JPH02217811A - Single-lens reflex camera with automatic focus detecting device - Google Patents

Abstract

PURPOSE:To easily take a picture without repositioning the camera by selecting a specific focus detection visual field area by shifting or rotating partial object light of the focus detection visual area to the position at which the partial object light of the specific focus detection visual field area, where a submirror is selected associatively with the selection of the focus detection visual field area, is reflected to a focus detection part. CONSTITUTION:A single focus detection part 25 is provided as a focus detecting means a moving mechanism moves the submirror 12 selectively to the position where object light beams L1 and L5 which are expected to reach partial visual fields set in a photographic visual field are reflected to a single focus detection part 25. The submirror 12 is moved to between 12a and 12e, a light beam which passes the center optical axis L1 is reflected at the position 12a along the optical axis Lo of the focus detection part 25, and object light having its center optical axis on the straight line L5 is reflected at the position 12e along center optical axis Lo of the same focus detection part 25. Consequently, the probability that a photographer puts the camera in focus on an intended main object without changing the camera angle by 1 deg. is improved greatly.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides an automatic focus detection device that automatically measures the deviation of the carrying lens to the in-focus position and drives the photographing lens to the in-focus position. Concerning single-lens reflex cameras.

[Prior Art] Conventionally, so-called TTL autofocus cameras have been commercially available that detect subject light transmitted through a photographic lens to detect the focus of the photographic lens. Most of these cameras perform focus detection using only subject light in a focus detection field of view set at the center of a photographic field of view (finder field of view) exposed to film, which is a recording medium.

[Problems to be Solved by the Invention] However, in such a conventional camera that has only one focus detection field of view at the center of the photographic field of view, it is difficult to detect the main subject on which the photographer is trying to focus. If the subject is outside the central focus detection field of view, first take a camera angle that brings the main subject into the central focus detection field of view, focus, and then perform the focus lock operation. I had to reposition the camera to get the desired camera angle before releasing the shot.

However, such a shadowing method requires a complicated operation since it is necessary to reposition the camera, and there is a problem in that it is particularly time-consuming when taking pictures using a tripod.

Furthermore, when the subject is moving, there is a problem in that it is easy to miss a photo opportunity while resetting the camera.

Furthermore, when the camera is repositioned for a relatively close-up subject, there is a problem that a so-called cosine error occurs in which the distance of the main subject differs between the time of focus and the time of the actual eye shadow, resulting in an out-of-focus image. .

The present invention has been made in view of these conventional problems, and is an automatic focus detection system that enables automatic focus control without changing the posture of the camera even when the main subject is in the peripheral area other than the center of the screen. The purpose is to provide a single-lens reflex camera with a device.

[Means for Solving the Problems] First of all, the present invention includes a main mirror including a semi-transparent part that reflects subject light to the finder system and allows the subject light to pass through, and The subject is a single-lens reflex camera that has a submirror that reflects subject light to focus detection means in a mirror box.

Claim 1 regarding such a single-lens reflex camera
In the invention, a single focus detection section is provided as the focus detection means, and each of the subject lights that should reach a plurality of partial fields of view set within the photographic field is directed to the single point of view by a submirror moving mechanism. The sub-mirror is configured to be selectively moved to a position where it is reflected to the focus detection section.

The invention of claim 2 also includes a sub-mirror moving mechanism that selectively moves the sub-mirror so that each of the subject lights that should reach a plurality of partial fields of view set within the projection field of view is reflected in different directions. A plurality of focus detecting sections constituting the focus detecting means are arranged in the direction of the submirror reciprocal optical axis corresponding to the movement position of the submirror moving mechanism.

[Function] In the single-lens reflex camera with an automatic focus detection device of the present invention having such a configuration, a plurality of focus detection visual field areas are set within the photographic field of view, and a selection operation of a specific focus detection visual field area is performed. In conjunction with this, the submirror is shifted or rotated to a position where it reflects the partial object light in the selected focus detection field of view to the focus detection section.

Therefore, if the main subject is not within the focus detection field of view set at the center of the photographic field of view, one or more other focus detection field of view set above, below, and/or to the left and right of the central focus detection field of view. By selecting a specific focus detection field of view that contains your main subject, you can easily take pictures without changing the camera.

[Embodiment] FIG. 1 is an explanatory diagram showing an embodiment of the present invention. In this embodiment, a single focus detection unit detects focus detection in a plurality of focus detection visual field areas set within the photographic field of view. It is characterized by performing a focus detection operation.

In FIG. 1, reference numeral 14 is a copying lens, and the subject light passing through the photographic lens is reflected by the main mirror 11, the screen mat 16, the pentaprism 17, and the eyepiece lens 18.
You will be guided by a finder system consisting of In addition, a part of the subject light that has passed through the photographic lens 14 passes through a semi-transparent part provided on the main mirror 11, and passes through a sub-mirror 12 disposed behind the main mirror 11.
guided by.

In this embodiment, the submirrors 12 are 12a and 12e.
It takes two positions.

When the sub-mirror 12 is at the position 12a, the subject light in the first focus detection field of view set at the center of the photographic field of view is reflected and enters a single focus detection section 25 disposed within the mirror box. On the other hand, when the sub-mirror 12 is at the position 12e, the subject light in the second focus detection field of view located slightly above the first focus detection field of view set at the center of the photographic field of view is 1
The light is reflected by the sub-mirror 12 located at position 20, and enters the same focus detection unit 25 along the same optical axis as at position @12a.

The relative position of the single focus detection unit 25 and the film surface 15 differs depending on the positions 12a and 12e of the submirror 12 because the optical axis direction differs, but by reading the positions 12a and 12e of the submirror 12, the position of the submirror can be determined. The position is corrected by calculation.

For this reason, the single focus detection unit 25 performs a focus detection operation based on the subject in the first focus detection field of view, which is the center of the photographic field, and a second focus detection operation that is preset at a different position with respect to the first focus detection field of view. The focus detection operation is performed based on the subject in the focus detection visual field area of the sub mirror 12 at the positions 12a, 1
This can be done with the selection operation 2e.

Next, in the embodiment of FIG. 1, the subject light in different focus detection visual field areas passing through the photographing lens 14, that is, the optical axis L1. L
The principle of movement control for the positions 12a and 12e of the submirror 12 in order to reflect the subject light of No. 5 by the submirror 12 so as to coincide with the incident optical axis 1o of the single focus detection section 25 will be explained.

In the embodiment shown in FIG.
Reflected light from the subject centered on the axis LO, which is perpendicular to LO and parallel to the vertical direction of the photographic screen.

The position and orientation allow focus detection based on the axis.

On the other hand, the sub-mirror 12 moves between positions 12a and 12e by rotational movement around a virtual rotation axis, which will be described next.

FIG. 2 shows the center light mL1 of the photographing lens 14 in the embodiment shown in FIG. 1 as the X axis, the reflection point P of the submirror 12 as the origin,
FIG. 3 is an explanatory diagram of an xy coordinate system in which the y-axis is a reflection optical axis LD for the focus detection unit 25 in a direction perpendicular to the central optical axis L1 from a point.

Further, in the xy coordinate system of FIG. 2, point Q is the intersection of the plane of the exit pupil 19 of the photographing lens 14 and the central optical axis, that is, the X axis, as shown in FIG.

Here, in the xy coordinate system of FIG. 2, connect the point corresponding to the center of the second focus detection visual field area on the film surface 15 of FIG. 1 and the Q point determined by the exit pupil 19 of the photographing lens 14. Let the straight line be L5, and let the angle of the straight line L5 with respect to the X axis be θ. In addition, the origin P and Q, which are the reflection points of the sub-mirror 12, are
Let the distance to the point be d.

Based on these conditions, a straight line expressed by the following equation is defined as T1.

(1-jan(θ/4))X+ (1+jan(θ/4)
)) Y=d-tanθ(cos(0/2)-sin(θ
/2))/5in(θ/2)...(1) What this straight line T1 means is that the sub-mirror 12 passes through one point on the straight line T1 and the sub-mirror 12 is rotated with the axis perpendicular to the plane of the paper as the virtual axis of rotation. By moving between the positions 12a and 12e, the light beam passing through the central optical axis L1 can be reflected in the direction along the optical axis 1o of the focus detection section 25 at the position 12a,
At the position 12e, the object light having the central optical axis along the straight line L5 can be reflected by the sub-mirror 12 so as to be directed along the central optical axis 10 of the same focus detection section 25. Also, by switching the positions 12a and 12e of the submirror 12, the same focus detection unit 2
The incident optical axis L1.5 is reflected to the central optical axis LO of 5. L5 is the exit u! of the photographing lens 14. In order to pass through the center Q of 19,
The object light flux used for focus detection in the first and second focus detection field of view areas is less likely to be vignetted by the photographing lens 14, and more light m can be used for focus detection, as well as being measured by the vignetting of the photographing lens 14. A focus detection optical system suitable for a phase difference type focus detection device that causes errors is realized.

In the embodiment shown in FIG. 1, the case was taken as an example in which two focus detection field areas, the first and second, were set within the photographic field of view, but the first and second focus detection field areas were further set. In addition to the focus detection visual field area, a third focus detection visual field area may be added. When the third focus detection visual field area is set in this way, the virtual rotation center of the submirror is determined for the first and second focus detection visual field areas, similar to the line 1 below in FIG. The straight line 1jlT2 that gives the virtual center of rotation of the submirror for the first and third focus detection visual field areas is determined, and the straight line T1 shown in FIG. 2 and the newly determined straight line 2
What is necessary is to give the sub-mirror 12 a motion centered around a virtual rotation axis passing through the intersection of .

Of course, when the focus detection field of view areas are two or three, the position of the virtual rotation axis of the submirror is exactly the same as in the above (1).
Even if it is not at the position determined by the formula, but in the vicinity, the advantage that the subject light beam used for focus detection is less likely to be eclipsed by the photographic lens can be taken advantage of, compared to when the rotation axis is set without consideration at all.

Furthermore, in the case of a single-lens reflex camera with an interchangeable photographic lens 14, if the distance from the reflection point P of the sub-mirror 12 at position 12a in FIG. 1 to the film surface 15 is r, then
(r+d) is the distance from the film surface 15 to the center Q of the exit pupil 19 of the photographic lens 14.

Here, the exit pupil 19 of the photographing lens 14 cannot be uniquely determined because (r+d) varies from about 5Qmm to about 300mm depending on the lens. However, −
It can be envisaged that (r+d) in the membrane has a value around 100 mm, ie in the range from 70 mm to 150 mm. Therefore, the straight line T1 in Fig. 2 is (100-r
> mm, i.e. (70-r) mm to (150-r>
If the straight line T1 of the above equation (1) is determined by regarding the point Q to be located in front of the point P by a range up to mm, and the virtual rotation axis of the sub-mirror is set on this straight line T1, the carrying lens Even when replaced, the submirror 12 can be switched between the positions 12a and 126 for the single focus detection unit 25 according to FIG. Light can be made to enter without being vignetted by the wL shadow lens 12.

Furthermore, considering the effective use of the area of the sub-mirror 12, among the virtual rotation axes set on the second straight line T1, the following (
The vicinity of the zero point given by the X, V) coordinates is advantageous.

LI [d-tan θ/2 tan (θ/4), −
(d/2)tanθ] 3rd. 4th. FIG. 5 is an explanatory diagram showing the moving machine groove of the sub-mirror 12 in the embodiment of FIG. 1, and FIG.
4 shows a state in which the submirror 12 is set to position 12e, and FIG. 5 shows a state in which the main mirror and the submirror are raised together with the release operation.

In FIG. 3, the sub-mirror 12 is fixed to a sub-mirror frame 31, and a spring 32 is connected between a pin 32 and a protrusion at the lower end of the sub-mirror frame 31 and a spring hook fixed to the main mirror 11.
5 is attached, and a tension force is applied between the two by a spring 35. Further, the upper end of the sub-mirror frame 31 is connected to a lever 33 whose tip is bifurcated by a sub-mirror @36, and the bifurcated portion of the lever 33 is engaged from below to a pin 34 fixed to the mirror box. Further, the sub-mirror shaft 36 is fitted into an elongated hole 38 of an ear portion 37 formed integrally with the fixed frame of the main mirror 11, and the sub-mirror 12 is moved while being guided by the elongated hole 38.

The mechanism for switching the sub-mirror 12 to the positions 12a and 12b includes a cam 41, a positioning board 42 that is moved by the rotation of the cam 41, and positioning pins 39 and 40 that position the sub-mirror 12 with respect to the positioning board 42.

That is, the positioning pins 39 and 40 are fixed to the positioning board 42, and as the cam 41 rotates, the positioning pins 39 and 40 are fixed to the positioning board 42.
2 moves along guide pins 44 and 45 on the fixed side of the mirror box relative to the guide groove 43, and this positioning board 4
2, the sub-mirror 12 can be moved between the position 12a (FIG. 3) or the position 12e (FIG. 4) shown in FIG. 1 by the positioning pins 39, 40.

Therefore, the central curve of the guide groove 42 that determines the moving direction of the positioning board 42 shown in FIG. 12 can be moved and switched between positions 12a and 12b.

In FIG. 4, the cam 41 is rotated relative to the position 12a of the submirror 12 in FIG. 3, and the positioning board 42 is pushed down.
By moving the positioning board 42 downward, the sub mirror 1
2 is shown moved to the switching position 12e by rotation about the virtual center of rotation on the straight line T1 in FIG.

FIG. 5 shows a state in which the main mirror 11 is mirror-up by the force of the spring 35 in the state of the sub-mirror 12 in the position 12a of FIG. and move upward.

FIG. 6 is an explanatory diagram showing an embodiment of the present invention. In this embodiment, a plurality of focus detection units are provided corresponding to the set number of focus detection visual field areas, and each focus detection unit A feature of the present invention is that the focus detection area subject light is switched by rotating a sub-mirror.

In FIG. 6, the object light that has passed through the photographic lens 14 is reflected by the main mirror 11 and guided to the finder optical system consisting of the screen mat 16, pentaprism 17, and eyepiece 18, and at the same time, part of the object light is reflected by the main mirror 11. 11
It passes through the semi-transparent part provided in the front sub-mirror 1.
The sub-mirror 12 guided by the mirror 2 can be selectively rotated around the rotation axis P by an external operating member 13 between positions 12a and 12b. Incidentally, the interlocking mechanism of the sub-mirror 12 by the external operation member 13 is disclosed in, for example, Japanese Patent Laid-Open No. 62-4.
Known means disclosed in Japanese Patent No. 4721 and the like can be used.

When the sub-mirror 12 is rotated to the first position 12a, a part of the subject light from the main mirror 11 is transferred to the sub-mirror 1.
2 and guided to the focus detection section 21. The optical axis passing through the center of the field of view of the object light reflected by the sub-mirror 12 on the focus detection section 21 is indicated by Ll.

Further, the sub-mirror 12 is located at the position 12b of the external operation member 13.
When the main mirror 11 is rotated, a portion of the object light that has passed through the main mirror 11 is reflected by the sub-mirror 12 located at the position 12b and is guided to the second focus detection section 22. This second
The optical axis of the subject light guided to the focus detection section 22 passing through the center of the subject is indicated by L2.

15 is a film surface, and during exposure to irradiate object light onto this film surface 15, the main mirror 11 and the sub mirror 1
2 is retracted upward so as not to obstruct the optical path to the film surface 15. When the mirror is raised, the light rays on the optical axes L1 and L2 that have passed through the photographic lens 14 reach the center of the film surface 15 and slightly below, as shown by broken lines.

Therefore, in the mirror set state shown in FIG. 6, the subject light incident on the focus detection units 21 and 22 is partial subject light corresponding to separate focus detection visual field areas centered on the center and slightly below the film surface 15. becomes.

Focus detection section 21 or 2 comprising focus detection means 208If4
2 is automatic focus detection that drives the photographing lens 14 to the in-focus position based on object focus detection information based on the object light incident by selective rotation of the position 12a or 12b of the sub-mirror 12, according to a known phase difference detection method, etc. control.

Note that since an inverted image of the subject is formed on the film surface 15, when viewing the photograph after it has been taken, the image on the film surface is usually inverted again and viewed as an erect image, or the image is viewed through the viewfinder system. The optical system is set so that even if there is an image, it can be seen as an erect image. Therefore, film surface 15
The fact that the second focus detection field of view corresponding to the optical axis L2 above is located slightly below the center means that the second focus detection field of view is located at the center of the photographic field of view in the photographed photograph and on the viewfinder screen. It has a positional relationship that is located slightly above the .

In this way, in the embodiment shown in FIG.
By selecting the focus detection visual field range through the operation of the sub-mirror 12 in step 3, focus detection can be performed based on the subject light reaching the center of the photographic screen, or based on the subject light reaching a specific part above the center of the screen. Focus detection can be performed arbitrarily. Of course, by driving the photographing lens 14 to focus using the focus detection results corresponding to the selection of the two focus detection field of view areas, it is possible to focus on the subject in the center of the photographic field, or to focus on the subject of information from the center of the R shadow field of view. You can focus.

Further, in the embodiment shown in FIG. 6, two focus detection sections are provided, but the number of focus detection sections may be three or more as appropriate.

FIG. 7 shows an embodiment in which three focus detection sections are provided.

In FIG. 7, some parts common to FIG. 6 are omitted, and the same members as in FIG. 6 are given the same numbers.

In FIG. 7, the sub-mirror 12 is rotated about the rotation center P to three positions shown as 12a, 12c, and 12d in response to a selection operation using an external operation member.

When the sub-mirror 12 is at the position 12a, a part of the subject light enters the focus detection unit 21, and the focus detection unit 21 detects the screen as shown in FIG. Focus detection is performed based on the subject light incident on the focus detection field of view area S1 at the center.

Further, when the sub-mirror 12 is at the position 12c, the focus detection section 23 can perform focus detection based on the subject light incident on the focal visual field area S3 in FIG. Furthermore, when the sub-mirror 12 is at the position 12d, the focus detection section 24 detects the focus detection visual field area S4 in FIG.
Focus detection can be performed based on the subject light incident on the area.

In the embodiment shown in FIG. 7, the object focus detection area 33°S4 is set at a position shifted upward and to the left with respect to the center object focus detection area S1 shown in FIG. , S3 may be set downward with respect to 81 in the center, and S4 may be set at a position shifted from the center in the right direction.

Furthermore, in the embodiment shown in FIG.
performs focus detection based on the brightness distribution along the horizontal direction of the screen, while the focus detection section 24 performs focus detection based on the luminance distribution along the vertical direction of the screen.
Although it has a structure that performs focus detection based on the power distribution,
The present invention is not limited to this, and it goes without saying that the plurality of focus detection sections may have different fields of view, brightness distribution directions, etc. used for focus detection.

Furthermore, in the embodiments shown in FIGS. 1, 6, and 7,
Although focus detection is performed using a single partial field of view, that is, a focus detection field of view, for one moving or rotating position of the sub-mirror 12, focus detection of a plurality of focus detection field of view ranges is performed at one mirror position. You can do it like this.

Specifically, the focus detection section 25 of FIG.
27710 or the like may be used instead of a focus detection section that can simultaneously detect the focus of a plurality of partial focus detection fields (S5-S6 or S7-88 in FIG. 9). In FIG. 9, the photographic screen A is shown in the same posture as in FIG. 8, and when the submirror is at the position 128 in FIG. Detection can be performed simultaneously, and when the submirror is in the position shown in FIG. 12e, focus detection can be performed simultaneously using the two partial focus detection fields 87 and 88 in FIG.

Furthermore, in the above embodiment, the operator selects the focus detection visual field area by the submirror using an external operating member, but the present invention is not limited to this, and the selection of the focus detection visual field area by the submirror is performed by the operator. Of course, fishing may be carried out automatically according to predetermined conditions under the control of a microcomputer built into the camera.

Furthermore, in the above embodiment, the focus detection visual field area other than the focus detection visual field area at the center of the photographic field of view is set to a range that is not affected by vignetting due to the exit pupil of the photographic lens. If vignetting occurs in a specific focus detection field of view when replacing the photographic lens, a limit range without vignetting is determined based on the photographic lens information, and focus detection is set to a range that exceeds this vignetting limit. Restrictions may be added, such as prohibiting the selection operation of the viewing area using the submirror.

[Effects of the Invention] As explained above, according to the present invention, the probability of focusing on the main subject intended by the photographer is greatly improved without changing the camera angle and re-holding the camera. When the main subject is out of the center of the photographic field of view, positive mode operation becomes easy, and since there is no need to change the camera angle, less camera angle can be effectively utilized.

In particular, when photographing a subject moving in the far and near direction at a position that is not in the center of the photographic field of view, by selecting a convenient focus detection field of view area in which the subject can be captured in advance, the selected focal point can be It is possible to track the intended subject while capturing it in the detection field of view, and to effectively capture the main subject at a position away from the center of the photographic field of view.

Furthermore, for objects at a relatively close distance, no cosine error occurs due to repositioning, and blurring in close-up photography can be reliably prevented.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing one embodiment of the present invention; Fig. 2 is an explanatory diagram of coordinates for determining the virtual center of rotation for moving the submirror shown in Fig. 1; Fig. 3 is an explanatory diagram of the submirror moving mechanism shown in Fig. 1. FIG. 4 is an explanatory diagram of the sub-mirror in FIG. 3 moved to the second position; FIG. 5 is an explanatory diagram of FIG. 3 when the mirror is raised; FIG. An explanatory diagram showing another embodiment: Fig. 7 is an explanatory diagram showing another embodiment in which the focus detection visual field area of the embodiment shown in Fig. 6 is increased to three; FIG. 3 is an explanatory diagram of an erect photographing field of view showing a focus detection field of view area with respect to the rotational position of the submirror. 11: Main mirror 12: Submirrors 12a to 12e: Submirror position 13: External operation member 14: lff1 shadow lens 15, film surface 16: Mat screen 17: Pentaprism 18: Eyepiece 19: l1FJ exit pupil 20: Distance measuring means 21 to 25: Distance measurement section 31: Sub-mirror frame 32: Spring hook pin 33 Nilever 34: Fixed pin 35: Spring 36: Sub-mirror shaft 37: Ear portion 38: Long hole 39.40: Positioning pin 41: Cam 42: Positioning Board 43 guide hole 44.45 guide pin

Claims (3)

[Claims] (1) A main mirror equipped with a semi-transparent part that reflects the subject light to the finder system and allows the subject light to pass through, and a focus detection means in the mirror box that detects the subject light that has passed through the semi-transparent part of the main mirror. In the single-lens reflex camera, the focus detection means includes a single focus detection section, and each of the subject light that is to reach a plurality of partial fields of view set within the photographic field of view is A single-lens reflex camera with an automatic focus detection device, comprising a submirror moving mechanism that selectively moves the submirror to a position where the submirror is reflected by a single focus detection unit. (2) A main mirror with a semi-transparent part that reflects the subject light to the finder system and allows the subject light to pass through, and a focus detection means in the mirror box that detects the subject light that has passed through the semi-transparent part of the main mirror. In a single-lens reflex camera, the submirror is selectively moved to a plurality of positions where each of the subject light that should reach a plurality of partial fields of view set within a photographic field of view is reflected in different directions. a sub-mirror moving mechanism; and a plurality of focus detecting units constituting the focus detecting means, each of which is installed in each direction of the reflected optical axis corresponding to the position of movement of the sub-mirror by the sub-mirror moving mechanism. A single-lens reflex camera with an automatic focus detection device. (3) The focus detection section is configured to be able to simultaneously detect the focus of each of the subject lights that should reach a plurality of partial fields of view at the submirror position selected by the submirror moving mechanism. A single-lens reflex camera with an automatic focus detection device according to items 1 and 2.