JP2679699B2 - Automatic focusing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a line image sensor.
The image of the subject is captured by using the
The point state is detected, and the shooting level is determined based on the detected focus state.
It relates to an automatic focus adjustment device that drives the lens and adjusts the focus.
You. [0002] Conventionally, a line image sensor as described above
Are used, for example, in focus detection devices for cameras. I
In this line image sensor, a line in a single direction
Since it can detect only the light intensity distribution in the shape of
was there. Video signal obtained by image sensor
In the focus detection device of the type that analyzes the
If there is no more than a certain amount of contrast on the
Cannot detect points. Line image as an image sensor
When using a di-sensor, the image line on the image sensor
Focus detection cannot be performed if the contrast in the direction is low.
Even when the
Trust is often sufficient. Take a picture of a person or outside scene
When shooting true, the horizontal contrast is vertical
Since there are many cases where the contrast is higher than the
When using a line image sensor for output,
It is reasonable to arrange the sensors horizontally. But this
, The horizontal contrast happens to be low.
However, if the subject has high vertical contrast, focus
It cannot be detected. Also, use the camera vertically
When doing so, the same problem occurs. This problem is two-dimensional
It is solved by using a different image sensor. This kind of
Japanese Patent Laid-Open No. 59-174807 discloses a focus detecting device.
Have been proposed. The gist of this proposal is that
Just line up dimensionally and form a subject image on it
From the array of light receiving elements,
If the output is read and the contrast is insufficient, the direction
Is changed and the output is read from the light receiving element array. Like this
Focus detection by searching for a direction that provides sufficient contrast
A two-dimensional image sensor
It is expensive because it is used. Therefore, instead of a two-dimensional image sensor
Uses multiple line image sensors with different line directions
However, in this case the line image in each direction
Focusing distance for each image sensor (from the current position of the shooting lens
The amount of lens movement until the object is in focus, that is, the focus state
Calculation of the focus state is completed.
It takes time to move, for example, repeat the calculation of the focusing distance,
When you drive the shooting lens to follow a moving subject
The responsiveness of the tree is lost. Problems to be Solved by the Invention
When calculating the focusing distance using the sensor, the calculation amount is small.
Eliminates and reduces calculation time. [0006] In a plurality of regions of the object scene
In the automatic focus detection device that can detect the focus state by
And form a subject image separately for each of the plurality of regions.
The optical means and the plurality of areas arranged in correspondence with the light
Multiple shots that receive the subject image formed by the academic means
Image means and video signals output from each of these image pickup means
For detecting the focus state for each image pickup means based on
Output from each of the above-mentioned image pickup means
Contrast based on the video signal
Contrast detection means to detect and contrast detection hand
The contrast detected by each imaging means
Based on the comparison means to be compared and the comparison result of the comparison means,
The above calculation based on the output of the image pickup means with low trust
Prohibition, based on the output of the imaging means with high contrast
Automatically by the control means that controls the above calculation
A focus detection device was constructed. The present invention is based on each image of a plurality of line image sensors.
For signal output, obtain the contrast of the image and
For image sensors that output a video signal with a high last
Therefore, the focusing distance is calculated. Con
It takes less time to calculate the trust, but the focus distance is calculated.
Since multiple calculations are required for a long time, the whole image
Only the selected image sensor, not the sensor.
By performing the focus calculation, the time required to calculate the focus distance can be shortened.
You can. Here, a video signal with a large contrast
Adopting the image sensor that is output is the control of the image.
The greater the last, the higher the reliability of the calculated focusing distance.
Because. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention mainly relates to FIG. 10 and its relations.
The description part is described in paragraph numbers 0020 to 0029.
You. First, the overall configuration and operation of the device of the present invention will be described.
Next, each part will be described in detail in order. FIG. 1 shows an optical system and image of an embodiment of the present invention.
2 is a perspective view of the arrangement of the image sensor, and FIG.
It is an exploded perspective view. In FIG. 1, 1 is a taking lens of the camera, and 6 is
Condenser lens, 8 is four re-imaging lenses, and 10 is
It is a image sensor. The condenser lens 6 is reassembled into four
An image of the pupil mask placed in front of the image lens 8 is taken as a lens.
1. Dotted circle drawn on the shooting lens in the figure
Is this projected image. The front surface of the condenser lens 6 has ten
A field mask 2 having a letter-shaped opening is arranged,
The focal plane is the planned focal plane of the taking lens 1 and the film plane of the camera
Is in a position equivalent to. The re-imaging lens 8 of the field mask 2
An image of the surface is formed on the image sensor 10. With this configuration
For example, one of the re-imaging lenses 8a '
The image on the lens 1 by the lens 6 is a, and similarly, the image of b '
Is the area that is surrounded by the circle
Formed on the field mask 2 by the passing object light
The image is displayed on the image sensor 10 by the reimaging lens'.
Formed. Similarly, change the area on the shooting lens
Formed on the field mask 2 by the passing object light
The image is formed on the image sensor by the re-imaging lens.
Is done. Rectangular shape arranged in a cross shape on the image sensor 10
The shape is the cross of the field mask 2 where X1 is a re-imaging lens.
X2 is a re-imaging lens, which is the image of the horizontal part of the aperture
Image of the horizontal part of the cross-shaped aperture of the field mask by
You. Similarly, Y1 and Y2 are reconnected to form a pair in the vertical direction.
Image of the vertical part of the cross-shaped aperture of the field mask by the image lens
It is. An image of the same part of the subject is formed on X1 and X2
However, the image of the subject taken by the taking lens 1 is exactly visible.
Formed on the field mask 2, that is, in focus
Image of the same part of the subject on X1 and X2 when
If you use the position of
When near the lens (front pin), on X1, X2
Re-images of the
Move away. Therefore, line in the direction of connecting X1 and X2.
With the image sensor, X1
X for the video signal of the subject image above _Two Of the subject image above
The video signals are slightly shifted and overlapped, and the phases of both video signals are
By detecting the shift amount that maximizes the
How much does the body image move from the correct focus position to which side?
Can be calculated. The above is the focus detection in this invention.
Although it is the principle of output, this case is related to the video signal processing operation.
JP-A-60-2472 filed by the patent applicant
No. 10. Image according to the above principle
On the surface of the sensor 10, the arrangement direction of X1 and X2 and
Line images are arranged along the direction in which Y1 and Y2 are orthogonal to each other.
Image sensor is installed. In FIG. 2, the taking lens is not shown and the single lens
After the transparent part in the center of the flex mirror, tilt it by 45 °
Photographed by the mirror arranged facing downward, the transmitted light is red
Outside line cut filter 3, field mask 2, condenser lens
It is turned toward the direction 6 and is further rotated by the 45 ° mirror 4.
The pupil mask 7 and the re-imaging lens 8 (two
(4 pairs). 5
Is a frame that combines all the above-mentioned elements into one unit.
You. The image sensor 10 moves in the horizontal direction (X
1 and X2) and the vertical direction.
Although the image sensor is arranged, the line image
A CCD image sensor is used as the sensor. The CCD image sensor is a photodiode.
One pixel and the condenser that integrates the output photocurrent
Elements, and such elements are arranged in an array
Then, the product is obtained when the photocurrent integration is performed for each element all together for an appropriate time.
Minute application of shift pulse to control gate
Shift register of the light quantity signal by the accumulated charge of each element.
To the shift register in parallel and then to the shift register
By applying a clock, the charge in the shift register
By sequentially reading the signal as a voltage signal, the video signal
Is to be obtained. FIG. 3 shows an embodiment of the present invention.
2 shows a circuit configuration around a CCD image sensor. In this figure
PD array I to PD array IV are CCD image sensors
An array of the above elements in the PD array I
At the position of X1 in FIG.
2 position, PD array II at Y1 position, PD array
Ray IV is located at Y2. Also PD array
Integration of photocurrent by the average brightness of the image projected on
Along the PD array I for monitoring,
The photodiode (PD) M1 is connected to the PD array II again.
In addition, the monitor photodiode (PD) M2 is arranged.
It is. G1 to G4 are paired with PD array I to PD array IV
Integral control gate array corresponding to each element of PD array
There is a one-to-one correspondence with. R1 and R2 are shift registers
is there. Shift register R1 corresponds to PD arrays I and IV
The integration control gates G1 and G4 have shifts.
When a top pulse is applied, each element in PD arrays I and IV is
The elementary photocurrent integrated charges are transferred to the shift register R1 in parallel.
Sent. Applied to the integration control gates G1 and G4
The timing of the shift pulse is different. Shift
The transistor R2 corresponds to the PD arrays II and III,
The charge signals in arrays II and III are transferred. These shi
The shift register uses two-phase transfer clock pulses φ1 and φ2.
Therefore, the information stored in the register is sequentially output.
Is forced. For the sake of convenience of the following explanation, some words are decided.
Keep it. Figure 1 shows the orientation of the line image sensor.
As shown, the x direction (horizontal) and the y direction (vertical) are determined.
These two directions are the directions indicated by arrows x and y in FIG. Total
Contrast is the difference between adjacent video signals.
It is the sum of the absolute values of the differences in data, and the difference in light and dark is large.
The more the light and dark are mixed in, the more the total contrast
Grows. "LowCon" is Low Conf
This is an abbreviation of "idence", meaning that the reliability of focus detection is low.
It is. The configuration and operation of each part of the device will be described in detail below.
You. (CCD image sensor circuit) In FIG.
The CCD analog shift registers R1 and R2 are
Charge transfer is performed with locks φ1 and φ2. There is no electricity at its output
A pressure converter and a buffer are provided to store the PD arrays I and IV.
The product charge is transferred through the analog shift register R1 to the OSI terminal
Output from the PD array II and III,
Output from OSII terminal via log shift register R2
You. The output side of the monitor PD is the accumulated charge of the PD array.
The configuration is similar to that of the
Is the accumulated charge of the monitor (PD) M1 at the AGCOSI terminal?
The accumulated charge of monitor (PD) M2 is AGCOSII pin.
Output from In addition, the reference voltage output of this monitor PD
For this reason, the PD is not connected or is shielded from aluminum.
A voltage converter connected to the PD is provided, and the reference voltage
DOS is output. This output is the shift pulse
It is used to control the timing of occurrence. The integration control gates G1 and G3 are x
Corresponding to the PD arrays I and III in the direction, via the terminal SH1
Then, the common shift pulse SH1 is applied. Likewise
Integration control gates G2 and G4 are
Compatible with Rays II and IV, common shifter via terminal SH2
Pulse SH2 is applied. Also each
The integration control gates G1 to G4 are connected via terminals SH.
So that the shift pulse SH can be applied all at once
It has become. Image obtained from CCD image sensor
The signal is suitable for focus detection regardless of the brightness of the subject.
The integration time is
Output of photodiodes (PD) M1 and (PD) M2
Controlled by force. Here, the x and y directions of the subject
Since the average brightness of the strips of
The pulses SH1 and SH2 can now be applied separately.
ing. The PD arrays I to IV are integrated clear signals ICG.
Cleared all at once by the pulse, and photocurrent from that point
Integration is started. Here, for example, the x-direction strip of the subject
If the minute has higher average brightness than the y direction, shift pulse
SH1 is output first, and the photocurrent of PD array I, III is output.
The integration signal is intermediate to the integration control gates G1 and G3
Is held. After that, the video signals of PD arrays II and IV are suitable.
When it reaches a positive value, a shift pulse SH2 is emitted and PD
The photocurrent integration signals of arrays II and IV are integrated control gates.
Intermediately held in G2 and G4. Then each gate G
The shift pulse SH is applied to 1 to G4 all at once.
Then, the video signals in the x and y directions are all shift registers R
1 is transferred to R2. As described above, the integration control gate G
1 to G4 temporarily hold the outputs of PD arrays I to IV
A machine for transferring this to the shift registers R1 and R2 in parallel
FIG. 4 shows a circuit configuration for that purpose. FIG.
Indicates the structure of one pixel, and the photoelectric conversion is performed by the PD array.
The load is transferred by the integral clear pulse ICG through the barrier gate.
Barrier to the first storage unit C1 that is charged to approximately the power supply level
It is accumulated through the gate. Average brightness of this PD array row
The integration signal whose degree is monitored by the monitor PD is properly integrated.
SH when the level is reached ₁ Or SH2 pulse is applied to each
The charge of the pixel is transferred from C1 to C2 in parallel.
At this time, the charge transfer due to the capacitance difference between V1, V2, C1 and C2
Is almost completely done. In this way ICG pulse application
To the SHn (n = 1 or 2) pulse application
The generated charge is transferred from the storage section C1 to C2, and
Of the PD array where the other image is projected in the state of
Wait for load accumulation to complete. In this second storage unit C2
No photocurrent is generated and the amount of charge is almost maintained.
You. When charge accumulation is completed in the other PD array, C
The charges of all pixels of the CD image sensor are stored in the second storage section C2.
It is in a state of being aligned at a level suitable for focus detection calculation.
Next, by applying SH pulse to the SH gate,
Information of all pixels in the analog shift register at an appropriate level
The signals are transferred in parallel, and thereafter, in synchronization with the transfer clock, OSI,
This charge is sequentially output from the OSII terminal. (Circuit for Detecting Focus and Adjusting Focus)
In Fig. 5, the image sensor is driven to perform focus detection and focus adjustment.
The circuit configuration to be performed is shown. 20 drives the image sensor 10
Then, input that information to perform focus detection calculation and drive the motor.
Focusing state display circuit for driving the lens through the circuit 90
Microcomputer for AF that controls 100
Data. AF microcomputer is AF star
The operation is started by turning on the power switch SAFS. 30 is x
Direction monitor output AGCOS1 is detected and x direction PD
A shift pattern for completing the integration of arrays I and III.
Shift pulse generating circuit for generating the pulse SH1, 31 is y
Direction monitor output AGCOS2 is detected and y direction PD
Shift pulse that completes integration for arrays II and IV
This is a shift pulse generating circuit for generating SH2. This time
The path is composed of a circuit as shown in FIG. Reference voltage D
OS is input to the buffer circuit Buf1 and from its output
Lowered by constant voltage ΔV1 by resistor R31 and constant current I31
Applied to the (+) input of the comparator Com1.
It is. The monitor output A is applied to the (-) input of this comparator.
GCOSn is applied. Integral clear pulse ICG
Both outputs DOS and AGCOSn become equipotential.
However, after that, the potential of AGCOSn becomes the charge in the monitor PD.
It decreases in proportion to the generated amount, that is, the amount of incident light. Compa
Looking at the input level of the rectifier Com1, when ICG is applied
The (-) input is as high as ΔV1 but decreases with charge accumulation.
If the (-) input falls below the (+) input, the comparator
The output is inverted. At the average level of the video signal at the time of this inversion
If focus detection is performed, an appropriate focus detection result will be obtained R
31, I31, that is, ΔV1 is set in advance. This time
The inverted signal of the comparator COM1 is reset by pulse ICG.
Set the flip-flop FF31 that has been set and output FF31.
Force inversion is performed by AND31, INV31 and delay circuit 32.
Converted to Russ and output as SHn (n = 1 or 2) signal
Is done. In addition, the application of pulse ICG causes this SHn signal
It takes a long time to output, as the brightness becomes lower.
Since it is necessary to set the maximum integration time, when this time elapses
The shift pulse SH is generated by a microcomputer.
It is also possible to limit the integration time.
You. Regarding how to handle these at low brightness, see JP-A-60-
It is equivalent to that described in No. 125817. The circuit 40 is a transfer clock generation circuit,
The basic clock supplied from the microcomputer to the terminal
The frequency is divided to generate φ1 and φ2 pulses. For Sφ terminal
The signal for switching the transfer clock frequency is micro
This signal is supplied from the computer 20, and this signal is both x and y.
When inputting the direction output, it becomes High, and the x, y direction
When inputting only one direction output of
Set the transfer clock frequency to Low to input the bidirectional output.
The charge transfer time can be shortened by inputting it as twice the power time.
ing. In addition, the second storage means C2 described above
It is necessary to synchronize the charge transfer to the shift register.
Therefore, the SH signal is input. 50 and 51 are each picture
Basic configuration with analog processing circuits for elementary output OSI and OSII
Is shown in FIG. Each pixel output is output to the differential amplifier Amp51.
And is output as a difference from the reference voltage V52. This out
Force is at the front of the output of each photodiode array PDI-IV
The dark output signal of the aluminum shading pixel provided in the
SP1 output by the microcomputer 20 when
Or, it is sampled by the signal of SP2 and is sampled by C51.
The differential amplifier A
Only the light output component is extracted by using mp52. Here, the dark output is sampled by each PD array I-IV.
The pull-hold is for PD arrays I, III and II, IV.
Are controlled with different integration times, and there is a difference in the dark output voltage.
This is because it occurs. Pixels extracted only in this way
The output is then input to the sample hold circuits 60 and 61.
And then input to the multiplexer 70. Multip here
The lexer 70 outputs the sampled and held pixel outputs I1, I
Depending on the input data selection zone signal SZ,
Selected and output from the D1 terminal to the A / D conversion circuit 80.
You. As mentioned above, the microcomputer is in both x and y directions.
When inputting data, the Sφ signal Hi is output and the transfer clock
Lock is generated at normal speed and AND2, OR1
The output switching of the multiplexer 70 is transferred via
Switch in synchronism with φ1. As a result, timing char
As shown in FIG. 8A, the CCD shift register R1,
The output signals of CCD shift register R2 are output alternately.
And digitized by the A / D conversion circuit 80
Input to the computer. On the other hand, enter only x or y direction
When inputting, the Sφ signal is set to Low and AND2
The output of the multiplexer is switched off by setting one input to Low.
The change is based on the selection signal SZ of the microcomputer.
become. At this time, the transfer lock of the CCD image sensor
The frequency becomes double speed. The microcomputer is in the x direction
From the standard part, and in the case of the y direction, the reference part output, and then SZ
Invert the signal and output CCD shift registers I and II x
Reference part output in direction Input standard part output in y direction. this
By making full use of A / D conversion time
Timing at this time that can reduce transfer time
Is shown in FIG. (Automatic Focus Detection Operation) In the present invention,
Several motion modes are possible for moving focus detection
You. Specific examples of operations in these modes
Tables 9 to 11 show. Fig. 9 shows focusing in x and y directions
If the subject is closer to the camera as a result of detection calculation
Lens based on the focus detection result for the determined direction
This is a flow for driving. Figure 10 shows the total coordinates in both x and y directions.
Compare the trust and give priority to the direction with high contrast
Focus calculation is performed on the lens to drive the lens, and LowCon
Only when the
This is a flow of motion. Where the contrast value is large
LowCon is the LowCon discrimination criterion.
And proposed by the applicant in Japanese Patent Laid-Open No. 60-247210.
As described above, the evaluation function YM (XN) / C by the correlation calculation
Because it is also conditioned that N is less than or equal to a predetermined value,
The evaluation function deteriorates significantly in cases such as perspective competing subjects
Cases are possible. FIG. 11 shows the focus detection function in the x direction.
Focusing is performed with priority, and the x direction is LowCon.
If the focus detection function in the y direction is used only when
You. First, FIG. 9 will be described. AF switch
When SAFS is turned on, the microcomputer 20
Is activated. First of all, the microcomputer is CCD image
Initialize the di-sensor. This is before power supply or transfer
Pre-stored in the register and photoelectric conversion unit while the clock is stopped.
Need to be performed once at startup because it discharges unnecessary charges
There is. Next, the microcomputer 20 sets the CCD image
An ICG pulse is supplied to the disensor 10 to start integration. This
By applying the ICG pulse of
While discharging the accumulated charge, the accumulated charge of the monitor output
Is also discharged, and as the pulse disappears
Accumulation of load starts. After that, the microcomputer
Inversion of both INT1 and TINT2 terminals, that is, PD array
The average of the charge accumulated in each pixel of I and III and PD arrays II and IV is
The shift pulses SH1 and S1 have reached a preset level.
H2 is generated, and the PD array is placed in the second storage unit C2 of each pixel.
The accumulated charges of I and III are PD in the second accumulation portion C2 of each pixel.
Wait until the charges accumulated in arrays II and IV are completely transferred. this
When the microcomputer detects completion, the microcomputer
The computer generates SH pulse and PD array I, IV
The accumulated charge is an analog shift register (CCD register)
The accumulated charge of PD arrays II and III is analog-shifted to R1.
It is transferred in parallel to the register (CCD register) R2. Thereafter, the OSI, O are synchronized with the transfer clock.
Each pixel signal is output from both terminals of SII,
The computer is an A / D conversion completion signal A for one pixel signal after this.
You can know the number of output pixels by counting / DEOC.
The darkness of the aluminum shading pixels installed in each PD array I to IV
Output the output sample signals SP1 and SP2, and continue to this
A / D conversion value of each light output pixel that is output
Image information is obtained by doing. This timing will be described later.
In this way, the digital output of all pixels required for focus detection calculation is performed.
After storing the tar information in the microcomputer,
The microcomputer starts the focus detection calculation. My
The black computer first performs a correlation calculation in the x direction. First
Create x-direction difference data. This difference data is Ux
(K) = Sx (k) -Sx (k + 4), Vx (k) = T
x-Tx (k + 4) of every 4th raw data
Take the difference. This is a low frequency component that cannot be used for focus detection calculation.
This is because Difference data of standard part and reference part 27
When 35 pieces are collected, the microcomputer slides into an image.
While increasing the amount by one pitch, each image shift
The correlation value YM (l) is obtained by the amount. Also the total contrast
A value, that is, the sum of adjacent data of the difference data is calculated. This
Among the correlation values YM (l) thus obtained,
A high image shift amount, that is, the value of the correlation value YM (l) is the minimum
Is obtained. This lx is the lens defocus amount
I was involved in this, but in the system used here
In order to obtain more accuracy, the correlation value and
Interpolation calculation is performed using the correlation value at the image shift amount. This supplement
For details on interval calculation, refer to JP-A-60-247211 for a detailed book.
Please refer to the explanation given by the applicant. Thus accuracy
Good and detailed image shift amount XM, correlation evaluation function YM (XM)
/ CX is required. This correlation evaluation function YM (XM) /
CX, total contrast value CX, and total output raw data value
LowCon discrimination is performed at three points. This LowCon discrimination
The details will be described in JP-A-60-247210.
Therefore, it is omitted here. Both ends of lx = 1 or 9
When the correlation value at is minimum, it is LowCon. If it is determined that it is not LowCon
XM-5 as the PX value, that is, the difference from the image shift amount during focusing
Ask for memory. Also, with lmin = 1x-1
Add memory and limit the image shift range of correlation calculation in y direction
You. On the other hand, when it is determined to be LowCon, the phase in the y direction is
Correlation performance over the entire range without setting the image shift range
Perform the calculation. In this way, note the limitation of the correlation calculation range in the y direction.
Then, the difference data in the y direction is set in the same way as in the x direction.
To create. Uy (k) = Sy (k) −Sy (k +
4), Vy (k) = Ty (k) −Ty (k + 4)
Similar to the one obtained in the x direction based on the difference data created by
The correlation value is calculated. However, here, the correlation calculation in the x direction
Only for image shift amount of lmin or more obtained from the result
Perform correlation calculation. This is because the closer the subject is to
Since the image spacing of is large, the phase in both x and y directions
The one with the larger image shift amount of the result of the function calculation is selected. Therefore ahead
Correlation calculation is performed only for a portion larger than the image shift amount in the x direction obtained in
This is sufficient, and the correlation calculation can be shortened. This
Thus, the correlation value is also obtained in the y direction, and the correlation
Calculate the high part. Next, perform the interpolation calculation as in the x direction.
Image shift amount xN, correlation as a result of correlation calculation in the y direction.
The evaluation function YM (XN) / Cy is calculated. This evaluation function
YM (XN) / Cy, total contrast value Cy in the y direction,
Correlation calculation image while discriminating the y-direction raw data peak value
The minimum correlation value image interval lx calculated for both ends lmin and 9 of the shift amount
Determines whether there is 1 or not, and is not LowCon
If it is determined that the image is out of focus from the in-focus state as PY
Store the quantity xN-5. Thus in both x and y directions
When the correlation calculation is completed by the
The lens is driven according to the correlation calculation results in both x and y directions.
U. First, it was determined that both directions were LowCon.
Microcomputer drives lens when separated
To find the lens position where contrast can be detected
(LowCon Scan) is performed. This action is all
Lens with the drive range scanned at least once
Stop the drive and perform focus detection calculation with the lens position as it is.
The lens and drive the lens when the contrast is detected.
It is a mode to resume motion. At least one is LowC
If it is not on, the magnitude of the image shift amount in the x direction obtained is large or small.
Compare and use the larger one as P for subsequent lens drive
It is used as the image spacing amount. Here at LowCon
The values of Px to Py are set to the Min value (-4).
Shall be. Despite the limitation when calculating in the y direction
First, I dare to compare the size here and there by one image shift amount.
Has a significant amount of differential focus within
This is because there is a large difference in the amount of defocus. This performance
The image shift amount P is converted to the differential focus amount, and
By multiplying different lens drive amount conversion factors
The drive amount is calculated, and the focus determination is performed. Lens drive amount is extremely high
When the lens is small and you do not need to drive the lens, focus
Is displayed, and if not, according to the lens drive amount
To drive the lens and perform focus detection again,
Re-integrate the image sensor. Next, referring to the flowchart of FIG.
The correlation calculation for the direction in which the contrast amount becomes large is excellent.
Go ahead and drive the lens, and the direction is perspective competing subject
When it becomes the LowCon state due to the influence of
First, perform the other focus detection correlation calculation, and
The operation of the focus detection device that drives the lens will be described.
You. To start the operation and complete the data input
As in the case of FIG. 9 described above, the image in both the x and y directions is displayed.
Image sensor data is stored in the microcomputer.
You. The microcomputer first obtains the difference data in the x direction.
Create in the same way as in the case of FIG. 9, and calculate the sum of the adjacent differences of the difference data.
By calculating, the x-direction total contrast value Cx is calculated.
You. Subsequently, the difference data in the y direction is created, and similarly, the y direction
The total contrast value Cy is calculated. Thus both x and y
After calculating the total contrast values Cx and Cy for both
Make a size comparison. Here, the total contrast value becomes large
The correlation calculation result for the direction shows that the total contrast value is small.
Is more reliable than the correlation calculation result for the direction
Usually considered. Therefore, the direction Z in which the total contrast value is large
The correlation calculation is preferentially performed for. About this correlation calculation
Then, the same method as that shown in FIG. 9 is used. Correlation
Image shift amount xM, correlation evaluation by calculating high parts and interpolation calculation
The value function YM (XM) / CZ is calculated. Use this result
To determine LowCon, and determine that it is not LowCon
If this is the case, the amount of image deviation XM
Calculate the deviation amount and calculate the differential focus amount and lens drive amount.
Go out. When the subject is in focus, the focus indicator is displayed.
When the lens is out of focus, the lens drive is performed according to the lens drive amount.
U. On the other hand, if it is determined to be LowCon, this time
Correlation calculation in the opposite direction is performed. This result correlates
Of the image shift amount XM, Y
Calculation of M (XM) / CZ is performed. Again using this result
LowCon is discriminated and it is discriminated that it is not LowCon.
If the image is misaligned, the image shift amount XM causes
Calculates the amount of deviation and the amount of differential focus and lens drive
I do. When the subject is in focus, the focus indicator is displayed.
When the lens is out of focus, the lens drive is performed according to the lens drive amount.
U. If it is determined to be LowCon, this time
Since both x and y directions are determined to be LowCon, the above-mentioned
Perform Low Con Scan. Finally contrast
X-direction (horizontal direction) where parts with high
Focusing is calculated with priority, and the x direction is determined to be LowCon.
Focus that performs focus detection calculation in the y direction only when separated
The detection device will be described with reference to the flowchart of FIG.
I do. In this focus detection device, the two examples shown in FIGS.
Unlike x, only data in the x direction is preferentially input. product
Minute time and data transfer time were reduced to
In order to improve the response, the CCD initialization is started after the AF operation starts.
When the rise is complete, the microcomputer transfers
The lock frequency is set to double the speed in the above example and Sφ = Lo
Figure 8 (b) shows the output of w and the output in one direction at high speed.
It will be carried out in such a form. Mark the integration clear pulse to start integration.
After addition, the microcomputer T indicates that the integration in the x direction is completed.
Wait for the inverted signal of INT1 signal. Inversion of TINT1 signal
Is detected, the microcomputer completes the integration in the y direction.
A shift pulse is generated regardless of whether it is completed or not, and the x direction
Input of the pixel output data of is started. First, P from OS1
D array I, x direction reference part pixel output is output, so S
Z = Hi is output, and the D1 output of the multiplexer 70 is I
1 signal, that is, the OS1 processed signal
A / D conversion of the output of the quasi-part pixel is performed to the microcomputer
input. During this time, the y-direction reference portion output from OS2 is output.
Power is ignored. When the input of this x direction reference part is completed
The microcomputer outputs Sz = Low and multiplies
The D1 output of the lexer 70 is connected to the I2 signal or image sensor.
Output of the reference section in the x direction by using the OS2 processed signal
Is A / D converted and input. Thus the reference part in the x direction,
Once you have filled in the references, you can
Difference data creation, correlation value calculation, highest phase similar to the above two examples
Function extraction, interpolation calculation, and LowCon determination are performed. Above two
As a result of the LowCon determination similar to that shown in the example, Low
Reliable data for the amount of image shift required instead of Con
If it is determined that the in-focus image shift amount
And the difference P = XM-5 is calculated. Defocus amount PF, lens
Calculate the drive amount, and if the lens drive amount is extremely small,
It is judged to be in focus and the focus is displayed, otherwise it is calculated.
The lens is driven according to the lens drive amount, and each image in the x direction is
The re-integration and refocus detection calculation are repeated for the prime. On the other hand, the focus detection calculation result in the x direction is LowC.
If it is determined to be on, the microcomputer
Next is the integration of the image sensor in the y direction and the focus detection calculation.
To start. Microcomputer inputs data in one direction
Output Sφ = Low to perform force
Y signal ICG is generated and thereafter the integration completion signal TI in the y direction is generated.
Wait for NT2 to reverse. Detect this inversion of TINT2
And this time, even if the integration in the x direction is completed or not, the SH
And the input of y-direction data is started. At this time
Contrary to the input in the x direction, SZ = Low is first output and the x direction is output.
I-direction reference part output only I
2 is passed by a multiplexer and data is input after A / D conversion
When this is completed, SZ = Hi is output and the x direction is referenced.
While ignoring the illuminating section output, only I1 in the y direction reference section output
Data is input after passing through a multiplexer and A / D conversion.
U. In this way, all the data in the y direction are input and finished.
Then, the microcomputer creates difference data in the y direction.
Completion, correlation value calculation, extraction of the highest correlation, interpolation calculation, LowC
The procedure is the same as that for performing the on determination in the x direction.
U. As a result of LowCon judgment, not LowCon
It is determined that the amount of image shift that has been generated is highly reliable data.
And the difference between the image shift amount and the focused image shift amount P = xM-5
Calculation, differential focus amount DF, lens drive amount
When the lens drive amount is extremely small, it is determined that the lens is in focus and the focus table is displayed.
Display, otherwise follow the calculated lens drive amount.
The lens is driven, and no refocus detection operation in the x direction is performed.
Without re-integration and refocus detection for each pixel in y direction
Repeat the operation. On the other hand, LowCon also in the y direction
If it is determined that there is LowCo in both x and y directions
Since it has been determined to be n, a LowCon Scan is performed.
Image sensor x, y re-product in both directions
Min., Refocus detection is repeated
wait. According to the present invention, even if a large number of image pickup means are used,
Imaging that outputs a high-contrast video signal from inside
Since the focusing distance is calculated by selecting the method, the calculation time
Not only is it shortened and the responsiveness of automatic focus adjustment is obtained.
Focus distance is calculated based on a high-contrast video signal
, So you can obtain a reliable focusing distance.
And

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an optical configuration of the present invention. FIG. 2 is an exploded perspective view of an optical portion of an embodiment. FIG. 3 is a circuit diagram around an image sensor in the embodiment. FIG. 4 is a circuit diagram of an integration control gate in the same embodiment. FIG. 5 is a circuit diagram of a portion for performing image sensor driving, focus detection, and focus adjustment in the same embodiment. Detailed circuit diagram [Fig. 7] Partial detailed circuit diagram of the same [Fig. 8] Time chart of operation of the above circuit [Fig. 9] Flow chart of one operation mode in the above embodiment [Fig. Flowchart [Fig. 11] Flowchart of another operation mode [Explanation of symbols] 1 Photographing lens 2 Field mask 6 Condenser lens 8 Reimaging lens (2 to 4) 10 Image sensor

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Toshio Kaida               2-3-3 Azuchi-cho, Chuo-ku, Osaka               Kokusai Building Minolta Co., Ltd. (72) Inventor Nobuyuki Taniguchi               2-3-3 Azuchi-cho, Chuo-ku, Osaka               Kokusai Building Minolta Co., Ltd.                (56) References JP-A-57-118206 (JP, A)                 JP-A-62-205324 (JP, A)                 JP-A-61-157080 (JP, A)

Claims (1)

(57) [Claims] In an automatic focus detection device capable of detecting a focus state in a plurality of regions of an object scene, optical means for forming a subject image separately corresponding to the plurality of regions, and arranged corresponding to the plurality of regions, A plurality of image pickup means for receiving a subject image formed by the optical means, and a calculation means for performing a calculation for detecting a focus state for each image pickup means based on a video signal output from each of these image pickup means , A contrast detecting means for detecting the contrast of each of the image pickup means based on the video signal outputted from each of the image pickup means, and a comparing means for comparing the contrast detected by each of the image pickup means by the contrast detecting means, Based on the comparison result of the means, the above-mentioned calculation based on the output of the image pickup means having a low contrast is prohibited, and the output based on the output of the image pickup means having a high contrast is used. There are automatic focus detection apparatus characterized by comprising a controller that controls so as to perform the above operation. 2. When the reliability of the focus state calculated based on the output of the image pickup means having a large contrast is low, the control means controls to perform the calculation based on the output of the image pickup means having a small contrast. The automatic focus detection device according to claim 1, which is characterized.