JPS62237412A - Automatic focusing device - Google Patents

Abstract

PURPOSE:To reduce a distance measuring parallax by a simple constitution, by turning one of a projecting element and a projecting lens, and one of a light receiving element and a light receiving lens, centering around the same revolving shaft, by interlocking with a movement of a photographic lens group. CONSTITUTION:Both a projecting lens 2 and a light receiving lens 3 are attached to a connecting plate 15, and rotated by a prescribed angle by using a revolving shaft 16 as the center of a rotation, in accordance with feed-out and feed-in of a photographic lens group 8 by an AF cam 19. In this case, as for a movement of the projecting lens 2, when the projecting lens 2 and the light receiving lens 3 rotate clockwise centering around the revolving shaft 16, the direction of a projected light beam changes its angle in the lower direction of L1' from L1. In this case, a distance in which the projected light beam crosses an optical axis of the photographic lens group 8 becomes a focused distance of the photographic lens group 8, and also, a reflected light therefrom is made to form an image on a boundary of a light receiving element 4, a distance measuring optical system which scarcely causes a parallax can be obtained by only a rotational operation by one revolving shaft 16.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a so-called differential active type distance measuring device that projects a light beam toward a subject and receives the reflected light with a light receiving element to determine the distance. The present invention relates to an automatic focusing device that reduces distance measurement parallax.

[Prior art] Conventionally, the distance to the subject is detected, the drive motor, display, etc. are driven based on the detection result, the distance to the subject is automatically detected, and the photographing lens or photographing surface is moved at the same time. Various devices have been proposed that automatically adjust the subject image to be in focus. A typical example is the so-called differential mode, in which a specific pattern of light is projected onto the subject, the reflected light from the subject is detected by two light receiving sections, and the distance to the subject is detected based on the difference in output between the two light receiving sections. There is an active type distance measuring device, which has the advantage of being able to obtain a relatively high-precision distance measuring operation with a simple configuration.

FIG. 1θ and FIG. 11 show a camera with an automatic focus adjustment device equipped with a conventionally known differential type active distance measuring device, in which a light emitting element 1 such as an infrared diode or semiconductor laser that emits near-infrared light is used. The light rays emitted from the lens 1 form a projection spot on the subject S by a projection lens 2 which is, for example, a molded aspherical lens. This projected light spot is reflected on the subject S, and the reflected light is passed through the light receiving lens 3, which is a molded aspherical lens, for example, to the SPC.
An image is formed on the light-receiving element 4, which is divided into two areas 4a and 4b.

In the focused state shown in FIG. 1O, the light receiving element 4
The center of the projected spot image formed above is the area 4a.
and 4b, and the output of area 4a is A, and area 4
Letting the output of b be B, A-B=0. In this way, when the outputs A and B are the same, or when the difference between them is extremely small, the state is in focus, and the image of the subject S is correctly formed on the film plane, image pickup tube, or imaging plane of the image pickup device. be done.

By the way, as shown in FIG. 11, if, for example, the subject S momentarily moves toward the camera side from the focused state of FIG. When the outputs from the regions 4a and 4b are amplified and integrated by the signal processing circuit 5 and the difference is calculated, A-B becomes negative, and after-focus is detected. The sign and magnitude of the difference signal obtained from the signal processing circuit 5 are calculated by the microprocessor 6 to drive and control the AF mode 7, and the photographing lens group 8 including the focusing lens group and the light receiving lens 3 are operated. Move together in the direction of the arrow. As a result, when A-B=O, the AF momo-7 stops and focuses on a new subject distance.

Note that in the actual configuration, A-B is I
It has a dead zone k so that it is in focus at A-Blk.

However, in this way, the light emitting element 1 and the light emitting lens 2
If they are fixedly arranged, the point being measured is not always at the center of the photographic screen, but changes depending on the distance, resulting in so-called distance measurement parallax.

For example, when the light emitting lens 2 and the light receiving lens 3 are arranged one above the other with the photographing lens group 8 in between as shown in FIG. 12 when viewed from the front of the camera, the distance measurement point position in the screen is shown in FIG. 13. Shown below. If the distance measurement visual field position at the time of distance IaR in FIG. 10 is PO, then the distance measurement position at a distance closer to it is Pi, and the distance at a longer distance is P2. Note that when the light projecting lens 2 is not on the vertical line of the photographing lens group 8, a lateral shift also occurs.

Such a shift in the field of view for distance measurement becomes large especially in the case of a zoom lens at its telephoto end, and depending on the size of the subject S, etc., it may cause a distance measurement error. Therefore, several methods have been proposed to eliminate this variation in distance measurement.

Fig. 14 shows an example for keeping the disparity of the distance measurement field at the center of the screen, and when compared with the examples shown in Figs. It is linked to 8. As a result, in the new focused state, the emitting ray and the receiving ray pass as shown by the two-dot chain line,
This means that there is no distance measurement parallax and the lens is in focus. However, in such a case, the light emitting lens 2 and the light receiving lens 3
It has disadvantages such as being mechanically complex because it operates both, the distance measurement accuracy is slightly degraded, and it is difficult to assemble and adjust, resulting in high cost. In addition, Fig. 10, Fig. 11, Fig. 1
Although Fig. 4 shows a type in which the light emitting/receiving lens 2.3 is activated, modifications such as providing a mirror and activating the mirror may be considered depending on the light emitting element 1, the light receiving element 4, or the configuration. .

FIG. 15 shows another conventional example of a camera equipped with a known semi-TTL differential active distance measuring device having a different configuration. Rather than making the optical elements of the system completely independent from the photographing lens group 8, a part of the lens forming the projection optical system is used also as the photographing lens system, as shown in Figs. 10 and 11. It is generally more compact than other types. The light emitting element 1 is optically arranged at a position equivalent to the focal plane on the photographing axis of the photographing lens group 8, and emits light at a focusing distance determined by the stopping position of the photographing lens group 8 with respect to the subject S. The spot image is focused correctly and there is no variation in distance measurement. The projected light beam from the light emitting element 1 that has passed through the projected lens 2 is aligned with the photographing optical axis by a gicroic mirror 9 that reflects only the light in the wavelength range of the projected light beam, and the lens group involved in focal length adjustment is aligned. The light passes through the photographing lens group 8 including lens 10 and is emitted to the subject S. That is, in the conventional example shown in FIG. 14, the light projecting lens 2 moves in conjunction with the movement of the photographing lens group 8, but in the conventional example shown in FIG. 15, this is not necessary. Note that the length indicated by RO in FIG. 15 indicates the base line length of the triangulation method.

FIG. 16 shows a modified example of a camera lens equipped with a TTL differential active distance measuring device having yet another configuration. In this case, both the light emitting element 1 and the light receiving element 4 are included in the photographing lens group 8. It is arranged via a guichroic mirror 9 at a position equivalent to the focal plane on the photographing optical axis.

Semi-TTL, TTL as shown in Figures 15 and 16
In all TL differential distance measuring devices, the distance measuring position is at the center of the screen, and there is no variation in distance measurement.
Compared to the external distance measuring method shown in FIGS. 10, 11, and 14, the loss of energy projected onto the subject S is large, which is disadvantageous in terms of the limit distance for distance measurement. Furthermore, the provision of the guichroic mirror 9 also has the disadvantage of increased cost.

[Object of the Invention] The object of the present invention is to provide an automatic focusing system for cameras, etc., which eliminates the drawbacks of the conventional examples described above, and can minimize the variation in distance measurement with a simple configuration even though it uses an external distance measurement method. The purpose of the present invention is to provide a regulating device.

[Summary of the Invention] The gist of the present invention for achieving the above-mentioned object is to provide a photographing lens group involved in focus adjustment, a light projecting element/light projecting lens for projecting light rays onto a subject, and a light beam reflecting from the subject. The light-receiving element has a fist light-receiving lens for receiving light, and one of the light-emitting element and the light-emitting lens and one of the light-receiving element and the light-receiving lens are moved in conjunction with the movement of the photographing lens group. This automatic focus adjustment device is characterized in that it is configured to rotate around the same rotation axis.

[Embodiments of the Invention] The present invention will be described in detail based on illustrated embodiments. Note that the same reference numerals as in FIGS. 10 to 16 indicate the same members.

FIG. 1 is a configuration diagram of the photographic lens group viewed from the front, and FIG. 2 is a sectional view viewed from the entrance direction of FIG. 1.

In this first embodiment, as in the case of the conventional example, 8 is a photographing lens group for focus adjustment consisting of, for example, about three lenses, and is fixed to a distance ring 11. is rotatably attached to a fixed lens barrel 13 via a helicoid 12. A frame 14 is fixed to the fixed lens barrel 13, and a light projecting element 1 and a light receiving element 4 divided into two areas 4a and 4b are attached to this frame 14. A light emitting lens 2 and a light receiving lens 3 are arranged in front of the light emitting element l and the light receiving element 4, respectively.These emitting and receiving lenses 2.3 are attached to a connecting plate 15, and this connecting plate The plate 15 is attached to a motor base plate 17 fixed to the frame 14 via a rotating shaft 16. The straight line connecting the light projecting lens 2 and the rotating shaft 16 and the straight line connecting the light receiving lens 3 and the rotating shaft 16 are approximately at right angles, and the straight line connecting the light projecting lens 2 and the rotating shaft 16 is longer. Furthermore, a cam follower portion 18 is projected from a portion of the connecting plate 15, and this cam follower portion 18 is in contact with an AF cam 19 provided on a portion of the distance ring 11. In addition, 7 is an AF motor, and its output gear 2
0, the focus gear 22 of the distance ring 11 is driven via the intermediate gear 21. Furthermore, zoom par 2
3. A variator lens 25 is driven by a moving ring 24, 26 is a front plate, 27 is an AF cover,
Reference numeral 28 indicates a visible light cut filter provided on the front surface of the AF cover 27.

Here, the light emitting lens 2 and the light receiving lens 3 are both attached to the connecting plate 15 as described above, and are rotated at a predetermined angle about the rotation axis 16 in response to the extension and retraction of the photographing lens group 8 by the AF cam 19. only rotates. At this time, the movement of the light emitting lens 2 is as shown in FIG.
The direction of the projected light beam shown in the figure changes in angle from Ll to below Ll'. At this time, the projected light beam Ll' is
If the distance intersecting the optical axis is the focusing distance of the photographing lens group 8, and if the configuration is such that the reflected light from this focuses an image on the boundary of the light receiving element 4, then only the rotation operation using one rotation axis 16 is possible. Therefore, it is possible to realize a distance measuring optical system with less variation.

To simplify the explanation, using the principle diagram in Figure 3,
Assume that the connecting plate 15, that is, the light projecting lens 2 and the light receiving lens 3, rotate clockwise by an angle θ about the rotation axis 16 as shown by the two-dot chain line. Then, the projection lens 2 has JEx in the y direction,
It moves in the X direction by JEx, which is extremely small compared to Ete. Further, the light receiving lens 3 similarly moves by ΔFy, which is extremely small compared to ΔFX and ΔFK. Here, JEx is a component for correcting the parallax, and JEx is a component of the distance measurement parallax deviation in the X direction, but it is so small that it can be almost ignored.

Also, JEx is the amount of movement for distance measurement, and considering JEx, in approximate calculation, ΔFx + Δ
E! is considered to be the amount of distance measurement movement from infinity to the closest distance RN (mm). Also, ΔF! contributes to a shift in the spot position on the light-receiving element 4 in the y direction, making it necessary to widen the width of the light-receiving area, but this does not pose a problem since it is minute.

Here, a rough calculation will be attempted using an approximate formula.

The distance between the projection and reception lenses 2 and 3 in the y direction is D = 13, the base line length that is the distance in the X direction is L = 30.5, the focal length of the reception lens 3 is fs = 22, and the focal length of the projection lens 2. Given the assumptions that Fe = 26 and close range RN = 1200, the scanning amount for distance measurement is ΔFx+-E
x= (22/1200) ・30.5=0.559m
m.

Next, since ΔFx=D o sin θ and ΔEx= L e (1−cos θ) geometrically, 0.
When calculated as 559=Do sin θ +L−Laces θ, it becomes θ=2, 3510.

From this, ΔEy=1.25mm, and ΔEy=
From Loginθ, y=58mm.

Therefore, although it is an approximate calculation, by arranging the light projecting lens 2 and the light receiving lens 3 having the above specifications in such a positional relationship, automatic focusing with less distance measurement parallax is easily possible.

In addition, in cases where the photographing lens group 8 has a relatively long telephoto position but a large aperture value, and the distance measurement accuracy may be poor, although variation is difficult, the cam value should be designed to eliminate variation. Priority may be given, and under conditions where the magnification is low and the lower aperture value is large, a primary cam can also be approximated.

FIG. 4 shows parts when the light emitting lens 2, the light receiving lens 3, and the connecting plate 15 shown in FIGS. 1 and 2 are integrally molded from synthetic resin, that is, the AF lens 3°, and (a) shows the front view. The figure, (b) is a plan view. This AF lens 30 includes a light emitting lens 2, a light receiving lens 3, a cam follower part 18, and a bearing part 3.
1. The spring hanging portion 32 is integrally molded, which is particularly effective in cases where the base line length may be short.

5 to 7 show the second embodiment, FIG. 6 is a sectional view of FIG. 5 viewed from direction A, FIG. 7(a) is a front view of the connecting plate, and FIG. 7(b) is a side view. It is a diagram. Whereas in the first embodiment described above, the light emitting lens 2 and the light receiving lens 3 are rotated around the same rotation center, in this embodiment, the light emitting lens 2 and the light receiving lens 3 are rotated around the same rotation center.
Both are fixed, and the light emitting element 1 and the light receiving element 4 are rotated about the same rotation axis. Therefore, in the embodiment shown in FIG. 1, the light projecting element 1 and the light receiving element 4 rotated clockwise from infinity to close range, whereas in this embodiment they rotate counterclockwise.

Here, 40 is a substrate to which the light receiving element 4 is attached, 41
is a substrate to which the light projecting element l is attached. Also, 42
are the mounting plates for these boards 40 and 41, and the rotating shaft 43
The cam follower section 44 is connected to the connecting plate 42 as shown in FIG.
A bearing 46 into which the rotating shaft 43 is inserted is attached to the motor base plate 45. On the other hand, the light projecting lens 2 and the light receiving lens 3 are fixed at the front side of a frame 47 attached to the fixed lens barrel 13 by being sandwiched between slit parts 48 and 49. The mounting plate 42 has tapped holes 50 and 51 for mounting the board 40, and the board 41.
Tapped holes 52, 53 are drilled for mounting. With this configuration, a distance measuring system with less parallax can be constructed by rotating around the single rotating shaft 43, as in the first embodiment.

8 and 9 show a third embodiment, and FIG. 9 is a sectional view of FIG. 8 viewed from direction A. In the first embodiment, the light projecting lens 2 and the light receiving lens 3 are rotated around one rotating shaft 16, and in the second embodiment, the light projecting element 1 and the light receiving element 4 are rotated around one rotating shaft 43. In contrast, in this third embodiment, the light projecting lens 2 and the light receiving element 4 are configured to rotate about one axis. The light emitting lens 2 and the light receiving element 4 are connected to a connecting plate 6
It is attached to 1. In this example, the AF momo
7, as shown in FIG. 9, is located at the rear compared to the previous two embodiments. Reference numeral 62 denotes a gearbox section of the AF momo-7, which has an output stage (not shown). This output stage meshes with the gear 63 and transmits the signal to the coaxial gear 21. A substrate 64 to which the light receiving lens 3 and the light projecting element 1 are attached is fixed to a frame (not shown). A rotating shaft 65 is caulked to the connecting plate 61, and a bearing portion 66 is fitted onto the rotating shaft 65. If such a configuration is adopted, the first
, unlike the second embodiment, the light receiving lens 3. Since the light receiving element 4 can be arranged closer to the photographing lens group 18 than the rotation axis position, it can be said that the overall structure is highly compact. Further, it is also possible to use the light projecting element 1 and the light receiving lens 3 as rotating elements based on this idea.

[Effects of the Invention] As explained above, the automatic focus adjustment device according to the present invention has the following effects:
"Emitter lens and light receiver lens" centered around one rotation axis
, "Light emitter and light receiver", "Light emitter and light receiver"
By rotating the "light emitting element and light receiving lens" by a predetermined angle in conjunction with the movement of the photographic lens group, it becomes possible to reduce distance measurement parallax with a simple configuration.

[Brief explanation of drawings]

Drawings 1 to 9 show an embodiment of an automatic focus adjustment device according to the present invention, and FIG. 1 is a front view of the first embodiment, and FIG. 2 is a view taken from direction A in FIG. 1. 3 is a diagram showing the principle of the present invention, FIG. 4(a) is a front view of a lens that integrates a light emitting lens and a light receiving lens, and FIG. 5(b) is a plan view.
The figure is a front view of the second embodiment, FIG. 6 is a sectional view taken from direction A in FIG. 5, FIG. 7 (a) is a front view of the connecting plate, and (b)
is a side view, FIG. 8 is a front view of the third embodiment, FIG. 9 is a sectional view taken from direction A in FIG. 8, and FIGS.
The figure shows the configuration of a conventional external distance measuring differential automatic focusing device. Figure 12 shows the arrangement of the light emitting lens and light receiving lens when distance measurement field of view shifts, and Figure 13 shows the arrangement of the conventional example. An explanatory diagram of the distance measurement field position within the screen. Figure 14 is a configuration diagram of a conventional parallax-free external distance measurement type differential autofocus Y1 node device. Figure 15 is a conventional semi-TTL differential type automatic FIG. 16 is a block diagram of a conventional TTL differential automatic focus adjustment device. 1 is a light emitting element, 2 is a light emitting lens, 3 is a light receiving lens,
4 is a light receiving element, 7 is an AF motor, 8 is a photographing lens group, 1
1 is the distance ring, 13 is the fixed lens barrel, 14.47 is the frame,
15.42.61 is the connecting plate, 16.43.65 is the rotating shaft, 18.44 is the cam follower part, 19 is the AF cam, 3o
is an AF lens.

Claims (1)

[Claims] 1. A group of photographic lenses involved in focus adjustment, a light projecting element/light projecting lens for projecting light rays onto a subject, and a light receiving element/light receiving lens for receiving reflected light from the subject. and one of the light emitting element and the light emitting lens and one of the light receiving element and the light receiving lens are rotated about the same rotation axis in conjunction with the movement of the photographing lens group. An automatic focus adjustment device characterized by comprising: 2. A straight line connecting the rotating shaft and one of the light projecting element and the light projecting lens and a straight line connecting the rotating shaft and one of the light receiving element and the light receiving lens are arranged so as to be substantially perpendicular to each other. The automatic focus adjustment device according to item 1.