JPS5844429A - Interchangeable viewfinder device - Google Patents

Abstract

PURPOSE:To put the focal plane of an optical viewfinder system and a bodyside focus frame plane in close contact, by providing the sliding mechanism part of the optical viewfinder system with a gap for absorbing inclination between the optical viewfinder system and a casing. CONSTITUTION:A gap 31 is formed between the opposite surfaces of a block 11 having a fixed optical viewfinder system and a fitting plate 12, and a gap 32 is provided between a guide pin 16 on the block 11 and a side wall of a long-sized hole 12b. The optical viewfinder system not only slides at right angles to a cover 13 because of the gap 31, but also slides while slanting within some angle range theta1 from the vertical direction Z. Further, it slides while slanting within some angle range theta2 from the vertical direction Z to the cover 13 even in a plane perpendicular to paper surface because of the gap 32. Consequently, a focusing screen 2 is brought into close contact with a focus frame 10 without fail.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an interchangeable finder device for a single-lens reflex camera.

Conventionally, an fT type has been proposed as an automatic focus detection interchangeable finder for an eye reflex camera, which has a built-in focus plate along with a pentaprism, an eyepiece, etc., but in this type of interchangeable finder, the It is required to reliably view the camera body and, at the same time, to ensure that the focal plane of the reticle is pressed tightly against the focal frame of the camera body. Therefore, the applicant filed a patent application No. 55-12946.
8 separates the finder optical system including the focusing plate of the replacement finder from the finder casing, and elastically connects them and fixes them to the casing.The casing is then placed in a predetermined position relative to the camera body using an attachment/detachment device. We proposed an interchangeable finder that includes a sliding mechanism in which the finder optical system is positioned by bringing the focal plane into contact with the body-side focal frame using a biasing force.

However, even if the finder optical system is movable in the direction perpendicular to the focal plane with respect to the slider mechanism and the removable device, if the body-side focal frame and the finder focal plane are not parallel to each other, the focal plane This makes it impossible to maintain close contact between the planes of the focal frame, leading to one-sided blurring of the finder image or focus detection errors.

The present invention solves these drawbacks of conventional devices, and when an interchangeable finder device is attached to a camera body, the focal plane of the finder optical system and the focal frame surface on the body side come into close contact with each other.
The object of the present invention is to provide a complete replacement finder device in which the finder casing is also securely attached to the body. To achieve the above object, the present invention provides a finder optical system in which a focus plate, a pentaprism, and an eyepiece are each fixed in a predetermined positional relationship, a casing containing the optical system, and a casing. In an interchangeable finder device for a single-lens reflex camera, which has a detachable device provided on the casing for attaching to a camera body, when the casing is attached to the camera body by the detachable device, the viewfinder optical The system has a sliding mechanism part that allows the system to move in the perpendicular direction, and a gap is provided in the sliding mechanism part to absorb the inclination between the finder optical system and the casing. An interchangeable finder device featuring:

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG.
468 is a cross-sectional view of an automatic focus detection interchangeable finder device that performs focus detection photoelectrically; and FIG. The focus plate 2, condenser lens 3, prism 4, pentaprism 6, and eyepiece lens 7 constitute a finder optical system in this embodiment, and are integrally incorporated into a finder device 8.

The light flux from the photographic lens (not shown) is reflected by a reflection mirror (quick return) inside the camera body.

It is reflected by mirror) 1 and goes to the n1 finder optical system,
The light beam that passes through the focus plate 2 and the condenser lens 3, enters the prism 4, and enters the half mirror 4a is partially reflected and travels to the light receiving section 5 for detecting the n1 focus. The light beam that has passed through the prism 4 passes through a pentaprism 6 and an eyepiece lens 7 before heading toward the photographer's eye. The focus plate 2, lenses 3 and 7, prisms 4 and 6, and light receiving section 5 are a finder device to be described later. , are fixedly supported by the block 11 in the position 8.

As can be seen in FIG. 1, since the focus plate 2 is not incorporated into the finder optical system, the optical path length from the focus plate for both the focus detection optical system and the observation optical system can be adjusted using the interchangeable finder alone.

This is extremely effective for optical systems such as focus detection optical systems where significant changes in optical path length result in focus detection errors, and also for observation optical systems where the diopter of the observed image is different from the camera of the interchangeable finder device. The advantage is that there is no variation due to the installation on the body, which produces sound.

2 and 3 are cross-sectional views showing in full detail the relationship between the interchangeable finder device of FIG. 1 and the camera body.

The external cover 13 and the mounting plate 12 of the finder device 8 are integrated with the stopper 20 at the edge mounting portion 12a, and the slide lever 14 for attaching and detaching the replacement finder and the finder device is attached to the pin 21.
It is slidably supported by the mounting plate 12. The slide lever 14 is provided on the outer wall of the exterior cover 13.
fc is operated by an operation member (not shown). Mounting plate 12
has at least one elongated portion 12bk extending in the vertical direction, and the elongated portion 12b is slidably engaged with the rLfC guide pin 16 provided on the block 11 of the exchange finder device 8. The aforementioned elements 2 to 7 are fixed to this block 11.

The block biasing spring 19 is attached to the flange portion 11 of the block 11.
n1 is inserted between a and the bottom surface 12c of the mounting plate 12, and applies an urging force in a direction in which the two move away from each other. The slide lever 14 is biased by a biasing spring 15 in a direction into which it engages with an exchange finder fixing pin 17 protruding from the mirror box 9 . The mirror box 9 is fixed to the camera body, and can be said to constitute a part of the camera body.

As is clear from the drawings, the external cover 13 includes the above-mentioned fc element systems 2 to 7 and other elements 11, 12, 14 to 16.
．． It covers 18.19.

Next, this operation will be explained. When the replacement finder device 8 is inserted into the mirror box 9 and pushed down, the focal plane of the focusing plate 2 at the bottom of the block, that is, the bottom surface 2 of the focusing plate 2
The block 11, which a is fixed to the mirror box 9 and comes into contact with the focal frame 10, will not fall any further than this n. When the cover 13 is further pushed down completely, the mounting plate 12 integrated with the cover resists the biasing spring 19 using the engagement between the pin 16 on the block 11 and the elongated hole 12b on the mounting plate 12 as a guide. Slide it down and press it down. At this stage, slide lever 1
The cam surface 14b of No. 4 contacts the upper surface of the nfC fixing pin 17 provided in the mirror box, and the slide lever 14 slides against the urging spring 15. When the cam surface 1 crosses over the pin 17, the sloped portion 14c comes to engage with the pin 17 as shown in FIGS. 2 and 3. Then, a positioning pin 18 fixed to the bottom surface of the mounting plate 12 and having a length n' comes into contact with the top surface 9a of the mirror box. In this way, installation of the replacement finder device is completed.

As mentioned above, the attachment/detachment mechanism and the exterior part of the replacement finder device are positioned with respect to the camera body via the positioning pin 18t, and the finder optical system is independently brought into contact between the focal frame 1'0 and the focal plate 2'. Since the positioning of the finder device 8 is done precisely, the finder optical path length does not change when the replaceable finder device 8 is attached to the camera body.

The replacement finder device 8 described above is removed from the camera body by sliding the lever 14 to the right in FIG. 3 using the externally operable operating member (not shown).

In the apparatus shown in FIGS. 2 and 3, the external cover 13 has an attachment/detachment lever 14 in the vertical direction, that is, the focusing plate 2.
The lever 14 is supported so as to be in a predetermined positional relationship with respect to the direction perpendicular to the focal plane of the focusing plate 2, and the finder optical system 2.3.4.6. The finder optical system 2.3.4.
6.7 is biased to press it against the camera body 9.

In the above-mentioned device, the focal plane 2 of the reticle 2 is thus
Even if the relative positional relationship between the attachment/detachment lever 14 and the finder optical system 2.3.4.6.7 in the direction perpendicular to a is not properly set, the replacement finder device can be firmly attached to the camera body 9. When the optical system 2.3.4.6.7 is moved from t' to t', the 2-finder optical system 2.3.4.6.7 can be pressed and fixed at a predetermined position on the camera body 9.

However, in this conventional device, the attachment/detachment device and the finder optical system are each positioned separately with respect to the camera body, so the focal plane 2a of the focus plate of the finder optical system and the top surface of the focus frame (Surface conjugate to the film surface of the body)
10&, but parallel between the top surface 9a of the camera body and the top surface tea of the focal frame 10, and the two pins 18
If the parallel relationship between each lower surface of the reticle and the lower surface 2a of the focusing plate 2 cannot be maintained due to accuracy, the contact is made only at a part of the reticle lower surface 2a and the upper surface 19m of the focusing frame. It becomes difficult to bring the entire surface into close contact, and the focal plane of the finder <
2&) is on the film plane on the body side and the conjugate focal plane (IOI
Only a part of the field of view is located at LJ, and this can cause blurring of one side of the field image or incorrect focus detection.

Therefore, the present invention proposes a sliding mechanism that allows the two surfaces to come into close contact with each other as a whole even if the above-mentioned parallel relationship is not maintained.

4, 5, and 6 show embodiments of the present invention, and FIG. 4 corresponds to FIG. 2 of the prior art, and FIG. 5 corresponds to FIG. 3 of the prior art.

FIG. 6 is a diagram showing how the focal plane of the reticle can be tilted inside the finder.

In Figures 4 and 5, 8# in Figures 1 to 3;
□□ Care materials. -0 symbol will be added and the explanation will be omitted completely. In this embodiment, a gap 31 is provided between the opposing surfaces of the block 11 and the mounting plate 12, and a gap 32 is provided between the pin 16 and the side wall of the elongated hole 12b. This is different from the prior art shown in FIG.

The interchangeable finder device 8 of this embodiment has the above-described configuration and is attached to the camera body 9 in the same manner as the prior art shown in FIGS. 2 and 3. However, due to the presence of the gaps 31, 32, it behaves somewhat differently than in the previously described embodiment. That is, this embodiment is the same as the prior art in that the finder optical system moves in a direction perpendicular to the focal plane 2a.

However, due to the existence of the gap 31, the finder optical system of this embodiment not only slides in the vertical direction with respect to the cover 13, but also within a certain angular range fiI from the vertical direction 2 with respect to the cover 131C as shown in FIG. It can be tilted and slid. Furthermore, as shown in FIG. 5, the finder optical system of this embodiment is tilted within a certain angle range θ2 from the vertical direction 2 with respect to the cover 13#C even in a plane perpendicular to the plane of the paper in FIG. It can be slid. Therefore, the top surface 9 of the camera body
Even if & and the upper surface 1''O'a of the focal frame 1o are not precisely parallel to each other.

Even if the lower surfaces of the two pins 18 and the lower surface 2a of the focusing plate 2 are not precisely parallel to each other, the focusing frame 10
As long as the upper surface 10B is placed at a predetermined position with high precision, the finder optical system is positioned at an angle θ1. θ
The focus plate 2 can be tilted and slid within a range of 2 degrees, and the focus plate 2 is always in close contact with the focus frame 10. In this way, the finder optical system is fixed in a predetermined positional relationship with respect to the camera body.

In other words, if the surface 9a and the surface 10& are not parallel to each other with high accuracy, or if the lower surfaces of the two pins 18 and the surface 2a are not parallel to each other with high precision, the external cover is removed from the finder optical system. 13 will be installed at an angle.

To explain this with Figure 6, if the position of the focusing plate parallel to the bottom surface of the pin 18 of the finder casing is taken as a reference plane and is in the state of a plane 31 (a plane perpendicular to the two axes) , J:rL in this example
For example, due to the gaps 31 and 32 of the sliding mechanism, the lower surface 2aFi of the reticle 2 can be tilted like the planes 32 and 33. Here, half of 01 in FIG. 4 corresponds to θy in FIG. 6, and half of θ in FIG. 5 corresponds to θX. In other words, when the parallel relationship is broken t', using the upper surface 10a of the focal frame 10 on the body side as a reference,
The finder focal plane 2a is in the state of the reference plane 31 in FIG. 6, and within the range of 20X and 2θy, the casing is tilted and fixed to the body n, and the focal plane 2a can be brought into close contact with 1G&.

This embodiment is as described above, and the finder optical system can slide in a direction perpendicular to the focal plane 2a of the focusing plate, similar to the prior art shown in FIGS. 2 and 3. Therefore lever and pin 1
4. If the distance between 18 and the focal plate 2 is not set accurately, the distance between the surface 9a and the focal frame 1 must be set for each camera body.
It goes without saying that the finder optical system can be fixed in a predetermined positional relationship with the camera body even if the distance between the

[Brief explanation of drawings]

Figure 1 was originally proposed by the applicant in the f'Lfc patent application filed in 1982.
2 and 3 are sectional views showing in detail the relationship between the interchangeable finder device shown in FIG. 1 and the camera body. FIGS. 4 and 5 are sectional views of the present invention. Fig. 2 and @3 are cross-sectional views corresponding to the embodiments of the present invention. !Explanation of symbols of main parts 1 2... Focus plate 6... Pentaprism 7... Eyepiece 8... Finder device 11... Block 13... Exterior cover 14... Slide lever 16...Guide pin 17...Replacement finder fixing bin 31.32...Gap application Person: Nippon Kogaku Kogyo Co., Ltd. Figure 6 Z 158-

Claims (1)

[Scope of Claims] 1. A finder optical system in which a reticle, a pentaprism, and an eyepiece are fixed in the required positional relationship, a casing containing the optical system, and a casing for attaching the casing to a gold camera body. In the interchangeable finder device for a single-lens reflex camera, the viewfinder optical system is independent of the attaching and detaching device when the casing is attached to the camera body by the attaching and detaching device. It has a sliding mechanism part that is movable in a direction perpendicular to the focal plane of the focusing plate, and a gap is provided in the sliding mechanism part to absorb the tilting between the finder optical system and the casing. An exchange finder device characterized by the following. 2. Move the finder optical system toward the body side so that the focal plane of the focus plate of the finder optical system and the focal frame of the camera body come into close contact when the casing is attached to the camera body by the attachment/detachment device. 2. The exchange finder device according to claim 1, further comprising biasing means for pressing the exchange finder device.