JPH0740984Y2 - Camera internal reflection prevention mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an internal reflection preventing mechanism for a camera.

[Conventional technology]

In order to prevent flare due to internal reflection in the camera, a light-shielding line formed by arranging a number of sharp thin grooves in the direction orthogonal to the optical axis on the inner wall of the exposure chamber, etc., or a completely matt black paint is used. It is painted or electrostatically flocked.

By the way, in order to easily enjoy taking pictures without having an ordinary camera, the applicant of the present invention has provided a lens-fitted film unit (trade name "Sharan Lu Hi."
Etc.) are commercially available. Such a lens-fitted photo film unit is a unit main body equipped with a simple photographing mechanism in which a photo film with a cartridge is built in advance, and is manufactured at a low cost as much as possible so as to be disposable.
For this reason, the above-mentioned conventional internal reflection preventing means is not preferable because it is costly and therefore, the inner surface of the exposure chamber is finished with a satin finish, and the main body including the exposure chamber is made of plastic or the like and integrally molded by a mold. .

[Problems to be Solved by the Invention] In the above-described conventional lens-fitted film unit, since the focal length of the taking lens is about 35 mm, a wide-angled image is taken for a 35 mm size film. Therefore, the image of the person becomes smaller than expected, which may cause dissatisfaction.

To solve this problem, the focal length of the taking lens should be lengthened, but this increases the optical path length after the taking lens, and along with this, the effective light flux that forms an image on the film approaches the inner wall of the exposure chamber. Come on. For this reason, there is a problem that a large amount of light that is incident on the inner wall of the exposure chamber and is not needed for image capturing, and a large amount of internal reflection causes a strong flare effect.

The present invention is intended to solve the above problems, and an object of the present invention is to provide an internal reflection preventing mechanism for a camera, which has a simple structure and can easily cope with cost reduction.

[Means for Solving the Problems]

In order to achieve the above object, the present invention provides a large number of ridges arranged in parallel in the optical axis direction on the inner wall of the exposure chamber of the camera along the optical axis. In particular, by applying the present invention to a camera having a Z-shaped optical axis formed by the first mirror and the second mirror, the influence of internal reflection can be effectively prevented.

[Action]

When the shutter is opened during shooting, the image is exposed on the film. At this time, harmful light other than the effective light that forms an image on the film also enters the exposure chamber, but such harmful light is generated by a large number of ridges formed on the inner wall of the exposure chamber along the optical axis direction. By diffusely reflecting on the surface and diffusing, the specular reflection component is considerably reduced, and the influence of flare due to this harmful light is reduced.

〔Example〕

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

Referring to FIG. 2 showing an external view of a lens-fitted photo film unit embodying the present invention, a simple photographing mechanism is incorporated in the unit body 10 and a 135
The film is loaded so that it cannot be taken out by the user. The unit body 10 is used while being put in the paper box 11. Therefore, the paper box 11 is formed with openings for exposing the taking lens 12, the finder objective opening 13, the shutter button 14, the film counter window 15, the film winding knob 16 and the like provided on the unit body 10 to the outside. ing.

FIG. 3 shows a vertical cross section of the unit body 10 taken along the optical axis of the lens. The unit body 10 is
It is roughly divided into a main body 20, and a front cover 21 and a rear cover 22 that hold the main body 20 so as to wrap it. The lens-fitted film unit in this embodiment is
The optical axis is bent in a Z-shape by the first and second two mirrors 25 and 26, and the focal length is made longer than usual while achieving compactness. Therefore, the light that has passed through the taking lens 12 passes through the shutter opening 28 of the shutter plate 27, is reflected by the first mirror 25, is then reflected by the second mirror 26, and is set in the exposure window 31 of the exposure chamber 30. To expose.

The main body 20 is integrally molded with a mold, and on both sides, as shown in FIG. 1, a cartridge chamber 34 for storing a cartridge (not shown) and a film roll chamber for storing a roll of film rolls. 35 and are provided in these chambers 3
An exposure chamber 30 in which the exposure window 31 is opened is formed between 4, 35. A mounting frame 36 for mounting the second mirror 26 is formed on the front side of the exposure chamber 30, and a mounting frame 37 for mounting the first mirror 25 is further formed on the upper portion of the exposure chamber 30.

The exposure room 30 has a request for a compact camera,
Since it is formed with the minimum necessary size, its inner wall 33 is located at a position close to an effective light flux forming an image. For this reason, the internal reflection cannot be effectively prevented only by the ordinary measure for preventing the internal reflection of the satin pattern. Therefore, in this embodiment, a large number of protrusions 40 that are long in the direction along the optical axis are arranged on each inner wall 33 along the optical axis. Each ridge 40 is finely formed to the extent that it does not adversely affect the film surface, and the protrusion amount is preferably about 0.6 mm.

FIG. 4 is a front view of the inside of the exposure chamber 30 as viewed from the exposure window 31 side, for explaining the arrangement of the protrusions 40. In the figure, the upper inner wall 33A of the exposure chamber 30 is provided with an opening 41 for securing an optical path for guiding the reflected light from the first mirror 25 to the second mirror 26.

The protrusion 40 is formed in a tapered shape whose height gradually decreases toward the exposure window 31 side. Figure 5 shows each ridge
40 is shown enlarged. The cross-sectional shape of each ridge 40 is an arc, but this is not limited to other elliptic curved surfaces and other curved surfaces as long as it can diffusely stray the stray light 50 and reduce its regular reflection component. Can also be used. The inner wall surface 33 of the exposure chamber 30 in which the protrusions 40 are formed, that is, the protrusions
On the surface of 40 and the surface of the flat portion 42 between these ridges 40, a satin pattern is formed as in the conventional case, and the stray light 50 is diffusely reflected and diffused to further effectively prevent the internal reflection. . In addition, the ridges 40 are arranged in parallel so that the ridges 40 are parallel to each other in order to easily perform die cutting. In addition, each ridge
Although the flat portion 42 is formed between the portions 40, it may be a groove portion having a curved surface that is continuous with the surface of each protrusion 40.

Next, the operation of this embodiment will be described.

First, the user rotates the film winding knob 16 to rotate the winding shaft in the cartridge to perform the initial feeding of the film. The sprocket 45 engages with the perforation of the film and rotates in conjunction with the film feeding.
When the film is pulled out from the film roll for one frame and set in the exposure window, the rotation of the sprocket 45 is restricted, and the film feeding is stopped. The shutter charge is also performed by the rotation of the sprocket 45 by the film feeding. Since the counter plate is connected to the sprocket 45, the number of frames that can be photographed, for example, “24” is displayed on the counter window 15.

Then, framing is performed by looking into the viewfinder eyepiece opening. Since the optical axis of the finder is parallel to the optical axis of the taking lens 12 and is close to each other at substantially the same height, parallax hardly occurs even for a subject at a short distance.

When you press the shutter button 14, the shutter device will
The shutter blades 29 on the shutter plate 27 open in, for example, “1/125” seconds, and an image is taken. Then, the subject light flux that has passed through the taking lens 12 reaches the film set in the exposure window 31 after being reflected by the first and second mirrors 25 and 26,
Exposure is performed. At this time, even if the subject light flux approaches the inner wall 33 of the exposure chamber 30, as shown in FIG. 5, the stray light 50 is generated on the surface of a large number of protrusions 40 formed on the inner wall 33 along the optical axis. The light is diffused and reflected at, and is reflected several times between the adjacent ridges 40, so that it is attenuated and the influence of flare is reduced.

When the shutter blade opens and closes, the winding stop of the winding knob 16 is released, and the winding of the film is permitted. Then, by rotating the knob 16, the exposed film is caught in the cartridge, and accordingly, the unexposed film is newly set in the exposure window 31. By this film feeding, the shutter charge is performed as described above, and the preparation for the next shooting is completed.

Next, the measurement result of the flare rate will be described.

The materials shown below were prepared.

Documents (1A), (1B) Film unit with lens of the conventional type that does not form ridge 40 only by forming a satin pattern on a smooth surface. Materials (2A), (2B) Project in the direction orthogonal to the optical axis. Horizontal stripe type film unit with lens with rows of materials Material (3A), (3B) Lens film unit with lens in this embodiment, with protrusion pitch of 1.1 mm Material (4A), (4B) This embodiment The film unit with a lens in which the pitch of the ridges is 1.2 mm Material (5A), (5B) The film unit with a lens in this embodiment, the pitch of the ridge is 1.3 mm Material (6A), (6B) The film unit with a lens in the present embodiment, in which the pitch of the ridges is 1.8 mm, each frame of the negative film photographed by these materials (1A), (1B), ... (6A), (6B) Flare in the center and four corners It was measured, showing a mean value of the measured value of this time in the table.

As can be seen from the above table, conventional type data (1A),
It can be seen that the flare rate of the present example is lower than that of (1B), (2A), and (2B). In addition, when the pitch is 1.8 mm, the flare ratio does not decrease so much compared to the conventional one, so the pitch of the ridges 40 is
It is desirable to set it to 1.1 to 1.3. Especially, when the pitch is 1.2, the flare ratio is 4
It can be seen that the corners are lowered, and that the four corners are significantly lowered.

In the above embodiment, the telephoto type lens-fitted film unit having a long focal length has been described, but the present invention is not limited to this, and is not a normal lens-fitted film unit or a disposable type. It can also be applied to ordinary cameras and the like. Also in this case, the inner surface reflection can be effectively prevented by arranging a large number of protrusions in parallel on the inner wall of the exposure chamber in the optical axis direction.

Further, in the above-described embodiment, the ridges 40 are formed on both side surfaces and the lower surface of the inner wall along the optical axis, but this may be formed on any one surface. For example, the inner surface reflection can be effectively prevented by forming the ridges only on the surface (the lower surface in the above embodiment) which is close to the light rays corresponding to the sky.

[Effect of device]

As described above, according to the present invention, since a large number of long ridges are arranged in parallel in the optical axis direction on the inner wall of the exposure chamber of the camera, harmful light other than effective light forming an image is formed. Are reflected on the surface of the ridges to diffuse and reduce the influence of flare. Moreover, the harmful light is attenuated by being reflected several times between the adjacent protrusions, so that the internal reflection can be effectively prevented. In particular, by forming the ridge in a taper shape whose height gradually decreases toward the exposure window side, it becomes possible to easily perform die cutting when integrally molding the main body.

[Brief description of drawings]

FIG. 1 is a perspective view showing the structure of a unit main body of a lens-fitted film unit embodying the present invention. FIG. 2 is a perspective view showing the external appearance of the lens-fitted film unit. FIG. 3 is a sectional view taken along the optical axis of the lens-fitted film unit. FIG. 4 is a front view showing the inner wall of the exposure chamber. FIG. 5 is a perspective view schematically showing a ridge formed on the inner wall of the exposure wall and stray light reflected by the ridge. 10 …… Unit main body 11 …… Paper box 12 …… Lens 25,26 …… Mirror 30 …… Exposure room 31 …… Exposure window 40 …… Ridge.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Junichi Takashiro 1-324, Uetake-cho, Omiya City, Saitama Prefecture Fuji Photo Koki Co., Ltd. (56) References JP-A-2-104343 (JP, A) JP-A 2-181129 (JP, A) Actually opened 59-189633 (JP, U) Actually opened 62-186122 (JP, U) Actually public 32-857 (JP, Y1)

Claims (2)

[Scope of utility model registration request] 1. An internal reflection preventing mechanism for a camera, characterized in that a large number of ridges extending in the optical axis direction are provided side by side on an inner wall of the exposure chamber of the camera along the optical axis. 2. In a camera having a Z-shaped optical axis formed by a first mirror and a second mirror, a large number of ridges extending in the optical axis direction are arranged on an inner wall of the exposure chamber of the camera along the optical axis. An internal reflection prevention mechanism for the camera, which is characterized by being installed.