JPH0731303B2 - Focus detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a secondary image shift type focusing device used in a single-lens reflex camera or the like, and an optical axis of a focusing unit and an optical axis of a camera side. The present invention relates to a focus detection device provided with an adjusting mechanism for adjusting, ie, a pupil exiting mechanism.

[Prior Art] Conventionally, in this type of focusing device, it is general that the tilt of the entire focusing unit is adjusted to perform pupil exit. For example, in the apparatus disclosed in Japanese Patent Laid-Open No. 60-39612, the focusing unit is attached to the front plate of the camera by using three screws and springs, and the posture of the focusing unit, that is, the inclination, is tilted by extending the screws. I am trying to adjust it. However, this type of system has a drawback in that when the focusing unit is incorporated into the camera, only the pupil adjustment can be performed, and parallax adjustment with respect to the viewfinder is difficult. The reason is that the focusing unit is lifted by the elastic force of the mounting spring and pressed against the head of the screw, so that the focusing unit cannot be smoothly moved in parallel. As described above, since parallax adjustment and other adjustments are difficult at the time of assembling, the workability of assembly and adjustment is poor, and the ranging accuracy is not so good.

[Object of the Invention] In order to remedy the drawbacks of the conventional example, an object of the present invention is to separate a screw for attaching a focusing unit and a screw for adjusting pupil exit, thereby adjusting pupil and parallax. It is an object of the present invention to provide a focus detection device capable of easily performing both.

[Summary of the Invention] The gist of the present invention for achieving the above-mentioned object is that, when a focusing unit body is attached to a camera, three focusing projection members with respect to the camera body are provided in the same direction in the focusing unit body. So as to project into one of the protruding members, and one of the projecting members is a fixing member, and the other two are adjusting members capable of height adjustment. The fixing member and the two adjusting members contact the camera body. The focus detection apparatus is characterized in that the camera body and the focusing unit body are combined so as to be in contact with each other.

Embodiments of the Invention The present invention will be described in detail based on the illustrated embodiments.

FIG. 1 shows a basic configuration diagram of an optical system according to the present invention,
Reference numeral 1 denotes a photographing lens, which has a field mask 2, a field lens 3, a diaphragm 4 having two openings 4a and 4b symmetrical with respect to the optical axis, and a secondary element 5a and 5b. An imaging lens 5 and a line sensor 6 consisting of two elements 6a, 6b are arranged.

The field mask 2 in this block prevents unnecessary light beams outside the distance measuring field from entering the focusing device system, and the field lens 3 connects the openings 4a and 4b of the diaphragm 4 and the exit pupil S of the photographing lens 1. By placing them in an image relationship, they play a role of effectively guiding the light flux passing through the photographing lens 1 to the tine sensor 6. The diaphragm 4 is for limiting the light flux, and the two elements 5a and 5b of the secondary imaging lens 5 reconnect the light flux passing through different areas of the exit pupil S of the photographing lens 1 onto the line sensor 6. It plays the role of making the image. Two elements 6a of the line sensor 6,
2 re-imaged by the secondary imaging lens 5 from the output of 6b
The defocus amount is detected by obtaining the correlation between the positions of the two images. The secondary imaging lens 5 forms a secondary image with parallax from the light fluxes passing through different areas of the exit pupil S of the taking lens 1 on the array of photoelectric elements of the line sensor 6.

FIG. 2 is a cross-sectional view when the focus detection system according to the present invention is applied to a single-lens reflex camera, in which a quick return mirror 7 is arranged behind the taking lens 1 and the light flux reflected upward here is a condenser. It is guided to a finder system including a lens 8, a penta roof prism 9, and an eyepiece lens 10. Further, a photosensitive film 11 is arranged behind the quick return mirror 7 and constitutes a photographing system together with the photographing lens 1. A sub-mirror 12 is attached to the back of the light transmitting portion of the quick return mirror 7 so that the sub mirror 12 is flipped up or returned together with the quick return mirror 7. On the reflection side of the sub-mirror 12, the focusing optical system of FIG.
As shown in the sectional view of the figure, the field mask 2 disposed near the planned image formation of the photographing lens 1, the field lens 3, the mirror 13 for bending the optical path, and the two openings 4a symmetrical to the optical axis. , 4b, a secondary imaging lens 5 and a line sensor 6 are sequentially arranged.

FIG. 4 is an exploded view showing a specific structural example of the focusing unit. Submirror shown in FIGS. 2 and 3
All optical elements from 12 to the line sensor 6,
They are attached together in one unit body 14.
An infrared cut filter 15 and an antireflection member 16 are inserted between the sub mirror 12 and the field mask 2, and the antireflection member 16 prevents reflected light on the surface of the infrared cut filter 15 from reaching the film 11. It is for doing.
Further, a fixed stage 17 and a rotary stage 18 are arranged in front of the line sensor 6, and the unit main body 14 has a mounting screw 19
Is fixed to the front plate of the camera by the line sensor 6, the line sensor 6 is temporarily held by the fixed stage 17 by the sensor holding pin 20, and the field lens 3 can be adjusted with respect to the unit main body 14 by the field lens adjusting pin 21. ing.

Pupil adjusting screws 21 and 22 are attached to the unit main body 14, and a positioning convex body 23 is integrally provided, and these have a role of adjusting the inclination of the optical axis and a direction parallel to the optical axis. Also serves as a guide for adjusting the moving direction.

Next, in this focusing unit, screws 21 and 22 for pupil adjustment are screwed into the unit main body 14, and then the arrows A1 and A2 in FIG.
Assemble according to the assembly procedure of A3 ....

A1: The infrared cut filter 15 is attached to the antireflection member 16.

A2: Attach the field mask 2 to the infrared cut filter 15.

A3: The field lens 3 has a hole 3a, a unit body 14 and a convex body 1
It is placed on the unit body 14 by fitting with 4d.

A4: The hole 16a of the antireflection member 16 is made into the dowel 14a of the unit main body 14.
The cut filter 15 is pressed into the unit body
Install in 14.

A5: Attach the mirror 13 to the unit body 14.

A6: The diaphragm 4 is attached to the secondary imaging lens 5.

A7: The positioning portion 5c of the secondary imaging lens 5 is attached to the unit body 14
The secondary imaging lens 5 is assembled into the unit main body 14 while being positioned in the rotational direction.

A8: The fixed stage 17 is attached to the line sensor 6.

A9: Attach the rotary stage 18 to the unit body 14.

A10: The fixed stage 17 sandwiches the rotary stage 18,
The fixed stage 17 is incorporated in the unit body 14, and the protrusion 17a of the fixed stage 17 is temporarily held by the engaging portion 14b of the unit body 14.

Next, the entire focusing unit is attached to the adjusting tool. The pupil adjustment screws 21 and 22 are positioned on the heads of the screw parts 21a and 22a.
Since the unit main body 14 is provided with a positioning convex body 23 separately, these positioning portions 21b and 2b are provided.
The position is determined by fitting 2b and the convex body 23 into the positioning hole of the adjusting tool. Also, the bottom surface 14f of the unit main body 14 is biased by a spring (not shown) and held by the adjustment tool.

Further, the adjustment procedure will be described according to the arrows S1 to S9 in the drawing (however, S3 is not shown).

S1: The sensor holding pin 20 is inserted into the hole 6c and the cutout hole 6d of the line sensor 6 to insert the line sensor 6 into the fixed stage 17.
Regulate the position of.

S2: The pupil is projected, that is, the focusing unit is aligned with the optical axis of the front plate of the camera body. Adjustment is performed so that the field lenses 3 correctly project the openings 4a and 4b of the diaphragm 4 into the exit pupil S of the taking lens 1. The line connecting the pupil adjusting screw 21 and the positioning convex member 23 and the line connecting the pupil adjusting screw 22 and the positioning convex member 23 are arranged at a substantially right angle. When turned, the entire focusing unit turns slightly around the Z axis around the positioning projection 23. Similarly, when the adjusting screw 22 is twisted, the adjusting screw 22 is slightly rotated about the Y axis, and the pupil adjustment can be performed by the rotation in these two directions. After the adjustment, the adjusting screws 21 and 22 are fixed with an adhesive.

S3: Although not shown, the shading correction is performed by using the uniform luminance surface chart, and the uneven light amount on the line sensor 6 and the uneven sensitivity of the line sensor 6 are collectively corrected by the EEPROM.

S4: The rotary stage 18 is chucked and rotated about the X ′ axis, and the line sensor 6 and the fixed stage 17 are integrally swung about the Y ′ axis to adjust the inclination of the line sensor 6. The adjustment method and principle will be described later with reference to FIG. After this adjustment, the fixed stage 17 and the rotary stage 18 are bonded and fixed.

S5: Remove the sensor holding pin 20.

S6: While keeping the chucking of the rotary stage 18, the rotary stage 18 is translated in the Y′-Z ′ plane, and the line sensor 6 is positioned by aligning the optical axis with the center of the line sensor 6.

S7: The rotary stage 18 is rotated to adjust the rotation of the line sensor 6 around the X'axis, and the line sensor 6 is adjusted in the Z'axis direction to adjust the glare.

The adjustment as the focusing unit is completed by the above procedure, so remove the focusing unit from the adjustment tool and proceed to the next S8, S9
Adjustment.

S8: When attaching the focusing unit to the front plate of the camera, in order to align the center of distance measurement with the center of the distance measurement frame in the viewfinder,
Adjust the parallax by moving the entire focusing unit in the Y-axis direction. In this case, a guide groove extending in the Y-axis direction is formed in the mounting portion on the bottom surface of the front plate of the camera at a position corresponding to the above-mentioned positioning convex body 23 and adjusting screws 21 and 22. At the bottom surface of the camera, that is, in the normal position of the camera, the ceiling of the groove abuts against the heads of these adjusting screws 21 and 22 and the positioning projection 23. Therefore, in the state where the focusing unit is placed on the front plate, the tilt of the focusing unit when the pupil is first projected is reproduced, and therefore it is not necessary to perform the pupil again here. Y along the groove
You can adjust the parallax with the rangefinder frame simply by translating it in the axial direction.

Since the parallax in the Y-axis direction corresponds to the longitudinal direction of the line sensor 6, the parallax does not need to be as accurate as in the Y-axis direction. Therefore, the parallax adjustment of the focusing unit and the finder in the Z-axis direction is not performed here. However, the parallax adjustment in the focusing unit is completed by positioning the line sensor 6 in the Y'-Z plane.

S9: After fixing the unit main body 14 to the front plate of the camera with the mounting screw 19, the focus of the focusing unit is electrically matched using the EEPROM.

The inclination adjustment of the line sensor 6 in the above-mentioned step S4 and its principle will be described in detail below. In FIG. 4, the rotary stage 18
The concave surface 18a around the chuck is chucked by the three claws of a jig (not shown), and the rotary stage 18 is rotated about the X'axis. In this case, the contact surfaces 17b, 18b of the fixed stage 17 and the rotary stage 18
Are parallel to each other and are inclined at a predetermined angle with respect to the optical axis. Further, since the rotation of the fixed stage 17 and the rotary stage 18 is restricted by the sensor holding pin 20, by rotating only the rotary stage 18, the fixed stage 17 and the rotary stage 18 are integrated around the Y ′ axis. Rotation is adjusted.

The principle is shown in FIG. 5 (a). Since the contact surfaces 17b and 18b of the fixed stage 17 and the rotary stage 18 are inclined with respect to the optical axis as described above, the normal N1 of the contact surface 18b Suppose the tilt angle is φ. At the initial position of the fixed stage 17, the normal line N1 is in the X'-Y 'plane. Here, when only the rotary stage 18 is rotated counterclockwise by the angle θ, the rotary stage 18 begins to tilt with respect to the optical axis as shown in FIG. It is represented by an inclination angle θy ′ from the optical axis of the normal line N2 at. Since the fixed stage 17 is shown so as to swing around the point C where the optical axis intersects the inclined surfaces 17b and 18b,
Although 17c is shifted by dz in the Z'-axis direction, the fixed stage 17 and the rotary stage 18 actually have the sensor holding pin 20.
The shift amount dz is generated by the contact surface.
The center of the line sensor 6 is not displaced from the optical axis because it is canceled by the sliding in the Z'axis direction between 17b and 18b.

The relationship between the angles θ and θy ′ described above is expressed as shown in FIG. What should be noted here is that the normal line N1 has a tilt angle θz ′ around the Z axis in addition to the tilt angle θy ′ around the Y ′ axis, but the actual adjustment range is −θ _{1 to} θ ₁ . Since it is a very narrow range, the tilt angle θz ′ is within the range.
It is almost negligible compared to y ', and there is no practical problem.

EFFECTS OF THE INVENTION As described above, in the focus detection device according to the present invention, the parallax adjustment for the pupil and the viewfinder in the focusing unit is completed by using one fixing member and two adjusting members. Therefore, the workability of the assembly and adjustment work is improved, which is advantageous for automatic assembly and adjustment.

BRIEF DESCRIPTION OF THE DRAWINGS The drawings show an embodiment of a focus detection device according to the present invention. FIG. 1 is a basic configuration diagram of an optical system, FIG. 2 is a sectional view inside a camera, and FIG. FIG. 4 is a sectional view of a part of the focusing unit seen from another direction, FIG. 4 is an exploded view of a specific configuration example of the focusing unit, FIG. 5 is a principle diagram of tilt adjustment of the line sensor, and FIG. It is a graph which represented the inclination quantitatively. Reference numeral 1 is a photographing lens, 2 is a field mask, 3 is a field lens, 4 is a diaphragm, 5 is a secondary imaging lens, 4 is a diaphragm, and 6
Is a line sensor, 7 is a quick return mirror, 12 is a sub-mirror, 13 is a mirror, 14 is a unit body, 15 is an infrared cut filter, 16 is an antireflection member, 17 is a fixed stage,
Reference numeral 18 is a rotary stage, 19 is a mounting screw, 20 is a sensor holding pin, 21 and 22 are pupil adjusting screws, and 23 is a positioning convex body.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Akira Akashi, Akira Akashi, 770 Shimonoge, Takatsu-ku, Kawasaki-shi, Kanagawa Canon Inc., Tamagawa Plant (72) Keishi Otaka 770, Shimonoge, Takatsu-ku, Kawasaki, Kanagawa Canon Inc. Company Tamagawa Plant (72) Inventor Takeshi Koyama 770 Shimonoge, Takatsu-ku, Kawasaki-shi, Kanagawa Canon Inc., Tamagawa Plant (56) Reference JP 60-39612 (JP, A) JP, U)

Claims (3)

[Claims] 1. When attaching a focusing unit body to a camera body, the focusing unit body is provided with three positioning projection members for the camera body so as to project in the same direction. One is a fixing member, and the other two are height-adjustable adjusting members, and the camera body and the focusing unit body are arranged so that the fixing member and the two adjusting members come into contact with the camera body. A focus detection device characterized by combining and. 2. The focus according to claim 1, wherein the fixing member is a convex body provided on the focusing unit body, and the adjusting member is an adjusting screw screwed into the focusing unit body. Detection device. 3. The focus detection according to claim 1, wherein the three positioning projection members serve as guides for adjusting the focusing unit main body with respect to the camera main body during parallax adjustment. apparatus.