Photography – With viewfinder
Utility Patent
1999-01-27
2001-01-02
Lee, Eddie C. (Department: 2851)
Photography
With viewfinder
C396S382000, C396S386000
Utility Patent
active
06169859
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a finder unit, and more particularly to a finder unit that is capable of adjusting diopter and optically displaying information relating to a visual field frame, etc. in the finder.
2. Description of Related Art
The diopter of a camera finder is adjusted by moving a diopter adjustment lens of an eyepiece along the optical axis. For example, as disclosed in Japanese Patent Provisional Publication Nos. 1-155325 and 1-291227, a conventional camera finder unit comprises the diopter adjustment lens that has a follower pin on an edge thereof, a diopter adjustment dial, and a rotary member that is rotated in association with rotation of the diopter adjustment dial. The rotary member has a cam groove on the circumferential surface thereof, and the follower pin engages the cam groove. Rotation of the diopter adjustment dial is transmitted to the rotary member, and the rotation of the rotary member moves the follower pin of the diopter adjustment lens along the cam groove on the rotary member thereby moving the diopter adjustment lens forward and backward along the optical axis.
According to this conventional diopter adjustment mechanism, however, a complicated mechanism is required to convert the rotation of the diopter adjustment dial to the rectilinear movement of the diopter adjustment lens. For this reason, a large space is needed for the finder unit, and the finder unit is difficult to assemble.
In the case of a conventional real-image finder, the finder visual field is restricted by a visual field frame member that is placed on a real-image plane so that the visual field of the finder can substantially correspond to a visual field of the taking lens. In the case of a conventional inverted Galilean finder, a semitransparent mirror is arranged on an optical path between an objective lens and the eyepiece, and an optical image frame representing the visual field frame is arranged on a reflective optical path of the semitransparent mirror. An image of the optical image frame is superimposed on an object image in the visual field due to the transmission and reflection of the semitransparent mirror. The optical image frame is illuminated by outside light taken through a light intake window.
However, the conventional optical image frame is sometimes difficult to see according to the brightness of the object image and the intensity of the outside light taken through the light intake window. Moreover, there is the necessity of changing the finder visual field according to the object distance due to a parallax. In order to change the finder visual field in the case of the real-image finder, the size and position of the visual field frame member must be changed according to the object distance, and therefore, the mechanism is complicated. In the case of the inverted Galilean finder, a double optical image frame is conventionally used so that a visual field frame for a normal shot and a visual field frame for a close shot can always be displayed in the finder visual field. In this case, it is difficult to see the object and determine which visual field frame is appropriate.
SUMMARY OF THE INVENTION
The present invention has been developed in view of the above-described circumstances, and has as its object the provision of a finder unit, which can reduce the size of the diopter adjustment mechanism without deteriorating the optical performance of the finder, and which is simple in structure, easy to assemble, capable of displaying information such as the visual field frame in the finder so that it can be easily seen, and makes it easier to adjust the position of the visual filed frame when the finder unit is assembled.
To achieve the above-mentioned object, the present invention is directed to a finder unit comprising: a diopter adjustment lens moving on an optical axis of the finder unit to adjust diopter of the finder unit and having a follower projection on an edge thereof; a first hollow cylinder enclosing the diopter adjustment lens movably on the optical axis and having a guide groove engaging with the follower projection; and a second hollow cylinder being coaxial with the first hollow cylinder and having a cam face engaging with the follower projection; wherein rotation of the second hollow cylinder relative to the first hollow cylinder moves the follower projection along the guide groove and the cam face such that the diopter adjustment lens moves on the optical axis.
According to the present invention, the second hollow cylinder or a diopter adjustment ring, which moves the diopter adjustment lens, is arranged coaxially with the first hollow cylinder, which supports the diopter adjustment lens movably on the optical axis. This eliminates the necessity for providing a special mechanism that supports the diopter adjustment ring rotatably, and thus, the finder unit is simple in structure and easy to assemble. Moreover, the optical performance is excellent because the pressing member presses the follower pin against the cam face to prevent the looseness of the follower pin. Accordingly, the diopter can be adjusted easily. The second hollow cylinder is preferably provided with a diopter adjustment dial, which is operated manually, formed on an external circumferential surface of the second hollow cylinder.
To achieve the above-mentioned object, the present invention is directed to the finder unit further comprising: an objective lens for forming an object image; an eyepiece; a display for displaying a visual field frame, the display being arranged outside an optical path between the objective lens and the eyepiece; and a semitransparent mirror for superimposing the visual field frame on the object image, the semitransparent mirror being arranged on the optical path.
According to the present invention, the display such as a liquid crystal display (LCD), which is illuminated by a light emitter such as a light-emitting diode (LED), generates the image of the visual field frame. The generated image is superimposed on the object image through the semitransparent mirror, and therefore, the visual field image displayed in the finder can be easily seen regardless of the brightness of the object image and the brightness of the outside light.
REFERENCES:
patent: 4206988 (1980-06-01), Miyamoto et al.
patent: 4268151 (1981-05-01), Kobori et al.
patent: 4712297 (1987-12-01), Crema
patent: 5005948 (1991-04-01), Takahashi et al.
patent: 5289320 (1994-02-01), Kobayashi
patent: 5434704 (1995-07-01), Connors et al.
patent: 5587754 (1996-12-01), Katayama et al.
patent: 5893650 (1999-04-01), Ohmura
patent: 1155325 (1989-06-01), None
patent: 1291227 (1989-11-01), None
Birch & Stewart Kolasch & Birch, LLP
Fuji Photo Optical Co., Ltd.
Lee Eddie C.
LandOfFree
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