Facsimile and static presentation processing – Facsimile – Picture signal generator
Reexamination Certificate
1998-06-29
2001-07-24
Lee, Cheukfan (Department: 2622)
Facsimile and static presentation processing
Facsimile
Picture signal generator
C358S474000
Reexamination Certificate
active
06266163
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image reading method and apparatus, in which light from a light source is irradiated on a transmission original or a reflection original through a slit, and the transmitted light or reflected light is read by a solid-state image pickup device.
2. Description of the Related Art
As a method for reading an original image, there is known a method in which slit light, whose longitudinal direction coincides with a main scanning direction, is irradiated on an original image and is moved in a sub-scanning direction perpendicular to the main scanning direction, and light reflected by or transmitted through the original image is guided to a solid-state image pickup device (CCD sensor) via a lens, thereby allowing reading of the original image.
The slit width of the slit light is usually larger than the read width of a CCD sensor. The distribution of the amounts of slit light is set so that light reflected by a reflector which covers the back of a light source is made convergent at one point, and therefore, the distribution is formed as a so-called Gaussian distribution having a relatively sharp peak.
For this reason, during sub-scanning movement, the position where the slit light is irradiated is displaced due to vibration and the like, and the amount of light may vary within the range of the read width of the CCD sensor.
SUMMARY OF THE INVENTION
In view of the above-described circumstances, an object of the present invention is to provide an image reading method and apparatus which, even when the position where slit light is irradiated changes due to vibration during image reading, can prevent variations in the amount of transmitted or reflected light within a region read by a solid-state image pickup device (i.e., a read range).
The present invention is an image reading method and apparatus in which light emitted from a light source and reflected by a reflector is scanned on a original image via a slit, and one of light transmitted through the original image and light reflected from the original image is made to form an image on a light receiving surface of a solid-state image pickup device, thereby allowing reading of the original image, the reflector is divided into a plurality of parts, and a first focal point of each of the plurality of parts of the reflector is the light source of the reflector, and second focal point of the plurality of parts of the reflector each being located at different regions on the original image.
Also, the present invention is an image reading method and apparatus in which a diffusion glass disposed at an open end of the reflector is used.
Also, the present invention is an image reading method and apparatus in which a first focal point of the reflector is the light source of said reflector, and second focal points of the reflector are located at one of a position nearer the light source than the original image and position farther away from the light source than the original image so that the second focal points are elsewhere than on the original image.
Also, the present invention is an image reading method and apparatus in which light from a light source is made to scan an original image via a slit and one of light transmitted through the original and light reflected by the original is made to form an image on a light receiving surface of a solid-state image pickup device, thereby allowing reading of the original, wherein light made into slit light by the slit is slit light of which longitudinal direction coincides with a direction perpendicular to a scanning direction, and a width of the slit light on the light receiving surface of the solid-state image pickup device is at least one and a half times a light receiving width of the light receiving surface of the solid-state image pickup device, and the center of the width of slit light and the center of the light receiving width of the light receiving surface of the solid-state image pickup device are set so as to substantially coincide with each other, and a variation in the amount of light in the width of slit light is set to be 20% or less.
According to the present invention, even when the position where slit light is irradiated changes due to vibration or the like, the variation in the amount of light on the light receiving surface of the solid-state image pickup device is limited to a predetermined range, thereby resulting in no adverse effect exerted on the amount of light for reading. For this reason, ununiformity of the amount of light for reading, caused by vibration, can be prevented.
Namely, in the state in which the width of the slit light is at least one and a half times the light receiving width of the light receiving surface of the solid-state image pickup device and the center of the width of slit light and the center of the light receiving width of the light receiving surface of the solid-state image pickup device are set so as to coincide with each other, light beam from the light source is guided so that the variation in the amount of light within the width of slit light is set to be 20% or less.
As described above, the range in which the position where the slit light is irradiated varies due to vibration or the like is obtained experimentally and empirically and the width of slit light is set so as to be slightly larger than the obtained range. For this reason, there is no possibility that, in ordinary use (i.e., when mechanical vibration generated during image reading and resonance thereof occur), the position where the slit light is irradiated varies exceeding the above range.
An allowable range of variation in the amount of light varies in accordance with brightness of a light source, the type of an original, reading accuracy of a solid-state image pickup device, a dynamic range of the solid-state image pickup device, and the like. With these factors considered, the allowable range of variation in the amount of light is empirically and experimentally set to be 20% at the maximum. When the amount of light varies exceeding this range, there is a possibility that, when the maximum vibration occurs, for example, when the original is read while the light source is moved in a sub-scanning direction, color irregularity occurs which can be found visually on pixels disposed adjacently in the sub-scanning direction.
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Fuji Photo Film Co. , Ltd.
Lee Cheukfan
Sughrue Mion Zinn Macpeak & Seas, PLLC
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