JPH0772380A - Focus detector - Google Patents

Abstract

PURPOSE:To provide a focus detector capable of making a light receiving part compact. CONSTITUTION:A central focus detecting zone provided on the optical axis of a photographing lens on a scheduled focusing surface, a periperhal focus detecting zone provided out of the optical axis, plural condenser lenses 61 to 63 which relay respective images formed on the respective focus detecting zones, plural mirrors 20 to 22 changing the directions of the respective images, plural pairs of separator lenses dividing the image into two and reforming the image, and plural areas arranged at the image reformed position are set in the focus detector. The condenser lenses 62 and 63 corresponding to the peripheral focus detecting zone are arranged to be eccentric to a center with respect to the center axis of a pair of separator lenses corresponding to the peripheral focus detecting zone.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focus detecting device capable of detecting the in-focus state of a photographing lens with respect to a subject in a plurality of zones within a screen to be photographed.

[0002]

2. Description of the Related Art This type of focus detection device is disclosed in, for example, Japanese Patent Application Laid-Open Nos. 1-155308 and 2-58012. In these publications, a plurality of focus detection zones are provided on a planned focal plane, and partial images viewed through the respective zones are divided and re-imaged on a plurality of line sensors by a pair of separator lenses. A configuration is disclosed that allows this.

[0003]

However, in the above-mentioned conventional focus detection device, the arrangement pattern of the focus detection zones on the planned focal plane and the arrangement pattern of the line sensor on the re-imaging plane are the same. However, there is a problem in that there is no degree of freedom to make an arrangement suitable for each request.

For example, in order to reduce the influence of the vignetting of the taking lens, the peripheral focus detection zone on the planned focal plane is arranged in the sagittal direction perpendicular to the radial direction of the taking lens. It is preferable to
On the other hand, the sensor units arranged on the re-imaging surface can be used by dividing a single line sensor into parts if the arrangement directions are the same.

Further, in the conventional focus detection device, when the distance between the focus detection zones on the planned focal plane becomes large, the distance between the light receiving regions on the re-imaging surface also becomes large, so that the light receiving portion becomes large. To do. Further, when the position or size of the exit pupil of the taking lens changes due to lens exchange or zooming, the pupil of the focus detection optical system may be vignetted, and the range in which the light flux can be taken in may be narrowed.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems of the prior art, and relates to the positional relationship of focus detection zones on the planned focal plane and the positional relationship of line sensors on the re-imaging plane. Focus can be freely combined and the light receiving unit can be made compact by reducing the distance between the light receiving areas on the re-imaging plane even if the distance of the focus detection zone on the planned focal plane becomes large. An object is to provide a detection device.

[0007]

In order to achieve the above-mentioned object, a focus detecting apparatus according to the present invention has a plurality of focus detecting zones arranged as a plurality of regions on a predetermined focal plane according to a first pattern. A sensor unit having a plurality of detection units arranged as a plurality of regions on the re-imaging surface according to a second pattern having a relative directionality different from that of the first pattern; At least one of a plurality of light beams that have passed through the focus detection zone and a first deflecting unit that deflects the plurality of light beams that have passed through the detection zone so as to match the relative directionality between the regions of the second pattern. And a second deflecting means for deflecting an optical path of one light beam in a direction approaching an optical path of another light beam.

[0008]

Embodiments of the focus detection device according to the present invention will be described below. The embodiment is a focus detection device that is used as, for example, a focus detection device of a single-lens reflex camera, and that detects a focus state of a photographing lens with respect to a plurality of subjects within a photographing range.

“Focus detection zone” as used herein
The term is defined as an area occupied by the area such as a CCD for focus detection that is actually used for focus detection when the area is projected on the photographic screen. Therefore, the easiest way to limit the focus detection zone is to match the size of the sensor to the zone, but if the size of the sensor is wider than the zone, match the light flux incident on the sensor to the zone. It is possible to use a method of providing an optical mask for limiting the above.

When an optical mask is provided, it is desirable to provide it on a surface that is optically equivalent to the image pickup surface. For example, a mask may be provided just before the planned focal plane and the re-imaging surface on which the sensor is provided, or a mask may be provided on both the planned focal plane and the re-imaging surface.

In the following embodiments, an opening having a width substantially corresponding to the focus detection zone is formed on the field mask arranged on the planned focal plane, and the light flux transmitted through this opening is used for focus detection. Therefore, for convenience sake, this opening is named “focus detection zone”. Since the field mask has a function of removing the cross toff between the sensors by limiting the light flux so that the excess light flux does not enter the sensor, the size of the aperture does not necessarily have to match the focus detection zone. However, in the following embodiments, they are set to match.

[0012]

Example 1 First, the basic arrangement relationship of optical elements in Example 1 will be described with reference to FIG. A field mask 10 for extracting a part of the subject image is arranged near the planned focal plane where the subject image is formed by the taking lens.
In this field mask, focus detection zones 11, 12, and 13 as three openings that determine the field of the focus detection system are formed as a plurality of regions according to the first pattern.

The planned focal plane is a film plane in the case of a photographic camera and a plane optically conjugate with an image sensor in the case of an electronic camera. Further, the planned focal plane is also optically conjugate with the focusing plate in a camera having an optical viewfinder system.

The focus detection zone is composed of a central focus detection zone 11 provided at a position intersecting the optical axis of the taking lens and two peripheral focus detection zones 12 and 13 provided on both sides in the longitudinal direction thereof. , Peripheral focus detection zone 12,
Reference numeral 13 is provided so that its longitudinal direction coincides with the sagittal direction orthogonal to the longitudinal direction of the central focus detection zone.
Therefore, the first pattern that determines the arrangement of the focus detection zone as an area is the “H” type.

2 divided in the horizontal direction of the pupil E of the taking lens
The light flux that has passed through the central focus detection zone 11 through the two regions E1 and E2 is deflected by 90 ° by the first mirror 20, and the pair of separator lenses 3 as a re-imaging optical system.
The image is re-imaged on the central region 41 of the CCD line sensor 40a as a light-receiving means provided on the re-imaging surface 40 after being divided through 0 and 31. A pair of separator lenses 30,3
1 indicates the images formed in the focus detection zone 11 respectively.
It has a function of re-imaging after being divided into two, and its pupil is optically conjugate with the pupil E of the photographing lens as the pupil of the focus detection system.

Two areas E vertically divided on the pupil E
The light fluxes passing through the peripheral focus detection zones 12 and 13 through 3 and E4 are deflected by 90 ° by the second and third mirrors 21 and 22, respectively, and the direction of the image is changed. C through 33, 34, 35
An image is formed on the peripheral regions 42 and 43 on the D line sensor 40a.

Light receiving area 4 on the CCD line sensor 40a
Images 1, 42, 43 are formed by respective re-imaging optical systems as a plurality of regions arranged according to a second pattern (“-” type in this example) different from the first pattern. It is provided at a position and receives a pair of divided and re-formed images. The finder system is provided with a focus area for the photographer to confirm the focus detection zone corresponding to the focus detection zone on the planned focal plane. The focus state of the taking lens is detected by using the output from the line sensor corresponding to the focus area overlapping the intended subject or the subject selected by the circuit on the camera side.

By deflecting the optical path with the mirror, the central focus detection zone 11 and the peripheral focus detection zones 12 and 13 are arranged in the first pattern "H" type on the field mask 10 located on the planned focal plane. In addition, a single linear CCD line sensor 40 on the re-imaging plane 40
Regions 41, 42, 43 can be arranged on a according to the second pattern of "-" type. Each mirror is
It functions as a first deflecting unit that deflects the light flux that passes through the plurality of focus detection zones and travels in the first pattern so as to match the relative directionality between the regions of the second pattern.

2 and 3 show details of the configuration of the above-described first embodiment. Each component from the field mask 10 to the CCD line sensor 40a is assembled as a single module and housed in the camera. The condenser lens 6 functioning as a relay lens is provided at the subsequent stage of the visual field mask 10.
1, 62, 63 are provided corresponding to each focus detection zone, and an auxiliary lens group 70 in which auxiliary lenses 71, 72, 73 are integrally formed, and a separator lens group in which separator lenses 30-35 are integrally formed 30a and CCD line sensor 40a are arranged in order.

The condenser lens 61 corresponding to the central focus detection zone is provided so that its optical axis coincides with the central axes of the separator lenses 30 and 31 and the optical axis of the auxiliary lens 71 as shown in FIG. . On the other hand, the condenser lenses 62 and 63 corresponding to the peripheral focus detection zone are provided so as to be decentered so that the optical axis indicated by the two-dot chain line is closer to the center side with respect to the central axis of the separator lens indicated by the one-dot chain line. .

In this embodiment, by eccentricizing the condenser lens, as shown in FIG. 4, the optical path of the light beam passing through the peripheral focus detection zone is deflected in the direction approaching the optical path of the light beam passing through the central focus detection zone. ing. That is, in this embodiment, the eccentricity of the condenser lens constitutes the second deflecting means for deflecting the optical path of at least one light beam toward the re-imaging surface in the direction of approaching the other optical path.

Next, the operation of the second deflecting means will be described with reference to FIGS. In these figures, in order to facilitate understanding of the second deflecting means,
The deflection action is described as a relative relationship between the two focus detection zones 11 and 12 and the light receiving regions 41 and 42, and is expanded and explained except the action by the first deflection means.

Considering the arrangement of the light-receiving regions arranged on the re-imaging surface, the light-receiving portion can be made compact as the light-receiving regions are brought closer to each other within a range where interference between the light-receiving regions does not occur. Is preferable.

However, if the interval d of the light receiving regions is shortened without changing the interval of the focus detection zones with respect to the configuration of FIG. 5A as a reference, for example, as shown in FIG. The directions of the light fluxes captured in the areas are greatly different, and vignetting occurs in the light fluxes incident on any of the light receiving areas.
It may not be possible to secure a sufficient amount of light.

Therefore, a prism 80 is used by inserting a prism 80 behind the condenser lens as shown in FIG. 5C or by decentering the condenser lens 62 as shown in FIG. 5D. By doing so,
The distance d between the light receiving regions can be reduced without changing the direction in which the light flux is taken in from the example shown in (a).

Further, in the case of forming an image on the light receiving area through the peripheral focus detection zone, in consideration of the case where the pupil of the photographing lens is small and the case where this pupil moves, in order to prevent vignetting, It is desirable to direct the direction of taking in the light flux to the light receiving area toward the optical axis side of the taking lens.

However, here too, if the direction of the light beam entering through the peripheral focus detection zone is directed to the optical axis side of the taking lens as shown in FIG. 6B, the state of FIG. 6A is taken as a reference. The distance between the light receiving regions 41 and 42 becomes large, and the light receiving section becomes large.

Therefore, a prism 80 is inserted behind the condenser lens 62 as shown in FIG. 6C, or
As shown in FIG. 6D, by decentering the condenser lens 62 and using its prism action, the distance between the light receiving regions is kept the same as in FIG. The taking-in direction of the luminous flux can be directed to the optical axis side of the taking lens. In addition, FIG.
(c) This is an example in which the distance between the light receiving regions is made smaller than that shown in FIG. 6 (a) by using the prism 81 having stronger power, and the light receiving portion is more actively made compact.

In FIG. 7 (a), contrary to the above, a prism 81 having a strong power is provided behind the condenser lens 61, and the light flux transmitted through the central focus detection zone 11 is deflected to pass through the peripheral focus detection zone 12. A configuration for bringing the light flux closer to the formed light flux is shown. Further, FIG. 7B shows an example in which a prism 80 having weak power is provided behind the condenser lens 62 in addition to the configuration of FIG.

[0030]

Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIG.
The focus detection device according to the present invention will be described. The device of Example 2 is
A total of six focus detection zones are provided, two in each of the areas where the image height increases in the order of the central portion, the intermediate portion, and the peripheral portion on the planned focal plane (not shown).

The light fluxes that have passed through the respective focus detection zones are condensed by the condenser lenses 61 to 66 and are deflected by the mirrors 20 to 22 constituting the first deflecting means, and then the separator lenses 30 to 35 ,. 30 '~
35 'is divided to form a pair of images on the light receiving regions 41 to 46, respectively.

The condenser lenses 62 and 63 for condensing the light flux from the focus detection zone in the middle portion are provided with a prism function by decentering or by adding a separate prism, and the incident light flux is incident on the peripheral portion. It has a function as a second deflecting means for deflecting outward so as to approach the light flux from the focus detection zone.

Light fluxes from the focus detection zones in the middle and peripheral portions pass through the condenser lens, and then the common mirror 2
However, since the light flux from the intermediate portion is deflected in the direction approaching the light flux from the peripheral portion, the light paths approach each other when reflected by these mirrors, and the light is re-coupled in the light receiving portion. The image positions are close to each other.

For comparison with FIG. 8, FIG. 9 shows the arrangement of the optical elements when the condenser lenses 62 and 63 have no prism action. As can be understood by comparing with FIG. 8, the areas of the mirrors 21 and 22 become large, and the positions of the light receiving regions 42 and 43 on the re-imaging plane are considerably separated from other light receiving regions. Also, the area becomes large, and the device cannot be made compact.

Next, based on FIGS. 10 and 11, of the optical system of the focus detecting apparatus of the second embodiment described above, the light fluxes that have passed through the focus detecting zones 12 and 15 in the intermediate and peripheral portions are re-imaged. The operation of the second deflecting means in the two sets of re-imaging optical systems will be described.

FIG. 10A is an explanatory diagram corresponding to the case where the condenser lens shown in FIG. 9 does not have a prism function. As described above, in order to effectively take in the light flux from the pupil of the taking lens, the taking-in direction of the light flux that passes through the focus detection zones off-axis, that is, in the middle portion and the peripheral portion is set to the optical axis Ax side of the taking lens. It is desirable to point.

However, when the receiving direction is changed by moving the light receiving area away from the optical axis as shown in FIG. 10 (b), the corresponding light receiving area is moved away from the optical axis of the taking lens and the focus of the central portion is changed. There is a problem that the distance from the light receiving area where the light flux from the detection zone is re-imaged becomes large and the light receiving section becomes large.

In FIG. 10C, the prism 8 is provided on both optical paths.
Nos. 0 and 80 are provided to keep the position of the light receiving area the same as in FIG. 10A, and the light beam capturing range is directed toward the optical axis side of the photographing lens.

FIG. 11 shows means for shortening the distance between the light receiving regions 42 and 45 while directing the direction of taking in the light flux toward the optical axis of the taking lens.

FIG. 11A shows an example in which the light receiving area 42 for receiving the light flux transmitted through the focus detection zone 12 in the middle portion is close to the other light receiving area 45 with reference to FIG. 10B. . If the light-receiving area is simply moved, the direction of the light beam taken into the focus detection zone 12 in the middle portion becomes too close to the optical axis.

Therefore, in the second embodiment of FIG. 9, FIG.
As shown in FIG.
The distance between the light receiving regions 42 and 45 is shortened while the prism action is provided by adopting a means such as providing 0 to keep the light beam taking-in direction the same as in FIG. 10B. Further, as shown in FIG. 11C, a light flux from the focus detection zone 15 in the peripheral portion may be deflected by a prism 80 provided behind the condenser lens 65 so that the light receiving regions 42 and 45 are brought close to each other. Good.

[0042]

As described above, according to the present invention, by disposing the first deflecting means, the arrangement pattern of the light receiving areas on the re-imaging plane is arranged in the focus detection zone on the planned focal plane. Can be determined independently of the pattern,
In addition, the second deflecting unit brings the optical path of one re-imaging optical system closer to the optical path of another re-imaging optical system, thereby bringing the light-receiving area on the light-receiving unit close to each other and photographing the light beam capturing direction. The effect of vignetting can be reduced in the optical axis direction of the lens.

[Brief description of drawings]

FIG. 1 is a perspective view of an optical system showing an outline of a focus detection apparatus according to a first embodiment.

FIG. 2 is a perspective view showing a main part of FIG.

FIG. 3 is a plan view showing a developed main part of FIG.

FIG. 4 is an explanatory diagram showing the operation of the first embodiment.

FIG. 5 is an explanatory view showing the action of the second deflecting means and a modification example thereof.

FIG. 6 is an explanatory view showing the action of the second deflecting means and a modification thereof.

FIG. 7 is an explanatory diagram showing an operation of the second deflecting means and a modification example thereof.

FIG. 8 is a perspective view of an optical system that shows an outline of a focus detection device according to a second embodiment.

9 is a perspective view of an optical system showing a case in which a second deflecting unit is not provided in the focus detection device of FIG.

FIG. 10 is an explanatory view showing the action of the second deflecting means and a modification example thereof.

FIG. 11 is an explanatory view showing the action of the second deflecting means and a modification example thereof.

[Explanation of symbols]

 10 ... Field mask 11 ... Central focus detection zone 12, 13 ... Peripheral focus detection zone 20, 21, 22 ... Mirror 30-35 ... Separator lens 30a ... Separator lens group 40 ... Re-imaging surface 40a ... CCD line sensor 41 ... Center Area 42.43 ... Peripheral area 61, 62, 63 ... Condenser lens

Claims (10)

[Claims] 1. A plurality of focus detection zones arranged according to a first pattern as a plurality of areas on a planned focal plane, and a plurality of areas as a plurality of areas on a re-imaging plane, the first pattern being between the areas. A sensor unit having a plurality of detection units arranged according to a second pattern having different relative directivities, and a plurality of light fluxes transmitted through the plurality of focus detection zones between the regions of the second pattern. A first deflecting means for deflecting so as to match the relative directionality; and a first deflecting means for deflecting an optical path of at least one of the plurality of light beams transmitted through the focus detection zone in a direction approaching the optical paths of other light beams. A focus detection device comprising: two deflecting means. 2. A condenser lens provided corresponding to each of the focus detection zones for condensing the light flux from each focus detection zone, and a pair of images of the light flux transmitted through the focus detection zone on the focus detection zone. The focus detection device according to claim 1, further comprising a separator lens for re-imaging the image. 3. The focus detection according to claim 2, wherein the first deflecting unit is configured by combining a plurality of mirrors provided between the condenser lens and the separator lens. apparatus. 4. The second deflecting means decenters an optical axis of at least one surface of the condenser lens with respect to an axis passing from the center of each focus detection zone to the center of the corresponding separator lens pair. The focus detection device according to claim 2, wherein the focus detection device is configured. 5. The focus detecting apparatus according to claim 2, wherein the second deflecting means is composed of a prism arranged near the condenser lens. 6. The focus detection zone is provided in a central portion and a peripheral portion on the planned focal plane, and the first and second deflecting means are provided from the focus detection zone provided in the peripheral portion. The focus detection device according to claim 1, wherein the light flux is deflected with respect to a light flux from a focus detection zone provided in a central portion. 7. The focus detection zone is provided as a plurality of areas on the planned focal plane where the image height increases in the order of a central portion, an intermediate portion, and a peripheral portion, and the second deflecting means includes the first deflecting means.
3. The focus detection according to claim 2, wherein the light flux from the focus detection zone of the intermediate portion is deflected toward the light flux from the focus detection zone of the peripheral portion on the planned focal plane side by the deflecting means of FIG. apparatus. 8. The focus detection device according to claim 1, wherein the distance between the regions in the second pattern is narrower than the distance between the regions in the first pattern. 9. A sensor unit including a plurality of detection units arranged according to a predetermined pattern on a surface optically equivalent to an image pickup surface, and each of the plurality of detection units is actually used for focus detection. A first beam deflecting light beam directed to each of the detection units such that a relative directionality of a plurality of focus detection zones defined as a region occupied when the region is projected on a photographic screen is different from an arrangement pattern of the detection units. A focus detecting apparatus comprising: a deflecting unit; and a second deflecting unit that deflects an optical path of at least one of the plurality of light beams directed to the detection unit in a direction approaching an optical path of another light beam. 10. The focus detection apparatus according to claim 9, wherein the focus detection zone is formed on a visual field mask arranged on a planned focal plane.