JPS59146010A - Focusing detecting method - Google Patents

Abstract

PURPOSE:To speed up focusing adjustment by finding the F number of an optical image formation system and the extent of a shift between images by pieces of luminous flux at two parts on an expected focal plane on the basis of outputs of photodetecting element arrays, and calculating the extent of a lateral shift between the focus position of an optical image formation system and the expected focal plane on the basis of those values. CONSTITUTION:The photodetecting element arrays 27 and 28 are arranged in front of and behind the expected focal plane 22 of the optical image formation system 21 or optically conjugate plane. Pieces of luminous flux from two parts of the exit pupil of the optical image formation system 21 are split and made incident to one photodetecting element array 27, and luminous flux from one of two parts of the exit pupil is split and the made incident to the other photodetecting element array 28. Then, the extent 8' of lateral shifting on the photodetecting element arrays 27 and 28 between images by the pieces of luminous flux from the two parts of the exit pupil on the expected focal plane 22 is detected on the basis of the outputs of the photodetecting element arrays 27 and 28 to calculates the F number of the optical image formation system on the basis of the detected extent, thereby calculating the extent dF of shifting between the focus position of the optical image formation system 21 and the expected focal plane 22.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention (J) relates to a focus detection method for detecting the focus state of an optical device such as a camera, microscope, or mirror.

There are several methods for detecting the in-focus state of the image formed by the imaging optical system. Figure 1 Δ is a one-line diagram showing a configuration example when the focus detection equipment that implements the blur image detection method is applied to a single-lens single-lens camera.
3 C111υ shadow lenses, the light beam from 1 is a quick return mirror J partially formed as a half mirror 2
3, the luminous flux transmitted through the -2 is reflected by the reflective mirror 4. It is guided to the splitter 5, where it is split into two, and enters the 1χ·1 light-receiving water droplet array (5△, 6 [3). ] 5 is arranged so as to be at an optically equivalent position to the planes 8 Δ, 8B separated by a certain distance Δ before and after the 7. In such a focus detection device, The sharpness of the image is determined from the output of each of the light-receiving element arrays 6A and 6B, and by comparing the two sharpnesses, the front focus, rear focus, and in-focus states are determined.

However, in general, the illuminance P of a point image formed by an imaging optical system is expressed as ()α-F 2- , , / dz2, where F is the F number and the amount of out-of-focus is (IZ). As shown in Figure 1 [3], the rate of change becomes extremely small as the amount of deviation from the bottle mill increases, as well as the rapid attenuation due to the deviation of the bottle mill. Even if the detection is accurate, as the amount of deviation from the bin increases, the difference in sharpness obtained for each light receiving element row 6A, 6B becomes small, and the Oka-kage lens 1 becomes front focus or rear focus with respect to the scheduled task ff1j 7. There is a drawback that even if there is a large deviation in the direction of the bin, it may be mistakenly judged as being in focus.One way to eliminate this drawback is to increase the optical path difference △, and when the deviation m is large. It is conceivable to create a sharp edge so that a large difference in sharpness can be obtained between the two, but in this way, for an image having only high-frequency components, the sharpness of becomes extremely low, and the difference does not change much over a wide deno-A-cus range, making focus detection difficult.Also, conversely, the optical path difference △
If the image is made smaller according to the image of the high frequency component, the focus and state of the image of the high frequency component can be detected with high precision.
J mentioned above, sea urchin bottle 1 - mistake C when the amount of deviation is large
This method has the disadvantage that it may be difficult to judge whether the image is in focus or not, and it is difficult to detect the focus because a sufficient difference in sharpness cannot be obtained with an image having only low frequency components. In addition, in such a detection method, since the difference in sharpness does not directly correspond to the amount of differential A-cushion with respect to the expected focal plane 7 of the photographing lens 1, the image carrier lens 1 is moved to the focusing position. There is a drawback that it is not possible to calculate the amount of movement of the stop to be positioned.

Figure 2A shows an example of the configuration when a focus detection device that implements the lateral shift image detection method is applied to a single-lens reflex camera. In this focus detection device, there are 1 and 4 total reflection mirrors.
The light beam reflected from the darkest lens 1 is passed through a fly's eye lens array 9 consisting of minute fly's eye lenses, and is brought close to the fly's eye lens array 9 to a plane that is optically conjugate with the predetermined focal plane 7 or near it. There are q people in the arranged light receiving element row 10.
I'm letting you do 4.

As shown in FIG. 2B, the light receiving element array 10L includes light receiving element groups 10Δ, 10B, and these light receiving element groups 10A,
10B each light receiving element 10Δ-1 to 10Δ-11 and 1
0B-1 to 10B-n are each one light receiving element 10
Δ-1, 10B-, 1; ~: 10A-n and 10B-n form a pair, and all of these light receiving elements are arranged in a straight line. Further, the fly-eye lens j7 ray 9 has 11 fly-eye lenses 9-1 and 9 corresponding to the n light-receiving element pairs, and the two light-receiving elements T constituting each light-receiving element pair are , the light beams that have passed through the different parts of the exit pupil of the photographic lens 1 (in Fig. 2, the upper and lower parts l) bordering on the plane perpendicular to the paper including the optical axis are separated and received. It's arranged like this.

In this configuration, when a small common part of the object image is projected onto the light receiving element array 10 through the lens 13 and the fly's eye lens array 9, the light receiving element group 10A is exposed to the photographing lens 1. In the figure, only the light beam that has passed through the lower part of J3C is incident on the light receiving element group 10B, and on the contrary, only the light flux that has passed through the upper part of the light receiving element group 10B is incident on the light receiving element group 10B. 'B L The intensity distribution of the projected image is in focus 1 (43), and when out of focus, it varies depending on the direction of deviation as shown in Figure 2 C. The focus detection device d5-C appropriately processes the outputs of the light-receiving element groups 10Δ and 10B to detect the lateral shift direction of C@, and based on this, the forward The focus states of pin, rear bin, and in-focus are detected.

A focus detection device that uses such a lateral shift image detection method has the advantage that the focus detection range is much wider than the detection method, but each fly-eye lens 9
q・ of the photographing lens 1 formed by -1・～9-n
In order to prevent the images of the first pupil from overlapping, it is necessary to leave a gap between successive prior eye lenses. For this reason, especially when the intensity distribution of the image has high frequency components that change rapidly, for example, 1.1, if the step part enters the gap between successive fly-eye lenses, a dead zone with a shift of several positions will occur. Focusing accuracy decreases. therefore,
When the high frequency component is b'''')@, the position determined to be in focus changes depending on the relative positional relationship between the image and each fly's eye lens, and the accuracy is insufficient.

One possible way to solve this problem is to further reduce the diameter of each fly-eye lens, or shorten the focal length of each fly-eye lens to reduce the gap between successive fly-eye lenses. However, if this is done, the usable light stripes will be reduced, resulting in poor sensitivity, and the addition of the fly's eye lens and any optical adjustment between each fly's eye lens and the light receiving element will become extremely difficult. In addition, although such a focus detection device can detect the amount of lateral deviation of the image, if the F number of the INN shadow lens 1 cannot be detected in some way in advance, the amount of defocus of the projection lens 1 with respect to the predetermined focal plane 7 may be Since the lens cannot be moved out, it is not possible to calculate the amount of movement needed to position the photographic lens 1 at the in-focus position.

As described above, in the blurred image detection method, the focus detection range in which the front bin, back bin, and focused state can be accurately detected is narrow, but especially for images with b high frequency components, the predetermined focal plane is It has the advantage that the optical path difference between the two light-receiving element arrays centered on the center is not relatively small, and the in-focus state can be detected with high precision. For wide images and especially those having low frequency components, there is an advantage that the in-focus state can be detected with high precision without almost producing the dead zone of several structures as described above.

However, in the blurred image detection method, the difference in sharpness found in each light receiving element row does not directly correspond to the amount of defocus of the photographing lens with respect to the intended focal plane. In addition, the lateral shift @ detection method can detect the lateral shift and hanging of the image, and the camera lens cannot be detected in some way in advance. It is not possible to calculate the amount of movement required to position the focus position.For this reason, in the conventional focus detection method, the focus state is detected while sequentially detecting the focus state. The drawback is that adjustments cannot be made quickly.

An object of the present invention is to provide a focus detection method that allows focus adjustment to be made easily and quickly, particularly by determining the amount of deviation of an imaging optical system from a predetermined focal plane.

In the focus detection method of the present invention, a pair of light receiving elements is arranged before and after a predetermined focal plane or an optically conjugate surface of an imaging optical system, and one row of light receiving elements is provided with a predetermined focal plane or an optically conjugate surface of the imaging optical system. The light beams from two parts of the exit pupil are separated and incident on the other light receiving element array, and the light flux from at least one of the two parts of the exit pupil is separated and incident on the other light receiving element row. 2 of the exit pupil that moves to the predetermined focal plane based on the output of
The amount of lateral shift of the image due to the luminous flux of two parts δJj J: and IF
The lateral deviation δ′ of the image produced by the light flux of il-6b is detected between the photodetector arrays, and the lateral deviation δ′ (this base (
While calculating the F number of the imaging optical system with X (this [
Based on the number and the amount of lateral deviation δ, the imaging optical system σ) Sicon 1
Displacement ff1 (I F) between the position and the planned focal plane
I is spelled as 1 old number.

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 3 is a diagram showing the configuration of an example of an optical system of a focus detection armor embodying the present invention. In this example, the light flux guided from the imaging optical system 21 to its predetermined focal plane 22 is divided by the half mirror 23, and the light flux is divided into two by the beam splitter 24, and then - The light receiving element arrays 2743 and 2ε3 (provided on the same base 1 26) are incident through a common lateral shift optical system 25.

The light-receiving element rows 27 and 28 have their light-receiving surfaces separated by a constant optical path difference △ before and after the intended focal plane 22, respectively.
．． A position optically equivalent to 30 (W is set here).

In this example, the horizontal shift optical system 25 is used to form two parts of the exit pupil of the quadratic optical system 21, for example, the and the upper part) 1', separating the bundles and separating them.

The resulting light flux is received by each of the r arrays 27 and 28 of light receiving elements.

Fig. 4 △l, light-receiving element row 27, 28 and Jli-+f
1 is a plan view showing the configuration and arrangement relationship of an example of the optical system 25;
Formed C1V plate 2G to \M< (formed, 1h each
It has 211 light-receiving elements linearly arranged, and two adjacent light-receiving elements, that is, the light-receiving element pair 27 A3 has a light-receiving element F27Δ+, 271'3+: ~: 27Δn, 2
7131) is the light receiving element array 28 (- indicates the light receiving element 2
8A+, 28B+: ～・: 28△n, 23 ['3n is 11 sore・] completed. -10,000, Lateral shift optical system 21)
In this example, the light receiving element pair of each light receiving element 91127.28 corresponds to E11.
``C mask: (consists of 19 live mask plates from the sl on which i is formed, and these masks 31 form the imaging optical system 21
The light beam transmitted through two parts of the exit pupil is separated,
Figure 4B (Indication of each light receiving element pair, e.g. λ light receiving element pair 27A+, 27113+) and the other photodetector f27 B + 1., -
! The bundle is then passed through the other part of the injector. ? In other words, on the mask 31, J, each light receiving element j
' A pair of light receiving elements with 162 turns, for example, light receiving element 27
A1 and 27B1 (FIG. 4, C-33 and 1) are made to have an angular dependence of the light they receive. This angular dependence can be determined by adjusting the width of the mask 331 and the distance between the light-receiving element rows 27 and 28 and the lateral optical system 25.
··Wear.

j, sea urchin configuration 44'th 3t, 8 receiver) and element row 27.
28, each of them is a group of light receiving elements forming a pair, for example, light receiving element group 27A+-・27Δn L13 and 28A+~28Δ "1 is one of the DJ departure groups of the imaging optical system.
For example, in FIG.
The light flux that has passed through the side part is returned to 1- and is received, and the other/) light is received
II, I3yo U 28 [3+ ・~2ε3 B
n is bundled in Q, J's (l!! i5 part, 4 transmitted through the part on the Iζ side bordering on the plane perpendicular to the plane of the paper containing >u'tMII of the imaging optical system 21). Mainly C light receiving 4
(J becomes. However, each photodetector - (column 27.2
Strong electric molecule 1 of the image received by both photodetector groups at 43 in 8
1 (, 1, pin 1 of the 1.-1 image optical system 21 on its light-receiving surface
When the ~ position is located, it is 15゛, and when the pin 1~ position is not on the light receiving surface, it is moved sideways in the opposite direction. Element rows 27d3 and 2B have their light-receiving surfaces separated by a constant optical path difference Δ before and after the predetermined focal plane 22, respectively.
Since −C is logically placed at the position 1i1[i,
j) Image forming optical system 214 is shown in Figure A (-shown).
The in-focus state where the focus position of the image to be formed is on the 2nd plane R-1- (this is U4, the planned focal plane 22
-1-r The upper side (15J, With the optical path difference △, both the light beams move in opposite directions perpendicular to the optical axis, and the bright Glt i mark of the image becomes 11 (I(
To L 'U 1. :L becomes equal.

In other words, in the focused state (for example, the imaging optical system 21
Image formed by J, 1) i sedge-shaped -00-C
The upper part of the imaging optical system 21 formed by the light-receiving element array 27, the predetermined focal plane 22, and the light-receiving element edge 280 (,' The intensity of the image (dashed line) of J, which is the luminous flux with the chief ray in the upper part, is Yli i.
The light receiving element row 274. The upper part formed by the two light beams (the image formed by the light beam t having the principal ray and the upper part formed by the light-receiving element array 28)) are approximately equal, and the lateral deviations from the image formed on the constant focal plane 22J are also approximately equal.Similarly, +f formed on the light receiving element 27
The image by Kuto and the image formed on the light receiving element array 28 by the light beam with a one-t likelihood line in the upper part (Ct) (J Kadababo) Also, IJ for the lateral deviation from the image formed on the -r steady plane 221 becomes equal, and as a result, both light-receiving cables 1j2
7.28, each luminous flux has an approximately equal blur of 1, ->' (1 area formed by n, and an approximately equal lateral shift of -4 in the group vs. 1 direction (,, 2). 4fru.

According to the present invention, in the out-of-focus state (-) of the front and rear focus as shown in FIG.
1 The focus of the imaging optical system 21 (Q is used to determine the deviation of the predetermined focal plane 22 (-d), but this deviation is 1t)
1 (1!-) is the light beam that has passed through the two exit pupils of the imaging optical system 21, for example, the optical system 21.
In 1), there is a luminous flux with the chief ray in the upper part bordering the axis, and a luminous flux with a round line in the lower part.
-e tI shadow is formed on the planned focal plane 221 of the image; J31
．． If the side-slip suspension of J is δ, there is a relationship of [-1-d[7('5), and it can be found by d 1'' = I · δ.

Here, "-" indicates the positive side of the imaging optical system 21, and "=" indicates the principal ray on the lower part).
．． 28, Zunawara Irera's equal light-receiving surface 129.3 (-)
If we take δ' as the amount of lateral shift in the equivalent light reception of the second saw 416 formed on each side, the optical path % between the two equal light receiving surfaces 29.30 is 2△, so [,,(Kδ ′/2△.Therefore, since the optical path difference 2△ is set to −j; (Seedlings≦1-remlδ' is, for example, the light receiving element where the light flux in the same direction is mainly received by the light-receiving element rows 27 and 28.)
Take out the output of 28Δ1) to 1.28A+, and
2 153 'l Described in Publication No. 33 - (Iru J
The number of light receiving elements corresponding to the amount of lateral shift can be determined by comparing the image information of each of the above as +=I-+, and calculating from this number of light receiving elements and its array bit. In addition, this horizontal 4' suspension δ' is ↑ 1, sea urchin 1 - nonba [3
2) and then it changes, or it goes out of focus.
The number of the camera lens etc. is 1.4.2. E3. Discrete if(
Since this δ' (ko2) is taken directly, G1 has some error, and C is also calculated. You can also selectively read out and use these !, 1 F'-) which is closest to the 1-Pumba obtained by calculation from the 1-Pumba.

-10,000, horizontal deviation (Hδ) at the predetermined focal plane 220
(Thus, the luminous flux of
It almost corresponds to the horizontal Yokosuri River. In other words, when a3 is in the focused state as shown in Fig. 7, the intensity distribution α, β, 7'i, and T of the planned focal plane 22 and the intensity of -C, and A are given by the intensity of The lower part of the imaging optical system (including the −EL rays) has an intensity angle Cχ′ at ℃ on the equilateral light-receiving surface 29,
1 for β′, γ′ and the luminous flux with the chief ray in the upper part,
Both light-receiving surfaces 30
, 7n are shown in Fig. 5) for the intensity molecules liα, β, γ at the predetermined focal plane 22F as explained in 13) within a range not far from the axis by 1; ``C'' is almost the same as the 7th one.
In the front bin state d3 shown in FIG. 13 and the rear bin state J3 shown in FIG. α′, β′,
γ′ and the strong 1α distribution α″, β″, γ″ at the equal-bilateral light-receiving surface 30]E with the principal ray b in the upper part are laterally shifted in the opposite direction, and the early lateral shift δ is Planned focal plane 22F
-[The lateral deviation of the image due to the oriented light beam is nearly identical, and the out-of-focus Φ is in a proportional relationship within a range not far from the optical axis of the imaging optical system. In this way, there is a lateral shift between the image of one of the light beams formed on the two light-receiving surfaces 29-1-, and the image of the other light beam formed on the two light-receiving surfaces 30-1. Since the amount of lateral deviation δ of the image due to both the light beams of the predetermined focal plane 220 coincides with cd, for example, the amount of lateral deviation δ of the image due to both the light beams from the light receiving element array 27 is Take out the output and connect it to the light receiving element array 2.
From 8, let us take out the output of the light receiving element group 28B1 to 28Bn, which receives the light beam in use.
Described in Publication No. 33
By sequentially comparing the number of light-receiving elements corresponding to the lateral deviation with a shift of 1-, it is possible to detect the lateral deviation δ from the number of light-receiving elements and the arrangement pips.

As described above, in the present invention, the F bumper F of the imaging optical system 21 and the lateral shift angle δ of the image ' on the predetermined focal plane 22 are obtained, and based on these F iJ3 and δ, the imaging optical system 21 The amount of deviation between the focus position and the planned focal plane 22 (out of focus fi
) dF is detected, but in this example,
Based on this shift Mid F, the amount of movement of the imaging optical system 21 in the optical axis direction is determined, and the movement direction is determined based on the light receiving element array 2.
7.28, the C imaging optical system 21 is automatically moved, and then both light receiving element arrays 27. Based on the output of 28, the sharpness or lateral shift of the image falling on the predetermined focal plane 22 is detected and verified, and if it is insufficient, the imaging optical system 21
While automatically moving in small steps,
Verification is repeated until the focus position falls within a preset focus range, and the imaging optical system 21 is finally positioned in the focused state. For this reason, the sharpness or lateral shift of the image on the predetermined focal plane 22 is
Detection is performed by comparing the sharpness of each image at 7°28, and a lateral shift image is detected based on the outputs of both light-receiving element arrays 27 and 28. Here, as an evaluation function for detecting the sharpness on each light-receiving element row 27.28 and the lateral shift image on the predetermined focal plane 22, - is the
7A+ ~27△n output is ``I~a ns light receiving element group 27B +~27B n output is b+~b
, and the light-receiving element group 28 A + of the light-receiving element array 28
The output of 28 A n is a + , ~'''n, and the output of light receiving element group 28 B + ~ 28 B n is b' 1 ~
b'
+++ b' 1-Hl, -2 -1a l-1-b' +++ l) or -ia' + -1b I+I l) can be used, and the sharpness of the light-receiving element array 27-1:'c Regarding the evaluation function for detecting the degree, for example, [3a=l (a
1+b 1) -(a +-+ +b l-1) Infax
For the evaluation function for detecting the sharpness on the light receiving element array 28, for example, F3b=l (a'!+b' +) (a' +
−++b′ + −+ ) 1max [1-2 to n] can be used, respectively.

As shown in FIG. 8A, the evaluation value Y based on the above-mentioned lateral deviation image evaluation function is Y=O at the in-focus position where the focus position is located on the predetermined focal plane 22, and Y>O in the front focus and rear focus states, respectively. and Y<O, and the polarity is reversed. Focus detection using this lateral shift image can effectively detect the focus state over almost the entire range of movement of the imaging optical system 21, and is particularly suitable for focus detection of images having low frequency components. Therefore, in this example, the above! When moving the imaging optical system 21 based on the ζ deviation ff1dF, this evaluation value Y is detected, and the direction of movement of the imaging optical system 21 is determined based on its polarity. On the other hand, in order to perform R-like focus detection using this evaluation value Y, a predetermined threshold value -1 is set. On the other hand, the sharpness, that is, the evaluation values 13a and Bb based on the image evaluation function, are as follows:
As shown in FIG. 8B, it is maximum when the pin 1 to position is located on each light receiving element row 27 and 28, Ba -8b to 0 at the in-focus position, and Ba -8b to 0 in the front focus and rear pin states. are Ba−Bb>oJ5 and Ba −
Bb <O, and the polarity is reversed. These evaluation values Ba
, Bb, although the detection range is narrow, focus detection based on blurred images is particularly useful for detecting focus on images with high frequency components. 3. Setting a predetermined threshold L2 to perform accurate focus detection; When a0Bb>2, focus detection is performed using this blurred image.

Furthermore, although not shown, the focusing range F+ is determined for the evaluation value Y.
(F+ <L+) so that when IYI≦T1, it is determined that the focus is on, and the evaluation value is 1Ba-Bbl.
Also, set the focusing range F2 (F2 >> 12 > to 1Ba-Bb
In-focus is determined when l≦F2. In addition, in this example, in order to increase the reliability and accuracy of the final focus detection after moving the imaging optical system 21 based on the deviation dF, a C threshold L3 is set for the evaluation values Ba and Bb. Shi, I
Y! <L+ and either Ba or Bb is 13
If it is smaller than , it is determined that verification is impossible and no further focus detection is performed.

FIG. 9 is a block diagram showing the configuration of an example of the signal processing circuit of this embodiment. In this example, the drive circuit 41 reads out the output of the light receiving element rows 27 and 28, converts it into a digital signal via the amplifier 42 and the A/D converter 43, and stores the image intensity distribution of each row in the storage circuit 44. Based on these image intensity distributions, necessary calculations and judgments are performed in a C-processor/judgment circuit 45, and based on the results, a motor 47 moves the imaging optical system 21 to the optical axis via a motor drive circuit 46. At the same time, the display circuit 48 displays each focus state of in-focus, front focus, and rear focus. Note that the operation of each part is controlled by a control circuit 49.

The operation of the signal processing circuit shown in FIG. 9 will be described below with reference to flowchart 1 shown in FIG. 10.

First, the image intensity distribution of the light receiving element rows 27 and 28 is stored in the memory circuit 4.
4, the calculation/judgment circuit 45 calculates the above-mentioned deviation md F and lateral deviation image evaluation value Y based on these image intensity distributions, and calculates the amount of movement of the imaging optical system 21 to the in-focus state. At the same time, the direction is determined, and based on the result, the imaging optical system 21 is moved by the motor 47 via the -C motor drive circuit 46. Next, in order to verify whether or not the moved imaging optical system 21 is in focus, the image intensity distribution of the light receiving element rows 27 and 28 at that position is loaded into the storage circuit 44 and calculated. - After calculating the evaluation values Y, B a , F3 and I3b mentioned above in the determination circuit 45,
First, it is determined that l Y l >L+, and when IYI>L+, then 3a +3b >l, 2 is determined, and Ba+Bb>
When l-2, that is, when the image has high frequency components,
Verification is performed by detecting a blurred image by comparing these 13a and Bb. When 1Ba-Bbl≦F2, the focus is determined and this is displayed on the display circuit 48, and when 13a-13b>Q, it is determined that the front is in focus and this is displayed on the display circuit 48. At the same time, the imaging optical system 21 is moved step by step in the direction closer to the predetermined focal plane 22 via the motor drive circuit 46 and the motor 47.
Verification is repeated until Ba-Bbl≦F2. Similarly,
When Ba - Bb < 0, it is determined that it is the rear bin, and this is displayed on the display circuit 48, and the motor drive circuit 4
6 and the motor 47, the imaging optical system 21 is moved stepwise in the direction away from the predetermined focal plane 22.
- Repeat the verification until Bbl≦F2.

Also, l Y l > L + ”C and 3a+3b<
When l-2, that is, when the image has low frequency components,
Verification is performed by detecting a lateral shift image using the evaluation value Y.

In other words, when IYI≦F1, it is determined that the focus is in focus and this is displayed on the display circuit 48, and when Y>O, it is determined that the focus is on the front and this is displayed on the display circuit 48, and the motor drive circuit 46 Then, the imaging optical system 21 is moved in steps in a direction closer to the predetermined focal plane 22 via the motor 47, and the verification is repeated until IYI≦F1.

Similarly, when Y<0, it is determined that it is the rear bin and this is displayed on the display circuit 48, and the motor drive circuit 46
Then, the imaging optical system 21 is step-moved via the motor 47 in the direction of moving away from the predetermined focal plane 22, so that IYI≦
Repeat the verification until it reaches F1'1J.

Furthermore, when IYI<1+, next determine Ba>L::+ and Bb>13, and when both are satisfied, Ba+3b
>12 is performed to perform verification using the above-mentioned blurred image or lateral shift image. Further, if either 3a≦L3 or 13b≦L3, it is determined that verification is impossible, and subsequent focus detection is stopped.

Note that this unverifiable state may be displayed on the display circuit 48.

According to the focus detection device of this embodiment described above, the amount of deviation d
Since the movement ω and direction of the imaging optical system 21 to the focused state are determined based on F and the lateral deviation image evaluation value Y, and the imaging optical system 21 is automatically moved based on this, the imaging optical system 21 is automatically moved. The key is to quickly adjust the focus. In addition, since the lateral shift imager value Y is detected by giving the two light-receiving element rows 27 and 28 an image in the focused state, it is possible to improve the focusing accuracy by the lateral shift, and also to detect this lateral shift. Since the final focus adjustment of the imaging optical system 21 is carried out by using both the power type and the blur power type, the focus adjustment can be performed in accordance with the subject image (with high viscosity).

It should be noted that the present invention is not limited only to the above-mentioned examples, and can be modified or changed in many ways.

For example, the light receiving element arrays 27 and 28 are not shown in FIG. Light-receiving elements 27C+ to 27C that receive and cover the light flux that has passed through the two parts
n-1, 28C+ to 28C: J where n-1 is located,
You can also compose the sea urchin.

In this case, image sharpness Ba, Bb in each light receiving element row 27.28 is set to each light receiving element group 2701 to 270n-+
, 28G+"-28Cn-+, and the outputs of the light-receiving elements 11\27C1-27Cn-+ are C1-CnI, the light-receiving element group 28C; +"
28 The output of Cn −+ is cl,, ~C' (5-1
For example, F-3a = lc +-+ -C+ 1max3b=
lc' i-I C' 1 )IllaX(1-
2~(n-'1)). By doing this, the light utilization rate of the blurred image method can be increased, the S/N ratio can be improved, and the focusing accuracy due to the blurred image can be improved since the dead zone of C is not a problem since the blurred image is used as a blurred image. Improvement 1! can be done. This is because each light receiving element array 27.
281-The spread of the sharp point image is
CI” 27 Cn −+ .

28C+"28Cn-+'s JI1~ frequency is determined by the light-receiving element bit, and the light-receiving element 4.Z of each light-receiving element group is successively straddled.

A similar effect regarding this dead zone can also be expected for the lateral shift force type. Also, the lateral shift optical system 25 has a large number of minute fly eye lenses 51 as shown in FIG. In this case, there is no need to block light as in the case of using a mask, so the light utilization efficiency can be increased.Furthermore, in the embodiment described above, in each light receiving element array 27, 28, the imaging optical system 21 However, the present invention is also effective even if one of the light-receiving element rows is configured to separate and receive the light flux from one part of the exit pupil. Furthermore, in the above-mentioned embodiment, the lateral shift image evaluation (
a Y and determined the moving direction of the imaging optical system 21 based on the shift id F based on its polarity, but the shift ff1d
It is also possible to detect the moving direction of the 8jj stem of the side-slip boat δ when calculating I-. Further, the present invention can be effectively applied not only to cases in which focus adjustment is performed automatically, but also to cases in which focus adjustment is performed manually.

In this case, the amount of movement and direction of the imaging optical system 21 based on or based on the amount of deviation d can be displayed, for example, by representing the size and length of an arrow corresponding to the direction of movement.

1- As described above, according to the present invention, two of the exit pupils of the imaging optical system are arranged on one side of the light-receiving element rows arranged before and after the scheduled function 1fii of the imaging optical system or a surface optically conjugate thereto. The luminous flux of one part is separated and incident on the other part, and a small amount of the luminous flux of one part is incident on the other part.

Based on the output of one row of these photodetectors, we can calculate the lateral shift angle δ of the image (at the focal plane of the imaging optical system and at the predetermined focal plane). Since the amount of deviation d between the focus position of the imaging optical system and the expected focal plane is determined based on these [-number, lateral, deviation aδ, etc.], focus adjustment can be performed quickly. can.

[Brief explanation of drawings]

Figures 1A and [3 are diagrams for explaining the method of detecting a blurred image, Figures 2A to G are diagrams for explaining the method of detecting a lateral shift image, and Figure 3 is a focal point for implementing the present invention. Diagrams showing the configuration of an example of the optical system of the detection device, FIGS. 4A to 4D show the configuration of an example of the horizontal shift optical system from the light-receiving element array d3, and the angular dependence of light of Okawa on the light-receiving element. The diagram, Fig. 5 Δ~1] shows a comparison of the intensity distribution of the lateral shift image between the two light receiving element arrays in the focused state () and the image intensity distribution on the predetermined focal plane C. 6 and B are the relationship between the focus position at J3 in the front focus and rear focus states, the lateral shift angle δ13 J: and the lateral shift amount δ' between the light-receiving element case j Figure 7 Δ~C shows the lateral shift and suspension of the light receiving element rows C between the light receiving element rows due to the light flux of the two parts of the exit pupil in the in-focus, front-focus and rear-focus states, and the lateral shift on the planned focal plane. Diagrams showing the relationship; FIG. 8 △J3 and 13 are diagrams showing an example of the horizontal shift image evaluation side curve and the blurred image evaluation side curve; FIG. 9 is a diagram showing the configuration of an example of the signal processing circuit. Figure 10 is a flow play 1 for explaining the operation.
・, FIG. 11 is a J'P plane view showing the configuration of another example of the light-receiving element array, and FIG. 12 is a plan view showing the configuration of another example of the lateral shift optical system. 21... Imaging optical system 22... Predetermined focal plane 23
...Half mirror 24...Beam splitter 25.
... Lateral shift optical system 26... Substrate 27.28...
Light-receiving element array 29.30...Both light-receiving surfaces 31...Mask 41...Drive circuit 42...Amplifier
43...A/D converter 44...memory circuit
45... Arithmetic/judgment circuit 46... Motor drive circuit 47... [-ta 48... Display circuit 4
9...Control circuit 51...Fly eye lens 1st country ^ Focus external relative Ma al Fig. 2: Fig. 3 Fig. 4 Fig. 4 CD Gun Fig. 5 800〇 6 Fig. 7 A Fig. Figure 7 Figure 11 Figure 12 Procedural amendment: January 14, 1981 1, Indication of the case 1988 Special if 1 Application No. 195 IL 3 No. 2,
Name of the invention Focus detection method 3, correction 4" Relationship between 11 cases - Patent applicant (O87), i-Linbus Optics - L business association rI, (1)
Page 8 of the specification, line 1 [1 ``Even if it is possible, taking lens 1'' is replaced with ``J, even if it is possible, due to lens replacement, etc.'' If the number of taking lens 1 is changed, the taking lens 1” to JJ
Correct, in line 4 of the same CI, ``Because I don't have a Jr. (2) Lines 1 to 2 of page 11 [1: ``Front surface perpendicular to the page and the Shimoda 11 portion'' is changed to ``the front side and other portions bordering on the plane parallel to the page'' Correct. (3) Line 19 of the 12th autograph [vertical, the upper side bordering on the blood] is 1) parallel to the hand 1) on the 1j side”, dr is correct 1
-ru. (4) No. 13 μ, lines 3 to 4 [1: Correct ``the part below 1111 perpendicular to the page'' to ``the part on the other side bordering on the plane parallel to the page'' 2. . (5) Insert the vertical and horizontal shafts as shown in Figure 5G of the drawing, and press the shaft as shown in the attached sheet. Representative Patent Attorney Akatsuki Sugimura Hidegai 1 Figure 5 (Corrected Figure) 91 Only 1

Claims (1)

[Scope of Claims] 1. One row of light receiving elements arranged 1'1" in front and behind a 1" constant working surface of the imaging optical system or a surface optically conjugate to each of them;
1 One light-receiving element array separates the light flux of two parts of the UL exit pupil of the imaging system, and the light flux of the C input QJ is separated, and the other light-receiving element array has two parts of the Q=J exit pupil. The luminous fluxes of the two parts of the exit pupil in the predetermined focal plane are separated into two parts of the exit pupil in the predetermined focal plane (J), and based on the output of the element η11, The lateral deviation ti't' of the resulting image is determined by δ, and the lateral deviation δ' between the r arrays of light-receiving elements of the image due to the light beam of the same portion is detected, respectively, and the lateral deviation 1' is δ.
′, calculate the ``)-value'' of the C imaging optical system based on ′, and
Based on this F number and the lateral deviation δ, the focus detection method is characterized in that the position of the pin 1 of the optical system and the amount of deviation dF of the m-key focusing plane are calculated. 2. Based on the output of each light-receiving element array, the sharpness or lateral deviation of the image relative to the predetermined focal plane is detected, and depending on this sharpness or lateral deviation, the image optical system relative to the predetermined focal plane is detected. The focus detection block according to claim 1, characterized in that it detects the final in-focus state of the bale.
law, 7