JP2757853B2 - Focus detection device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera and the like.
The present invention relates to a focus detection device for an optical system. 2. Description of the Related Art Conventionally, an image light of an object is separated by a separator lens.
Separation and re-imaging to form an image on the light receiving element.
With the configuration that detects the focus state of the optical system with respect to the target object
Proposed. [0003] However, the size of the target area is low.
Device for detecting the focus state for a plurality of areas having different
If the above configuration is applied to the
The same number of separator lenses and light-receiving elements as
And For example, the focus state of four areas was detected.
If not, use 4 sets of separator lens and 4 light receiving elements each
Will be installed. However, the number of areas
The following inconveniences occur when the number of members is increased
You. First, increasing the number of members hinders miniaturization.
It becomes Install components close to each other for miniaturization
Harmful light is generated because the light beams overlap each other
Fear also arises. Furthermore, when installing members for each area
Has the same performance (production accuracy and installation accuracy) of all members
But it is practically difficult. Book
The invention can be applied to the subject area without causing the above-mentioned disadvantages.
Detect focus state for multiple different areas
The purpose is to obtain a device that can: [0005] To achieve the above object, the present invention
The present invention provides a method for separating an image of an object into two images and performing re-imaging.
Image formed by a parator lens and the separator lens
Having light receiving means for receiving image light of a focused object
In the detection device, a plurality of
In order to allow the light beam to pass through, a plurality of openings are provided at the position of the light beam.
Having a field mask having the field mask.
Position to receive the luminous flux from the above multiple areas that passed through the
Have a plurality of light receiving elements, and the separator lens is a pair.
The image of the object is formed on the above
It is characterized by the fact that Also,
Has a condenser lens, one condenser lens
The light beam formed by the light is incident on the plurality of light receiving elements.
It is desirable to configure as follows. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In comparison with an embodiment of the present invention,
First, a conventional apparatus will be described. Fig. 1 (a) shows the conventional focusing
It is a field view showing a detection area. As shown in the figure,
One narrow area in the center of the field of view is more focused on the indication frame
This is indicated as the detection range, and the sensitivity range of the actual focus detection device is also
One very narrow area in the center of the area corresponding to the field of view
Was limited. Therefore, automatic focusing (hereinafter referred to as AF)
U), the operator first has to do with his framing intention
First, align the indication frame at the center of the field of view with the image of the main object.
Focus detection sensitivity range to the main target and perform AF
After that, the focus state is fixed, so-called AF LOCK,
After that, it was necessary to perform framing by intention. Also
When following a moving object, always keep the main object
It is very difficult to keep in the focus detection
Moving objects often deviate from the focus detection sensitivity range
The AF operation becomes unstable. In the embodiment of the present invention,
A device without complicated operation, that is, as shown in FIG.
Equipment that has multiple focus detection sensitivity ranges
You. Hereinafter, preferred embodiments of the present invention will be described.
You. FIG. 2 shows an optical configuration of the embodiment of the present invention. Departure
An optical system according to an embodiment suitable for a single lens reflex camera
In FIG. 2 (a) schematically showing the whole, the taking lens (1) is
Part of the transmitted light is reflected by the main mirror (2).
Proceed to the finder section (5), and the rest is half of the main mirror (2)
Automatically focuses through the transparent part and is reflected by the sub mirror (3)
Proceed to detection module (4). To the viewfinder (5)
Light is imaged on the matte surface (7) and passes through the pentaprism (9).
Output to the photographer's eyes. One of the finder light
The part repeats total reflection within the mat using the diffraction grating (8).
Led to the spot metering element (10) arranged on the side of the
Used as detection light of the photometric element. FIG. 2 (c) shows a diffraction grating on the mat surface (7).
And the arrangement of the spot metering elements (BV1) to (BV4)
Show. Diffraction gratings are arranged in four planes as shown
And directs light incident from below to the side edges of the mat.
And each light exit port has a photometric element BV1
BV4 is arranged. [0008] The light passes through the main mirror (2) and passes through the sub-mirror (3).
The light sent to the lower part of the camera body is an infrared cut filter
(11), field mask (12) placed near the focal plane,
Lens (13), mirror (14), re-imaging lens (separator
Image on the photoelectric conversion element (16) via the (data lens) system (15)
Is done. The details are shown in FIG. In FIG. 2B, an infrared cut filter (1
The light passing through 1) is applied to the field mask (1
Reach 2). The field mask is the four zones shown in Fig. 1 (b).
Only the light of This light is a condenser lens (1
After passing through 3), after being deflected 90 ° by the mirror (14),
Pupil is divided by the lens (15), and the first zone is (PAL1)
And (PAR1), the second zone is (PAR2) and (PAR
2), zone 3 is (PAL3) and (PAR3), zone 4
(PAR4) and (PAR4)
Two images of the sub-portion and the reference portion are formed on the photoelectric conversion element. The images of the reference portion and the reference portion (PA
Lz), the image interval Xz between (PARz) (z = 1 to 4) is
Focusing at a predetermined interval Lz, Xz> Lz
Sometimes, the subject is close to the lens position, and Xz <Lz
The subject is far from the lens position.
And Fig. 2 (d) is an expanded view of the optical system of Fig. 2 (b).
It was done. Next, FIG. 3 shows an electrical configuration of the present embodiment.
You. This embodiment is a microprocessor that controls the entire camera.
Sessa (hereinafter referred to as control microcomputer) (COP), AF control
Microprocessor (hereinafter referred to as AF microcomputer)
(AFP). (S1) is photometry and A
Start switch for starting F, (S2) is a camera shooting operation
Release switch to start the operation, (S4) is the main switch
Of shutter curtain of color and focal plane shutter
Switch that is turned off by the page and turned on when the exposure is completed
In either case, the open / close signal is input to the control microcomputer (COP).
Is forced. The spot photometers (BV1) to (BV1)
The output of 4) is a multiplexer (AEMP) controlled by a microcomputer
(COP) is selected and output by the selection signal AEMPS.
And the value digitized by the A / D converter (AEAD)
And input to the control microcomputer (COP). Control microcomputer
(COP) is automatically output from the lens data output circuit (LDM).
The amount of defocus detected by the focus detection unit is
AF such as conversion coefficient to convert to lens extension amount according to
Necessary data and data such as maximum aperture value and minimum aperture value
(LDS) and enter only the data necessary for AF
Transfer to AFP. The control microcomputer (COP) has an
ISO data output means for outputting the data of the pex value Sv
Input data from the stage (SVM). Control microcomputer (C
OP) performs exposure calculation based on these input data, and
The output signal (AES) is output to the exposure display (AED) and displayed.
The release signal of the release switch (S2)
After the signal is input, the exposure control signal (BCS) is
Output to the roller (BCR) to control the exposure
You. On the other hand, the AF control microcomputer (AFP)
AF consisting of CCD via interface (AFIF)
Drives the sensor (CCD) and outputs the AF sensor (CCD).
Force is analog processed by AF interface (AFIF).
A / D conversion is performed, and digital image information is input.
Perform AF calculation according to the input information and calculate defocus amount
Put out. Further, the AF microcomputer (AFP) has the above-described control.
This is determined by the lens data sent from the microcomputer (COP).
Is converted to the lens extension amount, and only that value
Output of motor (MO) to motor encoder (ENC)
(DCL) while checking the rotation amount,
Drive using a motor driver (MDR)
You. Furthermore, the AF microcomputer (AFP) can check the in-focus state, etc.
For this purpose, the focus state signal (FAS) is displayed on the focus display device (FA).
D) to display the in-focus state. Next, a control microcomputer (COP) and an AF microcomputer
The transmission and reception of signals with the AFP will be described. (AFS
T) is from the control microcomputer (COP) to the AF microcomputer (AF
AF star sent to P) to start AF operation
Signal (AFST) from the "H" level
By changing to the “L” level, the AF microcomputer (A
FP) starts the AF operation. (AFE) is controlled by the AF microcomputer (AFP).
AF operation is completed by the microcomputer (COP) and the microcomputer is in focus.
This is an AF end signal for transmitting
(AFE) becomes “H” level, AF end status
State is communicated. (AFSP) is the control microcomputer
(COP) stops AF operation to AF microcomputer (AFP).
This is an AF stop signal sent to
(AFSP)
The computer (AFP) stops the AF operation. Further, (AFZS) represents the four zones described above.
Becomes “H” level when any of is selected
AF zone selection signal, (SZS) is the selected
It is a signal indicating a zone. (LDTS) is the control microcomputer
(COP) input from lens data output circuit (LDM)
Data required for AF operation in lens data (LDS)
AF lens to transfer the image to the AF microcomputer (AFP)
Data bus. Referring to FIG. 4 and FIG.
Control operation flow of components Microcomputer (COP), AF control
Each of the microcomputers (AFP) will be described. Reli
Switch (S1) is turned on by pressing the first button up to the first step
And the interrupt terminal of the control microcomputer (COP)
An interrupt signal is applied to (INT0) (# 1 in FIG. 4). This
The control microcomputer (COP) is in the stop mode by the signal of
And set the AF start signal (AFST) to "L".
To operate the AF control microcomputer (AFP) (# 2 in FIG. 4),
The light operation is started (# 3 in FIG. 4). Next, the control microcomputer
(COP) inputs data required for exposure calculation. Immediately
Sv data and lens data are output from the Sv value output means (SVM).
Input various lens data from the data output means (LDM)
(# 4 in FIG. 4), only the lens data necessary for AF
Output to icon (AFP) (# 5 in Fig. 4)
Enter Next, the control microcomputer (COP) is an AF microcomputer.
Input AF zone selection signal (AFZS) from AFP
Then, it is determined whether or not it is "H"(# 7 in FIG. 3). This signal
(AFZS) will be described later, but "L" is output at the beginning of operation.
Therefore, here we will add a description of the case of "L"
deep. When the AF zone selection signal (AFZS) is "L"
In this case (if AF zone is not selected), AF zone is selected
The main subject cannot be limited, and the photometric element cannot be selected.
Therefore, the control microcomputer (COP) uses the photometric data (BV1)
The average of (BV4) is taken as the photometric value (# 8).
The exposure calculation is performed (# 11 in FIG. 4). Exposure calculation ends
And the control microcomputer (COP) sends the result to the exposure display
Output and display (# 12). Completion of the above one loop operation
The switch (S1) is pressed continuously
And shutter charge is completed if it is pressed
Is in focus (# 14) or in focus (# 15)
Check, and if both are satisfied, release
Interrupt from the interrupt terminal (INT1) as enabled
After permitting (# 16), return to re-input of each data (# 4)
Forms a loop and is not satisfied with one or the other
Indicates that each data is re-input without releasing the release (# 4)
To form a loop. Then, the switch (S1) is not depressed.
Stop the metering and display, and stop the AF operation.
Output an AF stop signal (AFSP)
The F start signal (AFST) is set to “H” level. next
Enable interrupt from terminal (INT0) and switch (S2)
From the terminal (INT1) from the
After the IF is reset to 0, the operation enters the stop state. On the other hand, the operation of the AF microcomputer (AFP) is restricted.
AF start signal (A sent from the microcomputer (COP)
FST) is an interrupt terminal (INT) of the AF microcomputer (AFP).
A) (# 30 in Fig. 5)
Start operation. AF microcomputer (AFP)
First, the AF end signal (AFE) is dropped to "L" and the AF zone
During the AF operation with the selection signal (AFZS) set to “L”, the zone
When outputting to the control microcomputer (COP) that it is not selected
Flag L set to 1 when both are driven
The DF is set to 0 (# 31 in FIG. 5). Next, the initialization of the CCD which is the AF sensor
After performing the initialization (# 32 in FIG. 5), the number of AF zones is indicated.
Set the variable Z to 4 (# 33) and set the control microcomputer (CO
Input lens data necessary for AF operation from P) (# 3)
4). Next, the CCD is controlled. First, CCD integration
When the amount of integrated light reaches an appropriate level, or
Preset maximum integral for low object brightness
When the time is reached, a shift pulse is applied and the CCD
Data, that is, image information as digital values
(FIG. 5 # 35). This operation will be described in detail later.
However, here, the CCD data for all zones 1 to 4
Enter the data. Next, whether the contrast of the subject is low or not
Low contrast (hereinafter abbreviated as low contrast)
Is set (# 36 in FIG. 5). This flag is
Only if focus detection was possible during the second CCD integration.
This is the first CCD integration here.
Set the flag. This flag will be
The focus is detected or the focus is detected again without changing the lens position.
It is used to determine whether to perform a crop. Where
Low contrast means that the contrast of the subject is low at a certain lens position.
The lens position where the contrast is high.
Drive, for example, one reciprocation over the entire drive range.
Is Rukoto. Next, focus detection calculation is performed for the four zones.
Data preprocessing (# 37) to determine the priority to be performed
To # 57), pre-correlation (# 57 to # 72), pre-correlation lowcon
Determination (# 73 to # 81), prioritization of zones (# 83
To # 94). More on these behaviors later
As mentioned above, the closest subject among the subjects included in each zone
Zones that include the subject, that is, simplified calculations in each zone
And select the zone with the largest image interval
Focus detection only when the
Performing a relational operation increases the operation time, so the operation time is short.
This is to measure contraction. In # 82, whether the variable Z is 0
Check whether or not the variable Z is 0.
About lowcon. The low contrast is determined here after the main correlation.
To repeat once again, it is simple and called lowcon
A narrow discrimination of the discrimination area is performed. In this way, the front phase
A more accurate match for the zone selected by the
A focus state detection calculation is performed (# 96 to # 105). This correlation performance
A low contrast check is performed based on the
Is not a low contrast and the defocus amount is calculated.
Is issued (# 112) or all zones are low-con
This correlation calculation and low contrast
Perform for each zone according to the ranking. All zones are low
And the low-con flag is set.
When the lens position is extremely large
Defocusers that cannot be detected because they are too far apart
The lens position and change the lens position.
Many times during one round trip from the closest shooting distance to infinity
Lens that can detect the focus state by repeating CCD integration and calculation
A low contrast scan for searching the position is performed (# 110 to # 110).
# 33). It is determined that it is not a low contrast and the defocus amount
If is calculated, first to store this state
The low contrast flag is cleared (# 113).
Lens drive is performed even if the low contrast occurs in the integration of
Redistribution of all CCD zones at the same lens position
Minutes and recalculations are performed. This is the main subject
There is no change in the distance to the camera and the previous main subject is included
Selected when the main subject deviates from the zone
In the zone, low-con scan is performed.
Greatly changes the lens position near the focal point
This is to prevent the situation. Next, the AF control microcomputer (AFP)
AF to specify the metering zone to the icon (COP)
The zone signal (SZS) selected by the control microcomputer (AFP)
Output to control microcomputer (COP), AF zone selection signal
(AFZS) is set to High and output. After this, control myco
AFN selection signal AFZ whose flow (COP) side is # 7
When the branch to S (# 7) is reached, A
F zone signal (SZS) is input (# 9) and the photometric zone
Performs spot metering calculation based on the photometer output (# 10)
It will be. Here, the AF zone selection signal at # 7 in FIG.
If (AFZS) is determined to be “H”, the AF is terminated in # 7-1.
It is determined whether the completion signal (AFE) is "H". And
When the AF end signal (AFE) has reached the in-focus state with "H",
If the flag BIF is 1 in # 7-2,
Determine. If the flag BIF is not 1, # 7-3
Then, the flag BIF is set to 1 and the routine goes to # 9.
Conversely, if this flag BIF is 1, the Bvc
The process proceeds to step # 11 without updating. Therefore, the lens
AF zone selection signal (AFZ
The photometry data corresponding to (S) will be AE locked.
You. In # 7-1, the AF end signal (AFE) is not "H"
If the lens has not reached the in-focus state, the flow goes to step # 7-4.
Reset the BIF to 0 and proceed to # 9. Next, the AF control microcomputer (AFP) calculates
Focus zone with preset defocus amount
It is determined whether or not it is within the focus zone (# 115), and
When it is determined that there is a noise, the AF end signal (AFE) is
Set to “H” and let the control microcomputer (COP) complete the AF operation.
Instructs and displays the focus, and prompts the release permission (#
121, # 123). Conversely, if it is outside the focusing zone,
Conversion that converts the defocus amount to the input lens extension amount
Use the coefficient to determine the lens extension using the pulse count of the encoder.
(LEP) (# 116), and the counter (PC) is calculated.
To drive the motor by the calculated pulse count
(# 117, # 118, # 119) to calculate the lens position
Moves by the set lens extension amount and stops the motor
(# 120). After that, the CCD is re-integrated,
It is necessary to recheck whether the camera is in focus.
CCD was selected by the previous operation to reduce
Performs reintegration and data output only for CCD
(# 127). Prior to this, the row of only the selected CCD was
The variable Z is set to 1 in order to perform the
The data (LDTS) necessary for the operation is transferred to the AF microcomputer (AFP)
It is input (# 125, # 126). After this, the block
This correlation calculation is performed only for the
Feed out. At this stage, it was judged low-con
In that case, leave the lens position as described above
The operation from the integration of the CCDs in all zones is repeated. More than
Appropriate regardless of the position of the main subject in the viewfinder
Automatic focus adjustment and spot measurement for the main subject
Of an autofocus camera having means for controlling exposure by light
This is a basic operation. Next, a supplementary explanation of the parts for which the description is omitted
Add light. First, data provided to reduce the calculation time
Pre-processing, pre-correlation, pre-correlation low contrast, zone priority
Figure 6, 7, 8 and 9
Will be explained. First, the data pre-processing routine shown in FIG.
explain about. First, the AF microcomputer (AFP)
The variable Z indicating the number of colors is set to 1 and the contrast value
Is set to 0 and the contrast calculation is performed.
A variable j indicating the number of times of execution is set to 0 (# 37, # 3
8, # 39). Next, the image adjacent to the CCD serving as the reference
The difference between the A / D converted data between the elements is calculated, and this difference is calculated.
Is positive or negative, and matches the data Ldj for each determination result.
And store it in memory (# 40, # 41, # 4
2). That is, the output data of each pixel of the reference unit is LDj
Then, in # 40, LDj (Z) −LDj + 1 (Z)... (1) is calculated, and it is determined whether the result is positive or negative.
You. If the result is positive, the variable j is determined in # 41.
Is set to 1 and if the result is negative,
In this case, the value Ldj is set to 0 in # 42. Next, in step # 43, the same operation as in equation (1) is performed.
The result is taken as the contrast value C.
Value | C | is added to the previous contrast value C (Z) to obtain
Total contrast value C (Z) up to the obtained difference data
You. Then, 1 is added to the variable j in # 45, and the variable
j becomes k-1 (where k is the number of pixels of the reference portion).
The operations of # 38 to # 45 are repeated until the operation is completed. When j becomes equal to k-1 in # 46, four
Of the above # 38 to # 45 for all of the AF zones
In order to perform the operation, the variable Z indicating the number of AF zones is
4 is determined. And if the variable Z is not 4,
In # 48, 1 is added to the variable Z, and the process returns to # 38.
Are repeated until # 4 becomes 4. When the variable Z becomes 4 in # 47, the process proceeds to # 49.
No. In # 49 to # 57, # 37 to # 47 for the reference part
(Except for # 38, # 42, and # 43)
From the pixel data to be used for all four AF zones
To obtain a contrast value. Where l is the reference part
And the difference data is positive or negative as Rdj
It is memorized. Each of the contrasts of the first to fourth reference portions is described above.
Values C (1) to C (4), reference part difference code data Ldj (1) to L
dj (4), [j = 1 to k-1], reference part difference code data
Rdj (1) to Rdj (4), [j = 1 to l-1] are prepared.
Thus, the pre-processing operation is completed (FIG. 6). Next, a flowchart of the pre-correlation routine will be described.
This is shown in FIG. AF microcomputer (AF
P) sets a variable Z indicating the number of AF zones to 1 in # 58.
And at # 59, 1-bit difference data of the reference part (Ldj)
The difference data (Rdj) of the 1-bit reference part for one pixel
Indicates the number of shifts when shifting by minutes to obtain a correlation value
Set the variable n to 1. Furthermore, AF microcomputer (AFP)
Sets the variable hn (Z) indicating the degree of correlation at # 60 to 0
And the calculation performed when one correlation value is obtained in # 61.
A variable j indicating the number of times is set to 0. Then, in # 62, the difference between the 1-bit reference portion
Data (Ldj) and 1-bit reference part difference data (Rdj)
Is calculated, and when both data are not the same (that is,
Is not 0), it is determined that the degree of correlation is not good, and #
At 63, 1 is added to the variable hn (Z). Both data are identical
# 63 is skipped. # 62, # 63
Is performed by the number of contrasts (k-1) obtained in the reference part.
(# 64, # 65). Further, the AF microcomputer (AFP) has a maximum correlation.
The operation for calculating the number of shifts obtained is performed. First, in # 66
Whether variable n is 1 (indicating no shift)
And if n = 1, a value indicating the degree of correlation in # 68
A variable hn (Z) is set in Mhn (Z), and an image interval error Mn is set.
(Z) is determined by n-Lz. Here, Lz is the focus state.
This is the image interval. On the other hand, when variable n is not 1 in # 66
Represents the correlation value Mhn (Z) stored in # 67 and this time
Is compared with hn (Z) obtained by the above calculation. The current correlation value hn (Z) is a memo.
If the correlation value Mhn (Z) is smaller than
It is judged that the degree is high, and it proceeds to # 68, and the correlation value at that time
And an image interval error. Conversely, the current correlation value hn
(Z) is smaller than the stored correlation value Mhn (Z).
If not, skip # 68. # 6 like this
The operations of 0 to # 68 are performed 1−k + 1 times to obtain the minimum correlation value (the maximum correlation value).
(Large correlation) and the image interval error at that time are obtained (# 69, # 69)
70). Further, the operations of # 59 to # 70 are performed by four AF
For all AF zones, and for each AF zone
The minimum correlation values Mhn (1) to Mhn (4) and the image at that time
After obtaining the interval errors Mn (1) to Mhn (4), the pre-correlation routine is completed.
(# 71, # 72). Here, the variable Z is 4 in # 71.
The above calculation is completed for all AF zones.
For example, the process proceeds to a pre-correlation low-contrast determination routine shown in FIG. In the pre-correlation low contrast determination routine of FIG.
Low contrast with the result of the pre-correlation routine
Perform a strike determination. First, the AF microcomputer (AFP)
To perform low contrast discrimination for the F zone,
In step # 73, the variable j is set to 1. And in # 74
Contrast value C (j) calculated for each AF zone
Is greater than or equal to a predetermined value CS.
Is the minimum correlation value Mhn (j) obtained in the previous correlation routine.
It is determined whether the value is less than the fixed value SM. And each
For the AF zone, the contrast value C (j) is a predetermined value C
S and the minimum correlation value Mhn (j) is predetermined.
If the value is less than the value SM, the AF zone
It is determined that focus detection is possible, and the zone is determined in # 76.
Resets the low contrast zone flag LZF (j) corresponding to
Cut. On the other hand, if the contrast value C (j) is a predetermined value CS
Is less than or the minimum correlation value Mhn (j) is
If the value is equal to or larger than the value SM, the initial value is set to 4 in # 78.
Subtract 1 from the set variable Z, and in # 79,
Judging that the focus detection is not possible for the AF zone,
The low control zone flag LZF (j) corresponding to the zone
Is set to 1. Then, the operations of # 74 to # 79 are performed.
In order to perform for all AF zones, the variable j is set at # 80.
It is determined whether it is 4 or not. If it is not 4, 1 is set to the variable j in # 81.
In addition, the process returns to # 74. If the variable j becomes 4 in # 80, focus is set in # 82.
A variable Z indicating the number of AF zones determined to be capable of point detection is
It is determined whether it is 0 or not. And if this variable Z is 0
It is determined that focus detection is not possible for all AF zones.
And proceeds to step # 109 shown in FIG. 5, and the variable Z must be 0.
If there is an AF zone where focus can be detected,
In order to determine the priority order of AF zones for performing
Proceed to zone priority routine. In the zone priority routine of FIG.
First, the AF microcomputer (AFP) first sets the variable j in # 83.
Set to 1 and a variable M1 for storing the image interval error
〜M4 is set to −LZ, and the variable Q is set to 0.
Then, in step # 84, the low contrast corresponding to each AF zone
It is determined whether or not the activation flag LZF (j) is set.
You. Here, for a certain AF zone, the low contrast zone
If the lag LZF (j) is set, the AF zone
Need to determine priorities for this correlation
Since there is no AF, the process proceeds to step # 94, where 1 is added to the variable j, and the next AF
# To determine the low contrast zone flag corresponding to the zone
It returns to 84. In step # 84, the locomotors corresponding to the respective AF zones
When the zone flag LZF (j) is not set
Performs the operations of # 85 to # 93 so that the focus can be detected.
Only in the AF zone, the image gap error is
In short order, the subject distance corresponding to the detected focus position
Are ranked, and the image interval is incorrect according to the ranking.
The differences are also stored. That is, the AF zone capable of focus detection
AF zone determined to have the shortest subject distance
M1, M2, M3 in order from the image interval error corresponding to
The numbers of the AF zones are stored in the order of B1, B2,
They are stored as B3 and B4. Here, pre-processing, pre-correlation, pre-correlation low contrast
Separate description of zone prioritization in this embodiment
Has been performed, but in addition to the specified value or CCD data
Before binarizing the CCD data with the average output value of the data
Steps in FIG. 10 for processing or obtaining a correlation value of the main correlation
Exclusive of two data instead of # 97 operation (subtraction)
Perform a logical sum operation and add the results to obtain the minimum value.
A similar function is performed by means of calculating the shift position and performing pre-correlation.
It can be realized. Next, the procedure of this correlation will be described in detail.
Add. As the correlation value, the zone specified in the previous correlation is used.
Output value of the reference pixel and the reference pixel
Evaluate the sum of the differences. This correlation value H (P) is used as a reference pixel row.
On the other hand, the reference portion pixels are shifted one by one to l−k + 1 pixels.
(# 96 to # 99) and find the minimum value H (PM)
(# 101). Next, the AF microcomputer (AFP) determines the true minimum phase.
Interpolation calculation is performed to find the relevant value. First, AF microcomputer
(AFP) indicates that the shift amount PM is 1 or 1−
It is determined whether it is k + 1. And this shift amount
When PM is not 1 or 1−k + 1, # 103
The image interval LBi at the time of focusing is reduced from the result of the interpolation calculation
The image interval XM is obtained in the same manner, and the minimum correlation value YM is further obtained at # 104.
Ask for. On the other hand, in # 102, the shift amount PM is 1 or
When l−k + 1, the interpolation calculation cannot be performed.
In step # 105, the image interval XM is obtained from the shift amount PM.
The minimum value H (PM) calculated in # 101 is
It is assumed that the correlation value is YM. The image with the smallest correlation value in this operation
The interval has already been predicted in advance from the result of the pre-correlation Mn (Bi).
As expected, the expected image in the designated zone
Perform calculations only in the vicinity of the interval to reduce the calculation time
Is also possible. The minimum correlation value YM thus obtained,
Low contrast determination is performed again based on the image interval at the time. here
This minimum correlation value YM is determined by the contrast value obtained in the preprocessing.
The condition is that the divided value is equal to or less than a predetermined value. Predetermined
If it is greater than or equal to the value, the zone will be
It is considered (# 106-1). In the first loop, the defocus amount is obtained, and the
Lens drive has already been performed and the lens has been moved to near focus.
Later, in the case of the second or more calculation work in CCD reintegration
Is (# 106-2, LDF = 1) the target subject is a moving subject
The defocus amount suddenly increases
(When the value exceeds a certain value D), the subject
The zone is in a low-con
Then, reintegration of all zones is performed (# 107). vice versa
If the absolute value of the image interval XM is less than the fixed value D in # 107
For example, the process proceeds to step # 112 shown in FIG.
And then drive the lens. The pre-correlation is merely a simple correlation.
For special image information and in the first loop
Causes a large difference in the amount of defocus between the previous correlation and the main correlation.
Can be considered. At this time, another focus detection zone
The main subject closer to the camera than the subject in the calculated zone
It includes the possibility of existence. Therefore, in this embodiment,
As an example, subtract the image interval of the main correlation from the image interval of the preliminary correlation.
(Where the variable q is initially set to 0
(# 95 in FIG. 5), q = 1 in # 106-3.
Then, the process proceeds from # 106-4 to # 106-5. )as a result
Is greater than 1, that is, 1 pit
When the correlation is more than ch, the subject is far from the camera
(# 106-5) stores the calculation result, and then
After finishing the main correlation of the selected zone (# 106-4),
Compare this correlation result between the first selection zone and the second selection zone
(# 106-7), the zone having the large image interval
Select the image and defocus according to the image interval calculation result.
The amount is obtained and the lens is driven. Conversely, if the subtraction result is smaller than 1, the first
From which the correct zone was selected by pre-correlation
The defocus amount is obtained according to the result of the main correlation image interval calculation.
Then, proceed to lens drive. FIG. 11 shows a similar operation.
Is the pre-correlation image of that zone in # 106-5
In the second selected pre-correlation image interval amount instead of the interval amount,
(# 106-5 '), which is exactly the same as the effect described above.
Achieve the same effect. As described above, the flow of the entire operation in the present embodiment is described.
-End of explanation of electric circuit configuration, AF sensor (CC
D) and the detailed configuration of the AF interface (AFIF)
Will be described. FIG. 12 shows an AF sensor according to this embodiment.
Two examples of the configuration of CCD used as (CCD)
You. FIG. 12A shows output CCD registers arranged in series.
FIG. 12 (b) shows a configuration in which output registers are arranged in parallel.
Are all one-chip CCDs.
You. First, a description will be given of a configuration common to FIGS. 12 (a) and 12 (b).
I will tell. The images of the first block to the fourth block are divided into pupils.
The reference portion photodiode array (P
AL1) to (PAL4), reference part photo as reference part image
Imaged on diode arrays (PAR1) to (PAR4)
It is. Here, each photodiode array is
It includes a storage unit corresponding to the auto array. Reference part
K photodiode array, reference photodiode
The array has m pixels (k <m). Reference part photodiode array (PAL1)
~ (PAL4) CCD integration time control near each
For monitoring subject brightness
(MP1) to (MP4) are arranged, respectively,
The photocurrent generated in the mode (MP1) to (MP4) is integrated and cleared.
Charged to almost power level according to gate pulse (ICG)
Charge of the capacitors (C1) to (C4)
Decrease at a slope proportional to the amount of light. The power of this capacitor
The voltage is high input impedance and low output impedance.
Monitor output to outside via buffer (AGCOS1-4)
Is output as The integral clear gate pulse (ICG) is
Between the pixel storage (photodiode array) and the power supply
Applied to the provided MOS gate, the integration clear gate
While the pulse (ICG) is “H”, the storage section is almost at the power supply voltage level.
The bell is charged and cleared. After this, the integral clear game
When the pulse (ICG) is "L", the MOS gate (MOS)
Is open and generated in the photodiode array
Charged to power supply voltage with photocurrent proportional to image brightness distribution
The charge in the storage section is released, and information on the luminance distribution of each pixel is stored.
Can be Each pair of the reference part and the reference part of each block
On the other hand, a MOS gate between the charge storage section and the register
(MOS) is installed and SH pulses (SH1) to (SH4)
When “H” is applied, each gate is closed and integration
The charge accumulated after applying the rear gate pulse (ICG)
Is transferred to the Monitor outputs (AGCOS1) to (AGCOS1)
A DOS circuit is provided as a compensation output in S4).
This circuit is connected to the monitor output capacitor and buffer.
It is formed of the same characteristics, and its input end is
Circuit that responds to the integral clear gate pulse (ICG).
The potential that has been charged to almost the power supply voltage
It keeps outputting even after the gate pulse (ICG) disappears. Next, the difference between the configurations of FIGS. 12 (a) and 12 (b)
Is added. FIGS. 12 (a) and 12 (b) show CCD registers.
The configuration of the star and the configuration of the subsequent CCD output stage are different.
You. FIG. 12A shows that the CCD register is directly connected to each zone.
Output registers at the end of the CCD registers.
And the output is the first zone reference section, the second zone
Zone reference section, first zone reference section, second zone reference section,
4 zone reference section, 3rd zone reference section, 4th zone reference
Section, the falling edge of the transfer clock φ1 in the order of the third zone reference section.
Output sequentially in synchronization with the On the other hand, the CCD image shown in FIG.
The output configuration of the sensor is different for each zone.
With a total of four at the end of each CCD register
Are in a parallel configuration having a buffer. First
From the buffer outputs # 4 to # 4, reference parts and reference
The output of the illuminator is synchronized with the falling edge of the transfer clock φ1.
Output next. In this CCD image sensor, 4
Fig. 1 to perform control with different integration times in one zone
In 2 (a), the output ends of both the reference and reference sections of each zone
Pixels shaded with an aluminum mask are provided (shaded area)
For correction of dark output level that fluctuates greatly with degree and integration time
Used as pixels. In FIG. 12B, the dark output level is shown.
Bell correction pixels (shaded area) are set only on the output end side of each reference section.
And is used for correcting both the reference portion and the reference portion. Next, the AF interface (AFIF)
Circuit configuration and specific driving method of CCD image sensor
And add an explanation. First, the serial type CC shown in FIG.
Diagram of driving method of CCD image sensor with D register
13 will be described. In FIG. 13, the left side of the drawing is C
Connection with CD image sensor, right side is AF microcomputer
(AFP). First time after AF operation started
CCD integration requires output of all zones. At this time
Is the integration clear gate from the AF microcomputer (AFP)
Integration is started by application of a pulse (ICG). This pulse mark
In addition, the CCD pixel storage and monitor output are initialized.
After the disappearance of this pulse, the two simultaneously store the photoelectric conversion output.
Start multiplication. On the other hand, the power supplied from the AF microcomputer (AFP)
Original clock φ0 and a clock obtained by dividing the clock by a plurality of stages.
The AF timing control circuit (AF
TC), the AF microcomputer (AFP) sends all zone output commands.
Command is supplied with a zone selection symbol (AFZS).
Lock is a cycle whose period can be A / D converted
Select φa. Integral clear gate pulse (ICG)
Input to the reset input of the R / S flip-flop
Reset R / S flip-flop to CCD
Transfer clock φ1 to “H” and φ2 to “L”.
To standardize. In this state, the accumulation of the pixel accumulation unit proceeds, and at the same time,
Monitor accumulation is also a constant level V1 from the compensation output
Monitor output begins to drop. At this time, pixel storage
The electric charge accumulated in the product section is converted into A / D conversion and focus detection
V1 in that the average output level is appropriate for the output operation.
Is set in advance. The level of the object is determined in order from the zone having the highest object brightness.
V1 and each comparator (COM11) to (CO
M14) is inverted and its output is
Shift to CCD image sensor via cut pulse generator
The pulses are supplied as pulses (SH1) to (SH4). This
Shift pulses (SH1) to (SH4) to the image sensor are
Shifts the charge in the element storage unit to the transfer register
However, since the transfer clock is not supplied to the register,
Charge is held at the potential of the register corresponding to the element
Is done. Thus, the comparator (COM11)-
When the inversion of (COM14) is completed,
At the point when the output (TINT) of the
The output of each zone with average level output is stored in the register
It will be in the state that was done. Here, the output (TINT) of the AND gate is inverted.
All the CCD image sensors are transferred to the AF microcomputer (AFP).
As an integration complete signal for the zone, and OR gate and delay
Being input to the R / S flip-flop via the element
Is used as a transfer clock application start signal. FIG.
Figure 4 shows the time chart. After that, φ1
Is output in synchronization with the falling edge of
The timing control circuit counts φ2 to output in the dark.
Sampling at each timing when outputting force correction pixels
Signal, and the AD converter
Supply an external signal (ADS). Thus, the output of the CCD is based on the first zone.
Section, 2nd zone reference section, 1st zone reference section, 2nd zone
Reference section, fourth zone reference section, third zone reference section, fourth zone
At the time of integration of the zone reference part and the third zone reference part, respectively.
After the interim dark output correction is performed, A / D conversion is performed.
Output in synchronization with the A / D conversion completion signal
To be input to the computer (AFP). Next, in this circuit, step # 127 of FIG.
The integration driving of the selected zone shown in FIG. Ma
The zone signal (SZS) is output from the AF timing control circuit (A
FTC), the counter inside the circuit
Set the number of transfer clocks required before the zone is output.
Is After applying the integral clear gate pulse (ICG),
AF microcomputer (AFP) is a monitor of the block you want to output
(COM11) to (COM14) output (I
NT1) to (INT4), and select
Manual shift signal (SHM) is generated at the same time as inversion of data
Then, the stop of the transfer clocks φ1 and φ2 is released. AF timing system with counter set
The control circuit (AFTC) counts the clock φa and
Until the counter becomes equal to the set value, the original clock φ
When 0 is supplied to the CCD and the output of the selected zone is output
Only an A / D-convertable clock is supplied to the AF microcomputer.
(AFP) synchronizes data only for that zone with (EOC)
Supplied, perform counter setting, and
High speed transfer is performed when the
The same operation is performed for the remaining pixels. Do this
Reduce wasteful data dump and integration time with
Then, the speed of the AF operation is increased. Timechart of this action
FIG. Finally, the parallel CCD shown in FIG.
Fig. 1 shows the driving method of a CCD image sensor having a register.
6 will be described. The left side of the drawing is a CCD image sensor.
The AF interface is on the right side of the
Terminal (AFIF), the rightmost terminal row is the AF microcomputer (A
FP). In this CCD image sensor, after AF starts
The first driving method for all zones of CCD is as follows.
The time can be shortened and obtained. First, AF My
Con (AFP) is stored in each pixel storage unit and monitor
Integral clear gate pulse (ICG) to eliminate charge
Generate. At this time, the zone signal indicating the first zone
Signal (ZS), the output terminal of the multiplexer (MPX)
(AGCOS0) outputs the input signal (AGCOS1).
The input signal (SH0) is output from the output terminal (SH1).
The input signal (OS1) is output from the output terminal (OS0).
Is set to Then, the CCD image for the first zone
Monitoring the charge storage of the di-sensor
(MPX) via the signal (AGCOS 1) to the comparator
(COM20). No.
Charge accumulation in the monitor unit and each pixel unit in one zone progresses
In this case, the signal (AGCOS1) is output to a subsequent analog processing circuit and
When the level reaches an appropriate level V1 for the subsequent focus detection calculation, the
The output of the parator (COM20) is inverted and the shift pulse
(SH0) is shifted through the multiplexer (MPX).
As the pulse (SH1), the CCD image sensor in the first zone
Supplied to Further, the signal (AGCOS1) becomes the level V1.
If the preset maximum integration time has elapsed without reaching
Is the manual shift pulse from the AF microcomputer (AFP).
Shift pulse (SH0) by applying the pulse (SHM).
The shift pulse (SH1) is output via the multiplexer (MPX).
Then, it is supplied to the CCD image sensor in the first zone.
The supply of this shift pulse (SH1) causes the first zone
The CCD image sensor terminates the charge storage operation and stores the pixel.
The charge accumulated in the stacking section is transferred to the first zone through the shift gate.
Is shifted to the CCD shift register (Rg1). Here, a shift pulse (SH0) is generated.
The input signal of the delay and one-shot circuit (DO) is φ1,
Transfer clock generation that generates two φ2 transfer clocks
Circuit (TCG) and the transfer clock φ1 is “H”.
The shift pulse (SH1) is in the first zone
Phase to be supplied to the CCD image sensor
It is arranged. Then, the falling edge of the transfer clock φ1
Synchronized with the above, stored in the CCD image sensor in the first zone
The photoelectric conversion output (OS1) of the formed image is output to the multiplexer (M
PX) via the output terminal (OS0). Next, immediately after the generation of the shift pulse (SH0)
The AF microcomputer (AFP) has a second integral clear gate.
Supply pulse (ICG) to CCD image sensor
You. This second integral clear gate pulse (ICG)
With the integration start signal for the CCD image sensor in the zone
And the second zone immediately after the end of the charge accumulation operation in the first zone.
The charge accumulation operation of the monitor and pixel
To discharge the charged electric charge continuously.
You. After that, the AF microcomputer (AFP)
Output correction in the photoelectric conversion output (OS1)
The output of the pixel for use to the sample and hold circuit (S / H)
Each pixel output and the memory
A / D conversion of the difference between the output of the dark output correction pixel and the output
Enter as information. Here, the control from the AF microcomputer (AFP) is performed.
CCD image cell by dual shift pulse (SHM).
When the charge accumulation of the sensor is forcibly terminated,
Monitor by the output of data (COM20) to (COM22)
Automatic gain adjustment according to the average accumulation level of the output of the
A circuit (AGC) automatically adjusts the gain. Sand
The automatic gain adjustment circuit (AGC) has a photoelectric conversion output
(OS0) and the output of the sample and hold circuit (S / H)
Input, the difference between the two outputs is amplified and output
You. The output of the automatic gain adjustment circuit (AGC) is A /
It is input to a D conversion circuit (ADC) and converted to a digital value.
The digital value is used as image information by the AF microcomputer (A
FP). In this way, the image information of the first zone is
When input to the microcomputer (AFP),
Of the CCD image sensor in the second zone where accumulation has started
The charge accumulation state is detected. For this, first, A
F microcomputer (AFP) sets signal (TINTC) to "L"
The manual shift pulse (SHM) is the shift pulse (SH
0) is prohibited, and the zone signal (ZS)
Is switched from the first zone to the second zone. By this
And the output terminal (AGCOS0) of the multiplexer (MPX)
Outputs an input signal (AGCOS2).
(SH0) is output from the output terminal (SH2), and the output terminal
(OS0) so that the input signal (OS2) is output.
Is set. The AF microcomputer (AFP) outputs a signal (T
(INT0) is confirmed, and the signal (TINT0) is
Sometimes charge accumulation in the CCD image sensor in the second zone
Is already excessive, so again the integration clear gate pulse
(ICG) to the CCD image sensor and the second zone
Of the CCD image sensor is restarted.
Conversely, when the signal (TINT0) is “L”, the second zone
The charge accumulation of the CCD image sensor of the
Image information to CD microcomputer AF microcomputer (AFP)
Not completed while importing. So AF Maiko
(AFP) changes the signal (TINTC) to "H" again.
Wait for the reversal of (TINT0). Then, this signal (TINT0) is inverted.
Or from the CCD image sensor in the first zone
Of the signal (TINT0) at the time required to capture the image information
Maximum charge determined by adding the inversion wait time
When the accumulation time has been reached, a shift pulse (SH0) is issued.
Generated charge of the CCD image sensor in the second zone
The accumulation ends. Similarly, the CCD image in the third zone is
Start of charge storage of the image sensor, acquisition of image information of the second zone
Charge accumulation state of the CCD image sensor in the third zone
CCD image cells for all zones in the order of
The charge accumulation of the sensor and the capture of the image information are performed. Here, since the subject has low luminance, it takes a long time.
When the charge accumulation time is required, the driving time of the CCD is reduced by the time of (image information fetching time) × {(the total number of zones) −1}.
When a long charge storage time is not required instead of low brightness
However, the driving time of the CCD is not reduced. However, in the circuit configuration shown in FIG.
The shift pulse (SH1) gates (SHG1) to (S
HG4) and registers (Rg1) to (Rg4)
By adding a shifter section and shift gate section,
Even when the body is in high brightness, the charge
Performs the first shift operation of the charge stored in the buffer unit from the
Integration completion signal (TINT0) at the time of detecting the above-mentioned charge accumulation state
If has already occurred, register
A second shift operation of charges to (Rg1) to (Rg4) is performed.
To reduce the driving time of the CCD.
Can also be. In the circuit configuration shown in FIG.
Buffer and shift gate units similar to those described
Stops the transfer clock φ1 during the charge accumulation operation.
That the complicated circuit configuration can be simplified
Both reduce problems such as noise due to complicated circuit configuration.
Can be reduced. In the above embodiment, the lens has reached the focused state.
So-called shutter release is allowed when
Although the camera was of the AF priority type, the present invention is not limited to this.
The camera is not locked, regardless of whether it is in focus.
The shutter is released according to the release operation.
A loose-release camera may be used. Further, the focus detection sensitivity range corresponding to the AF zone
And the photometric sensitivity range for exposure control always match exactly
There is no need, for example, one focus detection range with one photometric sensitivity range
It may cover a wider range including the sensitivity range,
One in the range other than the metering sensitivity range that gazes at the center of the shooting range
Photometric sensitivity range covers multiple focus detection sensitivity ranges.
You may do it. In the latter case, the area covered by one photometric sensitivity range is
No matter which of the multiple focus detection sensitivity ranges is selected,
The photometric sensitivity range may be selected. Change
Monitor the charge accumulation state of the CCD image sensor.
Provided for each CCD image sensor
Use the output of the monitor section as it is as the photometric signal.
CCD image corresponding to the selected focus detection sensitivity range
Monitor provided for monitoring the charge accumulation state of the di-sensor
Output is selected according to the focus detection sensitivity range.
It may be used as information on the photometric sensitivity range. Further, in the present embodiment, the shortest object distance
Lens focus adjustment with priority given to AF zone where
The present invention is not limited to this.
The object distance, for example, the shortest detected subject distance.
Focus is in the middle between the separation and the longest detected subject distance.
It may be configured to adjust the focus so that
Focused on the longest subject distance issued
Adjustments may be made. Also, what zones are prioritized
Alternatively, it may be configured to be able to switch between selections.
Here, based on the statistical data of commonly taken photos
So that the most suitable zone for general shooting is selected.
It is only necessary to decide whether or not to switch zones at the time of camera design.
No. According to the present invention, an image of an object is separated into two images.
A separator lens for re-imaging and the separator lens
Hand that receives the image light of the object imaged by the lens
A focus detection device having a step
In order to allow light beams from a plurality of regions to pass,
A field mask having a plurality of openings in
The step is the light from the plurality of areas that has passed through the field mask.
A plurality of light receiving elements are provided at the position for receiving the bundle,
The data lens consists of a pair of lenses
Since an image of an object is formed in a plurality of areas,
Does not require as many separator lenses and is therefore small
Without deteriorating performance and causing performance degradation
In addition, focus detection in a plurality of regions can be performed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view for comparing a focusing area and a photometric area in a conventional and an embodiment of the present invention. FIG. 2 is an explanatory view of an optical system of the embodiment. FIG. 4 is a flowchart showing the operation of the control microcomputer in FIG. 3; FIG. 5 is a flowchart showing the operation of the AF microcomputer in FIG. 3; FIG. 6 is a data pre-processing routine in the embodiment; FIG. 7 is a flowchart showing a pre-correlation routine in the above embodiment. FIG. 8 is a flowchart showing a pre-correlation low contrast determination routine in the above embodiment. FIG. 9 is a flowchart showing a zone prioritization routine in the above embodiment. FIG. 10 is a flowchart showing the present correlation routine in the embodiment. FIG. 11 shows a modification of FIG. FIG. 12 is an explanatory diagram showing a configuration example of a CCD in the embodiment. FIG. 13 is a circuit diagram showing a configuration example of a CCD driving circuit in FIG. 12. FIG. 14 is a timing chart showing the operation of FIG. FIG. 15 is a timing chart of the integration driving operation of the selected zone in FIG. 5; FIG. 16 is a circuit diagram showing another configuration example of the CCD driving circuit of FIG. 12; FIG. 17 is a timing chart showing the operation of FIG. Explanation: 15: Separator lens PAL1, PAL2, PAL3, PAL4: Light receiving element PAR1, PAR2, PAR3, PAR4: Light receiving element 13: Condenser lens

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Toshio Kaida Examiner, Osaka International Building Minolta Co., Ltd. 2-3-13 Azuchicho, Chuo-ku, Osaka City Toshiyasu Kimura (56) References JP-A-59-40610 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) G02B 7/11

Claims (1)

(57) [Claims] In a focus detection device having a separator lens that separates an image of a target object into two images and performs re-imaging, and a light receiving unit that receives image light of the target object formed by the separator lens, different target regions are provided. In order to allow light beams from a plurality of regions to pass therethrough, the device has a field mask having a plurality of openings at the positions of the light beams, and the light receiving means is provided at a position for receiving the light beams from the plurality of regions passing through the field mask. A focus detection device comprising a plurality of light receiving elements, wherein the separator lens forms an image of an object on the plurality of light receiving elements by a pair of lenses. 2. 2. The focus detection device according to claim 1, wherein the focus detection device has a condenser lens, and a light beam formed by one condenser lens is incident on the plurality of light receiving elements.