Television – Camera – system and detail – Optics
Reexamination Certificate
1999-11-30
2004-06-08
Vu, Ngoc-Yen (Department: 2612)
Television
Camera, system and detail
Optics
C348S375000, C348S374000, C396S508000, C359S698000, C359S699000, C359S700000
Reexamination Certificate
active
06747703
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a diaphragm mechanism and a shutter mechanism for a camera, and more particularly to a diaphragm device and a shutter device for an electronic camera, such as a digital video camera and a digital still camera, which photographs an object by converting an optical image of an object into electric signals using a solid photographing element including a charge coupled device (CCD) or the like.
2. Discussion of the Background
In a video camera for photographing a dynamic image, generally a solid photographing element such as a solid photographing element including a charge coupled device (CCD) is used as a photographing light receiving element. Furthermore in recent years, digital still cameras have come in widespread use. Such digital still cameras photograph an object image by using a solid photographing element to obtain image data of a still image of the object and record it digitally into an integrated circuit (IC) card or a floppy disk. Among these digital cameras, some are capable of photographing not only a still image but also a dynamic image (a movie image).
As methods of reading out photoelectric-converted pixels in a solid photographing element such as, for example, a CCD solid photographing element, there are a field read-out method and a frame read-out method. For photographing a still image, there are increasing cases of using the frame read-out method which is advantageous in resolution and the like.
In the frame read-out method, an odd number of field transfer read-out operations and an even number of field transfer read-out operations must be performed sequentially. Further, physical light shielding is generally required to the CCD solid photographing element immediately after completion of an appropriate exposure in order to prevent a defective phenomenon such as a smear caused by an exposure during the read-out operation.
In a CCD solid photographing element of a total pixel read-out type, the light shielding after the exposure as described above is not required. However, the above total pixel read-out type CCD solid photographing element is hard to enhance in the number of pixels for manufacturing reasons. Therefore, from the viewpoint of difficulties in manufacturing, an interlace-type CCD solid photographing element is still advantageous though it requires physical light shielding.
The following is general process of photographing a still image with an electronic camera having an electronic finder with a monitor display of a liquid crystal display (LCD) and a zoom lens in which light shielding is performed after completion of an exposure in the frame read-out method.
(1) Turn on the camera.
(2) Set the camera to a photographing (i.e., recording) mode.
(3) Measure luminance of an outside world, particularly that of a field of photographing. Then, a diaphragm is automatically set according to the measured value.
(4) A through image captured by the CCD solid photographing element is displayed, for example on an LCD monitor screen.
(5) Set a zoom position, if necessary.
(6)Determine the composition and depress a release button.
(7) An auto-focus (AF) mechanism is actuated and the photographing lens is moved to a focal position.
(8) An exposure for the CCD solid photographing element is commenced.
(9) The CCD solid photographing element is shielded from the exposure light after an appropriate time period.
(10) The CCD solid photographing element reads out data by an odd number field transfer and by an even number field transfer.
(11) A signal processing device performs display, recording, or other processing appropriately onto image information read out from the CCD solid photographing element.
(12) Start the next photographing operation, or stop the photographing and turn off the camera.
When using a single-focus lens or a fixed-focus lens instead of the zoom lens or in photographing with an electric flash, a process partially different from the above is applied. In every case, however, two different operations, diaphragm setting and light shielding, are required in the photographing process as above, and various improvements have been attempted.
For example, Japanese Patent Publication No. 2622296 discloses accomplishing a diaphragm function and a light shielding function by providing a plurality of diaphragm apertures and a shielding portion adjacent to each of the diaphragm apertures.
Additionally, Japanese Unexamined Patent Publication No. 7-11616 discloses accomplishing a diaphragm function and a light shielding function in almost the same manner as the above Japanese Patent Publication No. 2622296 by providing a turret-type diaphragm sheet having a plurality of diagram apertures and a shielding sheet having a double-sheet configuration arranged separately from the diaphragm sheet with the diaphragm sheet and shielding sheet coupled with each other.
As described above, generally, two separate types of operations, diaphragm setting
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and light shielding, have been required in a still image photographing process, and therefore, as disclosed in the Japanese Patent Publication No. 2622296 and Japanese Unexamined Patent Publication No. 7-11616, the diaphragm function and the light shielding function are achieved by providing diaphragm apertures and shielding members, each operated independently.
In the Japanese Patent Publication No. 2622296, however, because the exposure and light shielding operations are performed by simply sliding a diaphragm sheet having a plurality of diaphragm apertures, there is a problem that light shielding is performed by a shift of a diaphragm aperture itself having a diaphragm aperture size selected during an exposure. In other words, the exposure operation is generally continued until the diaphragm aperture selected during the exposure is covered behind any end portion of a peripheral portion of an opened diaphragm aperture of the optical system, and therefore an irregular exposure occurs on a surface of the image obtained. In addition, when a moving object is photographed, an unfavorable phenomenon may occur, such as a blurred image, or a deformed object image depending upon a moving direction of the diaphragm aperture and that of the object for photographing even if the camera has a shutter speed (an exposure time between a commencement of the exposure and completion of the light shielding) at which an image can be captured normally.
In addition, because the shielding operation is started from an end of the diaphragm aperture, particularly when a large aperture size is selected, time is consumed from a commencement of light shielding to a completion thereof, which causes the same results as caused by a low shutter speed and a long exposure time, thus causing a problem that blurring easily occurs from an unsteady hold on the camera.
Furthermore, in the Japanese Unexamined Patent Publication No. 7-11616, a shielding sheet having a double-sheet configuration is arranged separately from the turret-type diaphragm sheet. As a result, it is further needed to arrange a coupling member and an energizing spring for opening or closing the shielding sheet, by which the mechanism is complicated.
Still further, because there is no arrangement of a positioning device on the shielding sheet, when the diaphragm aperture is positioned with a stepping motor, due to a step position precision of the stepping motor itself or the like, a diaphragm aperture cannot be set in an accurate position.
Furthermore, when a desired diaphragm aperture size is selected with a turret-type diaphragm sheet, diaphragm apertures having other diaphragm aperture sizes pass the opened diaphragm aperture of the optical system. Therefore, there is a problem that the shielding sheet is opened and closed on all such occasions wastefully, which causes a deterioration of durability of the mechanism or some failure and also generates uncomfortable mechanical sounds when the mechanism is operated.
More recently, there are various improved constitutions in which the shutter is operated after th
Hannett James
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Ricoh & Company, Ltd.
Vu Ngoc-Yen
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