JP3520914B2 - Interchangeable lens digital camera with a structure to protect the flat-type image sensor from dust - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an interchangeable lens digital camera using an electric flat type image pickup device such as a CCD. 2. Description of the Related Art FIGS. 1 and 2 schematically show a conventional digital camera with interchangeable lenses. The conventional lens-interchangeable digital camera mainly includes an interchangeable lens 1, a shutter film 3, a planar imaging device 4, and a casing 7. FIG.
, The single-lens reflex type is cited as an example, so that the mirror 2 and the mat 5 are included. In the conventional digital camera shown in FIG. 2, a light beam incident from a lens passes through a lower part of a mirror 11 which is bounced, and is guided to a flat-type image sensor. The image formed on the image sensor is a flat type image sensor 4
Thus, the light is converted into an electric signal according to the intensity of the light. As shown in FIG. 1, since the mirror 2 is lowered and the shutter film 3 is closed when the lens is replaced, the flat-type image sensor 4 cannot be directly seen. A point to be noted here is that in the case of a conventional lens-interchangeable digital camera, the flat-type image sensor has a structure in which the flat-type image sensor touches the outside atmosphere, ie, air mixed with dust and dust when the lens is exchanged. It is that you are. Even if the shutter is closed when the lens is replaced, dirty air such as dust enters between the lens and the shutter. When the shutter is opened next time, the dirty air is transferred to the flat-type image sensor 4. I will touch it. That is, as shown in FIG. 1, air 12 contaminated by dust or the like enters the inside of the casing 7, and often adheres to the image pickup device 4 in the state of photographing shown in FIG. Some models have optical filters that do not transmit ultraviolet or infrared light, such as low-pass filters, band-pass filters, and high-pass filters. The purpose of the present invention is to prevent the occurrence of dust and to protect the CCD optically. [0004] Therefore, the conventional lens-interchangeable digital camera as shown in FIG. 1 has several problems. One of them is a decrease in image quality due to dust or dust such as dust floating in the air adhering to the charged planar image sensor 4. At the place where dust adheres, the image sensor, which is a group of light receiving elements in units of pixels with a size of several microns, is shielded by dust, so that the pixel can output an output faithful to the given incident light. I couldn't, and output it as an image like a black dot or blot. As a second problem, it is very difficult to remove dust and dirt attached to the image pickup device.
Removing dirt by contacting a flat image sensor, which is a precision component, with a rag or the like may damage the microlens on the element surface or the image sensor itself, so it is impossible for ordinary users to clean the surface. there were. The only way is to blow it off with air.However, it is very difficult to completely remove dirt and dust, such as by blowing up other dirt and dust with the blown air and attaching it to the surface of the flat-type image sensor again. there were. It should be noted here that such a problem has been reduced to only one or a very small number since a silver halide film type interchangeable lens type camera is always supplied with a new film. In a digital camera, since the image sensor is always in the same position in the same state, the adverse effects of the adhesion of dust and dust will continue until the dirt and dust are removed, and if the user uses it without realizing it, many It is highly likely that the number will be affected. This is a problem peculiar to the digital camera, which has not occurred in the silver halide film camera, and cannot be ignored especially in a digital camera capable of photographing a large number of images. [0007] In order to solve the above problems, in one embodiment of the present invention, a protective glass for dust prevention is provided, and a structure is provided in which dust does not adhere to the flat-type imaging device. The material of the protective glass may be any material as long as it is transparent with a visible light transmittance of 80% or more, and is not particularly limited to glass. Here, a protective glass is installed in front of the shutter curtain and on the lens side, and the space between the protective glass, the shutter curtain, and the image sensor is always clean by sealing the space between the dustproof casing and the protective glass with packing or the like. The structure is such that dirt or dust does not directly come into contact with the image sensor, and is arranged so that the protective glass can be easily cleaned when it becomes dirty. As a result, no dirt or dust is attached to the image pickup device, and the protective glass on the front surface of the flat type image pickup device is not located at the image forming point of the objective lens. Unlike dirt, dust, and dust on the element, light to a specific pixel is not blocked, and in fact, only a slight decrease in the amount of light according to the density ratio of the light flux, does not significantly affect the output image There is also a merit. This effect is greater when the protective glass is as far away from the image sensor as possible, so it is desirable that the position where the protective glass is installed be as far as possible from the image sensor. Further, by disposing the protective glass in front of the shutter film, even a general user can easily wipe and clean the surface of the protective glass without any special operation such as opening the shutter, thereby improving maintainability. Leads to. An image recording apparatus according to the present invention will be described below with reference to the accompanying drawings. 3 and 4 show one embodiment of the present invention. The digital camera device according to the present invention mainly includes an interchangeable lens 1, a protective glass 8, a shutter film 3, a flat image sensor 4, a dustproof casing 9, and a packing 10. In the embodiment of the present embodiment, the single-lens reflex type of the digital camera is mentioned as an example, so that the mirror 2 and the mat 5 are included, but these are not essential requirements of the present invention. In this embodiment, as shown in FIG. 3, the protection glass 8 is provided on the lens side of the shutter film 3 to prevent dirt such as dust from directly adhering to the flat-type image sensor 4. The space between the protective glass 8 and the flat-type image sensor 4 is sealed by a dustproof casing 9 and a packing 10.
Or, it has a structure that does not allow dust equivalent to it to enter. This portion may have an airtight structure, into which an inert gas, dry air, or the like may be added, or may be reduced in pressure or increased in pressure. A necessary requirement is that the light receiving surface of the imaging element has a structure that does not directly contact the outside air that is contaminated with dust or the like. FIGS. 3 and 4 also illustrate the movement of dust such as dust. In FIG. 3, air contaminated by dust or the like flows into the body of the camera when the lens is replaced or the lens is removed. However, as shown in FIG. 8 blocks dust and the like that are likely to adhere to the image sensor 4, so that the surface of the flat-type image sensor 4 does not have dust or the like and is always kept in a clean state. Further, even when dust or the like adheres to the protective glass 8, since the protective glass is at a distance from the light receiving surface of the flat-type image pickup device 4 and is at a defocus position out of focus, the light amount is slightly increased. Only attenuates, and does not enter a light-shielding normal state in which black spots and the like occur. Further, unlike the surface of the delicate flat-type imaging device 4, even if the surface of the protective glass is dirty, it can be easily wiped and cleaned. As described above, according to the present invention, direct shading due to the attachment of dust or the like to the flat-type image sensor has been eliminated, and phenomena such as black spot output have been significantly reduced. Further, since the filter such as a protective glass is a flat surface, it can be easily cleaned, and the maintainability is improved. Furthermore, since the protective glass is not located at the image forming point of the objective lens, even if dirt adheres to the protective glass, light is directly shielded unlike dirt, dust, and dust on the image sensor. In fact, it can be accommodated by a slight decrease in the amount of light according to the density ratio of the light flux. For this reason, even if a little dirt, dust, dust, etc. adhere, it does not greatly affect the output image, so that it is not necessary to frequently clean the image. Was done. [0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic internal sectional view of a conventional interchangeable lens digital camera with a lens removed. FIG. 2 is a schematic internal sectional view of a conventional lens-interchangeable digital camera with a lens attached. FIG. 3 is a schematic internal cross-sectional view of the digital camera with interchangeable lenses according to the present invention, with the lens removed. FIG. 4 is a schematic internal cross-sectional view of the digital camera with interchangeable lenses according to the present invention, with a lens attached. [Description of Signs] 1 Interchangeable lens 2 Mirror 3 Shutter film 4 Flat-type imaging device 5 Mat 6 Light flux 7 Casing 8 Protective glass 9 Dust-proof casing 10 Packing 11 Floating mirror 12 Dust in air 13 Dust attached

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03B 17/02

Claims (1)

(57) [Claims] [Claim 1] In a lens-interchangeable digital camera using an electric planar imaging device, the planar imaging device is protected from dust and dirt between a shutter curtain and a movable mirror. A member, which is provided between the flat image pickup device and
Sealed with dustproof casing and packing, and flat
Defocuser out of focus with respect to the light receiving surface of the image sensor
Digital camera, which is located at