JP3177994B2 - Focus detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focus detecting device such as a camera.

[0002]

2. Description of the Related Art Conventionally, a phase difference detection method has been known as a focus detection method in a single-lens reflex camera. This method will be described with reference to FIG. Shooting lens 2
The light beam that has passed through the first region 21a and entered the field mask 3
1. An image is formed on the photoelectric conversion element array 41a through the field lens 32, the aperture opening 33a, and the re-imaging lens 34. Similarly, the light beam transmitted through the area 21 b of the photographing lens 21 enters the field mask 31 and the field lens 3.
2. An image is formed on the photoelectric conversion element array 41b through the aperture 33b and the re-imaging lens 35.

Here, in a so-called front focus state in which the photographing lens 21 forms a sharp image of a subject before a predetermined focal plane, a pair of subject images formed on the photoelectric conversion element arrays 41a and 41b approach each other, On the other hand, in a so-called rear focus state in which a sharp image of the subject is formed behind the planned focal plane, they move away from each other. At the time of focusing, in which the photographing lens 21 forms a sharp image of the subject on the predetermined focal plane, the subject images on the photoelectric conversion element arrays 41a and 41b relatively match. Accordingly, the pair of subject images are photoelectrically converted by the photoelectric conversion element arrays 41a and 41b and converted into electric signals, and further, these signals are arithmetically processed by a microcomputer (not shown) to perform relative processing of the pair of subject images. Is obtained, a focus adjustment state of the photographing lens 21, here, a shift amount from the in-focus state and a shift direction thereof (hereinafter, referred to as a defocus amount DF) are obtained.

In a conventional device of this type, as shown in FIG. 21, an area (a) of about ± 2 to ± 3 mm on a focus detection surface 50 centered on a position (b) intersecting with the optical axis LX of the photographing lens. ) To (c) as a focus detection area, an image in this range is formed on the photoelectric conversion element arrays 41a and 41b on the IC substrate 41 by a pair of re-imaging lenses 34 and 35, and the two photoelectric conversion element arrays 41a and 41b are formed. The focus detection is performed by detecting the relative image shift amount from the image output of (1).

In a focus detection device of a single-lens reflex camera, it is necessary to prevent vignetting in a focus detection optical system even for an interchangeable lens having an open F value of about F5.6. The exit pupil position of the F5.6 photographing lens is often somewhere in the range of about 50 mm to 200 mm indicated by hatching, and vignetting is caused by the F5.6 lens whose exit pupil position is in this range. Does not occur, the spread α of the detection light beam needs to be about F7.

Further, by projecting the apertures of the re-imaging lenses 34 and 35 around the exit pupil position 100 mm (in the range of L1 in the figure) by the field lens 32, a point (image height 2-3 mm from the optical axis) is obtained. Regarding the light beam (broken line) passing through (a) and (c), the focus can be detected without vignetting for the F5.6 lens having the exit pupil position of 50 mm to 200 mm. By adopting such a configuration, in the conventional focus detection device, focus detection was possible without vignetting in a range of about 3 mm in image height.

[0007]

By the way, there is a demand that focus detection should be performed at positions (d), (e) and (f) which are at least 3 to 4 mm away from the center of the optical axis. Therefore, for example, the re-imaging lenses 61a and 61b and the IC substrate 71 are arranged as shown in FIG. 21 so that (d), (e) and (f) around the point (e) having an image height of 7 mm as the focus detection area. So that In this case, the focus detection optical system is configured such that the apertures of the re-imaging lenses 61a and 61b are
Thus, a conjugate image is formed almost at the position of the exit pupil position of 100 mm. In this case, as is apparent from the figure, the focus detection areas (d), (e), and (f) are
The use of the photographing lens of 5.6 does not cause vignetting only when the exit pupil position of the photographing lens is in the range of L1 around 100 mm. Therefore, usable interchangeable lenses are limited, and there are many practical problems.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a focus detection apparatus capable of accurately performing focus detection on a photographic lens having various exit pupil positions even when a position distant from the optical axis of the photographic lens is set as the center of the focus detection area. Is to provide.

The present invention will be described with reference to FIGS. 1 and 2 showing one embodiment. (1) A plurality of pairs of photoelectric conversion element arrays Sa and Sb, Sc and Sd, Se and Sf, and a plurality of pairs of light fluxes of a subject image passing through the photographing lens 1 are arranged on a predetermined surface. Photoelectric conversion element arrays Sa and Sb, Sc and Sd, Se
A pair of re-imaging lenses La and Lb for re-imaging on Sf and Sf
And a plurality of field lenses Fa, Fc, and Fe that are arranged near the predetermined focal plane of the photographing lens 1 and guide the light flux of the photographing lens 1 to the pair of re-imaging lenses La and Lb. , Fc, and Fe are Poa, Poc, Po on different exit pupil positions of the photographing lens 1, respectively.
e, pupil apertures Na and Nb of a pair of re-imaging lenses La and Lb
Are characterized in that they have optical performance to connect the respective conjugate images. (2) The focus detecting device according to (1), wherein the selection unit CU selects a pair of photoelectric conversion element arrays Sa and Sb, Sc and Sd, and Se and Sf.
And the selecting unit CU includes a plurality of pairs of photoelectric conversion element arrays Sa based on information on the exit pupil position of the photographing lens 1.
And Sb, Sc and Sd, and Se and Sf. 1 and 19 showing one embodiment.
The present invention will be described with reference to FIG. (3) A plurality of pairs of photoelectric conversion element arrays provided respectively for a plurality of focus detection areas set close to each other in a predetermined area outside the optical axis of the photographing lens 1. Re-imaging for re-imaging Sa and Sb, Sc and Sd, Se and Sf, and luminous flux of the subject image passing through the photographing lens 1 into a plurality of pairs of photoelectric conversion element arrays Sa and Sb, Sc and Sd, and Se and Sf. A lens L and a field lens F arranged near the predetermined focal plane of the photographing lens 1 for guiding the light flux of the photographing lens 1 to the re-imaging lens L, wherein each of the plurality of pairs of photoelectric conversion element arrays is a pupil; An information generating unit EPO for generating information on the exit pupil position of the photographing lens 1 which is applied to focus detection devices arranged in a direction orthogonal to the division direction, and a plurality of pairs of photoelectric conversions based on the information on the exit pupil position Element array S
a and Sb, Sc and Sd, and Se and Sf, a pair of normally functioning photoelectric conversion element arrays are selected, and focus detection information is calculated based on output signals from the selected pair of photoelectric conversion element arrays. And a control unit CU for outputting a control signal for controlling the photographing lens 1. (4) The focus detecting device according to claim 3, wherein the re-imaging lens L and the field lens F are
A plurality of pairs of photoelectric conversion element arrays Sa and Sb, Sc and Sd,
Lens portions La, Lb, L corresponding to each pair of Se and Sf
c and Ld, Le and Lf, and Fa, Fc, and Fe, respectively.

[0009]

(1) Since a plurality of field lenses Fa, Fc, and Fe have different optical performances, a pair of re-imaging lenses are provided on Poa, Poc, and Poe on different exit pupil positions of the photographing lens 1. L
The conjugate images of the pupil openings Na and Nb of a and Lb are respectively formed.
Only one pair of re-imaging lenses is required, and miniaturization is possible. (2) The invention of claim 2 The selection means CU selects one of a plurality of pairs of photoelectric conversion element arrays Sa and Sb, Sc and Sd, and Se and Sf based on information on the exit pupil position of the photographing lens 1. . (3) A plurality of pairs of photoelectric conversion element arrays Sa and Sb, Sc and Sd,
By Se and Sf, focus detection is performed on each of a plurality of focus detection areas set close to each other in a predetermined off-axis area. A plurality of pairs of photoelectric conversion element arrays Sa and Sb, Sc and Sd, Se and Sf, based on information on the exit pupil position of the photographing lens 1 output from the information generating means EPO.
The focus detection information is calculated by selecting a pair of normally functioning photoelectric conversion element arrays from among them. The control unit CU outputs a control signal for controlling the photographing lens 1 based on the focus detection information. A plurality of pairs of photoelectric conversion element arrays Sa and Sb;
Each pair of Sc and Sd and Se and Sf is arranged in a direction orthogonal to the pupil division direction, and focus detection is performed by any one pair of photoelectric conversion element arrays.

In the means and means for solving the problems which explain the constitution of the present invention, the drawings of the embodiments are used for easy understanding of the present invention. It is not limited to the example.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment A first embodiment of a focus detection device according to the present invention will be described with reference to FIGS. FIG. 1 is a view showing the concept of the present invention, in which a plurality of light beams entering through a plurality of regions on an exit pupil of a photographing lens 1 form images on a focus detection surface 2, respectively, and further a focus detection module described later. The light enters the MD, is re-imaged on the photoelectric conversion element array, and focus detection is performed for each light beam.

As shown in detail in FIG. 2, the focus detection module MD is an IC substrate on which a plurality of photoelectric conversion element arrays Sa, Sb, Sc, Sd, Se, Sf are arranged on a plane conjugate with the focus detection plane 2. S, and each region Ta, T of the taking lens 1
b, Tc, Td, Te, Tf Re-imaging lenses La, L for forming an image of a light beam passing through each photoelectric conversion element array
b, a lens plate L having aperture stops Na and Nb disposed in front of the lens substrate L and facing each re-imaging lens, and three portions Fa and F having different optical performances.
c, Fe, the pupil aperture N of the re-imaging lenses La, Lb
The conjugate image of a, Nb is converted into the regions Ta, Tb, Tc, Td, T
e, a field lens F for forming an image on a different exit pupil position through Tf, and a field mask M having a rectangular opening MO so that unnecessary light flux does not enter the photoelectric conversion element array. In FIG. 2, reference numerals Da, Dc, and De denote focus detection areas on the focus detection surface 2. The pair of photoelectric conversion element arrays Sa, Sb, Sc, Sd are formed by the re-imaging lenses La, Lb and the field lens F. This is an area where Se and Sf overlap and are projected.

Here, the field lens F will be described with reference to FIG. Three parts F of field lens F
As shown in FIG. 3, a, Fc and Fe are re-imaging lenses La and Lb on different exit pupil positions POa, POc and POe.
The pupil apertures Na and Nb have a power to connect the respective conjugate images, and have a shape shown in FIGS. 4A and 4B, for example.

In general, the exit pupil of the interchangeable lens of a 35 mm single-lens reflex camera has a length of 50 mm to 30 mm around 100 mm.
0 mm, the exit pupil position POa,
POc and POe are, specifically, 50 to 85 m each.
m, about 75 to 135 mm, and 120 mm or more. Here, P0a <POc <POe.

The field lens F shown in FIG. 4A is obtained by dividing the photographing lens into three parts with the side far from the photographing lens being flat, and the field lens shown in FIG. And the photographing lens side is divided into three parts. As described above, dividing the photographing lens side is preferable in light beam separation. Also, the field lens Fe farthest from the optical axis has the aperture pupils Na and N on the exit pupil POe furthest.
Although the image b is formed, the field lens Fe farthest from the optical axis may form the images of the aperture pupils Na and Nb on the closest exit pupil POa. From an optical design point of view, it is preferable to make it as shown.

As can be seen from FIG. 1, the light beam passing through the lower regions Ta and Tb on the exit pupil of the photographing lens 1 passes through the field lens Fa to form the re-imaging lens L.
The light fluxes formed on the photoelectric conversion element arrays Sa and Sb by a and Lb and passing through the areas Tc and Td set slightly higher than the areas Ta and Tb are transmitted through the field lens Fc to the re-imaging lenses La and Lb. The light flux formed on the photoelectric conversion element arrays Sc and Sd by Lb and passing through the areas Te and Tf set slightly higher than the areas Tc and Td is passed through the field lenses Fe and re-imaged by the re-imaging lenses La and Lb. An image is formed on the photoelectric conversion element arrays Se and Sf. In this specification, a pair of photoelectric conversion element arrays Sa and S
b, Sc and Sd, and Se and Sf are referred to as first to third array pairs, respectively, and are represented by symbols S1 to S3. Note that the relative positional relationship between the regions Ta to Tf in FIG. 1 with respect to the pupil opening of the taking lens changes depending on the pupil position of the taking lens.

Further, in FIG. 1, CU is a CPU, RO
A control circuit including M, RAM, and other peripheral circuits, and three pairs of photoelectric conversion element array pairs S1 each forming a pair.
A focus detection calculation unit AFC that detects an image shift between the respective arrays of each set based on the signals from S3 to S3, obtains a defocus amount from the focus detection surface 2 of the photographing lens, and performs focus detection. The EPO is a pupil position information generating unit that generates information on the exit pupil position of the photographing lens, and generates a value previously written in the lens ROM of the interchangeable lens according to the focal length. Generates a value corresponding to the focal length that changes with zooming. Also, HPO
Is a sensor position information generation unit that generates height position information of the focus detection module MD. LD denotes a driving unit of the photographing lens, and DS denotes various display units.

For example, when the focus detection device is of a general-purpose type that can be incorporated into various cameras having different specifications, the height position of the focus detection module MD from the optical axis differs depending on each model. Therefore, a correspondence table of the exit pupil position range in which the focus can be detected by each of the array pairs S1 to S3 with respect to the height of the focus detection module MD is created in advance in the ROM, and at the time of assembly, each model is passed through the sensor position information generation unit HPO. Is input to the control circuit CU. When the focus detection module MD is installed at a certain height position, the first to third array pairs S
Since the range of the exit pupil position of the photographing lens from which the focus can be detected is determined in 1 to S3, control is performed so as to select such a condition based on the sensor height position signal from the sensor position information generation unit HPO.

This will be described in more detail with reference to FIG. FIG. 5 is a diagram showing an exit pupil position range in which each of the three array pairs S1 to S3 can perform focus detection without vignetting, and PX indicates a spread of a light beam at each exit pupil position. Now, when the focus detection module MD is installed as shown in FIG. 5, the first array pair S1 moves the exit pupil position range of A to the second
The array pair S2 can detect the focus in the range B and the third array pair S3 can detect the focus in the range C without vignetting.

That is, when the height position of the focus detection module MD is determined, the exit pupil range in which the focus can be detected for each array pair is determined. Therefore, the sensor position information is input to the control unit CU through the sensor position information generation unit HPO. By selecting the correspondence table between the array pair and the exit pupil position, the focus detection module MD can be used as a versatile focus detection device.

FIG. 6 shows an embodiment in which the focus detection module MD is moved in the direction perpendicular to the image shift detection direction so that the height from the optical axis can be adjusted. SD is the focus detection module M
This is a driving device for driving D, and the photographer can set the focus detection module MD at an arbitrary position. RE is a sensor that detects the height position of the focus detection module MD and outputs information on the sensor height position.

The apparatus of this embodiment is suitable for use as follows. When focus detection is performed by the first array pair S1 using the photographing lens whose exit pupil position is at the height position of FIG. 5, the focus detection area is shifted to an area close to the optical axis. Consider a case where the module MD is moved to the optical axis side. If the exit pupil from which the array pair S1 can perform focus detection without vignetting deviates from a due to the movement of the focus detection module MD, focus detection becomes impossible. In such a case, by automatically switching to the second array pair S2 or the third array pair S3 in conjunction with the height position of the focus detection module MD and the exit pupil position, the optical axis can be further shifted without vignetting. Focus detection can be performed on a near area.

FIG. 7 shows a specific example in which the focus detection module is made movable. An opening 12 for guiding a focus detection light beam near the optical axis guided through the main mirror MM and the sub-mirror SM is formed in the center of the focus detection module mounting portion 11. The light flux passing through the opening 12 is guided onto a pair of photoelectric conversion elements of the focus detection module of the above, thereby performing focus detection in a region near the optical axis. On the other hand, grooves 13 and 14 are engraved on both sides of the opening 12, and each of the grooves 13 and 1 is formed.
4, focus detection modules MD1 and MD2 each having the same configuration as that shown in FIG. 2 are slidably provided. In each of the focus detection modules MD1 and MD2, openings 15 and 16 for opening an off-axis focus detection light beam guided through the main mirror MM and the sub-mirror SM are opened, and light beams passing through the openings 15 and 16 are provided. The light is guided onto three pairs of photoelectric conversion element arrays provided on the sensor substrate S of each of the modules MD1 and MD2. Thereby, focus detection outside the optical axis is performed.

Each movable focus detection module MD1,
The position of MD2 is detected as shown in FIG. That is, the sliding resistance 17 is extended along the groove 13 (14), and the contact points 18 that contact the sliding resistance 17 are provided on each of the modules MD1 and MD2. Since the resistance value between the end of the sliding resistor 17 and the contact 18 changes according to the module position, the detection circuit 19 can read the voltage value corresponding to the resistance value to detect the positions of the modules MD1 and MD2. .

Now, when the focus detection in the region near the optical axis is performed by the signals from the pair of photoelectric conversion elements of the focus detection module (not shown) installed in the module mounting portion 11, the focus detection is performed in the region outside the optical axis. Is performed, the operator selects the focus detection module MD1 and sets the focus detection area to an arbitrary desired position. At this time, the position of the focus detection module MD1 is detected by the detection circuit 19, and the exit pupil position of the photographing lens is read by the exit pupil position information generation unit EPO shown in FIG. 1, and based on the position of the focus detection module MD1. An optimal array pair for the exit pupil position is selected from the three array pairs S1 to S3, and focus detection is performed based on focus detection signals from the selected pair of array pairs.

When focus cannot be detected by any of the array pairs, the focus detection module may be moved so that focus can be detected by any of the array pairs.

As shown in FIGS. 9 and 10, even when the focus detection module MD is away from the optical axis LX, the focus detection module MD looks like an area RX in the exit pupil at a predetermined position.
When the sliding groove 20 is formed with a curvature surface, almost the entire area of the photographing screen can be detected. In the case of a 35 mm single-lens reflex camera, the center of curvature of the groove 20 is preferably set in a range of about 70 to 140 mm in front of the focus detection surface, and particularly preferably set to about 100 mm.

If the direction of the focus detection module can be changed according to the position of the focus detection area as in the embodiments of FIGS. 9 and 10, focus detection can be performed by any set of array pairs in any focus detection area. it can.

FIG. 11 shows three pairs of photoelectric conversion element arrays Sa.
And Sb, Sc and Sd, and Se and Sf. RG1 to RG3 are shift registers, which are connected to the output terminal OUT via switches SW1 to SW3, respectively. Each of the switches SW1 to SW3 is controlled by a control circuit CU to extract a desired focus detection signal.

In the configuration shown in FIG. 1, the focus detection module MD outside the optical axis may not be movably installed but may be fixed. Further, any pair of photoelectric conversion elements may be selected based on the open F value regardless of the exit pupil position. Alternatively, the selection may be made based on the exit pupil position and the open F value.

-Application Example 1- Next, a bright lens having a small open F value may have a plurality of off-optical axis focus detection areas where vignetting does not occur. In this case, the focus detection calculation can be performed based on the focus detection signals from the plurality of regions. Hereinafter, three examples will be described.

(1) An embodiment in which the S / N ratio is improved at low luminance to improve the focus detection accuracy will be described with reference to the flowchart of FIG. This program is shown in Fig. 1.
In the control circuit CU. In step S1, it is determined whether or not the brightness is low. If the brightness is low, it is determined in step S2 whether or not there are a plurality of areas without vignetting. If the focus can be detected in a plurality of areas, the process proceeds to step S3, where focus detection signals from a plurality of array pairs free from vignetting are synthesized. This is achieved by closing at least two of the switches SW1 to SW3 described above,
The signal extracted from the output terminal OUT is a composite signal. In step S4, a defocus calculation is performed based on the composite signal, and in step S5, the focus detection result is displayed and the lens is driven. In step S6, it is determined that the subject is in focus. If the subject is out of focus, the process returns to step S1, and the above-described procedure is executed again. If the brightness is not low, or if there is only one area without vignetting, step S
Proceeding to 7, the defocus calculation is executed based on the focus detection signal from the array pair corresponding to the area where no vignetting has occurred.

As described above, since the defocus calculation is performed by combining the focus detection signals of a plurality of areas where no vignetting occurs, the S / N ratio at low luminance is improved and the focus detection calculation accuracy is improved.

(2) An embodiment in which priorities are assigned to a plurality of focus detection areas and more appropriate focus detection calculation is performed will be described with reference to FIG. In step S11, it is determined whether there is a plurality of focus detection areas where no vignetting occurs. If there are a plurality of focus detection areas, the process proceeds to step S12. In step S12, each focus detection signal is sequentially processed in a predetermined priority, and
If the focus detection calculation is obtained at any time, the focus detection calculation is terminated at that time. 1 focus detection area without vignetting
If there is only one, the process proceeds to step S13, and a focus detection calculation is executed based on the focus detection signal from the focus detection area. In step S14, it is determined whether or not focus detection is possible based on the magnitude of the obtained defocus amount. If affirmative, in step S15, lens drive and focusing display are performed based on the focus detection calculation result. If it is determined in step S15 that the focus cannot be detected, the process proceeds to step S16, where the photographing lens is scanned and the electric charge is newly stored in the photoelectric conversion element array. Then, the process returns to step S11, and the above-described steps are repeated.

(3) Such an algorithm of (2) can be modified as follows. Step S in FIG.
12 may be replaced by step S22 in FIG. That is, when there are a plurality of focus detection areas without vignetting, a focus detection calculation is performed based on all focus detection signals, and one focus detection result is extracted by a predetermined selection algorithm. In this case, not only one focus detection result is selected, but a plurality of focus detection results may be combined to obtain an optimum one focus detection result.

Second Embodiment FIG. 15 shows focus detection for a plurality of focus detection areas by the focus detection module MD3 near the optical axis, and focuses outside the optical axis as in the first embodiment. FIG. 3 is a diagram illustrating a focus detection device that performs focus detection by detection modules MD1 and MD2. In FIG. 15, reference numeral 51 denotes a photographing lens, 52 denotes a field mask, 53a denotes a focus detection field lens near the optical axis, 53b and 53c denote focus detection field lenses off the optical axis, and 54a denotes a focus detection aperture near the optical axis. Aperture, 5
Reference numerals 4b and 54c denote off-optical axis focus detection aperture stops, 55a denotes a re-imaging lens near the optical axis, 55b and 55c denote off-optical axis re-imaging lenses, 56a denotes a focus detection sensor substrate near the optical axis, Reference numerals 56b and 56c denote off-optical axis focus detection sensor substrates.

Here, the focus detection field lenses 53a near the optical axis are provided with portions 53 having different optical performances.
1, 532, 533, and the re-imaging lenses 55a for focus detection near the optical axis are re-imaging lenses 551, 552, 55
3 is provided. Further, three pairs of photoelectric conversion element arrays 561, 562, and 563 are provided on the sensor substrate 56a.
The light beams passing through a pair of focus detection areas set near the optical axis of the photographing lens 51 are
1,532,533 and re-imaging lenses 551,55
An image is formed on each of three pairs of photoelectric conversion element arrays 561, 562, and 563 through 2553.

FIG. 16 (a) shows reference numerals 61, 62, 6 in a viewfinder of a camera provided with such a focus detection device.
The focus detection area is displayed as indicated by 3, 64, 65. Here, the focus detection areas 61 to 63 are focus detection areas near the optical axis set in a circle surrounded by a dotted line, 64 and 65.
Is a focus detection area outside the optical axis. The radius of the focus detection area near the optical axis is set to 7 mm to 12 mm. Note that D
a, Dc and De are focus detection areas shown in FIG. When the focus detection areas Da, Dc, De outside the optical axis are intentionally separated from each other, reference numerals 66 to 6 in FIG.
The focus detection areas may be individually displayed as shown in FIG.
In this case, displays Ba, Bc, and Be indicating which area is selected may be provided outside the screen frame. In a bright lens having a small open F value, the focus detection areas Da, Dc,
It is preferable to increase the number of selectable focus detection areas by positively setting the interval of De.

Such a focus detection device has the following advantages. Now, as shown in FIG. 15, when three focus detection areas 61 to 63 are set near the optical axis and two focus detection areas 64 and 65 are set outside the optical axis, the sensor substrate near the optical axis is simply set. If 56 is extended to provide an off-optical axis focus detection photoelectric conversion element array integrally, the size of the substrate is increased and the cost is increased. On the other hand, as shown in FIG. 17, the field lens 53′b,
If the optical performance of 53'c is set as shown by the broken line, it is optically unreasonable and not preferable. Further, there is a possibility that focus detection in a focus detection area outside the optical axis cannot be performed depending on the exit pupil of the photographing lens. Therefore, if the configuration as shown in FIG. 15 is employed, the cost of the sensor substrate can be minimized without increasing the size of the sensor substrate, and the optical performance of the off-optical axis focus detection field lens can be improved. Further, the exit pupil of the photographing lens is different, and focus detection outside the optical axis can be performed over a wide range.

-Modification of Second Embodiment- The focus detection device outside the optical axis of the second embodiment can be configured as shown in FIG. 18 or FIG. The configuration shown in FIG. 18 differs from the configuration of the first embodiment in that three pairs of re-imaging lenses are provided according to a plurality of focus detection areas. In this case, openings Ma, Mc, and Me corresponding to the three focus detection areas are opened in the field mask M, but other configurations are the same.

The advantages of the configuration shown in FIG. 18 are as follows. When the distance between the focus detection areas Da, Dc, De outside the optical axis is increased (for example, 1 to 2 mm), the optical differential performance is improved as compared with the case where a pair of re-imaging lenses is provided as shown in FIG. be able to.

On the other hand, the configurations of FIGS. 1 and 2 have the following advantages as compared with FIG. In the case of FIG. 2, the mutual positions of the three pairs of arrays provided on the sensor substrate S are positioned on the order of submicron. Therefore, the image of the photoelectric conversion element array Sc by the re-imaging lens La and the image of the photoelectric conversion element array Sd by the re-imaging lens Lb are mutually strict (especially, the pixels) in the focus detection area Dc on the focus detection surface 2. If the position of the re-imaging lens substrate L and the sensor substrate S is adjusted so as to overlap in the direction perpendicular to the array direction, an image of the photoelectric conversion element array Sa by the re-imaging lens La can be obtained.
The image of the photoelectric conversion element array Sb by the re-imaging lens Lb coincides with the focus detection area Da on the focus detection surface 2;
The image of the photoelectric conversion element array Se by the re-imaging lens La and the image of the photoelectric conversion element array Sf by the re-imaging lens Lb match in the focus detection area De on the focus detection surface 2.

On the other hand, in the configuration of the focus detection device shown in FIG. 18, since three pairs of re-imaging lenses are provided on one plastic substrate L 'by molding, the positions of the respective lenses are positioned on the order of submicrons. It is not possible and the alignment work is difficult.

The focus detection module MD of FIG. 19 includes a plurality of photoelectric conversion element arrays S on a plane conjugate with the focus detection plane 2.
a, Sb, Sc, Sd, Se, Sf are arranged on an IC substrate S, and images of light beams passing through the respective regions Ta, Tb, Tc, Td, Te, Tf of the taking lens 1 on each photoelectric conversion element array. Re-imaging lenses La, Lb, Lc, L
a lens substrate L having d, Le, and Lf;
A diaphragm plate (not shown) having an aperture stop facing each re-imaging lens disposed in front of the image-forming lens, and re-forming an image of a light beam which passes through each area of the taking lens 1 and forms an image on the focus detection surface 2 It is composed of a field lens F for projecting onto each photoelectric conversion element array via an image lens, and a field mask (not shown) having a rectangular opening so that unnecessary light flux does not enter the photoelectric conversion element array. In the figure, D indicates a focus detection area on the focus detection surface 2, and PO1 and PO2 indicate different exit pupil positions.

As can be seen from FIG.
The light beam passing through the regions Ta and Tb set below the light-receiving elements is re-imaged by the re-imaging lenses La and Lb.
The light flux formed on the Sb and passing through the areas Tc and Td set slightly above the areas Ta and Tb is formed on the photoelectric conversion element arrays Sc and Sd by the re-imaging lenses Lc and Ld. The light beams passing through the regions Te and Tf set slightly above Tc and Td are re-imaging lenses Le and Lf.
With this, an image is formed on the photoelectric conversion element arrays Se and Sf.
In the optical system shown in FIG. 19, three pairs of photoelectric conversion element arrays see almost the same detection area D. Therefore, even if a photoelectric conversion element array pair in which vignetting occurs due to a photographing lens occurs, the same detection is performed in another pair. There is an advantage that the area can be detected.
However, when a bright lens having a small F value is used, there is a disadvantage that the number of detection areas cannot be increased even if no vignetting occurs in any of the photoelectric conversion element pairs. That is, in the case of FIG. 1, in the case of FIG. 18, and in the case of FIG. 19, there are advantages and disadvantages, and the type to be used is selected.

[0046]

According to the first aspect of the present invention, it is possible to realize a focus detection device which can correspond to various types of photographing lenses having different exit pupil positions, and to prevent deterioration of focus detection accuracy due to vignetting or the like. it can. According to the second aspect of the invention, by providing the selection means in addition to the effect of the first aspect,
Since an optimal photoelectric conversion element array can be selected at the exit pupil position of the photographing lens, accurate focus detection can be performed. According to the third and fourth aspects of the present invention, the photoelectric conversion element array arranged outside the optical axis of the photographing lens is susceptible to vignetting and is difficult to achieve focus detection accuracy. Thus, the focus detection information is obtained by selecting the normally functioning photoelectric conversion element array from the plurality of pairs of photoelectric conversion element arrays, so that accurate focus detection can be performed.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing an outline of the present invention.

FIG. 2 is a perspective view showing details of a focus detection module.

FIG. 3 is an explanatory diagram of a field lens included in the focus detection module.

FIG. 4 is a diagram showing a shape of a field lens.

FIG. 5 is a diagram showing a relationship between an exit pupil position range in which focus detection can be performed by each of the first to third photoelectric conversion element array pairs.

FIG. 6 is a diagram showing an embodiment in which the focus detection module is movable.

FIG. 7 is a perspective view showing a moving mechanism of the focus detection module.

FIG. 8 is a diagram showing a mechanism for detecting a position of a movable focus detection module.

FIG. 9 is a plan view showing a mechanism for directing a focus detection direction of a movable focus detection module to a predetermined area within an exit pupil regardless of its height position.

FIG. 10 is a perspective view of the mechanism shown in FIG. 9;

FIG. 11 is a diagram showing a circuit for extracting a focus detection signal from a photoelectric conversion element array.

FIG. 12 is a diagram showing an example of a combination of a plurality of focus detection signals when focus detection is possible in a plurality of focus detection areas outside the optical axis at low luminance.
The flowchart which shows the procedure which can improve an N ratio.

FIG. 13 is a flowchart showing a modification of the procedure in FIG. 12;

FIG. 14 is a flowchart showing another modification of the procedure in FIG. 12;

FIG. 15 is a diagram showing an embodiment in which a plurality of focus detection areas as shown in FIG. 1 are set outside the optical axis and a plurality of focus detection areas are also set for a focus detection area near the optical axis.

16 is a diagram showing a display example in a shooting screen of the embodiment shown in FIG.

FIG. 17 is a view for explaining effects of the embodiment shown in FIG. 15;

18 is a perspective view showing a modification of the off-optical axis focus detection device of the embodiment in FIG.

19 is a perspective view showing another modified example of the off-optical axis focus detection device of the embodiment in FIG.

FIG. 20 is a diagram illustrating a conventionally known phase difference type focus detection optical system.

FIG. 21 is a diagram illustrating a range in which focus can be detected by a conventional focus detection module.

[Explanation of symbols]

1: photographing lens 2: focus detection surface F: field lens Fa, Fb, Fc: part of the field lens having different optical performance L: lens substrate La to Lf: re-imaging lens N: aperture stop Na, Nb: pupil aperture S : IC substrate Sa to Sf: photoelectric conversion element array S1 to S1: pair of photoelectric conversion elements MD: focus detection module EP1: first exit pupil position EP2: second exit pupil position CU: control unit EPO: Exit pupil position information generator HPO: Sensor position information generator

Claims (4)

(57) [Claims] 1. A plurality of pairs of photoelectric conversion element arrays disposed on a predetermined surface, and a pair of re-imaging lenses for re-imaging light beams of a subject image passing through a photographing lens onto the plurality of pairs of photoelectric conversion element arrays. And a plurality of field lenses arranged near the expected focal plane of the photographing lens and guiding the light flux of the photographing lens to the pair of re-imaging lenses, wherein each of the plurality of field lenses is the photographing lens. A focus detection device having optical performance of forming conjugate images of the pupil apertures of the pair of re-imaging lenses on different exit pupil positions. 2. The focus detection device according to claim 1, further comprising a selection unit for selecting one of said plurality of pairs of photoelectric conversion element arrays, wherein said selection unit includes information on an exit pupil position of said photographing lens. A focus detection device, wherein one of the plurality of pairs of photoelectric conversion element arrays is selected based on the following. Wherein each other in the optical axis outside the predetermined area of the photographic lens
Each of multiple focus detection areas set close to each other
A plurality of pairs of photoelectric conversion element arrays provided, a re-imaging lens for re-imaging a light flux of a subject image passing through the imaging lens on the plurality of pairs of photoelectric conversion element arrays, and a schedule for the imaging lens. A field lens that is arranged near the focal plane and guides the light flux of the photographing lens to the re-imaging lens, and each pair of the plurality of pairs of photoelectric conversion element arrays is arranged in a direction orthogonal to the pupil division direction. An information generating means for generating information on the exit pupil position of the photographing lens; and a pair of normally functioning ones of the plurality of pairs of photoelectric conversion element arrays, based on the information on the exit pupil position. Control means for selecting a photoelectric conversion element array, calculating focus detection information based on output signals from the selected pair of photoelectric conversion element arrays, and outputting a control signal for controlling the photographing lens Focus detecting apparatus comprising: a. 4. The focus detection device according to claim 3, wherein the re-imaging lens and the field lens each include a lens unit corresponding to each pair of the plurality of pairs of photoelectric conversion element arrays. Focus detection device. [0001]