JP3385215B2 - Multi-point focus detection device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focus detection device suitable for optical equipment such as a single-lens reflex camera and capable of focus detection for a plurality of focus detection areas.

[0002]

2. Description of the Related Art In recent years, a single-lens reflex camera equipped with a multi-focus detection unit capable of detecting focus in a plurality of distance measuring areas has been developed. The optical system of the conventional multi-focus detection unit has a structure in which a subject light beam that has passed through a plurality of on-axis and off-axis focus detection areas is bent by a mirror and is made incident on a horizontally arranged light receiving element. . For example, the object light beam that has passed through the axially long axis on-axis focus detection area is deflected once by one mirror to form a subject image on the horizontally long light receiving element array. The light flux transmitted through the vertically long peripheral focus detection area arranged off-axis is deflected twice by the two mirrors to form a subject image on the corresponding horizontally arranged light receiving element array.

In such a configuration, the light fluxes transmitted through the respective focus detection areas must be separated and independently guided. Therefore, if the number of off-axis focus detection areas is increased, the conventional configuration requires a larger mirror. You have to increase the number of mirrors. However, if the mirror is made large, there is a risk that the mirror may cut off the optical path. When the number of mirrors is increased, it is difficult to arrange the optical paths so as not to interfere with each other. Further, the intervals of the light fluxes transmitted through the respective focus detection areas become too close to each other, and the optical systems for guiding the respective light fluxes to the light receiving element array eclipse the other light fluxes.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a multi-point focus detection device capable of increasing the focus detection area with a simple structure.

[0005]

SUMMARY OF THE INVENTION According to the present invention, which achieves this object, each light beam transmitted through a plurality of peripheral focus detection areas provided in a predetermined arrangement pattern in an off-axis area on a planned focal plane is
A focus detecting device for causing a corresponding light receiving element array arranged in an arrangement pattern different from the predetermined arrangement pattern to receive light on a re-imaging plane located on one plane, wherein the plurality of focus detection areas include first Peripheral focus detection area and a second peripheral provided on the same side as the first peripheral focus detection area with respect to the center of the planned focal plane and off-axis from the first peripheral focus detection area. A deflection optical member that includes a focus detection area, and that deflects the light flux that has passed through the first peripheral focus detection area and the light flux that has passed through the second peripheral focus detection area and guides the light flux to the first reflection member. The first peripheral light flux reflected by the first reflecting member and
And the second peripheral luminous flux to the corresponding photodetector array, respectively.
And a second reflecting member that reflects toward the deflecting optical member.
Is the first circumference that has passed through the first peripheral focus detection area.
The side luminous flux is transmitted through the second peripheral focus detection area
It is deflected in a direction approaching the second peripheral light flux and
First deflection optical element for incidence on the first reflection member
And a second circumference passing through the second peripheral focus detection area
The side luminous flux is transmitted through the first peripheral focus detection area
The first peripheral light flux is deflected in a direction approaching the first peripheral light flux, and
Second deflection optical element for incidence on the first reflection member
And is set such that the first peripheral light flux and the second peripheral light flux reflected by the first reflection member intersect and then enter the second reflection member. Have.

[0006]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described below with reference to the drawings. FIG. 4 shows an outline of a single-lens reflex camera to which the focus detection device of the present invention is applied. The AF single-lens reflex camera includes a camera body 11 and an AF-compatible taking lens 51 that is attachable to and detachable from the camera body 11. The camera body 11 includes so-called multipoint focus detection means (multipoint autofocus means) and automatic focus adjustment means.

The subject light flux that has entered the camera body 11 from the taking lens 51 is reflected by the main mirror 13 toward the pentaprism 17 that constitutes the finder optical system, reflected by the pentaprism 17 and emitted from the eyepiece. On the other hand, a part of the subject light flux that has entered the half mirror section 14 of the main mirror 13 passes through this portion and is reflected downward by the sub mirror 15 to form a multi-AF sensor unit (multi-focus detection sensor unit) as multi-point focus detection means. ) 21. The multi-AF sensor unit 21 is, for example, a so-called phase difference type distance measuring sensor, and in the present embodiment, six line sensors (212A to 212F, see FIG. 1) corresponding to six distance measuring areas.
Is equipped with.

The main CPU 35 calculates the defocus amount by a predetermined calculation based on the integrated data for each line sensor input from the multi AF sensor unit 21. Then, based on these defocus amounts, the defocus amount and the priority of the line sensor to be used are set, and the rotation direction and the rotation speed of the AF motor 39 (the number of pulses output by the encoder 41) are calculated. Then, the main CPU 35 determines the AF motor 3 via the AF motor drive circuit 37 based on the rotation direction and the number of pulses.
Drive 9 During this driving, the main CPU 35
The pulses output by the encoder 41 are counted in conjunction with the rotation of the AF motor 39, and when the count value reaches the number of pulses, the AF motor 39 is stopped.

The rotation of the AF motor 39 is performed by the gear block 4
6. The signal is transmitted to the photographic lens 51 side through the connection between the joint 47 provided on the mount portion of the camera body 11 and the joint 57 provided on the mount portion of the photographic lens 51. In the taking lens 51, the focus adjusting lens 53 is moved back and forth via the lens driving mechanism 55.

The main CPU 35 has a built-in ROM for storing programs, a RAM for temporarily storing predetermined data for arithmetic and control, a reference timer for timing, a hard counter and an A / D converter, An EEPROM 43 as an external memory means is connected. This EEPROM4
3, various constants peculiar to the camera body 11 as well as predetermined values necessary for the integral control of the present invention are stored.

Further, this camera is provided with a photometric switch SWS which is turned on by half-pressing a release button (not shown) and a release switch SWR which is turned on by fully pressing the same. ON / OFF information of these switches SWS and SWR is input to the main CPU 35.

The main CPU 35 functions not only as a control means for generally controlling the operations of the electronic components of the camera body and the photographing lens, but also as an integral control means with the multi-AF sensor unit 21 and the peripheral control circuit 23. And the AF motor 39 and the like constitute lens driving means.

On the other hand, the photographic lens 51 is provided with a focus adjusting mechanism 55 for moving a focus adjusting lens 53 as a focus adjusting optical system along the optical axis, and a mount portion of the photographic lens 51. A lens side joint 57 is provided which is connected to the joint 47 and transmits the rotation of the AF motor 39 to the focus adjusting mechanism 55.

FIG. 1 shows an outline of an embodiment of the multi-AF sensor unit 21, and FIG. 2 shows an embodiment of an arrangement pattern of focus detection areas. In this embodiment, six focus detection areas 70A, 70B, 70C, 70D, 70 are provided.
E, 70F and six CCD line sensors 212A, 212B, corresponding to the focus detection areas 70A-70F.
It has 212C, 212D, 212E and 212F.

FIG. 2 shows the arrangement of the focus detection areas 70A to 70F on the photographing screen 70. The focus detection areas 70A to 70F are provided with a horizontally-long central focus detection area 70A substantially in the center and a horizontally-long upper peripheral focus detection area 70B above the focus detection areas 70A to 70F. Vertically long left and right peripheral focus detection areas 70C and 70D are arranged as focus detection areas. Further, outside the left and right peripheral focus detection areas 70C and 70D, in parallel with them, vertically long peripheral focus detection areas are formed. Left and right most peripheral focus detection areas 70E and 70F are arranged. On the other hand, six line sensors 212A to 212F
As shown in FIG. 1, the arrangement pattern (arrangement) is a pattern in which three sensor rows arranged in a row at a predetermined interval are arranged in parallel in two rows, and the focus detection areas 70A to 70A.
It is different from the arrangement pattern of F. In the figure, in the upper row, the line sensor 212B is provided in the center and the line sensors 21 are provided on both sides thereof.
2C and 212D are arranged, the line sensor 212A is located in the center of the lower row, and the line sensors 212E and 21 are located on both sides of the line sensor 212A.
2F is arranged. In addition, these line sensors 2
12A to 212F are formed on a single circuit board.

The multi-AF sensor unit 21 has focus detection areas 70A to 70A near the planned focal plane (equivalent to a film surface (not shown)) on which the primary image of the subject is formed by the taking lens 51 or near the planned focal plane. Rectangular focus detection openings 72A, 72B, 72C, 72D, 72E, 72F for taking out a subject image in an area corresponding to 70F.
A mask (focus detection area regulation plate) 72 having the above is provided. FIG. 3 is an enlarged plan view of the mask 72 as seen from above the front of the camera. Each focus detection opening 72A-
72F is arranged in a shape and a position corresponding to the focus detection areas 70A to 70F, and each defines the focus detection areas 70A to 70F. That is, the light flux that has passed through each of the focus detection openings 72A to 72F becomes the focus detection area 7
Object images corresponding to the object images in 0A to 70F are formed on the corresponding line sensors 212A to 212F to enable focus detection for the objects in the focus detection areas 70A to 70F. In the present specification, the direction in which the light flux comes to the member is referred to as “front”, and the direction in which the light flux travels from the member is referred to as “rear”.

Behind the mask 72 are condenser lenses 73A, 73B, 73C, 73D, 73E and 73F.
Each focus detection opening 72A, 72B, 72C, 72D, 72
The condenser lens 73 is provided corresponding to E and 72F.
Behind A, 73B, 73C, 73D, 73E, 73F, optical path adjusting prisms 75A, 75C, 75D, 7
5E and 75F are arranged.

First, the two center focus detection apertures 72A,
An optical system relating to the light flux that passes through 72B will be described. A prism 75A as a deflecting element arranged behind the central condenser lenses 73A and 73B serves as a central upper luminous flux LB that passes the central upper luminous flux LB transmitted through the condenser lens 73B.
The light is refracted (deflected) in the direction in which the distance from A is narrowed. Then, the central light beam LA and the central upper light beam LB transmitted through the prism 75A
Is reflected by the central mirror 77A and deflected by approximately 90 °, and the line sensor 212 as a corresponding light receiving element is reflected.
Proceed toward A, 212B. In the illustrated embodiment,
The principal ray of the central light beam LA coincides with the optical axis O of the taking lens 51.

Each light beam LA reflected by the central mirror 77A,
LB is a corresponding optical path adjusting prism 79A, 7A.
The interval is adjusted by passing through 9B. And each luminous flux LA,
The LB is divided into two by the corresponding division lenses 83A and 83B, and the corresponding line sensors 212A and 2B are divided.
A pair of subject images are formed on 12B at intervals according to the subject distance. In the figure, reference numerals 81A and 8A
1B indicates the opening of the separator mask.

Each photodiode of each line sensor 212A, 212B accumulates (integrates) an electric charge according to the brightness of the image formed on each photodiode.
The accumulated charge is read by a known drive circuit (not shown), converted into a video signal by the signal processing circuit, and output to the CPU 35. The CPU 35 obtains an interval (phase difference) between the pair of subject images formed on the line sensors 212A and 212B by an algorithm based on a so-called phase difference detection method, calculates a defocus amount from the interval, and further adjusts the focus. The drive direction and drive amount of the AF motor 39 required to move the optical system 53 to the in-focus position are calculated as the number of pulses.

Next, the peripheral focus detection areas 70C-70
The configuration of the focus detection optical system regarding the peripheral distance measurement areas 70C and 70E in F will be described. The left peripheral light flux (left first peripheral light flux) LC that has entered through the left peripheral focus detection opening 72C and has passed through the condenser lens 73C is the prism 75.
The first mirror 76 is separated from the central light beam LA by C
The light is refracted (deflected) in the direction of being incident on C, is reflected by the first peripheral mirror 76C in the direction of being incident on the second peripheral mirror 77C, and is line sensor 212 by the second peripheral mirror 77C.
It is reflected toward C.

On the other hand, the leftmost peripheral light flux (left second peripheral light flux) LE which has entered from the leftmost peripheral focus detection opening 72E and has passed through the condenser lens 73E approaches the left peripheral light flux LC by the prism 75E, and then comes to the first peripheral light flux LC. Of the first peripheral mirror 76C.
It is reflected by C in the direction of incidence on the second peripheral mirror 77C, and the line sensor 21 is reflected by the second peripheral mirror 77C.
It is reflected toward 2E.

Here, the light beams LC and LE reflected by the first peripheral mirror 76C are the first and second peripheral mirrors 76C,
77C intersects each other, and the upper and lower positions are switched when the light enters the second peripheral mirror 77C. Therefore, the second
Left peripheral, leftmost peripheral luminous flux L reflected by the peripheral mirror 77C of
As for C and LE in FIG. 1, the upper side is the left peripheral light flux LC and the lower side is the left most peripheral light flux LE.

The left peripheral light flux LC and the left most peripheral light flux LE reflected by the second peripheral mirror 77C pass through the optical path adjusting prisms 79C and 79E, respectively, and their intervals are adjusted. Then, the left peripheral and leftmost peripheral luminous fluxes LC and LE are transmitted through the corresponding division lenses 83C and 83E and are divided into two.
The left peripheral and leftmost peripheral luminous fluxes LC and LE divided into two forms a pair of subject images at predetermined intervals on the line sensors 212C and 212E, respectively. In the figure, reference numeral 81
Reference symbols C and 81E indicate openings in the separator mask.

The structure of the focus detection optical system for the right peripheral distance measuring areas 70D, 70F will be described. In the present embodiment, the structure is symmetrical to the optical system for the left peripheral distance measuring areas 70C, 70E. Right peripheral light flux L that is incident from the right peripheral focus detection opening 72D and transmitted through the condenser lens 73D
D is refracted (deflected) by the prism 75D in the direction of being separated from the central light beam LA and incident on the first mirror 76D, and the first peripheral mirror 76D causes the second peripheral mirror 77D.
Is reflected by the second peripheral mirror 77D toward the line sensor 212D.

On the other hand, the rightmost peripheral light flux L that has passed through the rightmost peripheral focus detection aperture 72F and the condenser lens 73F.
F is refracted (deflected) by the prism 75F in the direction in which it approaches the right peripheral light beam LD and is incident on the first peripheral mirror 76D, and is reflected by the first peripheral mirror 76D in the direction in which it is incident on the second peripheral mirror 77D. (Deflected), second
It is reflected (deflected) toward the line sensor 212F by the peripheral mirror 77D.

Here, the right peripheral and right most peripheral light fluxes LD and LF reflected by the first peripheral mirror 76D intersect between the first and second peripheral mirrors 76D and 77D, and are directed to the second peripheral mirror 77D. When incident, the upper and lower positions are swapped. Therefore, the right peripheral light flux LD, LF reflected by the second peripheral mirror 77D is the right peripheral light flux LD on the upper side and the right most peripheral light flux LF on the lower side in FIG.

The right peripheral light flux LD and the right outermost light flux LF reflected by the second peripheral mirror 77D pass through the optical path adjusting prisms 79D and 79F, respectively, and the intervals between the right peripheral light flux and the right outermost light flux LD, LF are adjusted. . The right peripheral and rightmost peripheral luminous fluxes LD and LF are associated with the corresponding split lenses 83D and 83D.
After passing through F, the light beam is divided into two, and the right and left most peripheral light fluxes LD and LF, which are divided into two, are line sensors 212D and 212D, respectively.
A pair of subject images are formed on the 212F at predetermined intervals.
In the figure, reference numerals 81D and 81F indicate openings in the separator mask.

As described above, according to the embodiment of the present invention,
The left and right peripheral, most peripheral light fluxes LC and LE, LD and LF are the first and second peripheral mirrors 76C and 77C, 76D and 77D.
Since they intersect, the left and right marginal light fluxes LC and L
E, LD and LF are the first and second peripheral mirrors 76C and 77.
Since the incident positions on C, 76D and 77D are close to each other and the incident position on the second peripheral mirrors 77C, 77D is lowered (away from the focus detection area), the first and second peripheral mirrors 76C, 76D, 77C are , 77D, or the area can be reduced. Therefore, the peripheral mirror 76
C, 76D, 77C, 77D are peripheral light fluxes LC, LD, L
E and LF are no longer a concern. Further, since the crossed left light fluxes LC and LE and right crossed light fluxes LD and LF are separated after crossing, the second peripheral mirror 77C and the second peripheral mirror 77D.
Left light flux LC, LE, right light flux LD, LF after being deflected by
It is easy to provide optical systems that transmit light without interfering with each other.

In the illustrated embodiment, the peripheral light flux and the most peripheral light flux are made to intersect between the first mirror and the second mirror, but the intersecting position is not limited to this, and the first and second mirrors are not limited to this. It may be configured such that it intersects in front of the first mirror, on the first mirror, on the second mirror, or behind the second mirror. Further, in the illustrated embodiment, the peripheral and outermost peripheral focus detection areas are provided as the off-axis focus detection areas, but the present invention is not limited to these shapes and sizes, and the inside of the peripheral focus detection area is provided. Alternatively, the focus detection area may be provided outside the outermost focus detection area.

[0031]

As is apparent from the above description, the invention according to claim 1 is a pattern which is arranged off-axis at a predetermined focal plane.
Each of the light fluxes that have passed through the peripheral focus detection areas arranged by the screen is reflected by the first and second reflecting members, and the arrangement pattern different from the predetermined pattern on the secondary image plane.
In a focus detection device for causing a corresponding light receiving element array arranged in a center to receive light, the light flux that has passed through the first and second focus detection areas is crossed between the first and second reflecting members by a deflecting optical member. It is possible to form the reflecting surfaces of the first and second reflecting members in a small size because the light is deflected in the direction of the first and second reflecting members, and the first and second peripheral luminous fluxes are eclipsed by the first and second reflecting members. There is no fear. Furthermore, the first and second intersections
Since the peripheral light fluxes of (1) and (2) are separated and then separated from each other, it becomes easy to provide the optical systems through which the first and second peripheral light fluxes are transmitted without being interfered with each other after being reflected by the second reflecting member.

[Brief description of drawings]

FIG. 1 is a perspective view showing a main part of an embodiment of a focus detection device of the present invention.

FIG. 2 is a diagram showing an example of an array of a plurality of focus detection areas on a shooting screen in the same camera.

FIG. 3 is a diagram showing an arrangement of focus detection openings of a mask of the same focus detection device.

FIG. 4 is a diagram showing an outline of a single-lens reflex camera to which an embodiment of the focus detection device of the present invention is applied.

[Explanation of symbols]

11 Camera Body 21 Multi AF Sensor Unit 212A 212B 212C 212D 212E
212F CCD line sensor 51 shooting lens 70 shooting screen 70A central focus detection area 70B upper peripheral focus detection area 70C 70D first peripheral focus detection area 70E 70F second peripheral focus detection area 72A 72B 72C 72D 72E 72F focus detection aperture 73A 73B 73C 73D 73E 73F Condenser lens 75A 75C 75D 75E 75F Prism 76C 76D First peripheral mirror 77A Central mirror 77C 77D Second peripheral mirror 79A 79B Optical path adjusting prism 81A 81B 81C 81D 81E 81F Separator mask aperture 83A 83B 83E 83C 83D Split lens

Claims (2)

(57) [Claims] 1. The light beams transmitted through a plurality of peripheral focus detection areas provided in a predetermined arrangement pattern in an off-axis region on the planned focal plane are re-imaged on a plane on the re-imaging plane. Is a focus detection device that causes a corresponding light-receiving element array arranged in an arrangement pattern different from the arrangement pattern to receive light, wherein the plurality of focus detection areas are a first peripheral focus detection area and a center of the planned focal plane. And a second peripheral focus detection area provided on the same side as the first peripheral focus detection area and off-axis from the first peripheral focus detection area. A deflection optical member that deflects the light beam that has passed through the detection area and the light beam that has passed through the second peripheral focus detection area to guide it to the first reflecting member, and the first peripheral member that has been reflected by the first reflecting member. light And the
Two peripheral light beams are directed to the corresponding photodetector array
And a second reflecting member that reflects the reflected light, and the deflection optical member transmits the first peripheral focus detection area.
The first peripheral luminous flux that has been generated is used as the second peripheral focus detection area.
Deflection in a direction approaching the second peripheral light beam that has passed through
The first peripheral member to be incident on the first reflecting member.
Transmission through the deflection optical element and the second peripheral focus detection area
The second peripheral luminous flux that has been generated is used as the first peripheral focus detection area.
Deflection in a direction approaching the first peripheral light beam that has passed through
To allow the second peripheral component to enter the first reflecting member.
A deflecting optical element, and is set so that the first peripheral light flux and the second peripheral light flux reflected by the first reflecting member intersect and then enter the second reflecting member. A multi-point focus detection device characterized by: 2. A pair of the first peripheral focus detection area and the second peripheral focus detection area are symmetrically provided with respect to a central focus detection area arranged on the axis . Multi-point focus detection device.