJ is a flag indicating that the subject image signal has low contrast, and r5DFLGJ is a flag indicating that the amount of deviation between the two images is relatively small, i.e. Photography lens FL
This is a flag indicating that the amount of out-of-focus of NS is relatively small. This flag indicates that there is almost no deviation between the two images, that is, that the two images are in focus.

Next, the contrast evaluation amount ZD of the adopted focus evaluation amount is compared with a predetermined value LOTH (step 151). As a result, if ZD<LCTH, it is assumed that the contrast is low, rLcFLG J is set to "Y'" (meaning YES), and subroutine rWPRED J is ended. If ZD≧LC:TH, it is assumed that the contrast is sufficient to perform focus detection, and the process moves to the first step 153. In step 153, the absolute value PR of the image shift amount PR is compared with a predetermined value "3", and if PR>3, that is, the image shift amount is 3 pixels or more, the subroutine rWPR
Exit ED J. If PR≦3, the amount of out-of-focus is relatively small, so set r5DFLGJ to “Y” (step 154), then compare PR with a predetermined value “1” (step 155), and as a result, if PR>1 , that is, when the image shift amount is one pixel or more, the sub Jl/-5-rWPREII J ends here. If PR > 1 (7), it is assumed that the focus is almost in focus and r NJFFLG J is set to "Y" (step 158), and finally, PR is compared with a predetermined value JFTH (step 157), where the predetermined value JFTH is the image shift. The amount PR is a value that can be considered to be in focus.

As a result, if PR>JFTH, the subroutine rWPRED J is ended here. If PR≦JFTH, it is assumed that the lens is in focus, and rJFFLGJ is set to "Y" (step 158), and the subroutine rWPREDJ is ended. Note that the four flags LCFLG,
5DFLG, NJFFLG, JFFLG
The function of this will be explained later.

Next, the subroutine rNPRED J will be explained. rNPRED J is focus detection processing that is applied when the focus is near, and focus detection processing is performed only on data within the range corresponding to the distance measurement frame in the finder among all sensors. This will be explained using FIG. 1O, which shows the positional relationship between the two. In the diagram, FFRM is a distance measurement frame on the finder. In the subroutine rNPRED J, the range of the distance measurement frame FFR is further divided into three areas as shown by R1+R2 and R3.
Area RI * R2+ in distance measurement frame FFR for each part
The pixel in the sensor array SA where R3 is located is determined by the pixel positions N Rs , N R2 , and N R2 corresponding to the beginning of each part.
N R3 is checked in advance in the adjustment process, and the control circuit PRS
At this time, the NNPX contained in each part is the same (Rr = R2 = R3).
In this embodiment, the value NNPX is also stored in the EEPROM.
, N R2 and N R3 are respectively r8J ,, rl 4
J, r2Qj, and (NNPX +k) is the range to be processed in this case (the shaded area in Figure 12). Pixels may shift, but as described above, since it is stored in EEPROM, the distance measurement frame F
The calculation range for FRM and focus detection processing can be matched.

RItR2+ shown for the image signal in FIG.
R3 is the divided region in the above-mentioned sub)Lt-chinrNPREI].

The operation when subroutine rNPRED J is called will be described according to the flowchart of FIG. In step 200, the number M of pixels to be calculated is set to NNPX. In the subroutine rWPRED J described above, the number of calculated pixels M was variable according to the relative displacement amount k, but in this focus detection process, it is fixed to NNPX. This is because while rwpRED J uses all pixel outputs for calculations, rNPRED J uses a part of the output of the sensor array SA, so data at the end of the corresponding sensor output will not be lost due to displacement. It is from. Therefore, in rNPRED J, rWPRED
There is no recalculation performed with the number of calculated pixels M constant in steps 120 to 141 of J, and since no recalculation is performed, the evaluation amount X(k),
Find Y(k) at the same time.

Steps 210 to 221 are focus detection processing for the image data of the region R1. In Figure 0, the same processing parts as rWPRED J are given the same step numbers. In the subroutine rNPRED J, the range of relative displacement amount is (-4 to 4).
), this is because the amount of image shift is originally small since r NPRED is applied near focus. In this case, as shown in steps 212 and 213, the starting position NR of the region R1 is taken into consideration. This processing process is shown in FIG. 13(a), in which the solid line represents the focus evaluation amount X(k), and the broken line represents Y(k). rltlP
i'lEI] The image shift amount P in the region R1 is determined by the same process (steps 140 to 146) as explained in J.
Find R. Step 221-r! The image shift amount PR, and the contrast evaluation amount ZD1 are stored in the RAM in the control circuit PR9.Similarly, in steps 230 to 241, the image shift amount PR2 and the contrast evaluation amount ZD2 in the area R2 are stored in the RAM in the control circuit PR9. ) is calculated, and in steps 250 to 261, the image shift amount PR3 in the region R3 is calculated.
, contrast evaluation amount ZD3 (see Figure 13(C))
These are also stored in the RAM in the control circuit PR5.

In steps 270 to 278, the 3
Image shift amounts PR+ and P of the three regions RI, R2, and R3
It is determined which of H1 and PH1 the image shift amount should be set as the final image shift amount PR. That is, in this embodiment, among the three regions, the one with sufficiently high contrast and the largest amount of compensation shift is used.

The meaning of adopting the maximum amount of image shift here is that when the amount of image shift is positive, it is back in focus, and the subject that is most back in focus is the closest subject, and the focus is on that subject. be. After determining the final image shift amount PR and contrast evaluation amount ZD, the focus state is determined in step 280. The processing here is the same as the processing explained in rWPRED J, so the explanation thereof will be omitted. .

As described above, in a state where the amount of out-of-focus is large, the subroutine rWPRED is used to determine the amount of image shift at that time, that is, the out-of-focus amount of the photographing lens FLNS is determined by the subroutine rNPRED J when the amount of defocus is large. Quantity detection can be performed.

Returning to FIG. 2, the explanation from step 15 is continued. In step 15, the flag LCFLG is checked to check the contrast during the focus detection process of PRED J or rNPRED J that was performed earlier. LCFLG is "Y".
, the contrast is low and the flag vSN is set to “WD” so that the next focus detection process uses rWPRED J.
” then step 35), the blue routine rDIsP to display
J, execute the lens control subroutine r LENSJ (step 19.20), and execute the aforementioned display routine rD.
Since IsPJ is not directly related to the present invention, it will be omitted here, but the lens control subroutine rLENSJ will be described later.

In step 16, the flag VSN is checked again.
When the VSN is "'WD", the processing from step 17 onwards is performed, and when the VSN is "'NR", the processing from step 28 onwards is performed.

First, the processing when VSN="WO" will be explained. VSN=
“WD” refers to the previous focus detection process.
In step 17, the flag RCFL is set.
Check G. RCFLG is "Y" when focus detection processing is performed twice in the rAFJ routine. In this embodiment, when executing the rAFJ routine, rWPR is initially set at the VSN set in the previous rAFJ.
Execute either ED J or r NPRED (
In addition, in the early stage when the release was performed, VSN was °“w
o"), but when the resulting image shift amount is not suitable for each condition, reset the VSN and set the flag RCFLG to "Ypa" and then perform a different tt6 focus detection process rNPRED J or rWPRED J will now be executed. RCFLG is a flag for this purpose. VSH resetting will be described later.

When flag RC:FLG is N'', that is, during the first focus detection process, flag 5DFLG is checked (step 1).
8), 5DFLG is rlilPRE as mentioned above.
D J or rNPREI) A flag set in J (5DFLG at this step is set in rWPRED J), and when this flag is “Y” (within 3 pixels), the current focus state is compared. Lte means close to focus 1. ．． 'Ru, Jutte, VSN is "WD" Te5D
FLG is “N” (3 pixels or more) Oak 1f, rWP
RE[] J + [i Blue routine to display as being off rDIsPJ, lens control subroutine r LEN
Move on to SJ execution. On the other hand, if 5DFLG is "Y", it is more appropriate to recalculate with rNPRED J.
That is, thinking that it is possible to obtain a highly accurate image shift amount PR, set VSN to "NR" (step 21), and temporarily store the image shift amount PR in the buffer BPR (step 22).
, RCFLG is set to ``Y'' (step 23), and the routine starts again from step 12 (actually, step 12 → step 14 → step 15 → step 16 - step 2).
8→Step 33→) is executed. The reason why the image shift amount PR is temporarily stored in the buffer BPR in step 22 is that the result calculated in the primary subroutine rNPRED J is not appropriate, that is, rNPRED
As a result of calculation in J, 5DFLG in step 33 is “
N” (more than 3 pixels), subroutine rWP
RED J This is to use the image shift amount PR obtained at the first time (step 34→step 27→).

When RCFLG is °Y' in step 17, that is, when the second focus detection process is performed, the process moves to step 24, where S
t] Check FLG. As a result, S[1FLG is “
In the case of "N", the focus detection processing at this time is "rWPRED", so the focus detection processing here is displayed as being appropriate.
Move on to the execution of LENJJ. Also 5DFLG is 'Y
”, RCFLG is Y and VSN is “WD”, so the first focus detection process was performed with rNPRED J, and the result was not appropriate with rNPRED J. As will be explained later, in the first rNPRED J, it is determined that the flag NJFFLG is "Y", that is, it is not appropriate unless it is almost in focus, but 5DFLG is "
If it is “Y”, the flag NRSDFLG is set to “Y′° (not in focus, but within 1 pixel), which means N
If RSDFLG is “Y”, 1 of rNPRED J
This means that although it was not almost in focus, it was relatively close to being in focus. At this time, the image shift amount PR at NPRED J is temporarily stored in the buffer BPR. Therefore, if 5DFLG is "Y" in step 24, rWP
Since the second RED J is relatively close to focus, the flag NR9DFLG is checked in step 25 to refer to the result of the first rNPRED J.

If NRSDFLG is "N" (1 pixel or more), the first time is not appropriate, and rWPRED J
Blue routine rDI displayed using the second image shift amount PR
SPJ, the process moves to execution of the lens control subroutine rLENsJ. If NRSDFLG is "Y", the first focus detection process will be performed at rNPR in the next rAFJ.
ED J (set VSN to “'NR” Step 2
6) rNPRED already stored in buffer BPR
J The first image shift amount PR is taken out (step 27), and the process temporarily moves to execution of a display blue routine rDISPJ and a lens control subroutine rLENsJ.

Reversing the flow, if the VSN is determined to be "NR" in step 16, the flag RCFLG is checked in step 28. Here, when RCFLG is °°N°゛, rN
PRED J If the first time is Y”, r NPREDJ
It means the Zth time. If “N”, step 29
Te5DFLGwof Nickt Le, 5DFLIJ
<When it is "N'", rNPRED J is not appropriate, so in order to perform the second focus detection process on rWPRED J, set VSN to "1110" (Step 30)
, rWPRED' image shift amount PR is buffer BP.
Step 22) to temporarily store RCFLG in R.
Y" (step 23), and the routine returns to step 12 (actually, step 12 → step 13 → step 15 → step 17 → step 2)
The process moves on to the execution of 4→). 5DFLG in step 29
is Y”, flag NJFFLG is set in step 31.
Check. This was explained in step 25 above, but in the first rNPRED J, it is determined by NJFFLG whether the focus detection process was appropriate.

In step 31, NJFFLG is set to “”N” (1 pixel or more,
If the focus is within 3 pixels), it means that the focus is not substantially focused, but it is relatively close to the focus, so the focus detection process is performed again in case the situation arises. 11, the process moves to step 3°.In addition, in step 22, the rNPREDJ i-th image shift amount PR, which is temporarily stored in the buffer BRP, is determined as necessary, that is, rWPREI]
J Used in the second step 27.

Poems for which RCFLG is “Y” in step 28 are rNPR.
This is the Z-th time of ED J, and as can be seen from the above, the first time means that the result was determined to be inappropriate in rWPRED J. Also, as mentioned above, check the 5DFLG in the stave 233, and if it is "Y'°, r NPRE
The second DJ is determined to be appropriate, and the routine moves to execution of a blue routine rDISPJ for displaying the image shift amount PR as it is, and a lens control subroutine r LENSJ. If 5DFLG is N II, rNPRED J The second time is considered inappropriate, and the focus detection process in the next rAFJ is r WP
RED" (set VSN to "WD" and step 34), rWPRED J At the first time, take out the image shift amount PR stored in the temporary storage buffer BPR (
In step 27), the process moves to execution of the display blue routine rDISPJ and the lens control subroutine rLENSJ.

To briefly summarize the process flow of r AFJ above,
When rAFJ is called, the image signal t of sensor array SA
[Includes rIMAGE J, fi focus 1 processing rWPRED J or rNPRED J.
Based on the premise that NPRED J is applied when the focus is near, if the detected image shift amount is inappropriate for the processing at that time, the same image signal is recalculated using an appropriate processing method, and eventually the lens control The image shift amount PR used is rWPRED J when the amount of out-of-focus is large, and rN when it is close to focusing.
It is calculated by PRED J.

In other words, when the amount of out-of-focus is large, it is better to perform focus detection processing using rWPRED J, so that the out-of-focus state can be better understood.
If this result is determined to be near focus, rN
This is because focus detection accuracy can be improved by performing focus detection processing using PRED J.

Next, using the flow shown in FIG. 14, subroutine r LE
Let me explain about NSJ. At step 60, the flag LCF is
Check out LG. As mentioned above, this flag is set to °°N'' when the contrast evaluation amount of the image signal to be subjected to focus detection processing is high.When LCFLG is N'', the image signal is sufficient for focus detection processing. First, the lens communication circuit LC controls the photographing lens FLNS based on the image shift amount PR, which is the processing result.
Check the signal BSY input to OM (step 6
1) While this signal BSY is "H'", it is impossible to communicate with the in-lens control circuit LPRS, so the signal BSY is "H'".
The signal BSY waits until it becomes L” (low level).
When becomes L°', the in-lens control circuit LPRS transmits the coefficient S of the defocus versus lens movement amount of the photographing lens FLNS.
is input from the signal DLC (step 62).Next, the defocus amount DE of the photographing lens FLNS is determined from the image shift amount PR.
F is calculated using the formula DEF=PR (step 63), which is a value set in advance by the focus detection optical system. Next, from the defocus amount DEF and the coefficient S, the movement amount FP of the photographing lens FLNS is calculated as FP=
Calculated by DEF/S (step 64), FP corresponds to the count a of the encoder circuit ENC. Then, in step 65, the signal date SY is checked again, and the signal BS
When Y becomes L'''.

The lens movement amount FP (signal DCL) is communicated to the intra-lens control circuit LPRS (step 66), while the LC
: When FLG is "Y", it is assumed that the contrast is not sufficient, and the photographing lens FLNS is set to perform a search operation.
(7) Calculate the movement amount FP as F P =CDEF/S (step 67), C:DEF is the amount of lens movement to be moved in one search operation converted into a defocus amount, and is It is set.

When the lens movement amount FP is input, the in-lens control circuit LPR9 controls the drive of the photographing lens FLNS based on the information.When the photographing lens FLNS is stopped, the image signals A(i) and B(i) are controlled. A series of rAFJ processing for focus adjustment that started from the input is completed.

According to this embodiment, the range of pixels (effective range) corresponding to the finder distance measurement frame is checked in advance in the adjustment process, and the EEP
Since it is stored in the ROM, no mechanical adjustment is required, resulting in very high work efficiency. Furthermore, even if you want to change only the finder distance measurement frame to a different one (matte surface, subrift image) in cameras with the same configuration, it is easy to do so. Further, after the assembly is completed, if it is found that the sensor has uneven sensitivity, or if it is found that the AF optical system has aberrations, it is possible to easily avoid that part and use it.

(Correspondence between the invention and the embodiments) In this embodiment, the photographic lens FLNS is included in the imaging optical system of the present invention, the field lens FLD, the secondary imaging lenses FCLA and FCLH are included in the optical system, and the sensor array SAA is included in the optical system.
, SAB is a photoelectric conversion means consisting of a plurality of pixels, and a CPU
corresponds to the calculation means, and the EEPROM corresponds to the storage means.

(Modified example) In this embodiment, an "image shift type" device has been described, but the present invention is not limited to this, and a so-called "sharpness type" focus detection device that detects a contrast change on a focal plane can be used. can also be applied.

(Effects of the Invention) As explained above, according to the present invention, a storage means for storing an effective pixel range that generates an effective photoelectric conversion signal is provided, and the effective pixel range stored in the storage means is stored. Since the focus detection process is performed based on this, mechanical adjustment of the photoelectric conversion means is not required, and design changes can be accommodated.

[Brief explanation of drawings]

FIG. 1 shows the focal point of a camera suitable for implementing the present invention? A
A block diagram showing an example of a joint device, FIG. 2 is a flowchart of a part of it, and FIG. 3 is a flowchart of a part of it.
4 and 5 are diagrams showing an example of the image signal output from the sensor array, FIG. 6 is a partial flow chart, and FIG. 7 is a diagram showing the correspondence between two images during focus detection calculation. Figure 8 is a diagram showing changes in evaluation quantities, Figure 9 is a diagram also showing changes in some evaluation quantities, Figure 1 is a partial flowchart, Figure 1 (
The figure shows the relationship between the positions of the finder rangefinder frame and the sensor array, Figure 12 shows the correspondence between two images during focus detection calculation, and Figure 13 shows changes in some evaluation quantities. FIG. 14 is a partial flowchart. FIG. 15 is a layout diagram showing an optical system of a general secondary imaging type focus detection device. PR9... Control circuit, LCOM... Lens communication circuit, LNSU... Lens unit,
SDR・・・Sensor drive circuit, SAA, SAB・
...Sensor row, FLNS...Photographing lens, k...Relative displacement amount. Fig. 7, Fig. 8, Fig. 10] 3 Fig. 14 C NPRED-1 Fig. 11 1 ゛ Fig. 12 A (PA) A (PA)
c) Figure 15

Claims (1)

[Claims] (1) a photoelectric conversion means consisting of a plurality of pixels; an optical system that images the light passing through the imaging optical system on the photoelectric conversion means;
A focus detection device comprising: a calculation means for detecting a focus state of the imaging optical system by performing predetermined focus detection processing on a photoelectric conversion signal from the photoelectric conversion means; A focus detection device comprising a storage means for storing an effective pixel range for generating a photoelectric conversion signal.