Facsimile and static presentation processing – Facsimile – Picture signal generator
Reexamination Certificate
1999-06-10
2003-10-28
Lee, Cheukfan (Department: 2622)
Facsimile and static presentation processing
Facsimile
Picture signal generator
C358S475000, C358S506000, C358S509000
Reexamination Certificate
active
06639696
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image reading apparatus and more specifically to an image reading apparatus for optically reading an image recorded on an original which is to be read such as a photographic film.
2. Description of the Related Art
According to photographic processing methods proposed recently, a film image recorded on a photographic film is separated into components of red, green and blue and is read. The image data obtained from the reading is subjected to various types of corrections and recorded on a recording material or displayed on a display unit. Note that the term photographic film used here refers to a film whose negative image or positive image is visualized by development after a photograph has been taken of an object.
Technology for realizing an image reading apparatus for use in reading the film image in this type of photographic processing method has been proposed in, for example, Japanese Patent Application Laid-Open No. 6-233052, in which is disclosed a plurality of photoelectric conversion elements having different photometric amount limits (saturation light amount) are used as image sensors and depending on the amount of light carrying image information, the photoelectric conversion devices are selected, there by making it possible to read an image over a wide dynamic range.
However, because the technology described in the aforementioned JP-A No. 6-233052 is not provided with means for adjusting the width of the luminous flux passing through image-forming lens for forming an image on a photoelectric conversion element, it is not capable of reading an image with an optimum luminous flux width corresponding to the reading determining conditions (the conditions for determining the reading conditions) and it is not possible to always obtain high quality image data from all types of reading determining conditions.
Namely, although if a high resolution reading is required, the focusing magnification of the focusing lens needs to be increased to obtain image data composed of many pixels, in this case, the depth of field becomes shallow so that the picture quality deteriorates. Although the width of luminous flux passing the focusing lens is required to be smaller to respond to this phenomenon, because the technology described in the above JP-A No. 6-233052 has no means for adjusting this luminous flux width, high quality image data cannot be obtained.
SUMMARY OF THE INVENTION
Accordingly, the present invention has been achieved to solve the above problems, and therefore, it is an object of the invention to provide an image reading apparatus capable of obtaining high quality image data in accordance with reading determining conditions.
To achieve the above object, according to a first aspect of the present invention, there is provided an image reading apparatus comprising: a light source for illuminating an original object to be read; focusing means provided with a diaphragm capable of altering the width of the luminous flux of a light beam projected through the diaphragm, and for focusing an image recorded on said original document to be read; an image sensor for separating said image recorded on said original document to be read, reading said image, and outputting said image as image data when a light which has passed through said focusing means is projected onto said image sensor; and control means for controlling the state of said diaphragm for adjusting the width of said luminous flux in accordance with the reading determining conditions of the original object to be read.
In the image reading apparatus of the first aspect of the invention, an original object to be read is illuminated by a light source and an image recorded on the original object to be read is focused by a focusing means having a diaphragm capable of changing the luminous flux width of a projected beam. Then, an image recorded on the original object to be read is separated into a plurality of pixels and read, so that it is output in the form of image data. The above original object to be read includes transparent originals and reflective originals. The above image sensor includes a line CCD and area CCD.
In the image reading apparatus of the first aspect of the present invention, the state of the diaphragm provided on the focusing means is controlled by the control means so as to adjust the luminous flux width of light projected into the focusing means in accordance with the reading determining conditions of the original object to be read.
As described above, in the image reading apparatus of the first aspect of the present invention, the focusing means contains a diaphragm capable of changing the luminous flux width of the projected light and the condition of the diaphragm is controlled so that the luminous flux width is adjusted in accordance with the reading determining conditions of the original object to be read. Therefore, the luminous flux width of light passing through the focusing means can be controlled to the optimum width in accordance with the reading determining conditions, so that high quality image data can be obtained.
According to a second aspect of the present invention, there is provided an image reading apparatus according to claim 1, wherein one of said reading determining conditions is a focusing magnification of said focusing means and said control means controls the state of said diaphragm so that the higher said focusing magnification, the smaller the width of said luminous flux.
In the image reading apparatus of the second aspect of the present invention, one of the reading determining conditions according to the first aspect is a focusing magnification of the focusing means and the condition of the diaphragm is controlled by the control means so that the higher the focusing magnification, the smaller the luminous flux width.
That is, generally the higher the focusing magnification of the focusing means, the shallower the depth of field, so that the picture quality deteriorates. To suppress the deterioration of the picture quality, the luminous flux width of light passing through the focusing means is controlled so as to become smaller as the focusing magnification increases.
As described above, in the image reading apparatus of the second aspect of the present invention, one of the reading determining conditions according to the first aspect is a focusing magnification and further, the condition of the diaphragm is controlled so that the higher the focusing magnification, the smaller the luminous flux width. Therefore, the optimum luminous flux width can be set in accordance with the focusing magnification so that high quality image data can be obtained.
According to a third aspect of the present invention, there is provided an image reading apparatus according to claim 1, wherein one of said reading determining conditions is the effective F number on said original object to be read and said control means controls the state of said diaphragm so that said effective F number is constant.
In the image reading apparatus of the third aspect of the present invention, one of the reading determining conditions according to the first aspect is the effective F number of the original object to be read and the condition of the diaphragm is controlled by the control means so that the effective F number is constant.
The effective F number of the original object to be read is proportional to the F number indicating the brightness of the optical system (the brighter, the smaller) and proportional to an inverse number of the focusing magnification. Therefore, to make such a effective F number constant, the F number is increased as the focusing magnification is increased. To increase the F number, the optical system needs to be darkened. Therefore, to make the effective F number constant, the diaphragm is controlled so that the luminous flux width of light passing through the focusing means is reduced as the focusing magnification is increased.
As described above, in the image reading apparatus of the third aspect
Fuji Photo Film Co. , Ltd.
Lee Cheukfan
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