Television – Camera – system and detail – Optics
Reexamination Certificate
1998-04-22
2003-10-28
Vu, Ngoc-Yen (Department: 2612)
Television
Camera, system and detail
Optics
C348S342000, C348S368000, C348S296000
Reexamination Certificate
active
06639629
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a camera having a solid image pick-up element as a image receiving means, and specifically, to a camera having a solid image pick-up element as a image receiving means in which an image obtained through a picture-taking lens is received by a solid image pick-up element and a still image is processed as digital data.
A camera having a solid image pick-up element as a image receiving means photoelectrically converts an image obtained through a picture-taking lens by a solid image pick-up element such as a CCD, and the obtained image signal is processed as digital data.
Recently, in order to increase resolution, the density of pixels of the CCD is highly increased, and at the same time, the size of the CCD is being reduced. As a result, a pitch of the pixel of the CCD is greatly reduced.
Further, as a means for increasing the image quality, a stop (a diaphragm with an aperture) is used to optimize a quantity of light entering into the CCD, in the same manner as in a common silver halide film camera.
As described above, in a camera in which a solid image pick-up element using the CCD with a small pixel pitch is applied to an image receiving means, it was considered that the high resolution is obtained as an increase of the number of pixels of the CCD and the image quality is increased.
However, the following has been found: when a small aperture is applied to limit the quantity of light entering into the CCD, diffraction is generated, thereby, MTF characteristics of the picture taking optical system are deteriorated, and the resolution and contrast of the obtained image are lowered, resulting in hindrance of an increase of the image quality.
SUMMARY OF THE INVENTION
Accordingly, the object of the present invention is to realize a camera having a solid image pick-up element as a image receiving means which does not deteriorate the image quality even when a stop is used to limit the quantity of light.
As a result of deep consideration relating to the above-described problems, it has been discovered that a specific relationship is realized between the pixel pitch of the solid image pick-up element and stop value (F-number) relating to the image quality, and a new structure has been found in which the image quality is not deteriorated even when the stop is used to limit the quality of light.
(1) A camera having a solid image pick-up element as a image receiving means comprising a picture taking lens which structures an optical system to form an image of the object on the image forming surface; a stop means which controls an aperture area and controls the quantity of light entering to the image forming surface; and a solid image pick-up element which is provided at the position of the image forming surface of the picture taking lens and photoelectrically converts the image obtained by the picture taking lens and generates an image signal, the camera having a solid image pick-up element as a image receiving means is characterized in that the pixel pitch of the solid image pick-up element is not larger than 7.0 &mgr;m, and the stop value (F-number) at the minimum aperture of the stop means is smaller than 5.6.
In a camera having a solid image pick-up element as a image receiving means, when the pixel pitch of the solid image pick-up element is not larger than 7.0 &mgr;m, the stop value at the time of the minimum aperture of the stop means is not larger than 5.6, and as the result, even when the stop is used to limit the quantity of light, a decrease of the resolution and contrast due to the influence of the diffraction can be suppressed to the minimum, and thereby, a camera having a solid image pick-up element as a image receiving means which does not deteriorate the image quality can be realized.
(2) A camera having a solid image pick-up element as a image receiving means comprising a picture taking lens which structures an optical system to form an image of the object on the image forming surface; a stop means which controls an aperture area and controls the quantity of light entering to the image forming surface; a solid image pick-up element which is provided at the position of the image forming surface of the picture taking lens and photoelectrically converts the image obtained by the picture taking lens and generates an image signal; and a signal processing means to process the image signal, the camera having a solid image pick-up element as a image receiving means is characterized in that, when the pixel pitch of the solid image pick-up element is not larger than 7.0 &mgr;m and the stop value of the stop means not smaller than 5.6, the signal processing means conducts processing to emphasize the high frequency component of the image signal.
In the camera having a solid image pick-up element as a image receiving means, when the pixel pitch of the solid image pick-up element is not larger than 7.0 &mgr;m, and the stop value at the time of the minimum aperture of the stop means is not smaller than 5.6, processing to emphasize the high frequency component of the image signal is conducted, and as the result, even when a stop whose value is not smaller than 5.6, is used to limit the quantity of light, a decrease of the resolution and contrast caused by a decrease of the high frequency component due to the influence of the diffraction can be suppressed to the minimum, and thereby, a camera having a solid image pick-up element as a image receiving means which does not deteriorate the image quality can be realized.
As the result, even when a stop is used to limit the quantity of light, a decrease of the resolution and contrast due to the influence of the diffraction can be suppressed to the minimum, and thereby, a camera having a solid image pick-up element as a image receiving means which does not deteriorate the image quality can be realized.
In this connection, when such the image signal processing is conducted, by changing the degree of emphasis of the high frequency component corresponding to the stop value of the stop means, the deterioration of MTF caused by the diffraction generated corresponding to the stop value (by stopping down), can be compensated.
(3) A camera having a solid image pick-up element as a image receiving means comprising a picture taking lens which structures an optical system to form an image of the object on the image forming surface; a quantity of light control means which controls the quantity of light entering to the image forming surface; a solid image pick-up element which is provided at the position of the image forming surface of the picture taking lens and photoelectrically converts the image obtained by the picture taking lens and generates an image signal; and a signal processing means to process the image signal, the camera having a solid image pick-up element as a image receiving means is characterized in that the pixel pitch of the solid image pick-up element is not larger than 7.0 &mgr;m; the quantity of light control means is composed of the first quantity of light control means which controls the aperture area and controls the quantity of incident light, and the second quantity of light control means to control the quantity of incident light without depending on the aperture area; and the stop value at the time of minimum aperture of the first quantity of light control means is not larger than 5.6
In the camera having a solid image pick-up element as a image receiving means, when the pixel pitch of the solid image pick-up element is not larger than 7.0 &mgr;m, the stop value at the time of the minimum aperture of the first quantity of light control means is not larger than 5.6, and the second quantity of light control means to control the quantity of light without depending on the aperture area is used jointly with the first quantity of light control means. As the result, even when a quantity of light control means is used to limit the quantity of light, a decrease of the resolution and contrast due to the influence of the diffraction can be suppressed to the minimum, and thereby, a c
Koizumi Yukinori
Takayama Jun
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