JPH0119563B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic focus detection device for a camera equipped with an automatic focus detection element such as a self-scanning photoelectric element (hereinafter referred to as an image sensor), and more specifically, an adjustment means for adjusting the position of the image sensor. This invention relates to an automatic focus detection device for a camera equipped with a camera.

An image sensor has a row of photoelectric elements arranged at a position equivalent to the imaging surface of a lens system, and a scanning circuit corresponding to each row of photoelectric elements converts the light intensity distribution of a subject into a time-series electric signal. An automatic focus detection device is configured to automatically detect the focus of a lens system using the electrical output of such an image sensor.

2. Description of the Related Art Conventionally, an automatic focus detection device is known that is applied to a single-lens reflex camera 1, for example, as shown in FIG. In the figure, numeral 2 is a lens system, 3,
Reference numeral 4 denotes an optical member for converting the optical path of the object light L ₀ , 3 a semi-transparent mirror, and 4 a total reflection mirror. The reflected light _L1 whose optical path has been changed by the total reflection mirror 4 is received by an image sensor 6 fixed at a position equivalent to the film 5 serving as an imaging surface. Note that the reference numeral 7 is a shutter facing the aperture A, and the reference numeral 8 is a focal plate that receives the reflected light _L2 whose optical path has been changed by the semi-transparent mirror 3. The reflected light L ₂ that has passed through the focusing plate 8 reaches the eyepiece 11 via the condenser lens 9 and the pentaprism 10 . When exposing the film 5, the semi-transparent mirror 3 and the total reflection mirror 4 are moved out of the optical path by a moving mechanism (not shown). In addition,
The semi-transparent mirror 3, total reflection mirror 4, and image sensor 6 are attached to a mirror box body 12, and this mirror box body 12 is attached to a camera housing 13. Further, the image sensor 6 is connected to an electrical circuit (not shown) that processes its electrical output.

However, according to such an automatic focus detection device, the image sensor 6 is fixed at a position equivalent to the film 5;
Even if a slight positional shift occurs when the camera body 2 is attached to the camera housing 13, there is no appropriate means for correcting it. Therefore, it is necessary to improve the manufacturing precision of the fixing member of the image sensor 6, etc., and the workability is poor as it takes time and effort to make adjustments during installation, and there are also problems in terms of after-sales service for users.

This invention has been made in view of the above-mentioned problems, and allows adjustment of the image sensor 6 to be carried out easily.Moreover, the mirror box main body 12 with each component attached as described above is attached to the camera housing 13. The purpose of the present invention is to provide a device capable of adjusting from different directions before and after mounting a mirror box main body 12, taking into consideration the mounting configuration.

In order to achieve the above object, an automatic focus detection device for a camera according to the present invention includes a mirror box installed in a camera body between a photographing lens and an imaging surface, and a photographing lens provided in the mirror box. an optical member that converts the optical path from the optical member to the imaging surface; an automatic focus detection element that receives the light whose optical path has been changed by the optical member and is disposed at a position equivalent to the imaging surface; and the automatic focus detection element is fixed. The holding plate has one end screwed into a screw hole provided in the mirror case, the other end inserted through a through hole in the holding plate, and a plurality of threaded grooves for rotation adjustment on both end surfaces. It is characterized by comprising a screw and a positioning means for keeping the relative position of the holding plate constant with respect to the screw.

The present invention will be explained below based on the drawings. Note that the same reference numerals are given to the same constituent parts as in the prior art, and redundant explanation will be omitted.

2 and 3 show a first embodiment of the invention. First, to explain the configuration, reference numeral 14 in the figure is a holder, and a circuit board 15 is fixed on this holder plate 14, and this circuit board 15 fixes and electrically connects the image sensor 6. The circuit board 15 has a pair of board ends 15a and 15b bent downward at a predetermined interval on the mount side (not shown) (right side in FIG. 2). Further, one side of the circuit board 15 (the right side in FIG. 3) has a board end portion 15c bent upward. These substrate ends 15a, 15b, and 15c are connected to an electric circuit that processes the electrical output of the image sensor 6.

Reference numerals 16a, 16b, and 16c are compression springs, and these compression springs 16a, 16b, and 16c are compressed between the holding plate 14 and the bottom plate 12a of the mirror box body 12, and are provided with adjustment screws 17a and 1, respectively.
7b and 17c are inserted through the holding plate 14, and each compression spring constitutes a positioning means for keeping the relative position of the holding plate 14 with respect to the adjusting screws 17a, 17b, and 17c constant. Of course, each adjusting screw 17a, 17b, 17
c passes through the circuit board 15 and the holding plate 14 and is screwed onto the bottom plate 12a. That is, the holding plate 1
4 is capable of so-called three-point adjustment. Note that the head and tip of each adjustment screw 17a, 17b, 17c are provided with screw grooves h ₁ , h ₂ , h _{3 and 3} for screw rotation.
t ₁ , t ₂ , and t ₃ are formed.

A rising piece 12b is formed on the mount side of the bottom plate 12a of the mirror box body 12, and this rising piece 12
The apron 18a of the cover 18 is tightened with the screw 19 at b.
It is attached by. Both sides of the cover 18 are inserted into and supported by receiving portions 19a and 19b fixed to both inner wall surfaces m ₁ and m ₂ of the main body 12 of the mirror box. Further, a hole 18b is formed at a position where the cover 18 faces the image sensor 6 to allow the reflected light _L1 to pass therethrough.

Note that the symbol H _L indicates the board end 15 of the circuit board 15.
a, 15b are holes for extending below the mirror box main body 12, and H _U is a hole for extending the substrate end portion 15c to the side of the mirror box main body 12.

Next, the effect will be explained.

First, for example, when assembling a camera, a reference lens for adjustment as the lens system 2 is attached. Pass the object light L ₀ through this reference lens,
The reflected light _L1 is received by the image sensor 6 and focused on the image sensor 6. If the focus is misaligned based on the electrical output information of the image sensor 6, use an adjusting tool such as a screwdriver from below the mirror box body 12 to tighten the tips of the adjusting screws 17a, 17b, and 17c. thread groove
Insert into t ₁ , t ₂ , and t ₃ and adjust the screw holes. As a result, the holding plate 14 moves in the vertical direction in the figure, changing the angle of the image sensor 6 with respect to the reflected light _L1 and the position in the optical path direction, thereby correcting the misalignment state.

Next, in a so-called completed camera state in which the mirror box body 12 is attached to the camera housing 13, adjustment using the thread grooves t ₁ , t ₂ , and t ₃ at the tip is generally impossible. If this happens, tighten the tightening screw 19 from the mount side.
Unscrew and remove cover 18. In this way, the thread grooves h ₁ , h ₂ , h ₃ of each head of the adjustment screws 17a, 17b, 17c are exposed. Then, the fully charged moving mechanism is operated to evacuate the semi-transparent mirror 3 and the totally reflected light 4. As a result, the adjustment screw 17a,
The screw 17b can be adjusted by inserting an adjustment tool from the aperture A side, and the adjustment screw 17c can be adjusted by inserting an adjustment tool from the mount side.

In this way, the image sensor 6 is adjusted to the same position as the film 5 by adjusting means including adjusting screws 17a, 17b, 17c, etc.

4 to 6 show other embodiments of the adjusting means.

The second embodiment shown in FIG. 4 has adjustment screws 17a, 17.
b, 17c near the head are screwed onto the retaining plate 14,
The tip portion thereof is simply inserted through the bottom plate 12a, and flanges 20a, 20b, and 20c are attached to prevent it from being pulled out. The other configurations are the same as those in the first embodiment, so explanations will be omitted.

In the third embodiment shown in FIG. 5, the compression springs 16a, 16b, 16c are omitted in the first embodiment, and the circuit board 15 and retaining plate 14 are fixed to the adjustment screws 17a, 17.
b, 17c head and flanges 21a, 21b, 2
1c, thereby forming a positioning means, and the tips of the adjusting screws 17a, 17b, 17c are screwed onto the bottom plate 12a. The other configurations are the same as those in the first embodiment, so explanations will be omitted.

The fourth embodiment shown in FIG.
a downward at the mount side end, and attach the bottom plate 12.
A hole 18b' facing the image sensor 6 is formed in the bottom plate 12a, and compression springs 16a, 16 are provided below the bottom plate 12a.
The circuit board 15 and the holding plate 1 via b and 16c
4 is positioned. Each compression spring 16a, 16b, 16c has an adjusting screw 17a, 1
7b, 17c are penetrated, and each screw 17a, 17
The tips of b and 17c are screwed onto the bottom surface 12a. The following configuration is the same as that of the first embodiment, so a description thereof will be omitted.

As explained above, according to the present invention, the automatic focus detection element can be adjusted from the bottom of the mirror box before the mirror box is assembled to the camera body, and from the bottom of the mirror box after the mirror box is assembled to the camera body. This can be done from inside the mirror box.

Therefore, when applied to a single-lens reflex camera,
Before assembling the mirror box, adjustments can be made with the optical member, that is, the quick return mirror, lowered, and after assembling, the mirror can be raised and adjustments can be made from the mount opening or from the film surface side.

Further, each of the embodiments described above has the following effects in addition to the common effects described above.

First, in the first embodiment, the image sensor can be easily and precisely adjusted using three adjusting screws on the holding plate. Further, since the thread grooves formed at both ends of each adjustment screw can be exposed to the inside and outside of the mirror case body, adjustment can be made from the outside of the mirror case body or the camera housing. Furthermore, since the adjusting means can be mounted below the main body of the mirror box, it can be installed compactly, and it can be covered with a cover, so it looks good, and the cover can also optically protect the image sensor and the like.

Next, in the second embodiment, by attaching a flange to the adjustment screw, firm attachment is possible.

Furthermore, in the third embodiment, since the compression spring can be omitted, the number of parts and the number of installation steps can be reduced.

Furthermore, in the fourth embodiment, the space below the main body of the mirror box can be effectively used, and the cover can also be used as the bottom plate, making it extremely easy to attach the holding plate and the like.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram illustrating a state in which a conventional autofocus detection element is attached to a single-lens reflex camera, and FIGS. 2 to 6 show each embodiment of the present invention. FIG. 3 is a cross-sectional view of FIG. 2, FIG. 4 to FIG. 6 are similar to FIG. 2, and FIG. 4 shows a flange attached to the adjustment screw. FIG. 5 is a sectional view showing a third embodiment in which the compression spring is omitted, and FIG. 6 is a sectional view showing a fourth embodiment in which the cover also serves as the bottom plate. 3... Semi-transparent mirror, optical member, 4... Total reflection mirror, optical member, 5... Film (imaging surface), 6... Image sensor (automatic focus detection element), 17a, 17
b, 17c...adjustment screw (adjustment means).

Claims (1)

[Scope of Claims] 1. A mirror box installed in a camera body between a photographic lens and an imaging surface, and an optical member provided in the mirror box to convert an optical path from the photographic lens to the imaging surface. , receiving the light whose optical path has been changed by the optical member,
an automatic focus detection element disposed at a position equivalent to the imaging surface; a holding plate to which the automatic focus detection element is fixed; one end screwed into a screw hole provided in the mirror box, and the other end screwed into a screw hole provided in the mirror box; inserted into the through hole of the holding plate,
An automatic camera comprising: a plurality of adjustment screws each having a screw groove for rotation adjustment on both end surfaces; and a positioning means for maintaining a constant relative position of the holding plate with respect to the adjustment screw. Focusing device.